Perioperative management of obstructive sleep apnea.

Obstructive sleep apnea (OSA) is the most common breathing disorder, with a high prevalence in both the general and surgical populations. OSA is frequently undiagnosed, and the initial recognition often occurs during medical evaluation undertaken to prepare for surgery. Adverse respiratory and cardiovascular outcomes are associated with OSA in the perioperative period; therefore, it is imperative to identify and treat patients at high risk for the disease. In this review, we discuss the epidemiology of OSA in the surgical population and examine the available data on perioperative outcomes. We also review the identification of high-risk patients using clinical screening tools and suggest intraoperative and postoperative treatment regimens. Additionally, the role of continuous positive airway pressure in perioperative management of OSA and a brief discussion of ambulatory surgery in patients with OSA is provided. Finally, an algorithm to guide perioperative management is suggested.

Assessing the predictive value of the bispectral index vs patient state index on clinical assessment of sedation in postoperative cardiac surgery patients.

PURPOSE: To compare the depth of sedation determined by Ramsay sedation scale (RSS) with electroencephalogram-based bispectral index (BIS) and patient state index (PSI). MATERIALS AND METHODS: Fifty mechanically ventilated cardiac surgical patients undergoing propofol and morphine sedation were assessed hourly for up to 6 hours or until tracheal extubation using the BIS, PSI, and RSS. Correlation between RSS, BIS, and PSI was determined, as well as the interrater reliability of RSS, BIS, and PSI. kappa statistics was used to further evaluate the agreement between BIS and PSI. RESULTS: There was positive correlation between BIS and PSI values (rho = 0.731, P < .001). The average weighted kappa coefficient was .40 between the BIS and PSI, 0.28 between the RSS and BIS, and 0.16 between the RSS and PSI. Intraclass correlation was consistently higher between the BIS and PSI at all time intervals during the study. Logistic regression modeling over study duration showed that the BIS was consistently better at predicting oversedation (area under the curve, 0.92) than the PSI (area under the curve, 0.78). A comparison of BIS and PSI receiver operating characteristic curves showed that the BIS monitor was a better predictor of oversedation compared with the PSI (P = .02). CONCLUSIONS: There is significant positive correlation between the BIS and PSI but poor correlation and poor test agreement between the RSS and BIS as well as RSS and PSI. The BIS is a better predictor of oversedation compared with the PSI. There was no significant difference between the BIS and PSI with respect to the prediction of undersedation.

Trends and outcomes of malignant hyperthermia in the United States, 2000 to 2005.

BACKGROUND: Malignant hyperthermia (MH) is a potentially fatal pharmacogenetic disorder with an estimated mortality of less than 5%. The purpose of this study was to evaluate the current incidence of MH and the predictors associated with in-hospital mortality in the United States. METHODS: The Nationwide Inpatient Sample, which is the largest all-payer inpatient database in the United States, was used to identify patients discharged with a diagnosis of MH during the years 2000-2005. The weighted exact Cochrane-Armitage test and multivariate logistic regression analyses were used to assess trends in the incidence and risk-adjusted mortality from MH, taking into account the complex survey design. RESULTS: From 2000 to 2005, the number of cases of MH increased from 372 to 521 per year. The occurrence of MH increased from 10.2 to 13.3 patients per million hospital discharges (P = 0.001). Mortality rates from MH ranged from 6.5% in 2005 to 16.9% in 2001 (P < 0.0001). The median age of patients with MH was 39 (interquartile range, 23-54 yr). Only 17.8% of the patients were children, who had lower mortality than adults (0.7% vs. 14.1%, P < 0.0001). Logistic regression analyses revealed that risk-adjusted in-hospital mortality was associated with increasing age, female sex, comorbidity burden, source of admission to hospital, and geographic region of the United States. CONCLUSIONS: The incidence of MH in the United States has increased in recent years. The in-hospital mortality from MH remains elevated and higher than previously reported. The results of this study should enable the identification of areas requiring increased focus in MH-related education.

Hospitalists and anesthesiologists as perioperative physicians: Are their roles complementary?

In recent years, there has been an increased emphasis on the role of anesthesiologists as perioperative physicians. However, a new group of physicians called hospitalists has emerged and established a role as perioperative physicians. Most hospitalists have specialized in internal medicine and its subspecialties. We reviewed American medical literature over the last 13 years on the roles of anesthesiologists and hospitalists as perioperative physicians. Results showed that the concept of the anesthesiologist as the perioperative physician is strongly supported by the American Board of Anesthesiology and the leaders of the specialty. However, most anesthesiologists limit their practice to intraoperative care and immediate acute postoperative care in the postanesthesia care unit. The hospitalists may fill a different role by caring for patients in the preoperative and sometimes in the postoperative period, allowing the surgeon to focus on surgery. These roles of the anesthesiologists and the hospitalists as perioperative physicians may be complementary. We conclude that if anesthesiologists and hospitalists work together as peri-operative physicians, with each specialty bringing its expertise to the care of the perioperative patient, care is likely to improve. It is necessary to be proactive and identify areas of future cooperation and collaboration.

Risk of noncardiac surgery after coronary drug-eluting stent implantation.

We examined the records of 38 patients who underwent 41 major and 18 minor noncardiac surgeries after successful drug-eluting stent (DES) implantation (57% sirolimus-eluting stents and 43% paclitaxel-eluting stents) at the Dallas Veterans Affairs Medical Center from April 2003 to January 2006. The mean patient age was 62 +/- 9 years, and all patients were men. A total of 41 major noncardiac surgeries (34% abdominal, 22% vascular, 17% genitourinary, and 27% other) were performed in 28 patients a median of 260 days after DES implantation. Also, 18 minor noncardiac surgeries (44% skin surgery, 44% injections, and 12% other) were performed in 10 patients a median of 297 days after DES implantation. No major adverse cardiac events or death occurred during or after the 41 major (0%, 95% confidence interval 0% to 9%) and 18 minor noncardiac (0%, 95% confidence interval 0% to 19%) surgeries. In conclusion, although our data were limited by the small sample size, they suggest a low risk of major cardiac complications in patients undergoing noncardiac surgery after coronary DES implantation.

Management of perioperative myocardial infarction in noncardiac surgical patients.

Perioperative myocardial infarction (PMI) is a major cause of morbidity and mortality in patients undergoing noncardiac surgery. The incidence of PMI varies depending on the method used for diagnosis and is likely to increase as the population ages. Studies have examined different methods for prevention of myocardial infarction (MI), including the use of perioperative beta-blockers, alpha(2)-agonists, and statin therapy. However, few studies have focused on the treatment of PMI. Current therapy for acute MI generally involves anticoagulation and antiplatelet therapy, raising the potential for surgical site hemorrhage in this population. This article reviews the possible mechanisms, diagnosis, and treatment options for MI in the surgical setting. We also suggest algorithms for treatment.

Comparison of knowledge of perioperative care in primary care residents versus anesthesiology residents.

Primary care physicians (internal medicine and family practice) are often asked to evaluate patients before surgery and prepare them for the procedure. The goal of our study was to examine primary care and anesthesiology resident physicians' knowledge of preoperative evaluation and preparation as well as perioperative changes during anesthesia and surgery. To this end, a questionnaire was sent to primary care resident physicians and anesthesiology resident physicians in our university hospital system. One hundred twenty questionnaires were distributed, and the overall response rate was 50.8%. Although there was agreement between anesthesiology and primary care residents in many of the areas surveyed, differences were observed in questions related to appropriateness of preoperative instructions regarding medications, utility of routine preoperative testing, and identification of expected physiologic changes during anesthesia and surgery. Of the maximum possible 36 points, the mean score for anesthesiology residents (27.55) was higher than the mean scores for primary care residents (21.4 and 20.24 for internal medicine and family practice, respectively), although overall scores were generally lower than expected for both anesthesiology and primary care residents. The level of training of the respondents did not significantly affect the responses. We conclude that primary care resident physicians were knowledgeable about most perioperative care, although some deficiencies were identified when these residents were compared with anesthesiology residents. Surveys such as ours may be used to identify areas of deficiencies that require further education for both groups of residents.

Ventilator-associated lung injury in patients without acute lung injury at the onset of mechanical ventilation.

OBJECTIVE: Although ventilation with small tidal volumes is recommended in patients with established acute lung injury, most others receive highly variable tidal volume aimed in part at normalizing arterial blood gas values. We tested the hypothesis that acute lung injury, which develops after the initiation of mechanical ventilation, is associated with known risk factors for ventilator-induced lung injury such as ventilation with large tidal volume. DESIGN: Retrospective cohort study. SETTING: Four intensive care units in a tertiary referral center. PATIENTS: Patients who received invasive mechanical ventilation for > or = 48 hrs between January and December 2001. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The main outcome of interest, acute lung injury, was assessed by independent review of daily digital chest radiographs and arterial blood gases. Ventilator settings, hemodynamics, and acute lung injury risk factors were extracted from the Acute Physiology and Chronic Health Evaluation III database and the patients' medical records. Of 332 patients who did not have acute lung injury from the outset, 80 patients (24%) developed acute lung injury within the first 5 days of mechanical ventilation. When expressed per predicted body weight, women were ventilated with larger tidal volume than men (mean 11.4 vs. 10.4 mL/kg predicted body weight, p <.001) and tended to develop acute lung injury more often (29% vs. 20%, p =.068). In a multivariate analysis, the main risk factors associated with the development of acute lung injury were the use of large tidal volume (odds ratio 1.3 for each mL above 6 mL/kg predicted body weight, p <.001), transfusion of blood products (odds ratio, 3.0; p < 0.001), acidemia (pH < 7.35; odds ratio, 2.0; p =.032) and a history of restrictive lung disease (odds ratio, 3.6; p =.044). CONCLUSIONS: The association between the initial tidal volume and the development of acute lung injury suggests that ventilator-associated lung injury may be an important cause of this syndrome. Height and gender should be considered when setting up the ventilator. Strong consideration should be given to limiting large tidal volume, not only in patients with established acute lung injury but also in patients at risk for acute lung injury.