BACKGROUND:: The stress responses from tracheal intubation are potentially dangerous in patients with higher cardiovascular risk, such as obese patients. The primary outcome objective of this study was to test whether, in comparison with the endotracheal tube (ETT), the Proseal™ Laryngeal Mask Airway (PLMA™)(Laryngeal Mask Airway Company, Jersey, United Kingdom) reduces blood pressure and norepinephrine responses and the amounts of muscle relaxants needed in obese patients. METHODS:: We assessed hemodynamic and hormonal stress responses, ventilation, and postoperative recovery in 75 morbidly obese patients randomized to receive standardized anesthesia with either an ETT or the PLMA™ for laparoscopic gastric banding. RESULTS:: In repeated-measures ANOVA, mean arterial blood pressure and plasma norepinephrine were significantly higher in the ETT group than in the PLMA™ group. In individual pairwise comparisons, blood pressure rose higher in ETT than PLMA™ patients after insertion and removal of airway devices, and after recovery. In ETT compared with PLMA™ patients, plasma norepinephrine was higher after induction of carboperitoneum (mean ± SD, 534 ± 198 and 368 ± 147 and pg/ml, P = 0.001), after airway device removal (578 ± 285 and 329 ± 128 pg/ml, P < 0.0001), and after recovery in postanesthesia care unit (380 ± 167 and 262 ± 95 and pg/ml, P = 0.003). Compared with use of the ETT, the PLMA™ reduced cisatracurium requirement, oxygen desaturation, and time to discharge from both the postanesthesia care unit and the hospital. CONCLUSIONS:: PLMA™ reduces stress responses and postoperative complaints after laparoscopic gastric banding.

Obesity hypoventilation syndrome (OHS) is defined by the triad of obesity, daytime hypoventilation, and sleep-disordered breathing without an alternative neuromuscular, mechanical, or metabolic cause of hypoventilation. It is a disease entity distinct from simple obesity and obstructive sleep apnea. OHS is often undiagnosed but its prevalence is estimated to be 10-20% in obese patients with obstructive sleep apnea and 0.15-0.3% in the general adult population. Compared with eucapnic obese patients, those with OHS present with severe upper airway obstruction, restrictive chest physiology, blunted central respiratory drive, pulmonary hypertension, and increased mortality. The mainstay of therapy is noninvasive positive airway pressure. Currently, information regarding OHS is extremely limited in the anesthesiology literature. This review will examine the epidemiology, pathophysiology, clinical characteristics, screening, and treatment of OHS. Perioperative management of OHS will be discussed last.

ABSTRACT:: The diagnosis of sympathetically maintained pain (SMP) is typically established by assessment of pain relief during local anesthetic blockade of the sympathetic ganglia that innervate the painful body part. To determine if systemic α-adrenergic blockade with phentolamine can be used to diagnose SMP, we compared the effects on pain of local anesthetic sympathetic ganglion blocks (LASB) and phentolamine blocks (PhB) in 20 patients with chronic pain and hyperalgesia that were suspected to be sympathetically maintained.The blocks were done inrandom order on separate days. Patients rated the intensity of ongoing and stimulus-evoked pain every 5 min before, during, and after the LASB and PhB. Patients and the investigator assessing pain levels were blinded to the time of intravenous administration of phentolamine (total dose 25-35 mg). The pain relief achieved by LASB and PhB correlated closely (r = 0.84), and there was no significant difference in the maximum pain relief achieved with the two blocks (t = 0.19, P > 0.8). Nine patients experienced a greater than 50% relief of pain and hyperalgesia from both LASB and PhB and were considered to have a clinically significant component of SMP. We conclude that α-adrenergic blockade with intravenous phentolamine is a sensitive alternative test to identify patients with SMP.

BACKGROUND:: The transient receptor potential ankyrin 1 (TRPA1) ion channel is expressed on nociceptive primary afferent nerve fibers. On the distal ending, it is involved in transduction of noxious stimuli, and on the proximal ending (within the spinal dorsal horn), it regulates transmission of nociceptive signals. Here we studied whether the cutaneous or spinal TRPA1 ion channel contributes to mechanical hypersensitivity or guarding, an index of spontaneous pain, in an experimental model of postoperative pain in the rat. METHODS:: A skin plus deep-tissue incision was performed under general anesthesia in the plantar skin of one hind paw, after which the incised skin was closed with sutures. Postoperative pain and hypersensitivity were assessed 24-48 h after the operation. Guarding pain was assessed by scoring the hind-paw position. Mechanical hypersensitivity was assessed with a calibrated series of monofilaments applied to the wound area in the operated paw or the contralateral control paw. Chembridge-5861528, a TRPA1 channel antagonist, was administered intaperitoneally (10-30 mg/kg), intraplantarly (10-30 μg), or intrathecally (10 μg) in attempts to suppress guarding and hypersensitivity. RESULTS:: Intraperitoneal or ipsi- but not contralateral intraplantar treatment with Chembridge-5861528 reduced mechanical hypersensitivity and guarding in the operated limb. Intrathecal treatment attenuated hypersensitivity but not guarding. Intraplantar Chembridge-5861528 suppressed preferentially mechanical hyperalgesia and intrathecal Chembridge-5861528 tactile allodynia. CONCLUSIONS:: The TRPA1 channel in the skin contributes to sustained as well noxious mechanical stimulus-evoked postoperative pain, whereas the spinal TRPA1 channel contributes predominantly to innocuous mechanical stimulus-evoked postoperative pain.

BACKGROUND:: Nitrous oxide converts vitamin B12 to its nonmetabolically active form, inhibits methionine synthase, and results in an elevation of plasma total homocysteine (tHcy). The authors investigated the effect of nitrous oxide anesthesia on the plasma tHcy concentrations in children the morning after surgery and whether blood concentrations of folate and vitamins B12 and B6 were associated with any potential increase. METHODS:: The authors measured plasma tHcy concentrations in 32 children before and 24 h after initial exposure to nitrous oxide (≥2 h). Genotype for methylenetetrahydrofolate reductase C677T and blood concentrations of folate, vitamins B12 and B6, and methylmalonic acid were measured before surgery.

BACKGROUND:: Although a high fraction of inspired oxygen (FIO2) could reduce surgical site infection, there is concern it could increase postoperative pulmonary complications, including hypoxemia. Intraoperative positive end-expiratory pressure can improve postoperative pulmonary function. A practical measure of postoperative pulmonary function and the degree of hypoxemia is supplemental oxygen requirement. We performed a double-blind randomized 2 × 2 factorial study on the effects of intraoperative FIO2 0.3 versus more than 0.9 with and without positive end-expiratory pressure on the primary outcome of postoperative supplemental oxygen requirements in patients undergoing lower risk surgery. METHODS:: After Institutional Review Board approval and consent, 100 subjects were randomized using computer-generated lists into four treatment groups (intraoperative FIO2 0.3 vs. more than 0.9, with and without 3-5 cm H2O positive end-expiratory pressure). Thirty minutes and 24 h after extubation, supplemental oxygen was discontinued. Arterial oxygen saturation by pulse oximetry was recorded 15 min later. If oxygen saturation decreased to less than 90%, supplemental oxygen was added incrementally to maintain saturation more than 90%. RESULTS:: Nearly all subjects required supplemental oxygen in the postanesthesia care unit. Nonparametric Wilcoxon rank sum test demonstrated no statistically significant difference between groups in supplemental oxygen requirements at 45 min and 24 h after tracheal extubation (P = 0.56 and 0.98, respectively). CONCLUSIONS:: Use of intraoperative FIO2 more than 0.9 was not associated with increased oxygen requirement, suggesting it does not induce postoperative hypoxemia beyond anesthetic induction and surgery. Therefore, it may be reasonable to use high inspired oxygen in surgical patients with relatively normal pulmonary function.

The troubled life and death of William Thomas Green Morton has been described in several texts. His first public demonstration of ether anesthesia was the highpoint of a life that was less than successful in many of his endeavors. Close examination of this life reveals a pattern of behavior that progresses from narcissistic traits to narcissistic personality pathology. This retrospective psychiatric analysis of Morton's life was undertaken to theorize as to why Morton, after having successfully demonstrated ether anesthesia, did not continue to develop anesthesia as a clinical specialty.Biographies about Morton were used to explore details of his life. The Diagnostic and Statistical Manual of Mental Disorders classification of narcissistic personality disorder was used to analyze his life. We conclude that Morton progressed from displaying narcissistic personality trait to disorder over his lifetime.

BACKGROUND:: Pharyngeal cooling decreases brain temperature by cooling carotid arteries. This study was designed to evaluate the principle of pharyngeal cooling in monkeys and humans. METHODS:: Monkeys (n = 10) were resuscitated following 12 min of cardiac arrest. Pharyngeal cooling (n = 5), in which cold saline (5°C) was perfused into the cuff at the rate of 500 ml/min, was initiated simultaneously with the onset of resuscitation for 30 min. Patients (n = 3) who were in an intensive care unit were subjected to 30 min of pharyngeal cooling under propofol anesthesia. RESULTS:: In the animal study, core brain temperature was significantly decreased compared with that in the control group by 1.9°C (SD = 0.8, P < 0.001) and 3.1°C (SD = 1.0, P < 0.001) at 10 min and 30 min after the onset of cooling, respectively. The cooling effect was more evident in an animal with low postresuscitation blood pressure. Total dose of epinephrine, number of direct current shocks, and recovery of blood pressure were not different between the two groups. The pharyngeal epithelium was microscopically intact on day 5. In the clinical study, insertion of the cuff and start of perfusion did not affect heart rate or blood pressure. Tympanic temperature was decreased by 0.6 ± 0.1°C/30 min without affecting bladder temperature. The pharynx was macroscopically intact for 3 days. CONCLUSIONS:: Pharyngeal cooling rapidly and selectively decreased brain temperature in primates and tympanic temperature in humans and did not have adverse effects on return of spontaneous circulation, even when initiated during cardiac arrest in primates.

BACKGROUND:: Bariatric surgery patients are at risk of perioperative airway collapse. Neuromuscular blockade should be fully reversed before tracheal extubation. The optimal dosage of the reversal agent sugammadex in the morbidly obese is still unknown. This study explored the sugammadex dose adjusted according to train-of-four ratio (TOFR). METHODS:: Prospective observational study of consecutive patients scheduled for laparoscopic bariatric surgery. To reverse a deep blockade (2 or fewer posttetanic twitches), a dose of sugammadex of 4 mg/kg ideal body weight (IBW) was followed by a second dose of 2 mg/kg IBW if the TOFR was less than 0.9 after 3 min. To reverse a moderate blockade (reappearance of the second twitch in the TOF), a 2 mg/kg IBW dose of sugammadex was followed by a second dose of 2 mg/kg IBW if the TOFR was less than 0.9 after 2 min. Sugammadex effectiveness was reflected by the time required to obtain a TOFr of 0.9 or more. RESULTS:: A total of 120 patients were included. The blockade was deep at the end of surgery in 43 and moderate in 77. The median times (range) to TOFR of 0.9 or more were 167 (20-460) seconds and 113 (28-300) seconds in deep and moderate blockades, respectively (P < 0.05). The percentage of patients requiring a second dose of sugammadex were larger after deep blockades (39.5%[n = 17] vs. 23.4%[n = 18] after moderate blockades); the difference was not significant. CONCLUSIONS:: A sugammadex dose calculated according to IBW is insufficient for reversing both deep and moderate blockades in morbidly obese patients.