Association of metabolic syndrome and surgical factors with pulmonary adverse events, and longitudinal mortality in bariatric surgery.

BACKGROUND: Postoperative pulmonary complications (PPC) in bariatric surgery have not been well studied. Additionally, many bariatric patients suffer from the metabolic syndrome (MetS), contributing to surgical risk. We examined the incidence of PPC and MetS in a large national bariatric database. Furthermore, we analysed the relationships between morbidity, mortality, PPC, MetS, and several other comorbidities and also surgical factors. METHODS: The Bariatric Outcomes Longitudinal Database (BOLD™) is a registry that includes up to 365 day outcomes. We analysed data between January 2008 and October 2010. The PPC tracked included pneumonia, atelectasis, pleural effusion, pneumothorax, adult respiratory distress syndrome, and respiratory failure. A composite pulmonary adverse event (CPAE) included the occurrence of any of these. MetS was defined as the combination of hypertension, dyslipidaemia, and diabetes mellitus. The association of MetS and additional comorbibities, procedural data, and patient characteristics with CPAEs was examined with appropriate statistical tests. RESULTS: A total of 158 405 patients had a low incidence of PPC (0.91%) and a low mortality (0.6%) after bariatric surgery. MetS was prevalent in 12.7%, and was a significant risk factor for CPAE and mortality. Age, BMI, ASA physical status classification, surgical duration, procedure type, MetS (P<0.001), and additional comorbidities were significantly associated with CPAEs. CONCLUSIONS: The incidence of PPC was low after bariatric surgery. Increasing age, BMI, ASA status, MetS, obstructive sleep apnoea, asthma, congestive heart failure, surgical duration, and procedure type were independently significantly associated with PPC. Pulmonary complications and MetS were significantly associated with increased postoperative mortality.

Awareness with recall during general anaesthesia: a prospective observational evaluation of 4001 patients.

BACKGROUND: We have prospectively evaluated the incidence and characteristics of awareness with recall (AWR) during general anaesthesia in a tertiary care hospital. METHODS: This study involves a prospective observational investigation of AWR in patients undergoing general anaesthesia. Blinded structured interviews were conducted in the postanaesthesia care unit, on postoperative day 7 and day 30. Definition of AWR was 'when the patient stated or remembered that he or she had been awake at a time when consciousness was not intended'. Patient characteristics, perioperative, and drug-related factors were investigated. Patients were classified as not awake during surgery, AWR, AWR-possible, AWR-not evaluable. The perceived quality of the awareness episode, intraoperative dreaming, and sequelae were investigated. The anaesthetic records were reviewed to search for data that might explain the awareness episode. RESULTS: The study included 4001 patients. Incidence of AWR was 1.0% (39/3921 patients). If high risk for AWR patients were excluded, the incidence was 0.8%. After the interview on the seventh day, six patients denied having been conscious during anaesthesia; hence, the incidence of AWR in elective surgery was 0.6%. Factors associated with AWR were: anaesthetic technique incidence of 1.1% TIVA-propofol vs 0.59% balanced anaesthesia vs 5.0% O2/N2O-based anaesthesia vs 0.9% other anaesthetic techniques (mainly propofol boluses for short procedures), P=0.008; age (AWR 42.3 yr old vs 50.6 yr old, P=0.041), absence of i.v. benzodiazepine premedication (P=0.001), Caesarean section (C-section) (P=0.019), and surgery performed at night (P=0.013). More than 50% of patients reported intraoperative dreaming in the early interview, mainly pleasant. Avoidable human factors were detected from the anaesthetic records of most patients. Subjective auditory perceptions prevailed, together with trying to move or communicate, and touch or pain perception. CONCLUSIONS: A relatively high incidence of AWR and dreams during general anaesthesia was found. Techniques without halogenated drugs showed more patients. The use of benzodiazepine premedication was associated with a lower incidence of AWR. Age, C-section with general anaesthesia, and surgery performed at night are risk factors.

The effect of bispectral index monitoring on anesthetic use and recovery in children anesthetized with sevoflurane in nitrous oxide.

UNLABELLED: The utility of bispectral index (BIS) monitoring to guide anesthetic administration has been demonstrated in adults. This prospective, randomized observer-blinded study was designed to evaluate the effect of BIS monitoring on anesthetic use and recovery characteristics in pediatric patients. After data collection in 38 historical controls, 202 patients age 0-18 yr were randomized into one of two groups: standard practice (SP) and BIS guided (BIS). Patients age 0-3 yr undergoing inguinal hernia repair (IH) and patients age 3-18 yr undergoing tonsillectomy and/or adenoidectomy (TA) were selected. All patients were anesthetized with sevoflurane in 60% N(2)O/O(2). Hernia patients also received a caudal epidural anesthetic before surgery. In the BIS group, anesthetic delivery was adjusted in an effort to achieve a target BIS of 45-60 during maintenance and 60-70 during the last 15 min of the procedure. BIS was recorded throughout surgery in all patients, but data were unavailable to the anesthesiologist in the SP group. In the TA patients, BIS monitoring was associated with a significant reduction in end-tidal sevoflurane concentration during maintenance (2.4 +/- 0.6%, SP and 1.8 +/- 0.4% BIS, mean +/- SD) and during the last 15 min of the procedure (2.1 +/- 0.7, SP and 1.6 +/- 0.6, BIS). There was a 25%-40% decrease in measured recovery times. In the patients 0-6 mo of age undergoing IH, sevoflurane concentrations during maintenance (2.0 +/- 0.4% SP, 0.9 +/- 0.8 BIS), during the last 15 min (1.6 +/- 0.4% SP, 0.6 +/- 0.6% BIS), and at the end of the procedure (1.1 +/- 0.6% SP, 0.3 +/- 0.3% BIS) were smaller in the BIS group. Emergence and recovery measures were unaffected by BIS titration. In the children 6 mo-3 yr of age, there were no significant differences between the SP and BIS groups in anesthetic use or recovery measures. IMPLICATIONS: Bispectral index monitoring in children results in less anesthetic use and faster recovery than standard practice.

Clinical impact of hypnotic-titration guidelines based on EEG bispectral index (BIS) monitoring during routine anesthetic care.

STUDY OBJECTIVES: To examine the impact on perioperative care of routine Bispectral Index (BIS) monitoring during general anesthesia throughout an entire operating room (OR) suite. DESIGN: Open, observational trial with retrospective analysis of guideline performance. Data were analyzed from 1,552 adult patients receiving general anesthesia with surgical times of at least 1 hour and who were extubated by postanesthesia care unit (PACU) discharge. Staff were trained using a simple decision matrix, which integrated BIS titration goals with anesthetic management. Unmonitored patients were compared to either BIS-monitored patients or to performance subgroups based on BIS measurements recorded during anesthetic maintenance ("deep", BIS < 50; "target", 50-65; "light", >65). SETTING: Large, urban academic/trauma center. MEASUREMENTS AND MAIN RESULTS: Demographic profiles of all groups and subgroups were similar. Anesthetic emergence, recovery times, and volatile drug use were significantly shortened or reduced only when BIS values were maintained between 50 and 65. Extubation time from end of surgery decreased by 2.1 minutes from 5.7+/-7 (37%); OR exit time decreased by 2.2 minutes from 9.3+/-6 (24%); eligibility for phase 1 PACU discharge decreased by 4 minutes from 22+/-42 (23%); and actual PACU discharge decreased by 15 minutes from 130+/-78 (7%). PACU extubation frequency decreased from 6.9% to 2.6%. Modest decreases in total intraoperative drug use were noted with an increase in PACU analgesic administration. CONCLUSIONS: Routine application of BIS monitoring throughout an OR suite impacted clinical outcome only if guideline targets were met. BIS values within the last 30 minutes of surgery were not predictive of emergence or recovery. Hypnotic maintenance at BIS < 50 did not confer any clinical advantage over unmonitored cases. Anesthetic maintenance at BIS values between 50 and 65 was associated with shortened emergence and recovery from general anesthesia.

Clonidine premedication decreases propofol consumption during bispectral index (BIS) monitored propofol-ketamine technique for office-based surgery.

BACKGROUND: Propofol-ketamine anesthesia is a room air, spontaneous ventilation (RASV), dissociative intravenous (IV) sedation technique reported to have a near-zero postoperative nausea and vomiting (PONV) rate. Clonidine premedication has been reported to control blood pressure intra- and postoperatively, as well as to reduce the requirements for hypnotic agents. The bispectral index (BIS) monitor is a reproducible, objective, observer independent, quantitative measurement of the hypnotic state. OBJECTIVE: This study was designed to compare the propofol consumption rate during BIS monitored propofol-ketamine anesthesia for office-based, elective female facial rhytidectomy in patients with and without clonidine premedication. METHODS: Six patients receiving clonidine (200 microg oral premedication administered 30-60 minutes prior to induction of anesthesia were compared with a recent, historical control group of six patients who received no premedication. A BIS of 60-70 was chosen as the standard of comparison for light hypnotic state. A dilute propofol solution was used to gradually titrate anesthesia to a BIS of 60-70 prior to the administration of ketamine. RESULTS: A statistically significant reduction in propofol consumption was observed in the clonidine premedicated female elective rhytidectomy patients compared with those not receiving the clonidine. Other than modestly increased requirements for IV fluids, there were no adverse effects observed with clonidine premedication.

Process analysis in outpatient knee surgery: effects of regional and general anesthesia on anesthesia-controlled time.

BACKGROUND: The performance of anesthetic procedures before operating room entry (e.g., with either general or regional anesthesia [RA] induction rooms) should decrease anesthesia-controlled time in the operating room. The authors retrospectively studied the associations between anesthesia techniques and anesthesia-controlled time, evaluating one surgeon performing a single procedure over a 3-yr period. The authors hypothesized that, using the anesthesia care team model, RA would be associated with reduced anesthesia-controlled time compared with general anesthesia (GA) alone or combined general-regional anesthesia (GA-RA). METHODS: The authors queried an institutional database for 369 consecutive patients undergoing the same procedure (anterior cruciate ligament reconstruction) performed by one surgeon over a 3-yr period (July 1995 through June 1998). Throughout the period of study, anesthesia staffing consisted of an attending anesthesiologist medically directing two nurse anesthetists in two operating rooms. Anesthesia-controlled time values were compared based on anesthesia techniques (GA, RA, or GA-RA) using one-way analysis of variance, general linear modeling using time-series and seasonal adjustments, and chi-square tests when appropriate. P < 0. 05 was considered significant. RESULTS: RA was associated with the lowest anesthesia-controlled time (11.4 +/- 1.3 min, mean +/- 2 SEM). GA-RA (15.7 +/- 1.0 min) was associated with lower anesthesia-controlled time than GA used alone (20.3 +/- 1.2 min). CONCLUSIONS: When compared with GA without an induction room for outpatients undergoing anterior cruciate ligament reconstruction, RA with an induction room was associated with the lowest anesthesia- controlled time. Managers must weigh the costs and time required for anesthesiologists and additional personnel to place nerve blocks or induce GA preoperatively in such a staffing model.

An introduction to bispectral analysis for the electroencephalogram.

The goal of much effort in recent years has been to provide a simplified interpretation of the electroencephalogram (EEG) for a variety of applications, including the diagnosis of neurological disorders and the intraoperative monitoring of anesthetic efficacy and cerebral ischemia. Although processed EEG variables have enjoyed limited success for specific applications, few acceptable standards have emerged. In part, this may be attributed to the fact that commonly used signal processing tools do not quantify all of the information available in the EEG. Power spectral analysis, for example, quantifies only power distribution as a function of frequency, ignoring phase information. It also makes the assumption that the signal arises from a linear process, thereby ignoring potential interaction between components of the signal that are manifested as phase coupling, a common phenomenon in signals generated from nonlinear sources such as the central nervous system (CNS). This tutorial describes bispectral analysis, a method of signal processing that quantifies the degree of phase coupling between the components of a signal such as the EEG. The basic theory underlying bispectral analysis is explained in detail, and information obtained from bispectral analysis is compared with that available from the power spectrum. The concept of a bispectral index is introduced. Finally, several model signals, as well as a representative clinical case, are analyzed using bispectral analysis, and the results are interpreted.