Complications in the Postoperative Care Unit
The complications associated with the administration of anesthetic agents were recognized almost immediately after the introduction of inhalation anesthesia in the mid 19th century. John Snow, the first recognized physician anesthesthetists in the Western World, and the author of what is probably the first major textbook on anesthesia, devoted one third of his text to the recognition and prevention of the sequelae of chloroform anesthesia. He noted that complications could be decreased by careful patient selection, but he wrote “it may be doubted whether this line of practice has had so much effect in limiting the number of accidents as in curtailing the benefits to be derived from the discovery of preventing pain by inhalation.” Rather, to decrease the incidence of postoperative complications, careful observation and maintenance of respiration were recommended. Snow noted that patients were more likely to vomit if they received anesthesia right after eating, but wrote that it would be too inconvenient for everyone concerned to schedule cases only in the early morning before breakfast.
Although only a few years later in 1863, Florence Nightingale wrote on the efficacy of special areas for observation of post surgical patients, the idea was not generally implemented. In his 1908 anesthetic textbook, for instance, Luke devoted only 2 pages to the treatment of patients after surgery. After nitrous oxide, he wrote, “most patients are ready for food in less than half an hour” and if they had a headache or were nauseated, “an hour’s rest on a couch and a little stimulant will soon put them right.” Vomiting was to be treated by withholding food, while allowing hot water sips with lemon, smelling Vinolia soap, sodium bicarbonate in black coffee and if all else failed, washing the stomach out. No specific area, care team, or protocols were presented.
Probably the first designated recovery area was established by Dandy and Firor – a 3-bed neurosurgical unit that opened at the Johns Hopkins Hospital in 1923. Still the idea was not generally adopted, and Gwathmay’s “Anesthesia”, published in 1924, noted only that patients should be left after anesthesia in a comfortable position in bed, with pillows under the head and shoulders. The patient was to be left alone to recover without talking or movement around him.
By 1939, Flagg, a professor from New York Medical College, redirected the emphasis to the patient. Underscoring the fact that many surgeries and anesthetics were performed at home rather than in hospitals, he noted that patients must be watched carefully until consciousness returned sufficient that she has found herself. As he described the postoperative condition, he observed: Ninety nine cases out of one hundred would probably make an uneventful recovery, if abandoned to themselves? The remaining one might die. Is it not worth the possible saving of one life in a hundred cases to watch carefully, the recovery of each? If that life was ours, there would be but one answer. Finally a need for postoperative evaluation was accurately realized.
The next 10 years, and the years following the Second World War, marked a burgeoning interest in anesthesiology. Post anesthetic observation areas were established at the Mayo Clinic and at the Hospital of the University of Pennsylvania. But in most hospitals, patients were still returned to large open wards where they were given bed space closest to the nurses’ station by the doorway and were displaced further down the ward by other post operative patients as they recovered. In 1942, Lundy advised that patients be returned to their rooms with mouth airways in place?and that the floor nurse return the airway to the operating room for use by other surgical candidates when the patient recovered.8
But post anesthetic mortality data made it clear that patients must be concentrated into a single area after surgery, and that specially trained personnel had to be provided to observe them. By the mid 1960s, appropriate practices were established that demonstrated daily their worth in terms of lives saved.
Postoperative evaluation in the post anesthetic care unit (PACU) requires that anesthesiologists, nurses, and surgeons are vigilant. They must identify the presence of surgical, medical, and anesthetic related problems that require prompt attention and be able to treat them effectively, ultimately ensuring the patients? safe discharge from the PACU. The decision regarding post anesthesia care is made first in the preoperative period when pain management techniques are discussed with the patient and, often, with the family, and also later in the operating room by the anesthesiologist based on the preoperative condition of the patient, and the surgical and anesthetic related intraoperative course. Today several options exist, such as transferring the patient directly to phase I (PACU), phase II recovery (accelerated recovery), or to intensive care units by specialty (pediatric, neonatal, neurosurgical, cardiothoracic). Special recovery areas exist in other areas of the hospital such as endoscopy, lithotrypsy, and radiology (angiography). In these latter areas most patients require a phase II level of care rather than phase I or PACU. A significant part of PACU care has become critical care (intensive care unit, ICU), and today, more than ever before, PACUs are functioning as ICUs due to the shortage of appropriately monitored beds and / or staffing problems.
Recent figures indicate that more than 65% of patients are ambulatory surgical cases as compared to the 1980s when the number of in-house patients predominated by far. Changing trends in PACU care are driven by the need to facilitate recovery with minimal morbidity and timely discharge to home. It is most likely that patients? recollections of the surgical and / or anesthesia experience will be only of the activities in the PACU.
Four distinct groups of surgical patients are found in the PACU:
1. ambulatory- these patients return to the same day unit and are discharged directly
2. early admission cases- these patients may or may not have an assigned bed but it is recognized that they will require admission to a surgical floor
3. intensive care monitoring- these patients have come to surgery from an ICU, or it is known that such a level of care will be required
4. initially ambulatory- this increasing group of surgical patients have undergone procedures such as endoscopy, endoscopic retrograde cholangio-pyelogram (ERCP) and angiography (embolization of cerebral vessels) not in the operating room, but requiring anesthesia and phase I or phase II care. These patients may have been treated as ambulatory and now may require a higher level of care.
Recovery for the ambulatory patient is described in three phases. Phase I (acute care area) is similar to that provided in the PACU where the patient emerges from anesthesia. In Phase II (step-down recovery area or pre-discharge area) the patient achieves the criteria for discharge home. Finally in Phase III the patient recovers completely from anesthesia and the acute effects of surgery. Due to the increasing availability of very short acting anesthetic agents, some patients may be eligible to bypass phase I recovery in PACU, and be discharged directly from the operating room or procedure area to phase II recovery based on fast tracking criteria (see below). These criteria have been adapted, modified, and graphed variously to match individual PACU needs.
Numerical scoring systems
The first scoring system was developed by Gaston Carignan et al. in 1964, and evaluated long-term recovery from 5 physiological variables at the second, fifth, and fifteenth days.
This system of scoring fell into disfavor mainly because it required long-term follow-up; this follow-up became completely impractical as patients returned home within hours.
A system that was based on the Apgar score was developed by Aldrete, and has been extensively used because it can be applied immediately and used again as a convenient means to evaluate safe discharge. A score of 9 achieved by the patient in the operating room or PACU enables a satisfactory move to phase II level of care.
More recently, several studies have indicated that formal admission to the PACU for an hour or more may not be necessary, especially in view of the wide spread use of fast acting agents. White and Song proposed fast tracking criteria that include the essentials of the modified Aldrete system and an additional scoring system for evaluation of post-operative pain and emesis. This scoring system may offer advantages over the modified Aldrete system by effectively bypassing the PACU to phase II, but does not address the significant problems of post operative nausea and vomiting that may occur hours after surgery and anesthesia. It also does not address post-operative pain that becomes problematic as the effects of intraoperative narcotics abate.
The American Society of Anesthesiologists has approved 5 nationally accepted standards for post-anesthetic care (appendix 1). It is extremely important for medico legal reasons that these recommendations are met or a note be appended to the patient’s record as to why modification was required.
Admission to the PACU
On arrival to the PACU, three essential steps are commonly performed.
Performance of each of these relatively simple functions is essential in decreasing the postoperative complication rate:
1. Provision of oxygen
2. Measurement and recording of vital signs by the nurse with communication of these data to the anesthesiologist.
3. A report by the anesthesiologist to the PACU nurse including but not necessarily limited to the following
- Brief medical history, patient’s name, age, sex, comprehension limits (e.g. native language, deaf or blind etc.)
- Diagnosis, surgical procedure, surgeon of record.
- Review of preanesthetic assessment including allergies, medical history, daily medications and other previous illnesses.
- Anesthetic course, anesthetic technique, anesthesiologist of record, complications, anticipated need for pain medications, estimated time of reversal of regional block, agents used (if appropriate), intraoperative fluid balance.
- Pre-transfer laboratory data.
- Time and dose of medications administered intra-operatively that should be administered postoperatively (e.g. antibiotics and steroids).
- Anticipated problems
- Postanesthetic orders (e.g. oxygen administration, fluid administration, antiemetic and analgesic treatment).
On accepting the patient, the PACU nurse evaluates and documents the patient’s status at regular intervals. As noted above, several post-anesthetic evaluation scales are used. The Aldrete score is the most convenient and widely used PACU aid but has some limitations, because patients with cardiac dysrhythmias, oliguria, or severe nausea and vomiting can all score 10 but may not be suitably recovered. Routine post-operative monitoring includes pulse oximetry, pattern and rate of reparations, cardiac rate and rhythm, blood pressure, and temperature. Timing of vital sign monitoring depends on the condition of the patient but is usually about once every 15 minutes for the first hour and half hourly thereafter.
Patients with factors identified as predictive of post-operative complications such as ASA III and above, neonates, premature infants, emergency surgical procedures, abdominal procedures, and operations that required general anesthesia lasting for many hours should be observed in PACU and not fast tracked to phase II care.
A review states that the Acute Physiologic and Chronic Health Evaluation (APACHEII) score may help in predicting need for ICU care in PACU patients. This scoring system, introduced in 1981 and refined in 1984 into the APACHE11 system provides a measure of severity of illness for patients in the ICU. It is based on 12 physiologic variables, including the Glasgow Coma Score (GCS), age and prior severe organ deficiency (chronic cardiorespiratory or renal disease). Weighted values are applied, yielding an APACHE 11 score with a maximum of 71: high scores correlate with more severe illness. Recording the score can be time consuming and controversy surrounds the ideal time to record variables and derive the score. It is, however, popular in the intensive care environment as a predictor of mortality and as a means to evaluate the quality of intensive care. Applying the score, Goldhill and colleagues found that 11.5% of critically ill patients whose anesthetic duration exceeded 5 hours experienced hemodynamic complications that required intensive care. Patients may require ICU care depending on the magnitude of the surgical procedure, intraoperative course, and preexisting illnesses. Due to changing trends in health care, it is not uncommon to see patients classified as ASA III presenting on the day of surgery without earlier preanesthetic assessment. The necessity to observe for complications increases in the PACU.
A prospective review of 18,473 patients admitted to a PACU at a University hospital indicated a complication rate of 23.7%. After pain, the most common problems cited were nausea and vomiting (9.8%), upper airway obstruction requiring treatment (6.9%), and hypotension (2.7%). Other complications included temperature abnormalities, fluid and electrolyte imbalance, drug interactions, and neurologic problems. Events correlated to the magnitude of surgery rather than to anesthetic technique (i.e. postoperative course was uneventful in 68.8% after minor surgery as compared with only 17.6% after major surgery). Surgical severity score was a better indictor of postoperative events than either age or American Society of Anesthesiologists score.
Another study from Sweden prospectively reviewed the perioperative course of 1,361 patients undergoing elective surgery. Forty-seven percent of patients had some untoward event in the immediate postoperative period. The most common problems were urinary retention (19.7%), circulatory events (1.4%), significant central nervous system deficiencies (7%), respiratory depression (5%), hypothermia, shivering, drug allergies, and agitation. Again, events correlated to the magnitude of the surgery rather than to anesthetic technique (e.g.complications occurred in 68.8% after minor surgery but in only 17.6% after major surgery).
It may be that the differences in findings between the Hines and the Ouchterlony study relate to different surgical and anesthetic techniques, e.g. more use of urinary catheterization and fast acting anesthetic agents in the U.S.15 Other national studies of patients who died within 24 hours of anesthesia indicated that while only a minority underwent non-emergent surgery, death was attributed to anesthetic factors in about one third, usually because of inadequate pre-anesthetic preparation and assessment and post-anesthetic care.
Complications in the PACU are both surgical and anesthesia related. Although patients in the PACU are usually under the principle care of anesthesiologists, a variety of complications can occur and many specialists may be involved. Therefore all physicians should have some familiarity with evaluation of post-operative problems and their management and a working knowledge of intraoperative events. A list of the most common complications occurring in the PACU. The presentation, evaluation, and management of these problems are illustrated in case scenarios.
CHAPTER TWO Treatment of Nausea and Vomiting
A 36-year-old female has undergone laparoscopic tubal reconstruction. As soon as her trachea was extubated, she vomited. On regaining consciousness she complained of nausea. She was given droperidol. Now In the PACU, she is complaining of dizziness and nausea and is now actively vomiting.
Post operative nausea and vomiting (PONV) remain an unpleasant and persistent problem for patients undergoing surgery. In fact PONV are among the most important factors contributing to delay in discharge of patients and an increase in unanticipated admissions after ambulatory surgery. Anesthesia providers are most often blamed for PONV, sometimes rightfully so, but often not. PONV involves many physiological and biological mechanisms. As the trend towards ambulatory surgery increases, PONV continues to pose serious challenges for anesthesia providers and other physicians because the potential cost savings of performing surgeries on an ambulatory basis may be negated by unanticipated hospital admission. Although PONV may be unavoidable in some patients for reasons not fully understood, there are risk factors that can be stratified.
Mechanisms involved in nausea and vomiting have been explained and there are many available perioperative treatment options. The vomiting center receives complex afferent inputs from several areas in the body, including the gastrointestinal tract, mediastinum, and cranial nerves. These impulses are further complicated by connections to the chemoreceptor trigger zone (CTZ) in the area postrema and to higher cortical areas including visual, olfactory, and vestibular centers. The vomiting center then sends efferents from the dorsal nucleus of the vagus and nucleus ambiguous to initiate the act of vomiting. Although this output is considered the final common pathway of the vomiting response, there is no single drug that can block all these pathways and thus serve as a universally effective anti-emetic agent. The vomiting center receives separate input from different types of receptors. The four major types of receptors include dopaminergic, histaminic, cholinergic muscarinic and 5-HT (serotonin). Antagonism of any of the receptors may alleviate emesis and form the basis of action of many drugs. Different classes of drugs with action on one or more of these receptors have been identified. Some of these agents tend to have a more prominent action at one or two receptors; thus a combination of drugs with effect on different receptors may have a greater anti-emetic action.
Prior to initiating treatment for PONV, it is always important to consider and appropriately treat other causes of nausea and vomiting, including pain, hypotension, hypoxemia, hypoglycemia, gastric bleeding, or increased intracranial pressure.
PONV occurs in 9 to 15% of all patients,28 with a rate of 35% in the post discharge period. It remains the number one cause of unanticipated adult admissions in the ambulatory setting.
Risk factors responsible for increased PONV are longer duration of anesthesia, inhaled anesthetics, intraoperative opioids, reversal agents, and elective procedures including gynecologic, laparoscopic, middle ear, orchipexy, termination of pregnancy and strabismus surgery.30,31 Other circumstances that increase the chances of PONV include female sex, premenstrual period, diabetes, pregnancy and non-smokers. Post operative risk factors that have been identified include untreated pain, hypotension, inadequate hydration, side effect of narcotics, anxiety and early oral intake. Marked, unexplained variations across hospitals and between anesthesiologists exist.
Vomiting likelihood in children increases with age; one study showed that children less than 3 years of age vomited 4% of the time, those 3-5 years 11%, 6-8 years 17%, and older children, 9-13 years had a 31% incidence. Avoidance of intra operative opioids and the use of local anesthetics or non-steroidal anti-inflammatory drugs, or both, all help to reduce PONV.
Short surgery, under local anesthesia or with propofol alone decreases the incidence of PONV. Propofol, although useful in reducing PONV, does not appear as efficacious in treating established PONV. Many recent articles have examined means to prevent or better treat PONV. Prophylactic ondansetron (0.1 mg/kg), droperidol (75 mcg/kg), and normal saline were compared in 102 children undergoing dental restoration with an inhalation or opioid anesthetic. The 24-h incidence of emesis was significantly less with ondansetron (9%) than with droperidol (32%) or placebo (35%).
In addition, ondansetron-treated patients had significantly shorter hospital stays. Cost-effectiveness of ondansetron for post-operative nausea and vomiting was studied recently. It was more cost effective to treat an established case of PONV than to use the drug prophylactically, especially as ondansetron has a limited anti-nausea effect.36 Currently, dolasetron is being increasingly used to treat PONV.
Non-pharmacologic alternatives are also considered with good patient satisfaction e.g. the use of acupressure in gynecological patients38 and acupuncture/acupressure in children by stimulating the P6 area. However, these practices are not, as yet generally established.
PONV is best prevented by identifying groups at high risk and then by designing an appropriate anesthetic technique. Patients with a history or high risk of PONV should be treated prophylactically and intra-operatively, with propofol used as an induction agent. Adequate hydration is essential and narcotics should be used sparingly. Regional techniques are beneficial for better postoperative pain relief. Analgesic adjuncts, such as ketorolac are also useful. Nitrous oxide, etomidate, ketamine and neostigmine should probably be avoided. Hypotension, pain, and anxiety must be reversed promptly. Antiemetics should be given early and patients kept recumbent. Oral fluids should be withheld for several hours postoperatively. Other classes of drugs, such as butyrophenones, phenothiazines or dopaminergic agents may be required. Aggressive and early treatment in the PACU will often avert an admission. It is however important that while the physician can assure the patient preoperatively that many steps can be taken to ensure that postoperative nausea and vomiting can and will be lessened, it is not possible in all cases to guarantee the absence of this disturbing complication.
The patient was given ondansetron 4 mg IV with some relief of nausea. She was maintained in a flat position in bed and fluid replacement was increased. Her husband was allowed to sit with her and the area kept as quiet as possible. The anesthesiologist explained that PONV was an unfortunate complication of her surgery and that it did not signify that anything untoward had happened. She was given midazolam1mg IV. Oral intake was withheld. She was assured that she would not be forced to leave the hospital until she felt better. About 1 hour later, she received a second injection of ondansetron. Thereafter, she felt much improved.
CHAPTER THREE The Patient with Cardiovascular Instability
A 63-year-old man has undergone carotid endarterectomy under general anesthesia. He was rather slow in regaining consciousness. He has a past history of hypertension maintained on several medications that he did not take on the morning of surgery. He is an insulin dependent diabetic and again, he did not take his insulin today. He has smoked 2 packs of cigarettes a day for 40 years. In the PACU, his blood pressure has increased to 200/110, and heart rate to 105/min. An occasional ventricular premature contraction is recorded.
Instability of the cardiovascular system is not uncommon in the postoperative period. Routine monitoring of blood pressure and electrocardiogram warns of these problems. Factors that may manifest in the PACU and impact adversely on the cardiovascular system are described. As part of the data collection study, the Yale review was aimed also at determining the relationship of four PACU cardiovascular events (hypertension, hypotension, tachycardia, bradycardia) to long-term outcomes (unplanned critical care admission or mortality) and at evaluating the contribution of anesthetic management compared with other perioperative factors after predicting these events.15 Patients with hypertension and tachycardia in the PACU were more likely to be admitted to an intensive care unit or to die. Bradycardia and hypotension were not associated with an increase in ICU admissions or mortality. Of note, patients with severe cardiovascular disease or those who had undergone major surgery are largely absent from this study. Anesthetic factors were not found to be significant in predicting cardiovascular events except for the use of propofol as an induction and maintenance agent, which increased the incidence of bradycardia.
A prospective study of 18,380 patients aimed to determine the relationship of PACU cardiovascular events to long-term outcomes and to evaluate the contribution of anesthetic management compared to other perioperative factors in predicting these events.41 One or more cardiovascular events occurred in 7.2%. Patients with postoperative hypertension or tachycardia (2.6% and 4% vs. 0.2% for patients with no events) were more likely to require an unplanned ICU admission and had increased mortality (1.9% and 2.3% vs. 0.3%). Bradycardia and hypotension were not associated with an increase in ICU admissions or mortality. PACU hypertension (2%) was associated with greater age, smoking, renal disease, female gender, and angina. PACU tachycardia (0.9%) was associated with intraoperative tachycardia and dysrhythmias. Risk factors for bradycardia (2.5%) included age, ASA status 1 or 2, and preoperative beta blocker therapy. Hypotension (2.2%) was associated with longer surgery completed after 6 P.M. and gynecologic intra-abdominal procedures. Anesthetic factors were not shown to be significant in predicting cardiovascular events.
New onset hypotension in the PACU is almost always a sign of drug overdose, or interaction, hypovolemia or blood loss. High-risk patients who are likely to have cardiac causes or mechanical causes, which impair venous return such as pericardial effusion or pneumothorax etc., are usually in ICU care. Treatment of hypotension includes deep breathing to wash out inhalation agents, supplemental oxygen, and adequate fluid replacement. In more severe cases (>40% decrease), isoproterenol 0.02ug/kg/min or dopamine 1-2ug/kg/min is necessary. Hypotension associated with tachypnea and basal rales requires furosemide 40-80 mg intravenously, nitroglycerine 0.6 mg sublingually or I.V. 5-20ug/kg/min, epinephrine 2-10 _ug/kg/min and possibly, aortic balloon-pump counterpulsation. Amrinone (a phosphodiesterase III inhibitor) also provides effective inotropic support. Hypotension due to myocardial ischemia requires admission to a cardiac care unit.
Postoperative hypertension is usually due to arteriosclerosis. Exaggerated responses to stimuli that generate vasoconstriction are common. Treatment requires adequate and early pain relief, bladder catheterization (if indicated), labetalol 5-10 mg/10 min to effect, hydralazine 5-10 mg/20 min as needed, and even sodium nitroprusside 0.5-5 ug/kg/min. A review of the dignosis and management of carotid stenosis including a metaanalysis of 5 randomized trials including 4043 patients undergoing coronary artery bypass surgery indicated that acadesine 15 minutes preinduction and continued for 7h decreased perioperative myocardial infarction by 27% and the risk of cardiac death by 50 % but did not affect the stroke rate. Following carotid endarterectomy hypertension occurred in 64% (214 of 330). Of 4 patients who suffered myocardial ischemia, none had hypertension. However of 11 patients who suffered new neurologic deficits, 10 had perioperative hypertension. It was unclear whether the deficit caused the hypertension or vice versa.
Certain procedures, including abdominal aneurysm repair, carotid endarterectomy (CEA), and intracranial surgery, have been associated with a higher incidence of hypertension. Sublingual administration of 25 mg captopril or 10 mg nifedipine have been shown to be equally effective for the treatment of arterial hypertension after abdominal aortic surgery. Several studies have focused on the safety of performing short-stay CEA.44 Of particular importance is the ability to identify patients who may be at risk of stroke or who may require ICU care, or both. Morasch et al. attempted to develop criteria that would indicate CEA patients that could be safely discharged to the ward or home and those who required ICU care. Only the presence of significant preoperative hypertension (more than three anti-hypertensive medications, blood pressure > 170 mm Hg systolic or > 100 mm Hg diastolic) enabled statistically significant prediction of the potential need for postoperative ICU level intervention. Other investigators have demonstrated that ICU care may be selectively provided in a cost efficient manner.
Hypertension and cerebral hyperperfusion are not uncommon in the immediate postoperative period after craniotomy. Perioperative hypertension in children is not common and is usually due to artifact caused by use of an inappropriately sized blood pressure cuff. However, both intraoperative and postoperative hypertension do occur and can be effectively treated with calcium channel blockers. Postoperative hypertension in patients without a prior history has also been observed and usually follows a benign course with resolution in 3 to 5 hours.
Patients should be treated after ascertaining the cause of hypertension such as emergence excitement, excessive pain, urinary retention, hypoxemia, hypercarbia, hypothermia (35oC), or nausea. Signs and symptoms of end-organ damage such as headache, disorientation, chest pain and hematuria require rapid treatment with vasodilators such as nicardipine, nitroprusside, nitroglycerin and / or mixed adrenergic blockers.
Tachycardia is usually due to increased sympathetic activity. Propranolol (2-5 mg), or esmolol (400 _ug/kg/min infusion) are therapeutic. Junctional tachycardia is usually due to digitalis overdose. Therapy may require DC countershock. Atrial fibrillation associated with a ventricular rate response >120bpm, requires digitalis (0.25-0.5 mg) or countershock. Recurrent atrial tachycardia associated with Wolff-Parkinson-White syndrome can be controlled with propranolol (0.5 mg) or verapamil (2.5 mg). Malignant hyperthermia as a cause of tachycardia is very rare. The appearance of a new ventricular dysrhythmia was associated with a statistically greater risk for myocardial infarction to develop.47
Junctional bradycardia is usually due to interaction between volatile anesthetics and neostigmine. Treatment includes atropine (0.4 mg), calcium chloride (5 ml of a 10% solution) or, isoproterenol. The infusion rate should not be increased above 10 ug/min if there is no effect. A transvenous pacemaker is indicated. Similarly bradydysrythmias due to increased parasympathetic tone may occur and if patients are symptomatic they should be aggressively treated with either insertion of cutaneous pacemakers or beta agonists. A cardiology consult is required.
Patients who have undergone carotid endarterectomy as in the case presented, have special considerations. Collaborators in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) have defined the medical characteristics of patients presenting with symptoms of carotid artery stenosis.
Myocardial infarction is the leading cause of death after carotid endarterectomy. One study noted that patients with angina had a mortality rate of 18%, compared to 1-5% in patients without cardiac symptoms.49 In another study of 506 patients with peripheral and cerebrovascular disease, only 7% had normal coronary arteries, 28% had mild to moderate disease and well compensated advanced coronary disease was evident in 30%.50 35% of patients were considered at increased risk for myocardial infarction. Blood pressure should be controlled preoperatively at levels no higher than 180/100. Pressures beyond this range increase the risk of postoperative hypertensive crisis, cardiac damage and intracerebral hemorrhage. Thus, the importance of cardiac evaluation is underscored. Although the majority of patients with carotid artery disease smoke, there is little evidence that preoperative pulmonary function testing has prognostic significance for postoperative respiratory difficulties. In the diabetic patient, blood sugar levels should be reduced, if possible, to levels below 150mg/dl. Considerable evidence points to an increase in the size of a cerebral infarct in areas of hypoxia if hyperglycemia exists. Thus, glucose containing solutions should not be infused unless a measured blood sugar level is below 70-80dl.
Other complications after carotid endarterectomy are listed. Postoperative ipsilateral hyperperfusion which may be associated with severe cerebral edema is one cause of neurologic deficit. Most strokes complicating carotid endarterectomy appear to be related to surgical factors involving thrombus emboli and intimal tears rather than to hemodynamic factors. Although the incidence of stroke varies between institutions, the combined morbidity and mortality should not exceed 3% for asymptomatic patients, a number increased to 10% for patients with recurrent disease in the same artery. The incidence of fatal myocardial infarction is 0.5% to 4%, representing about 40% of total perioperative morbidity (over 30 days).
Particular attention should be paid to patients who have undergone bilateral carotid endarterectomy over the past 12 months and may have sustained carotid body damage. This chemoreceptor reflexly increases ventilation in response to hypoxemia or acidosis. Although the medullary chemoreceptors contribute 87% of ventilation control, the peripheral receptors in the carotid body are responsible for the remaining 13%. Patients should receive a high infused oxygen concentration. Drugs that depress respiration should be used cautiously.
Preoperative examination should include documentation of any neurologic deficits including loss of vibration or position sense or small areas of decreased sensation.
On enquiry, the patient was not in pain. He was breathing comfortably and moving all his limbs. Pulse oxymetry values were above 95%. The blood pressure was measured in both arms and found to have a variability of 30mmHg. The arterial tracing was adjusted for vessel wall whip and was determined to be about 15mmHg lower that recorded initially. He was treated with labetolol 5mg times two for control of the hemodynamic status along with i.v. nicardipine in small boluses of 0.5 mg over a 20 minute period. A 12 lead EKG was read as within normal limits. Blood samples were drawn for measurement of enzymes, specifically MB fractions and were also found to be normal. Although his blood pressure returned to baseline levels, occasional ventricular beats were still noted. It was thus decided to observe the patient in a monitored setting for a further 24 hours. He was discharged to home without further incident on the following afternoon.
CHAPTER FOUR Respiratory Complications
A 32-year-old man was admitted to the PACU after a uvulo-palato-pharyngoplasty. He had a history of sleep apnea and smoked two packs of cigarettes per day. He weighed 140kg and was rather short in stature. His anesthetic had comprised mainly a narcotic technique to which low dose isoflurane had been added. For muscle relaxation, he had been given atracurium. Residual muscle relaxant effects had been reversed prior to extubation. Prior to transfer to the PACU he was responsive to commands but rather sleepy. Shortly after admission, his oxygen saturation monitor alarmed at 76%.
Postoperative pulmonary complications have been variably reported from 3 to 76%. Some of the more common problems are listed. Factors that increase the need for postoperative ventilatory support include preexisting lung disease, obesity, advanced age, smoking history, low preoperative arterial oxygenation, thoracic and upper abdominal surgery, recent large narcotic administration and large intraoperative blood loss with excessive crystalloid replacement. The primary mechanism of postoperative hypoxemia is pulmonary shunting secondary to decreased functional capacity caused by pain, abdominal distension, impaired diaphragmatic function, and the supine position. In contrast to previous years when many studies emphasized that preoperative pulmonary function testing did little or nothing to predict respiratory problems or the need for post-anesthetic ventilatory support, there have been few recent reports on respiratory complications.
Oxygen saturation < 93% occurred in up to 25% of patients in one study.52 At PACU admission, 15% of patients were desaturated. The addition of oxygen prevents desaturation below 90% in all but about 1% of patients. Patients who snore are at special risk and should receive supplemental oxygen.53 As noted in chapter 3 above, respiratory depressant effects of even small doses of narcotics due to chemoreceptor damage are exaggerated following carotid endarterectomy – especially if the other side was operated within the year.
Hypoxemia can be detected easily and rapidly in the PACU by routine use of pulse oximetry and confirmed with arterial blood gas measurements (PaO2, less than 60 mm Hg on 2l flow O2). Early recognition can facilitate therapeutic intervention before life-threatening hypoxemia develops. Features of hypoxia may overlap with those of hypercapnia. The early clinical signs of hypoxemia are tachycardia, tachypnea, agitation, and altered mental status, whereas hypotension, bradycardia, obtundation, and cardiac arrest are late signs.
Reactive airway disease is a potent cause of bronchospasm postoperatively. Placement of a laryngeal mask airway combined with positive pressure ventilation can maintain adequate oxygenation avoiding re-intubation and its propensity to increase bronchospasm. Patients with obstructive sleep apnea syndrome (OSAS) (i.e. snorers) are at considerable risk of desaturation. Sedatives, anesthetics and supine position impair upper airway muscle activity, jeopardize airway patency and decrease functional residual capacity predisposing these patients to desaturation. Sitting position and nasal continuous positive airway pressure (NCPAP) started, if possible, before surgery and continued for 48 h, allows freer use of analgesic drugs without complications.
Bronchospasm is usually associated with asthma or chronic obstructive pulmonary disease (COPD), and smoking. After open heart surgery, patients with severe COPD (FEV1 < 50% of predicted) have a higher incidence of death (19% vs. 2% in controls) and a higher incidence of serious pulmonary complications (23% vs. 4%).55 Clinical variables are better than preoperative spirometry as predictors of postoperative cardiopulmonary complications. Surprisingly, a study of 706 asthmatic patients, documented bronchospasm in only 12 patients (1.7%), postoperative respiratory failure in only 1 patient, and intraoperative laryngospasm in 2 patients. Complications increased with age and active disease.
A recent study indicated that children who developed laryngospasm intraoperatively were more than two times more likely to have an upper respiratory infection. They tended to be younger, scheduled for airway surgery and to have anesthesia supervised by a less experienced anesthesiologist. Appreciation of the risk factors should obviate cancellation of surgery in this group. A rare cause of bronchospasm is allergy to drugs (especially antibiotics), blood or blood products or latex. Treatment includes a nebulized selective B2 agonist (terbutaline or albuterol). Intravenous theophylline, 5-6 mg/kg, infused as 0.2 mg/kg/hr may be given concurrently with inhaled bronchodilators. Isoproterenol has both B1 and B2 effects. It may be inhaled from a metered nebulizer (2-3 doses, 123 ug/dose). Effects last 1 hour.
Pulmonary embolism is very unusual and should be a diagnosis of exclusion but should be suspected if there is unexpected cardiorespiratory collapse. Precipitating factors include obesity, oral contraceptive use, varicose veins, old age, prolonged immobility, hip surgery, and malignancy (especially brain tumors). Case reports have indicated successful use of nitric oxide to improve gas exchange especially after pulmonary thrombo-endarterectomy.
Aspiration may occur more frequently than was once thought. Gastric contents exceeding 25 ml and pH of the aspirate <2.5% increase the risk. Although 85% of outpatients have gastric volumes greater than 25 ml and 19% may exceed 75 ml with pH less than 2.0, the incidence of aspiration is small in ASA I and II patients (in one study, 1:3,200 anesthetics).59 Prophylactic use of H2 receptor antagonists does not decrease mortality or prevent pulmonary consequences. Time since ingestion of fluids also seems to have little effect on the incidence of postoperative vomiting. The pregnant patient is at special risk. Mechanical and hormonal factors retard gastric emptying. Should aspiration occur, supportive respiratory techniques include endotracheal intubation, lung washing and mechanical ventilation but only if symptoms develop. Steroid and/or antibiotic therapy in the absence of infection do not improve outcome. If the ambulatory patient remains asymptomatic for two hours, without hypoxemia on room air, and with a normal chest radiograph, he can be safely discharged home.59
Hoarseness and sore throat occur in about 32% of intubated patients (as compared to 6%, nonintubated)60 although it does not usually cause respiratory problems unless the airway was already compromised. Spontaneous resolution occurs within two weeks in 95%. Aerosolized beclomethasone prior to intubation prevents sore throat. Other prophylactic measures include an experienced intubator and use of bland lubricant.
The patient was stimulated, encouraged to breathe, and nasal airways inserted. Reversal of the effects of all drugs used during anesthesia was ascertained. The patient was positioned in a sitting position with oxygen supplementation. At first there seemed to be some improvement. However, arterial blood gas estimation indicated paO2 55mmHg while using a non- rebreathing mask. The patient was confused. The anesthetic record was reviewed and it was noted that difficulty had been encountered in securing the airway. The difficult airway cart was brought. In the meantime, a racemic epinephrine inhalation was administered as some bronchial wheezing was detected. More help was obtained. The airway was topicalised and the cords were visualized with difficulty using a fiberoptic bronchoscope. Edema was marked. A size 6.5mm endotracheal tube as passed with immediate relief of the obstructed breathing pattern. Midazolam was used for sedation. On the following day, the patient was fully awake. A tube changer was passed and the endotracheal tube removed. After an hour, the patient was comfortable, spO2 maintained at 95% on 2l nasal cannula. The tube changer was then removed.
CHAPTER FIVE Variations in Temperature
An 80-year-old male underwent a bilateral laparscopic inguinal hernia repair ander spinal anesthesia with midazolam and propofol sedation. In the PACU, his temperature is 34.5oC. he is sedated and when aroused is not able to answer simple questions. His repiratory rate is slow and the pulse oximeter is not registering a value.
Hypothermia is not uncommon postoperatively because of low ambient temperature, a poikilothermic state induced by anesthesia, and infusion of cold fluids. Decreased temperature impairs the immune system, increases the incidence of infection, increases blood loss leading to the need for transfusions, increases the incidence of myocardial infarction, prolongs the need for mechanical ventilation, decreases drug metabolism and increases mortality. Also of importance is the economic factor. Meta-analytic results have recently concluded that hypothermia averaging only 1.5Co less than normothermia can result in increased effects of complications that can cumulatively add between $2,500 – $7,000 per surgical patient to hospitalization costs across a variety of surgical procedures. Practical means to prevent hypothermia include the use of warming measures intra-operatively, (wrapping patients, especially their heads, in blankets, fluid warmers) and continued use of forced air devices postoperatively. Among all the warming devices, forced hot air warming devices have been found to be most effective.
Recently there has been a resurgence in the use of mild intraoperative hypothermia for neurosurgical cases, especially during clipping of aneurysms. Ideally, the temperature should not fall below 35o. Also, during closure of the dura, attempts should be made with forced hot air to return the temperature to normal. However, as these patients are not classified as ambulatory, there is time for close observation and monitoring in the ICU setting without the concern for prompt discharge. It is especially important in these patients to ensure normothermia. There is no evidence that applying hypothermia after a brain insult is beneficial except as a means to prevent hyperthermic episodes which significantly increase brain metabolism and cerebral metabolic utilization of oxygen at a time when cerebral blood flow and oxygen supply may be diminished.
Children are particularly prone to heat loss because of their relatively large body surface to total weight ratio which allows for much greater losses. Even after short procedures, temperature may be markedly reduced. Premature and small infants are unable to shiver and thereby increase their metabolism. Thus heat loss must be compensated by addition through conduction, radiation, and convection. Maintenance of normothermia is especially important in children who have undergone tonsillectomy when the risk of postoperative bleeding is ever present.
Although rare, malignant hyperthermia may present for the first time in the PACU. Most likely, it is due to a stress response combined with administration of triggering agents, including inhalation anesthetics and some neuromuscular blocking agents. Symptoms include hyperventilation, tachycardia, high temperature, marked metabolic acidosis, sweating and decreasing oxygen saturation. Treatment includes immediate cooling, establishment of more intravenous access routes and invasive monitoring, dantrolene, and correction of acid-base abnormalities.
Perhaps the most important aspect of the treatment of temperature abnormalities in the PACU is establishment, revision as necessary, and enforcement of operating room protocols. According to age, operating rooms should be warmed as should all fluids instilled to body cavities. Anesthetic agents and oxygen should be administered only through humidified systems. Warming systems should be available in all operating rooms. Only the part of the body to be operated should be exposed. Cleaning and disinfecting solutions that are applied to the skin should be at body temperature.
A woolen cap was placed on the patient’s head. Intravenous fluids were infused through a warming system. A hot air blanket was put over him and he was warmed with forced hot air to a temp of 36.5oC in about two hours. Throughout this period, he was given supplemental oxygen and the EKG was monitored for ectopy. When he was fully conscious again and able to communicate with his immediate family he was discharged to Phase II. He returned home later in the day.
CHAPTER SIX Fluid and Electrolyte Balance
A 72-year-old man has undergone a 2.5h transurethral resection of the prostate (TURP) initially under regional anesthesia and later under sedation. In the PACU, he is somewhat confused. He complains to the nurse that his vision is rather blurred. Suddenly he has a tonic/clonic seizure and becomes unconscious.
Complications of fluid and electrolyte imbalance occur mainly in elderly or debilitated patients, in hypertensive patients pretreated with diuretics, in diabetic and neurosurgical patients and in those who have just undergone long procedures with large fluid shifts. Hyponatremia, hypocalcemia and hypermagnesemia may delay return to consciousness. Any abnormal findings in these groups of patients should warrant measurement of electrolytes and prompt correction of abnormalities.
Hyponatremia (or water intoxication) is due to the syndrome of inappropriate antidiuretic hormone (SIADH) release or free water absorption during TURP. SIADH is associated with stress, general anesthesia, positive pressure ventilation, pulmonary carcinoma and diseases of the pituitary system. It is also a common complication after major head injury when a syndrome of cerebral salt wasting may occur. Free water absorption takes place during TURP when the irrigating solution is forced into open venous channels. Treatment includes diuresis with furosemide (40 mg) and, in an emergency situation, hypertonic saline. Hypocalcemia occurs when total serum calcium levels fall below 4-5 mEq/l. Etiologies include hepatic failure, massive volume replacement, acute pancreatitis, hypoparathyroidism, and end stage renal disease. Acute decrease in ionized calcium is associated with extreme hyperventilation, bicarbonate injection and rapid (>0.5-1 ml/kg/min) infusion of citrated blood (available calcium is chelated). Signs and symptoms include confusion, seizures, hypotension, QT prolongation, and muscle spasm (including laryngeal muscle spasm). Treatment requires correction of hyperventilation and replacement with calcium chloride (3-6 mg/kg over 10-15 min).
Hypermagnesemia (> 2.5 mEq/l) occurs in eclamptic patients treated with magnesium sulphate and those with end stage renal disease. Symptoms include suppression of deep tendon reflexes, sedation and coma. Cardiovascular collapse occurs at levels over 10-15 mEq/l. Treatment involves discontinuation of exogenous sources, support of cardiorespiratory function, and intravenous calcium.
The problem in the case presented, is free water absorption that has resulted in hyponatremia. The products of glycine, which is the irrigant most commonly used during prostatic resorption, cause temporary visual disturbances. Although the patient has sustained a seizure, further sedation and intubation are rarely necessary. Important is to protect the patient from himself, administer oxygen, establish the electrolyte levels and give furosemide 20-40mg (an elderly patient maintained on this medication preoperatively will require a higher dose). The patient and his relatives should be assured that his vision will return in a few hours.
CHAPTER SEVEN Common Endocrine Abnormalities
A 28-year-old, insulin dependent diabetic patient has undergone thrombectomy for a clotted arterio venous graft in his arm under local anesthesia with sedation. Preoperatively, he took half of his normal dose of long acting insulin. During the procedure, he received 100ml dextrose 5% in water. The anesthesiologist had given him 10u regular insulin to cover the dextrose. He has now been in the PACU for 30 minutes and he is complaining of dizziness, and he is sweating. His blood pressure is 70/30 and his heart rate is 125 bpm. There is no evidence of bleeding at the operative site.
Acute adrenal insufficiency or thyroid crisis are very rare postoperatively. Common endocrine problems relate to diabetes. Hyperosmolar, nonketotic coma (>1000mg/dl glucose) is a rare cause of hyperglycemia due to a disturbance of thirst mechanisms that occurs in elderly, debilitated patients or after major trauma (usually head injury). Severe dehydration, coma and seizures are common. Response to small doses of insulin (10-20 units) and rehydration is prompt.
Diabetes insipidus (DI), caused by underproduction of antidiuretic hormone, is usually associated with head trauma, hypophysectomy or a global cerebral hypoxic event. The diagnosis depends on polyuria (>300 ml/hr), hypernatremia, decreased urine osmolarity, increased plasma osmolarity, decreased urine specific gravity, hypotension, dehydration and coma. Vasopressin tannate, 5-10 units subcutaneously, is specific therapy. One-desamino 8-D arginine vasopressin (4-8 _mg) (DDVAP) is usually effective by nasal insufflation or intravenous administration. The dose may have to be repeated.
Insulin dependent diabetic children and those with end stage renal disease are very sensitive to small doses of insulin in the perioperative period. The regular insulin dose should be carefully adjusted and the blood sugar measured frequently, especially if general anesthesia is employed and the patient is not able to convey his feelings. Hyperglycemia in diet controlled diabetics is not usually problematic as the stress response to surgery and anesthesia generally releases catecholamines that reduce sugar levels. It is, however, important to monitor blood sugar levels in patients undergoing intracranial surgery or in other situations where diabetic patients may have been given steroids which increase gluconeogenesis. As noted in chapter 3, a glucose load is managed by anerobic pathways in hypoxic situations or when cerebral blood flow is reduced. The increased lactate levels increase the size of infracted areas of the brain especially in parts that may be threatened by reduced cerebral blood flow.
The case is best managed by offering the patient glasses of fruit juice or sugar water. Symptoms will resolve in minutes. Usually these patients can advise the doctor or nurse about the symptoms and request a glass of fruit juice or a piece of candy.
CHAPTER EIGHT Neurologic Deficits
A 90-year-old Italian woman who had lived in the Unites States for 65 years was admitted from a nursing home for below knee amputation for removal of a gangrenous foot. Medical history noted a resolved cerebral vascular accident, diabetes (not well controlled), and occasional confusion. After an uneventful general anesthetic that lasted 1 hour, she appeared to be psychotic. She spoke only Italian and did not respond to any questions in English. She did seem to recognize any of her family members. She also had a left sided hemiparesis.
Neurologic deficits are uncommon postoperatively although they represent a large number of malpractice claims – especially as they may be related to suboptimal intraoperative padding or positioning. Postdural puncture headaches (PDPH) may be apparent in the PACU. In a prospective nonrandomized observational study of 8,034 spinal anesthetics only 1 dural puncture was required in 97.9% (Group 1). In the remaining 2.1% (165 cases) multiple attempts were made (Group 2). The incidence of PDPH was 1.6% in Group 1 and 4.2% in Group 2. Thus, if lumbar puncture has been difficult and multiple attempts have been made the anesthesiologist should consider prompt hydration, caffeine, and administration of a blood patch.
New onset thoracic level paraplegia after lumbar surgery is rare. Turker et al. report 2 cases of this devastating complication.68 Initially movement was present but deteriorated to flaccid paralysis. Findings were consistent with cord edema and spinal cord infarct. Common to both cases was persistent blood loss, large volume replacement and prolonged surgery. Emergency evaluation of paraplegia should include full column myelography and an MRI, and evaluation of the heart and thoracic aorta for thrombus or dissection. If the posterior columns are spared, somatosensory evoked potential monitoring may not be useful if the lesion is in the distribution of the anterior spinal artery.
Transient focal neurologic deficits have been observed in patients emerging from brain tumor or carotid endarterectomy surgery – especially if a deficit existed preoperatively. The complication may be enhanced by a pharmacologic effect of anesthetic agents. A recent study of patients with central nervous system disease examined the effects of small doses of midazolam and fentanyl on motor function and demonstrated deterioration in 30% of patients. Of patients with focal motor abnormality or resolved prior motor deficit, 73% had transient exacerbation or unmasking of signs following sedation with these agents.
The incidence of neurologic injury after an axillary block is reported to be about 25%. However, how many of these complications are due to the block or failed surgery is unclear. Also some sporadic case reports of visual impairment following prolonged surgery in the prone position have been made. Common to these reports seems to be duration of several hours in a Trendelenburg position, considerable blood loss and replacement primarily with crystalloid and low urine output. Etiology may be linked to edema formation of the retina as, on turning, the patients were all observed to have marked facial edema. In most cases sight returned.
Management of the case described was mainly expectant. A small dose of flumazenil did not have any appreciable effect. The patient was monitored closely and given supplemental oxygen. The family was assured that the neurologic deficit would resolve. After about 5 hours, she was again able to communicate in English. Her motor function was completely restored in 30 hours.
CHAPTER NINE Drug Interactions
A 32-year-old, rather obese patient has just undergone a laparoscopic cholecystectomy. The case was managed under general anesthesia which, for the most part, was uneventful except for some mild hypertension which the anesthesiologist felt was related to position and increased intraabdominal pressure. At that time, he gave her several bolus infusions of propranolol and midazolam 3mg. Preanesthetic assessment noted that she had been taking many over the counter medications for indigestion. Although she is awake and feeling no adverse effects, her blood pressure is 75/45.
Whenever an unexpected change in neurologic status or vital signs occurs the medication sheet should be reviewed. Drugs given hours before may have a long duration. An average of 16 drugs are given perioperatively. Full disclosure of possible drug interactions requires a computer base. A few of the more common effects are listed.
1. Neuromuscular blocking effects of antibiotics (e.g. kanamycin) are potentiated by verapamil and possibly by other calcium channel blockers.
2. Hypokalemia (diuresis or rapid fluid replacement) may precipitate digitalis toxicity.
3. Quinine increases digitalis toxicity.
4. Dopamine effects are reduced by phenothiazines and antipsychotic drugs.
5. Phenytoin clearance is reduced by H2 blockers (ranitidine).
6. Benzodiazepines and propranolol effects are increased by ranitidine.
7. Diuretics and other vasodilators increasethe hypotensive effects of captopril.
8. The hypoglycemic action of chlorpropamide is potentiated by NSAIDs.
9. Beta-adrenergic blockers or digitalis combined with calcium channel blockers may prolong the AV node refractory period.
10. Ketamine enhances the dysrhythmogenicity of epinephrine.
11. The hypotensive effect of labetalol is enhanced by cimetidine and halothane
12. The clearance of steroids is reduced by phenytoin
13. Phenytoin accelerates meperidine metabolism and increases the production of breakdown products.
14. Propranolol combined with neostigmine causes severe bradycardia.
With the great resurgence of the use of herbal preparations, there is a potential for even more adverse drug reactions developing. Herbal preparations may contain several different compounds and because there is no regulation by the FDA, the amount of active ingredient is variable. To date several problems have been identified with some of the more popular herbal remedies.
The immunostimulatory effects of echinacea may offset the immunosuppressive actions of corticosteroids and cyclosporine. Since the herb is known to cause inhibition of the hepatic microsomal enzymes, its concomitant use with drugs e.g. phenytoin, rifampin, phenobarbital, which are metabolized by the hepatic microsomal enzymes, should be avoided as such a combination can precipitate toxicity of these drugs.
Garlic may augment the effects of warfarin, heparin, non-steroidal anti-inflammatory agents (NSAIDs), aspirin and may result in an abnormal bleeding time, that can at least theoretically increase the risk of intraoperative or postoperative bleeding. Awareness of this action is especially important for patients in the chronic pain setting who not infrequently have tried many different types of therapy and now may present for a neuraxial block.
Use of ginger may increase bleeding time; therefore, its use should be avoided in patients on anticoagulants like warfarin and heparin or drugs such as NSAIDs and aspirin. The caveat about neuraxial blocks as noted above also applies.
Although there have been no placebo-controlled double-blind studies regarding potential gingko-induced abnormal bleeding, concomitant use with aspirin, or any NSAIDs and anticoagulants such as warfarin and heparin, is not recommended as gingko may increase the potential to bleed in these patients. It would also be reasonable to avoid its concomitant use with anticonvulsant drugs (e.g. carbamazepine, phenytoin, phenobarbital) as it may decrease the effectiveness of these highly useful drugs. In addition, it has been suggested that gingko should be avoided in patients taking tricyclic antidepressant agents, as gingko might increase the seizure threshold lowering the efficacy of these agents.
Concomitant use of St. John’s wort is currently not recommended with photosensitization drugs (e.g. piroxicam and tetracycline hydrochloride), monoamine oxidase inhibitors (e.g. phenelzine), b-sympathomimetic amines (e.g. ma huang, pseudoephedrine hydrochloride or SSRIs (e.g. fluoxitine or paroxitine).
The use of ginseng should be avoided in patients on drugs like warfarin, heparin, NSAIDs and aspirin. Since ginseng can cause hypertension, attention should focus on perioperative hemodynamic variation as these patients are often volume depleted and since many anesthetic agents can cause generalized vasodilatory effects intraoperative hypotension may result. Concomitant use of ginseng with monoamine oxidase inhibitors (e.g. phenelzine sulphate), should be avoided as manic episodes have been reported with routine use of ginseng. Ginseng, with its potential hypoglycemic effects, should be avoided or at least be cautiously used in patients on insulin or oral hypoglycemic medications. Also, blood glucose levels should be monitored perioperatively in patients at risk. (e.g. neurosurgical patients receiving steroids, patients with diabetic and end stage renal disease).
Ethanol can increase the hypnotic effect of Kava-kava and it should be avoided in patients with endogenous depression as it increases the risk of suicide. Kava-kava can potentiate the effects of barbiturates and benzodiazepines and can cause excessive sedation.
Feverfew can inhibit platelet activity and it is suggested to avoid the use of this herb in patients taking medications such as, heparin, warfarin, NSAIDs, aspirin and vitamin E. Tannin-containing herbs like feverfew, can interact with iron preparations, thereby reducing their bioavailability.
Ephedra can interact with volatile general anesthetic agents (e.g. halothane) and cardiac glycosides (e.g. digitalis) to cause cardiac dysrrhythmias. Patients on ephedra, under general anesthesia, can have severe hypotension that can be controlled with phenylephrine instead of ephedrine. Use of ephedra with phenelzine or other monoamine oxidase inhibitors may result in insomnia, headache, and tremulousness. Concomitant use with oxytocin, can cause hypertension.
Postoperative evaluation is commonly performed in two steps, one in the immediate postoperative period in PACU and the second within 24 hours. The 24-hour follow-up helps in assessing the problems that occur following discharge from PACU, when the patient has recovered completely from the effects of sedatives. The purpose is to identify problems such as sore throat, hoarseness, nerve paresthesias, explicit recall, postdural puncture headaches, continued nausea and vomiting, inflammation over sites of invasive monitors etc. Respiratory problems requiring re-intubation, cardiovascular instability, acute renal failure, acute pulmonary edema and altered mental status are problems that require careful attention and reflection to further analyze the anesthetic plan in so far as it may be contributory. For the anesthesiologist, giving anesthesia for an operation is an everyday occurrence, for the patient undergoing anesthesia, it is a profound incident. Therefore, the postoperative follow up gives us the opportunity for patient education, treatment of any adverse events humanely and the ability to enhance a positive experience for the patient in relation to anesthetic care.
In a PACU, the physician evaluates the patient’s condition in relation to the surgical procedure and preanesthetic assessment and makes a plan to treat any complications until recovery is adequate. Intraoperative