Surgery (Austin & Northern Health) - Research Publications
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ItemNo Preview AvailableAcid-base status of critically ill patients with acute renal failure: analysis based on Stewart-Figge methodology(BMC, 2003-08)INTRODUCTION: The aim of the present study is to understand the nature of acid-base disorders in critically ill patients with acute renal failure (ARF) using the biophysical principles described by Stewart and Figge. A retrospective controlled study was carried out in the intensive care unit of a tertiary hospital. MATERIALS AND METHODS: Forty patients with ARF, 40 patients matched for Acute Physiology and Chronic Health Evaluation II score (matched control group), and 60 consecutive critically ill patients without ARF (intensive care unit control group) participated. The study involved the retrieval of biochemical data from computerized records, quantitative biophysical analysis using the Stewart-Figge methodology, and statistical comparison between the three groups. We measured serum sodium, potassium, magnesium, chloride, bicarbonate, phosphate, ionized calcium, albumin, lactate and arterial blood gases. RESULTS: Intensive care unit patients with ARF had a mild acidemia (mean pH 7.30 +/- 0.13) secondary to metabolic acidosis with a mean base excess of -7.5 +/- 7.2 mEq/l. However, one-half of these patients had a normal anion gap. Quantitative acid-base assessment (Stewart-Figge methodology) revealed unique multiple metabolic acid-base processes compared with controls, which contributed to the overall acidosis. The processes included the acidifying effect of high levels of unmeasured anions (13.4 +/- 5.5 mEq/l) and hyperphosphatemia (2.08 +/- 0.92 mEq/l), and the alkalinizing effect of hypoalbuminemia (22.6 +/- 6.3 g/l). CONCLUSIONS: The typical acid-base picture of ARF of critical illness is metabolic acidosis. This acidosis is the result of the balance between the acidifying effect of increased unmeasured anions and hyperphosphatemia and the lesser alkalinizing effect of hypoalbuminemia.
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ItemCircadian pattern of activation of the medical emergency team in a teaching hospital(BIOMED CENTRAL LTD, 2005-08)INTRODUCTION: Hospital medical emergency teams (METs) have been implemented to reduce cardiac arrests and hospital mortality. The timing and system factors associated with their activation are poorly understood. We sought to determine the circadian pattern of MET activation and to relate it to nursing and medical activities. METHOD: We conducted a retrospective observational study of the time of activation for 2568 incidents of MET attendance. Each attendance was allocated to one of 48 half-hour intervals over the 24-hour daily cycle. Activation was related nursing and medical activities. RESULTS: During the study period there were 120,000 consecutive overnight medical and surgical admissions. The hourly rate of MET calls was greater during the day (47% of calls in the 10 hours between 08:00 and 18:00), but 53% of the 2568 calls occurred between 18:00 and 08:00 hours. MET calls increased in the half-hour after routine nursing observation, and in the half-hour before each nursing handover. MET service utilization was 1.25 (95% confidence interval [CI] = 1.11-1.52) times more likely in the three 1-hour periods spanning routine nursing handover (P = 0.001). The greatest level of half-hourly utilization was seen between 20:00 and 20:30 (odds ratio [OR] = 1.76, 95% CI = 1.25-2.48; P = 0.001), before the evening nursing handover. Additional peaks were seen following routine nursing observations between 14:00 and 14:30 (OR = 1.53, 95% CI = 1.07-2.17; P = 0.022) and after the commencement of the daily medical shift (09:00-09:30; OR = 1.43, 95% CI = 1.00-2.04; P = 0.049). CONCLUSION: Peak levels of MET service activation occur around the time of routine observations and nursing handover. Our findings raise questions about the appropriate frequency and methods of observation in at-risk hospital patients, reinforce the need for adequately trained medical staff to be available 24 hours per day, and provide useful information for allocation of resources and personnel for a MET service.
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ItemLong term effect of a medical emergency team on cardiac arrests in a teaching hospital(BMC, 2005-12)INTRODUCTION: It is unknown whether the reported short-term reduction in cardiac arrests associated with the introduction of the medical emergency team (MET) system can be sustained. METHOD: We conducted a prospective, controlled before-and-after examination of the effect of a MET system on the long-term incidence of cardiac arrests. We included consecutive patients admitted during three study periods: before the introduction of the MET; during the education phase preceding the implementation of the MET; and a period of four years from the implementation of the MET system. Cardiac arrests were identified from a log book of cardiac arrest calls and cross-referenced with case report forms and the intensive care unit admissions database. We measured the number of hospital admissions and MET reviews during each period, performed multivariate logistic regression analysis to identify predictors of mortality following cardiac arrest and studied the correlation between the rate of MET calls with the rate of cardiac arrests. RESULTS: Before the introduction of the MET system there were 66 cardiac arrests and 16,246 admissions (4.06 cardiac arrests per 1,000 admissions). During the education period, the incidence of cardiac arrests decreased to 2.45 per 1,000 admissions (odds ratio (OR) for cardiac arrest 0.60; 95% confidence interval (CI) 0.43-0.86; p = 0.004). After the implementation of the MET system, the incidence of cardiac arrests further decreased to 1.90 per 1,000 admissions (OR for cardiac arrest 0.47; 95% CI 0.35-0.62; p < 0.0001). There was an inverse correlation between the number of MET calls in each calendar year and the number of cardiac arrests for the same year (r2 = 0.84; p = 0.01), with 17 MET calls being associated with one less cardiac arrest. Male gender (OR 2.88; 95% CI 1.34-6.19) and an initial rhythm of either asystole (OR 7.58; 95% CI 3.15-18.25; p < 0.0001) or pulseless electrical activity (OR 4.09; 95% CI 1.59-10.51; p = 0.003) predicted an increased risk of death. CONCLUSION: Introduction of a MET system into a teaching hospital was associated with a sustained and progressive reduction in cardiac arrests over a four year period. Our findings show sustainability and suggest that, for every 17 MET calls, one cardiac arrest might be prevented.