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To examine anesthesia recovery duration after ophthalmologic procedures performed at an ambulatory surgical center (ASC) and provide information that could be used to increase postanesthesia recovery unit efficiency.Ambulatory surgical center at tertiary medical center, Rochester, Minnesota, USA.Retrospective case series.Health records of adult patients having ophthalmologic procedures at an ASC from July 1, 2010, through September 30, 2016 were reviewed, and anesthesia recovery duration was calculated. Potential associations were assessed between clinical factors and prolonged recovery (upper 10th percentile of recovery duration by anesthesia type [general, intravenous sedation, or topical]).Among 20 116 procedures, the median recovery was 36 minutes (interquartile range [IQR], 28 to 48); general anesthesia had the longest recovery (79 minutes; IQR, 52 to 104 minutes) (P .001). Recovery was longest for orbitotomy and strabismus procedures and shortest for cataract procedures. Female sex, obstructive sleep apnea, greater disease burden, longer procedures, and intraoperative fentanyl administration were associated with prolonged recovery. Patients with prolonged recovery had more severe pain episodes (pain score ≥7 [scale 0 to 10]; 138 patients [6.9%] versus 140 [0.8%]; P .001) and received opioid analgesics during recovery (278 patients [13.8%] versus 293 [1.6%]; P .001). Prolonged recovery involved higher rates of emergency department visits and hospitalizations in the first 48 postoperative hours and higher 30-day mortality rates.Anesthesia recovery after ophthalmologic procedures at an ASC was associated primarily with the procedure and anesthesia type. Prolonged recoveries were associated with intraoperative fentanyl use, severe postoperative pain, and postoperative opioid requirements.

Although ambulatory surgery offers patients convenience and reduced costs, same-day cancellation of ambulatory surgery negatively affects patient experiences and operational efficiency. We conducted a retrospective analysis to determine the frequency and reasons for same-day cancellations in an outpatient surgery center at a large academic tertiary referral center. Of 41 389 ambulatory surgical procedures performed, same-day cancellations occurred at a rate of 0.5% and were usually unforeseeable in nature. Focusing on foreseeable cancellations offers opportunities for enhanced patient satisfaction, improved quality of care, and systems-based practice improvements to mitigate cancellations related to areas such as scheduling or patient noncompliance.

Background Glycogen storage diseases are rare genetic disorders of glycogen synthesis, degradation, or metabolism regulation. When these patients are subjected to anesthesia, perioperative complications can develop, including hypoglycemia, rhabdomyolysis, myoglobinuria, acute renal failure, and postoperative fatigue. The objective of this study was to describe the perioperative course of a cohort of patients with glycogen storage diseases. Methods This is a retrospective review of patients with glycogen storage diseases undergoing anesthetic care at our institution from January 1, 1990, through June 30, 2015 to assess perioperative management and outcomes. Results We identified 30 patients with a glycogen storage disease who underwent 41 procedures under anesthesia management. Intraoperative lactic acidosis developed during 4 major surgeries (3 liver transplants, 1 myectomy), and in all cases resolved within 24 postoperative hours. Lactated Ringer solution was used frequently. Preoperative and intraoperative hypoglycemia was noted in some patients with glycogen storage disease type I, all of which responded to administration of dextrose-containing solutions. No serious postoperative complications occurred. Conclusions Patients with glycogen storage disease, despite substantial comorbid conditions, tolerates the anesthetic management without major complications. Several patients who experienced self-limited metabolic acidosis were undergoing major surgical procedures, during which acidosis could be anticipated. Close monitoring and management of blood glucose levels of patients with glycogen storage disease type I is prudent.

Patients undergoing laparoscopic bariatric surgery have high rates of postoperative nausea and vomiting (PONV). Dexmedetomidine based anesthetic could reduce PONV rates.To determine if PONV rates differ in patients undergoing laparoscopic bariatric surgery with anesthesia primarily based on dexmedetomidine or standard anesthetic management with inhalational agents and opioids.University hospital.From January 2014 to April 2018, 487 patients underwent laparoscopic bariatric surgery and met inclusion criteria (dexmedetomidine, n = 174 and standard anesthetic, n = 313 patients). In both groups, patients received preoperative PONV prophylaxis. We analyzed rates of PONV and moderate-to-deep sedation. A propensity score was calculated and outcomes were assessed using generalized estimating equations with inverse probability of treatment weighting.Perioperative opioids and volatile anesthetics were reduced in dexmedetomidine patients. During anesthesia recovery the incidence of PONV was similar between dexmedetomidine and standard anesthetic patients (n = 37 [21.3%] versus n = 61 [19.5%], respectively; inverse probability of treatment weighting odds ratio = 1.35; 95% confidence interval .78-2.32, P = .281), and the incidence of sedation higher in dexmedetomidine patients (n = 86 [49.4%] versus n = 75 [24.0%]; inverse probability of treatment weighting odds ratio = 2.43; 95% confidence interval 1.47-4.03, P 0.001). Rates of PONV and sedation were similar during the remainder of the hospital stay. A secondary sensitivity analysis was performed limited to dexmedetomidine patients who did not receive volatile and results were similar.While dexmedetomidine-based anesthesia was associated with reduced opioid and volatile agents use, it was not associated with a reduction of PONV. The higher rates of moderate-to-deep sedation during anesthesia recovery observed with dexmedetomidine may be undesirable in morbidly obese patients.

Positioning-related injuries caused during surgery under anesthesia are most likely multifactorial. Pathologic mechanical forces alone (overstretching and/or ischemia from direct compression) may not fully explain postsurgical neuropathy with recent evidence implicating patient-specific factors or perioperative inflammatory responses spatially and even temporally divorced from the anatomical region of injury. The aim of this introductory article is to provide an overview of anatomic considerations of these mechanical forces on soft and nervous tissues along with factors that may compound compression or stretch injury. Three subsequent articles will address specific positioning-related anatomic considerations of the (1) upper extremities, (2) lower extremities, and (3) central nervous system and soft tissues.

We describe 3 patients who developed injury of upper and middle brachial plexus trunks during robotic-assisted prostatectomy, and review factors potentially associated with this type of injury. Three patients underwent robotic-assisted prostatectomy. Surgical exposure was facilitated by steep head-down tilt position. To secure patients and prevent sliding on the operating table, shoulders were supported with moldable beanbags. In all 3 cases, the left arm was abducted to approximately 90°, and the right arm was adducted. Postoperatively, all patients were diagnosed with left arm upper and middle trunk brachial plexopathies. The combination of arm abduction, extreme head-down position, and shoulder immobilization with beanbags resulted in several mechanistic forces that may have contributed to the development of brachial plexopathy in our patients. Steep head-down tilt may result in cephalad slide of the torso in relation to an abducted arm. When shoulder restraints are used to secure the patient, the compensatory movement of the shoulder girdle of an abducted arm is impeded. This may result in injurious stretching and compression of the brachial plexus, especially the upper and middle trunks. When steep head-down position is needed to facilitate surgical exposure, clinicians should consider adduction and tucking of both arms, and use of other methods to prevent sliding on the operating room table that do not require the use of restraints across the shoulder girdle.

Background The authors determined the incidence of cardiac arrest and predictors of survival following perioperative cardiac arrest in a large population of patients at a tertiary referral center. Methods Medical records of patients who experienced cardiac arrest in the perioperative period surrounding noncardiac surgery between January 1, 1990, and December 31, 2000, were reviewed. Logistic regression identified characteristics associated with immediate (>or= 1 h) and hospital survival, with P Results Cardiac arrest occurred in 223 of 518,294 anesthetics (4.3 per 10,000) during the study period. Frequency of arrest for patients receiving general anesthesia decreased over time (7.8 per 10,000 during 1990-1992; 3.2 per 10,000 during 1998-2000). The frequency of arrest during regional anesthesia (1.5 per 10,000) and monitored anesthesia care (0.7 per 10,000) remained consistent. Immediate survival after arrest was 46.6%, and hospital survival was 34.5%. Twenty-four patients (0.5 per 10,000) had cardiac arrest related primarily to anesthesia. From multivariate analysis, patients who experienced arrest due to bleeding were less likely to survive hospitalization (P = 0.001). Survival was also lower for patients who experienced arrest during nonstandard working hours (P = 0.006) and for patients who had protracted hypotension before arrest (P < 0.001). Conclusions The overall frequency of arrest for patients receiving anesthesia decreased during the study period. Most arrests were not due to anesthesia-related causes, and most patients experiencing anesthesia-related arrest survived to hospital discharge. Although many factors determining survival may not be amenable to modification, the fact that arrests during nonregular working hours had worse outcomes may indicate that the availability of human resources influences survival.

Background Dental injury is well-recognized as a potential complication of laryngoscopy and tracheal intubation. However, the frequency, outcomes, and risk factors for this problem have not been documented in a well-defined patient population. Methods The authors analyzed the dental injuries of 598,904 consecutive cases performed on patients who required anesthetic services from 1987 through 1997. Dental injuries were defined as perianesthetic events (those occurring within 7 days) that required dental interventions to repair, stabilize, or extract involved dentition or support structures. A 1:3 case-control study of 16 patient and procedural characteristics was performed for cases that occurred during the first 5 yr of the study. Conditional logistic regression was used for data analysis. Results There were 132 cases (1:4,537 patients) of dental injury. One half of these injuries occurred during laryngoscopy and tracheal intubation. The upper incisors were the most commonly involved teeth, and most injuries were crown fractures and partial dislocations and dislodgements. Multivariate risk factors for dental injury in the case control study included general anesthesia with tracheal intubation (odds ratio [OR] = 89), preexisting poor dentition (OR = 50), and increased difficulty of laryngoscopy and intubation (OR = 11). Conclusions Based on these data from a large surgical population at a single training institution, approximately 1:4,500 patients who receive anesthesia services sustain a dental injury that requires repair or extraction. Patients most at risk for perianesthetic dental injury include those with preexisting poor dentition who have one or more risk factors for difficult laryngoscopy and tracheal intubation.

COMPARTMENT syndrome is a potentially devastating perioperative complication that typically involves the legs or arms. 1 Most surgical patients have this problem while anesthetized and positioned in lithotomy or lateral decubitus positions. 2 We recently observed compartment syndrome of the hand in a patient who was anesthetized and positioned supine for a surgical procedure, a previously unreported perioperative complication in the absence of trauma or vascular obstruction in the upper extremity. A potential positioning cause for the compartment syndrome prompts this case report. To supplement this case report, we also have reviewed our experience with this perioperative problem during the past 15 yr, using a robust perioperative database to determine the frequency ratio and outcomes of this event.

Purpose To determine the safety and practicality of a combined anesthesiologist and registered nurse model of anesthesia care in cataract surgery. Setting Mayo Clinic, Rochester, Minnesota, USA. Design Case series. Methods This retrospective review comprised consecutive patients having phacoemulsification cataract surgery and peribulbar injection anesthesia combined with propofol intravenous sedation between August 1, 2004, and July 31, 2006. In all cases, anesthesiologist-supervised intravenous propofol sedation during injection anesthesia was followed by registered nurse observation for the remainder of the surgery. Outcome measures were the rate of subsequent anesthesiologist intervention, intraoperative complications, and associated risk factors. Logistic regression models were used to estimate risk for anesthesiologist intervention. Results The study reviewed 3656 cases. There were no serious medical complications leading to postoperative hospitalization. Fifty-four cases (1.5%) required subsequent intraoperative anesthesiologist intervention. Evaluation of systolic hypertension (40 of 54 cases, 74%) was the most common reason for anesthesiologist intervention. There was no correlation between anesthe-siologist intervention and patient age or sex ( P =.77 and P =.41, respectively). The risk for anesthesiologist intervention increased 2.2-fold for every 1 unit increase in the American Society of Anesthesiologists Physical Status score ( P =.007). Conclusion The monitoring of cataract surgery patients by registered nurses after anesthesiologist-supervised intravenous propofol sedation during injection anesthesia was associated with very low complication and anesthesiologist intervention rates. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

The green light potassium-titanyl-phosphate laser photoselective vaporization of the prostate is the latest modality for treatment of benign prostatic obstruction. Because of effective superficial tissue coagulation, intravascular absorption of fluid is minimal; therefore, development of transurethral resection syndrome is unlikely. To our knowledge, this is the first report of a patient undergoing photoselective vaporization of the prostate who developed full-blown transurethral resection syndrome because of intravascular absorption of sterile water. Absorption of hypotonic irrigant presumably occurred through the injury induced during insertion of the laser cystoscope.

We tested the hypothesis that the use of subarachnoid block (SAB) for vaginal hysterectomy produces superior postoperative analgesia and improves functional status at 12 weeks postoperatively.In this randomized controlled trial 89 patients received either standardized general anesthesia vs SAB with bupivacaine, clonidine, and morphine. Postoperatively, patients in both groups received multimodal pain management. Primary outcomes included evaluation of pain and functional status (SF-36 Health Survey) over the 12 postoperative weeks.Pain was well controlled throughout the study, as judged from the average pain numerical scale scores ofor = 3 in both groups, at all times studied. Intrathecal analgesia lessened pain and decreased the use of morphine both in the postanesthesia care unit (PACU) and over the first 12 hr after discharge from the PACU (P0.001). Although patients who received SAB had a lower frequency of postoperative nausea in the PACU than the patients in the general anesthesia group (P = 0.021), this effect was not extended beyond the PACU stay. Subarachnoid block did not affect the length of hospitalization. At the two-week follow-up 69% of patients in the SAB group and 48% patients in the general anesthesia group were pain free (P = 0.044). At all evaluation intervals patients' functional status was comparable between the SAB and general anesthesia group.A significantly better immediate postoperative analgesia was present in the SAB group, and the duration was consistent with the expected action of intrathecally administered drugs. Two weeks after surgery a higher percentage of the patients in the SAB group reported no pain. However, SAB had no effect on either length of hospitalization or patients' postoperative functional status.

The frequency and predisposing factors associated with cardiac arrest during neuraxial anesthesia remain undefined, and the survival outcome data are contradictory. In this retrospective study, we evaluated the frequency of cardiac arrest, as well as the association of preexisting medical conditions and periarrest events with survival after cardiac arrest during neuraxial anesthesia between 1983 and 2002. To assess whether survival after cardiac arrest differs for patients who arrest during neuraxial versus general anesthesia, data were also obtained for patients who experienced cardiac arrest under general anesthesia during similar surgical procedures during the same time interval. Over the 20-yr study period at the Mayo Clinic, there were 26 cardiac arrests during neuraxial blockade and 29 during general anesthesia. The overall frequency of cardiac arrest during neuraxial anesthesia for 1988 to 2002 was 1.8 per 10,000 patients, with more arrests in patients receiving spinal versus epidural anesthesia (2.9 versus 0.9 per 10,000; P = 0.041). In 14 (54%) of the 26 patients who arrested during a neuraxial technique, the anesthetic contributed directly to the arrest (high sympathectomy or respiratory depression after sedative administration), whereas in 12 (46%) patients, the arrest was associated with a specific surgical event (cementing of joint components, spermatic cord manipulation, reaming of the femur, and rupture of amniotic membranes). Patients who arrested during general anesthesia had a higher ASA classification than those who arrested during a neuraxial block (P = 0.031). Hospital survival was significantly improved for patients who arrested during neuraxial anesthesia versus general anesthesia (65% vs 31%; P = 0.013). The association of improved survival with neuraxial anesthesia remained statistically significant after adjusting for all patient/procedural characteristics, with the exception of ASA classification and emergency procedures. We conclude that a cardiac arrest during neuraxial anesthesia is associated with an equal or better likelihood of survival than a cardiac arrest during general anesthesia.

Pheochromocytomas and paragangliomas are often surgically curable. However, resection of these tumors can be life threatening. We undertook this study to determine the frequency of, and risk factors for, perioperative complications in patients undergoing resection of pheochromocytoma or paraganglioma. We retrospectively reviewed the medical records of patients during 1983-1996 who underwent surgical resection of catecholamine-secreting pheochromocytoma or paraganglioma. Preoperative risk factors, adverse intraoperative events, and complications occurring in the 30 days after operation were recorded. Blood pressures were collected from manual records. The ranked sum test and Fisher's exact test were used for analyses. Adverse perioperative events or complications occurred in 45 of 143 patients (31.5%; exact 95% confidence interval, 24.0% to 39.8%). Of these 45 patients, 41 experienced one or more adverse intraoperative events. The most common adverse event was sustained hypertension (36 patients). There were no perioperative deaths, myocardial infarctions, or cerebrovascular events. Preoperative factors univariately associated with adverse perioperative events included larger tumor size (P: = 0.007), prolonged duration of anesthesia (P: = 0.015), and increased levels of preoperative urinary catecholamines and catecholamine metabolites: vanillylmandelic acid (P: = 0.019), metanephrines (P: = 0.004), norepinephrine (P: = 0. 014), and epinephrine (P: = 0.004). Despite premedication of most patients with phenoxybenzamine and a beta-adrenergic blocker, varying degrees of intraoperative hemodynamic lability occurred.Few patients who had pheochromocytoma or paraganglioma resection experienced significant perioperative morbidity and none died in the largest retrospective study on this topic to date. This study confirms the very good perioperative outcomes demonstrated in smaller studies on this high-risk population, and identifies several risk factors for adverse outcomes.

Limited mobility of the cervical spine or temperomandibular joint may contribute to increased difficulty of laryngoscopy in patients who have severe diabetes mellitus. The frequency of difficult laryngoscopy in diabetics undergoing renal and/or pancreatic transplants has been reported to be as high as 32%. We retrospectively reviewed the anesthetic records of all adult patients who underwent renal and/or pancreatic transplant and endotracheal intubation from January 1, 1985 to October 31, 1995. Characteristics specifically reviewed included the presence of diabetes mellitus, type of organ donor, age, gender, body mass index, previous difficult laryngoscopy, known characteristics potentially related to difficult laryngoscopy, and degree of difficulty with laryngoscopy. Laryngoscopy was graded as easy, minimally to moderately difficult, and moderately to extremely difficult to perform. Factors associated with any degree of difficult intubation were univariately assessed by using Fisher's exact test. Of 725 patients, 15 (2.1%) were identified as having difficult laryngoscopies, although all underwent successful endotracheal intubations. Factors associated with difficult laryngoscopy were diabetes mellitus (P = 0.002) and characteristics known to be related to difficult laryngoscopy (P = 0.02). These findings confirm an increase in the frequency of difficult laryngoscopy in diabetic patients undergoing renal and/or pancreatic transplant, although no laryngoscopies were rated as moderately to extremely difficult. We conclude that the frequency of difficult laryngoscopy in these diabetic patients is much lower than previous reports have suggested.Previous studies have suggested that airway management of many diabetic patients may be difficult. Our medical record review of patients with severe diabetes undergoing organ transplants showed that extraordinary techniques were not required to successfully manage their airways.

A 95 kg, 34-year-old woman undergoes a laparoscopic tubal ligation. Shortly after endotracheal extubation and during transport to the PACU, she attempts to cough, and gags and vomits. As she is wheeled into the PACU, she is coughing and cyanotic. The anesthesiologist quickly reanesthetizes and reintubates her. Concerned that she may have aspirated the vomitus into her trachea, you suction her endotracheal tube and find thick bilious secretions. How important is pulmonary aspiration? What are the risk factors? When does aspiration occur during the perioperative period? How do you treat pulmonary aspiration? What went wrong here?

Objective To estimate the frequency of perioperative morbidities in patients who underwent anesthesia and a surgical procedure with no preoperative laboratory testing. Material and Methods We conducted an electronic database search of medical records of 56,119 patients who underwent surgical or diagnostic procedures and anesthesia at Mayo Clinic Rochester in 1994 and found 5,120 who had no laboratory tests done within 90 days before the procedure. From this group, we randomly selected 1,044 patients (87 from each month) to document the absence of preoperative tests, the presence of preexisting disease (by organ system), the type of anesthetic agent, and the outcomes and tests intraoperatively and postoperatively. Results The 1,044 patients ranged in age from 0 to 95 years (median age, 21). No deaths or major perioperative morbidities occurred (0.0%; exact 95% confidence interval, 0.00 to 0.35 %). Although 10 patients underwent blood typing and screening for antibodies immediately preoperatively, no blood transfusions were necessary. Intraoperatively, 17 laboratory tests and 1 electrocardiogram were obtained, and 3 results were abnormal. Postoperatively, 42 blood tests and 2 electrocardiographic procedures were per- formed. Five of the 42 blood tests showed abnormal results (hemoglobin levels in 3, serum sodium in 1, and arterial blood gases in 1). One electrocardiogram showed normal findings, and the other revealed normal results except for premature ventricular contractions. No laboratory test done intraoperatively or postoperatively was found to change surgical or medical management substantially. One patient who had unanticipated blood loss during an outpatient procedure was admitted to the hospital for observation. Conclusion All 1,044 patients, 97% of whom were relatively healthy, with no recent laboratory testing safely underwent anesthesia and an operation. We conclude that patients who have been assessed by history and physical examination and determined to have no preoperative indication for laboratory tests can safely undergo anesthesia and operation with tests obtained only as indicated intraoperatively and postoperatively. Current anesthetic and medical practices rapidly identify perioperative indications for laboratory evaluation as they arise.

Pulmonary aspiration of gastric contents during the perioperative period may be associated with postoperative mortality or pulmonary morbidity. Recent determination of the incidence of perioperative pulmonary aspiration and evaluation of factors related to clinical outcomes is lacking.We retrospectively reviewed the perioperative courses of 172,334 consecutive patients 18 yr of age or older who underwent 215,488 general anesthetics for procedures performed in all surgical specialties from July 1985 to June 1991. Pulmonary aspiration was defined as either the presence of bilious secretions or particulate matter in the tracheobronchial tree or, in patients who did not have their tracheobronchial airways directly examined after regurgitation, the presence of an infiltrate on postoperative chest roentgenogram that was not identified by preoperative roentgenogram or physical examination.Pulmonary aspiration occurred in 67 patients (1:3,216 anesthetics). Fifteen aspirations occurred in 13,427 (1:895) anesthetics of patients undergoing emergency surgery, and 52 occurred in 202,061 (1:3,886) anesthetics of patients undergoing elective surgery (P.001). Of the 66 patients who survived their surgery, 42 (64%) did not develop a cough or wheeze, a decrease in arterial hemoglobin oxygen saturation while breathing room air10% less than the preoperative value, or radiographic abnormalities within 2 h of aspiration. These 42 patients had no respiratory sequelae. Of the 24 patients who had one or more of these findings, 13 required mechanical ventilatory support for more than 6 h. Three of the six patients whose lungs required mechanical ventilation for more than 24 h died from pulmonary insufficiency (overall mortality = 1:71,829 anesthetics).This study suggests that patients with clinically apparent aspiration who do not develop symptoms within 2 h are unlikely to have respiratory sequelae.

Background Dental injury is well-recognized as a potential complication of laryngoscopy and tracheal intubation. However, the frequency, outcomes, and risk factors for this problem have not been documented in a well-defined patient population. Methods The authors analyzed the dental injuries of 598,904 consecutive cases performed on patients who required anesthetic services from 1987 through 1997. Dental injuries were defined as perianesthetic events (those occurring within 7 days) that required dental interventions to repair, stabilize, or extract involved dentition or support structures. A 1:3 case-control study of 16 patient and procedural characteristics was performed for cases that occurred during the first 5 yr of the study. Conditional logistic regression was used for data analysis. Results There were 132 cases (1:4,537 patients) of dental injury. One half of these injuries occurred during laryngoscopy and tracheal intubation. The upper incisors were the most commonly involved teeth, and most injuries were crown fractures and partial dislocations and dislodgements. Multivariate risk factors for dental injury in the case control study included general anesthesia with tracheal intubation (odds ratio [OR] = 89), preexisting poor dentition (OR = 50), and increased difficulty of laryngoscopy and intubation (OR = 11). Conclusions Based on these data from a large surgical population at a single training institution, approximately 1:4,500 patients who receive anesthesia services sustain a dental injury that requires repair or extraction. Patients most at risk for perianesthetic dental injury include those with preexisting poor dentition who have one or more risk factors for difficult laryngoscopy and tracheal intubation.

Postoperative nausea and vomiting have been reported to be associated with the use of nitrous oxide. To further investigate this possibility, 780 patients undergoing anesthesia and surgery were randomly divided into four groups: group I: enflurane/nitrous oxide/oxygen; group II: enflurane/air/oxygen; group III: isoflurane/nitrous oxide/oxygen; and group IV: isoflurane/air/oxygen. The frequency of postoperative nausea and vomiting was ascertained in the recovery room and at 24-h follow-up by blinded observers. Other data collected included gender, age, body mass index, previous history of postoperative nausea and vomiting, and postoperative narcotic use. The authors found no association between the use of nitrous oxide and subsequent development of postoperative nausea and vomiting. Use of the 95% confidence interval allowed the authors to project a maximum potential increase in the frequency of postoperative nausea and vomiting associated with nitrous oxide to be 5.4% with enflurane and 9.7% with isoflurane in the immediate postoperative period. Female gender, younger age, and a previous history of postoperative nausea and vomiting, but not body mass index, were found to be associated with postoperative nausea and vomiting (P less than 0.05). It is concluded that there is no association between the use of nitrous oxide and the development of postoperative nausea and vomiting.

The association between preoperative smoking cessation and postoperative pulmonary morbidity was studied prospectively in 200 consecutive patients undergoing an elective coronary artery bypass surgical procedure. Detailed respiratory, cardiovascular, and smoking histories were elicited. Preoperative arterial blood gas analyses and bedside spirometry were performed. Urinary cotinine levels were measured to verify smoking histories. During spirometry, severe angina developed in seven patients, who were hence excluded from the study; one patient died of hemorrhage intraoperatively. An observer unaware of patients' preoperative histories assessed the remaining 192 patients throughout the intraoperative and postoperative periods for pulmonary complications. Postoperative pulmonary complications occurred in a third of the current smokers. Patients who had stopped smoking for 2 months or less had a pulmonary complication rate almost 4 times that of patients who had stopped for more than 2 months (57.1% versus 14.5%). Patients who had stopped smoking for more than 6 months had rates similar to those who had never smoked (11.1% and 11.9%, respectively). Preoperative pulmonary dysfunction, increased pack-years of smoking, prolonged surgical time, and the use of enflurane were independently associated with postoperative pulmonary morbidity (P less than 0.05). We concluded that smoking cessation should occur at least 2 months preoperatively to maximize the reduction of postoperative respiratory complications.