Anaphylaxis is more common with rocuronium and succinylcholine than with atracurium.

BACKGROUND: Intraoperative anaphylaxis is a rare but serious occurrence, often triggered by neuromuscular-blocking drugs (NMBDs). Previous reports suggest that the rates of anaphylaxis may be greater for rocuronium than for other NMBDs, but imprecise surrogate metrics for new patient exposures to NMBDs complicate interpretation. METHODS: This was a retrospective, observational cohort study of intraoperative anaphylaxis to NMBDs at two hospitals between 2006 and 2012. Expert anesthetic and immunologist collaborators investigated all referred cases of intraoperative anaphylaxis where NMBDs were administered and identified those where a NMBD was considered responsible. New patient exposures for each NMBD were extracted from electronic anesthetic records compiled during the same period. Anaphylaxis rates were calculated for each NMBD using diagnosed anaphylaxis cases as the numerator and the number of new patient exposures as the denominator. RESULTS: Twenty-one patients were diagnosed with anaphylaxis to an NMBD. The incidence of anaphylaxis was 1 in 22,451 new patient exposures for atracurium, 1 in 2,080 for succinylcholine, and 1 in 2,499 for rocuronium (P < 0.001). CONCLUSIONS: In Auckland, the rate of anaphylaxis to succinylcholine and rocuronium is approximately 10-fold higher than to atracurium. Previous estimates of NMBD anaphylaxis rates are potentially confounded by inaccurate proxies of new patient exposures. This is the first study to report anaphylaxis rates using a hard denominator of new patient exposures obtained directly from anesthetic records.

Pulmonary barotrauma and cerebral arterial gas embolism during hyperbaric oxygen therapy.

Hyperbaric oxygen therapy (HBOT) is used to treat a variety of disorders. It is a safe treatment modality, but rare catastrophic complications may occur. In this case report, we describe the occurrence of irreversible spastic quadriparesis in a patient who suffered a cerebral arterial gas embolism (CAGE) during decompression from HBOT. The patient had a history of respiratory disease and was subsequently found to have bullous changes in the left lung, which almost certainly predisposed to this rare event. We discuss appropriate pretreatment screening to prevent such events and highlight the paradox that HBOT, the cause of the CAGE, is also the treatment of choice.

Lax sphygmomanometer standard causes overdetection and underdetection of hypertension: a computer simulation study.

OBJECTIVE: To quantify overdetection and underdetection of hypertension caused by systematic sphygmomanometer errors permitted by the current European standard (EN 1060 'noninvasive sphygmomanometers'). METHODS: We carried out Monte Carlo simulation of measurement of blood pressure (BP) of the adult Australian population using sphygmomanometers showing systematic errors compliant with the EN 1060 standard. We repeated the simulations limiting systematic sphygmomanometer errors to +/-1 mmHg. Simulated BP measurements included systematic sphygmomanometer error, random intraindividual BP variability and random measurement error. RESULTS: After three visits, underdetection of hypertension is common owing to variability of BP measurements and systematic errors of sphygmomanometers. After three visits, the wide tolerances of EN 1060 are responsible for approximately 4.9 and 11% of underdetection of systolic and diastolic hypertension, respectively. Underdetection is worse in some groups, for example, permitted sphygmomanometer error causes 20% of all undetected systolic hypertension in 18-24 year-old women. The current standard also results in overdetection of hypertension. Permitted sphygmomanometer error causes 5.8 and 14% of the overdetection of systolic and diastolic hypertension, respectively, after three visits. Overdetection is worse in some groups, for example, after three visits, permitted sphygmomanometer error causes 19% of falsely detected diastolic hypertension in 18-24 year-old men. For all adults, reduction of permitted sphygmomanometer error to +/-1 mmHg achieves approximately the same improvement in hypertension detection as at least one additional visit to the clinician. CONCLUSION: Systematic sphygmomanometer errors permitted by the current standard are a preventable cause of clinically significant overdetection and underdetection of hypertension. The standard should be revised to make the effects of equipment related systematic errors negligible compared with the effects of physiological variability.

Blood pressure variability causes spurious identification of hypertension in clinical studies: a computer simulation study.

BACKGROUND: The blood pressure (BP) of an individual varies considerably from day to day. Hypertension is commonly identified based on the average of two BPs taken at each of two visits, a practice consistent with current guidelines. We hypothesized that (i) in the setting of high-normal BP ("prehypertension"), this practice results in frequent spurious detection of hypertension, and (ii) that random, spurious detection of hypertension and flawed study design together explain why in the Trial of Preventing Hypertension (TROPHY) study candesartan appeared to suppress the development of hypertension for 2 years after cessation of therapy. METHODS: We used Monte Carlo simulation to quantify spurious detection of hypertension at repeated clinic visits in one million subjects with unchanging usual systolic BPs (SBPs) between 130 and 139 mm Hg and normal BP variability. Criteria for identifying hypertension derived from Rosner and Polk, Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7), and the Trials of Hypertension Prevention (TOHP), TROPHY, and Framingham studies were applied to Canadian Heart Health Survey data. On the basis of these simulations, we created a three-parameter model of Kaplan-Meier curves recorded in the TROPHY study. We used the model to analyze the rates at which hypertension was identified in the TROPHY study. RESULTS: TROPHY criteria spuriously identify hypertension in 76% of subjects over 18 clinic visits. Higher rates of spurious detection of hypertension are seen with JNC 7, TOHP and Framingham study criteria. Even highly conservative criteria falsely identify hypertension in 27% of subjects over 18 visits. Our three-parameter model suggests no postdiscontinuation benefit of candesartan. CONCLUSIONS: When applied over multiple visits, current criteria for detecting hypertension are intolerant of normal BP variation. The use of conservative criteria would reduce spurious identification of hypertension. The apparent long-term beneficial effect of candesartan seen in the TROPHY study can be explained by an inadequate method for detecting hypertension, and flawed study design.