Determinants of Serum 25-Hydroxyvitamin D Concentrations and a Screening Test for Moderate-to-Severe Hypovitaminosis D in Chinese Patients Undergoing Total Joint Arthroplasty.

BACKGROUND: Hypovitaminosis D is associated with adverse surgical outcomes. We quantified the environmental, demographic, and modifiable determinants of serum 25-hydroxyvitamin D (25-OHD) concentration and assessed the potential impact of a preoperative screening questionnaire for moderate-to-severe hypovitaminosis D (25-OHD <30 nmol/L). METHODS: In a retrospective cohort study of 227 Chinese patients (69 males and 158 females) undergoing 261 joint arthroplasty, we collected information on recent sun exposure, dietary vitamin D intake, vitamin D supplementation, and Western Ontario and McMaster Universities osteoarthritis index using a questionnaire and measured a fasting 25-OHD concentration using a liquid chromatography-tandem mass spectrometry before surgery. RESULTS: The multiple regression model on the determinants of 25-OHD concentration described 14% of the total variance, with the greatest relative contribution from ambient ultraviolet radiation (42%). A 4-item screening test for moderate-to-severe hypovitaminosis D had acceptable discrimination (area under receiver operating characteristic curve = 0.76, 95% CI, 0.65-0.87), good calibration (Hosmer-Lemeshow goodness-of-fit; P = .93). Decision curve analysis showed that the screening test can potentially reduce unnecessary 25-OHD testing by 390 per 1000 patients at a threshold probability of 10%. CONCLUSION: The screening test appears moderately useful in avoiding a substantial number of unnecessary 25-OHD testing in a setting where the prevalence of moderate-to-severe hypovitaminosis D is less than 10%.

Risk of perioperative respiratory complications and postoperative morbidity in a cohort of adults exposed to passive smoking.

OBJECTIVE: To evaluate the risks of perioperative respiratory complications and postoperative morbidity associated with active and passive cigarette smoking. BACKGROUND: Environmental tobacco smoke is associated with perioperative respiratory events in children, but its effect in adults is unknown. METHODS: We conducted a cohort study of 736 adult patients receiving general anesthesia for major elective surgery. Patients were classified according to their self-reported smoking history and urinary cotinine concentration within 48 hours before surgery. The main outcomes were composite measures of perioperative respiratory complications and postoperative morbidity on the third day after surgery. RESULTS: There were 313 (42.5%) never-smokers (reference group), 92 (12.5%) passive nonsmokers, 157 (21.3%) ex-smokers without environmental tobacco smoke exposure, 53 (7.2%) passive ex-smokers, and 121 (16.4%) smokers. The incidence of perioperative respiratory complications and postoperative morbidity was 9.5% [95% confidence interval (CI), 7.5-11.8] and 29.2% (95% CI, 26.0-32.6), respectively. Smoking was significantly associated with an increased risk of perioperative respiratory complications [relative risk (RR), 4.40; 95% CI, 2.20-8.80] and postoperative morbidity (RR, 1.86; 95% CI, 1.22-2.83). Although passive smoking was not associated with the risk of perioperative respiratory complications, the risk of postoperative morbidity was increased in passive nonsmokers (RR, 1.51; 95% CI, 1.04-2.21) and passive ex-smokers (RR, 2.21; 95% CI, 1.39-3.50). CONCLUSIONS: One in 5 adults was exposed to environmental tobacco smoke before surgery. Passive cigarette smoking showed very little, if any, increased risk of perioperative respiratory complications. Both active exposure and passive exposure to cigarette smoke increased the risk of postoperative morbidity.

The accuracy of urinary cotinine immunoassay test strip as an add-on test to self-reported smoking before major elective surgery.

INTRODUCTION: Smoking is a preventable cause of perioperative complications. An accurate and rapid classification of smoking status is essential as up to 35% of smokers deny smoking before surgery. We compared the diagnostic performance of a preoperative urinary cotinine immunoassay test strip (NicAlert®) as an add-on test to patient's self-reported smoking status. METHODS: Four hundred and sixty-five patients undergoing major elective surgery self-reported their smoking history and provided a sample for measuring urinary cotinine concentration by liquid chromatography tandem mass spectrometry (reference standard) and NicAlert®. Using the "either test positive" rule, the gain in diagnostic performance for NicAlert® add-on test was assessed using relative positive and negative likelihood ratios (LRs) and area under the receiver operating characteristic curve (AUROC) with 95% CIs. RESULTS: Of the 60 patients with a positive reference standard (adjusted cotinine ≥ 50 ng/ml), 10 (16.7%) denied current cigarette smoking. The NicAlert® add-on test had better test performance measures (sensitivity = 95.0%, specificity = 94.8%) than self-reported smoking history alone (sensitivity = 83.3%, specificity = 95.0%). The relative positive and negative LRs were 1.09 (95% CI = 0.95-1.24) and 0.30 (95% CI = 0.12-0.78), respectively. The AUROC for the NicAlert® add-on test (0.90; 95% CI = 0.84-0.96) was significantly higher than for the self-reported smoking history alone (0.78; 95% CI = 0.69-0.88) (p = .006). CONCLUSION: The NicAlert® add-on test strategy had excellent diagnostic test performance for identifying current smokers who are expected to have a high risk of perioperative complications.

The cost-effectiveness of an outpatient anesthesia consultation clinic before surgery: a matched Hong Kong cohort study.

BACKGROUND: Outpatient anesthesia clinics are well established in North America, Europe and Australia, but few economic evaluations have been published. The Perioperative Systems in Hong Kong are best described as a hybrid model of the new and old systems of surgical care. In this matched cohort study, we compared the costs and effects of an outpatient anesthesia clinic (OPAC) with the conventional system of admitting patients to the ward a day before surgery for their pre-anesthesia consultation. A second objective of the study was to determine the patient's median Willingness To Pay (WTP) value for an OPAC. METHODS: A total of 352 patients were matched (1:1) on their elective surgical procedure to either the clinic group or to the conventional group. The primary outcome was quality of recovery score and overall perioperative treatment cost (US$). To detect a difference in the joint cost-effect relationship between groups, a cost-effectiveness acceptability curve (CEAC) was drawn. A modified Poisson regression model was used to examine the factors associated with patients willing to pay more than the median WTP value for an OPAC. RESULTS: The quality of recovery scores on the first day after surgery between the clinic and conventional groups were similar (mean difference, -0.1; 95% confidence interval (CI), -0.6 to 0.3; P = 0.57). Although the preoperative costs were less in the clinic group (mean difference, -$463, 95% CI, -$648 to -$278 per patient; P <0.001), the total perioperative cost was similar between groups (mean difference, -$172; 95% CI, -$684 to $340 per patient; P = 0.51). The CEAC showed that we could not be 95% confident that the clinic was cost-effective. Compared to the conventional group, clinic patients were three times more likely to prefer OPAC care (relative risk (RR) 2.75, 95% CI, 2.13 to 3.55; P <0.001) and pay more than the median WTP (US$13) for a clinic consultation (RR 3.27, 95% CI, 2.32 to 4.64; P <0.001). CONCLUSIONS: There is uncertainty about the cost-effectiveness of an OPAC in the Hong Kong setting. Most clinic patients were willing to pay a small amount for an anesthesia clinic consultation.

Perioperative Systems as a quality model of perioperative medicine and surgical care.

OBJECTIVES: There has been a recent widespread international 'paradigm shift' to new Perioperative Systems for surgical patient care. These new systems are based on a multidisciplinary team providing an integrated process of care from the time a decision is made that a patient should have an operation until the patient has recovered from surgery. The objectives of this review were to outline the rationale for new Perioperative Systems, synthesize the evidence supporting these new systems and consider the current state of Perioperative Systems and its future development. METHODS: A systematic review of studies that focus on preoperative management practices to improve patient preparation for surgery and anaesthesia, with restriction to study designs with the highest levels of evidence for the synthesis of evidence. RESULTS: Perioperative Systems are regarded as the standard model of care in Australia, New Zealand, North America and increasingly in Europe. The benefits of Perioperative Systems include: increased surgical volume and flow (20-35%), shorter preoperative length of stay (-0.2 to -1.3 days), fewer cancellations of surgery (absolute reduction 1-8%), relative reduction in the number (23-55%) and cost (40-59%) of preoperative investigations and a lower risk of wound infection (relative risk 0.30, 95% CI 0.12-0.78) compared to the traditional system. The mean reduction in the total cost per patient associated with a Perioperative System was 8-18%. Future developments include offering health promotion activities in the weeks before surgery to improve long term patient outcomes after surgery. CONCLUSION: There is evidence of quality benefits for patients, clinicians and health administrators associated with new Perioperative Systems. Despite this, these systems are yet to be fully developed in many jurisdictions.

The additive interactions between ondansetron and droperidol for preventing postoperative nausea and vomiting.

Prophylactic ondansetron or droperidol reduces the incidence of postoperative nausea and vomiting (PONV). Previous studies showed that the combination of these two drugs produced better antiemetic effect than either drug alone. We present a nonparametric method to determine the pharmacologic interaction between ondansetron and droperidol and compared the observed response of the drug combination with that predicted from additivity. This is calculated as the product of the individual drug response, normalized to that of the controls. Five minutes before induction of anesthesia, 400 patients scheduled for laparoscopic gynecologic surgery were randomly assigned to receive 1) saline IV; 2) ondansetron 4 mg IV; 3) droperidol 1.25 mg IV; or 4) a combination of droperiodol 1.25 mg and ondansetron 4 mg IV. A standardized anesthetic technique and postoperative analgesic regimen were used. Patients were reviewed regularly for 48 h. Changes in the heart rate adjusted QT (QTc) interval were measured from electrocardiograms recorded before and 5 min after study drug administration. In a subgroup of 160 patients, QTc intervals were measured again at 2-3 h after surgery. During the first 48 h after the surgery, the proportion of patients experiencing PONV was 68% (95% CI 58-77) in the control group. A single dose of ondansetron or droperidol decreased the incidence of PONV to 30% (95% CI 21-40) and 28% (95% CI 20-38), respectively. The predicted incidence of PONV after drug combination, 11.8% (7.1-11.9), was similar to that observed, 12.1% (6.4-20.2), P = 0.94. The corresponding predicted and observed treatment responses in the combination group were 88.2% and 87.9%, respectively. There was a modest and transient increase in QTc interval after administration of ondansetron, droperidol, or their combination. The changes were however similar among groups. We conclude that the interaction between ondansetron and droperiodol was additive. Both drugs acted independently of each other through their specific mechanisms of action. The incidence of QTc prolongation did not increase with the drug combination.

Incidence and risk of adverse perioperative events among surgical patients taking traditional Chinese herbal medicines.

BACKGROUND: The use of traditional Chinese herbal medicines (TCHMs) among the presurgical population is widespread, but their impact on perioperative patient care is unclear. The authors estimated the incidence and risk of TCHM-related perioperative events. METHODS: In a Hong Kong cohort study, 601 patients undergoing major elective surgery were asked about their Western medicine and TCHM use in the 2 weeks before surgery. Unanticipated perioperative events were noted by attending anesthesiologists, blinded to patients' use of specific TCHMs. Modified Poisson regression models were used to obtain the relative risk of combined endpoints of perioperative events associated with TCHM use. RESULTS: Of the 601 patients, 483 patients (80%) took self-prescribed TCHM, and 47 (8%) took TCHM by prescription (with or without self-prescribed TCHM) in the 2 weeks before surgery. The crude incidences of any combined endpoints of preoperative, intraoperative, and postoperative events were 23% (95% confidence interval, 19-26%), 74% (95% confidence interval, 71-78%), and 63% (95% confidence interval, 59-66%), respectively. Compared with nonusers, patients who took TCHM by prescription were more likely to have a preoperative event (adjusted relative risk, 2.21; 95% confidence interval, 1.14-4.29). The authors present four case reports to highlight the effect of TCHM by prescription on prolonged activated partial thromboplastin time and hypokalemia in the preoperative period. In contrast, there was no significant association between the use of any type of TCHM and the occurrence of either intraoperative or postoperative events. CONCLUSIONS: The use of TCHM by prescription near the time of surgery should be discouraged because of the increased risk of adverse events in the preoperative period.

Possible interaction between sevoflurane and Aloe vera.

OBJECTIVE: To describe a patient with massive intraoperative bleeding after oral consumption of Aloe vera tablets. CASE SUMMARY: A 35-year-old woman lost 5 L of blood during surgery as a result of a possible herb-drug interaction between Aloe vera and sevoflurane. DISCUSSION: Aloe vera is a common herb used for antiinflammatory and antiarthritic activity, as well as antibacterial, hypoglycemic, and lipid-lowering effects. Compounds contained within Aloe vera can cause a reduction in prostaglandin synthesis, which may inhibit secondary aggregation of platelets. Sevoflurane inhibits thromboxane A(2) formation by suppression of cyclooxygenase activity, impairs platelet aggregation, and prolongs bleeding. Although the vascularity and size of the hemangioma were the most important factors for the massive intraoperative blood loss, concomitant use of sevoflurane and Aloe vera played a contributory role. An objective causality assessment revealed that this adverse event was possible as a result of the sevoflurane and Aloe vera interaction. CONCLUSIONS: There is a potential herb-drug interaction between Aloe vera and sevoflurane based on the antiplatelet effects of these 2 agents. Herbal medications with antiplatelet potential should be discontinued before anesthesia and surgery.

Educating patients about anesthesia: a systematic review of randomized controlled trials of media-based interventions.

UNLABELLED: In this systematic review, we compared the effectiveness of media-based patient education about anesthesia. Fifteen randomized controlled trials (n = 1506) were identified after a systematic search of electronic databases (MEDLINE, EMBASE, CINAHL, PSYCINFO, The Cochrane Controlled Trials Registry), published articles, and contact with authors. Outcomes assessed were anxiety, knowledge, and patient satisfaction. Anxiety levels before anesthesia were less intense in subjects receiving the video and printed information compared with those receiving no intervention (weighted mean difference of 3; 95% confidence interval [95%CI], 1-5 Spielberger's State and Trait Anxiety Inventory). Patients in the video group were more likely to answer all knowledge questions correctly compared with patients with no intervention (relative risk of 6.64; 95%CI, 2.05-21.52). The level of knowledge about pain management was higher in the video group compared with patients with no intervention (weighted mean difference of 17%; 95%CI, 9-25). However, the level of patient satisfaction with the intervention (expectation versus actual anesthetic experience) was similar between the groups (relative risk of 1.06; 95%CI, 0.93-1.22). This systematic review supports the use of video and printed information about general process and risks of anesthesia for patient education before surgery. IMPLICATIONS: The effectiveness of media-based interventions for educating patients about general process and risks of anesthesia were compared in this systematic review. The use of video and/or printed information can decrease patient anxiety and increase patient knowledge. However, patient satisfaction was similar between media-based intervention and nonintervention groups.