Biomedical subjects

Graeme Hart

Publications and source records attributed to Graeme Hart.

10 recordsLinked to original sources

PubMed2007

Circadian rhythm of blood glucose values in critically ill patients.

OBJECTIVE: To test whether there is a circadian rhythm of blood glucose control in critically ill patients and whether morning blood glucose is an accurate surrogate of overall blood glucose control. DESIGN: Retrospective multiple-center observational study. SETTING: Intensive care units of three tertiary hospitals and one affiliated private hospital. PATIENTS: Cohort of 8,307 consecutive critically ill patients. INTERVENTIONS: Extraction of blood glucose values from electronically stored measurements. Extraction of demographic and outcome data from unit and hospital databases. Statistical assessment of variations in blood glucose control over each 24-hr cycle. MEASUREMENTS AND MAIN RESULTS: We studied 208,362 blood glucose measurements in 8,307 patients (5.5 measurements/day/person). In each hospital, there was a circadian rhythm of blood glucose control (p<.0001). The differences between highest and lowest blood glucose concentration in different time periods in each hospital were 0.27, 0.28, 0.95, and 0.22 mmol/L. There was also significant variation in the incidence and notional duration of hyperglycemia. The differences between the lowest and highest incidence of hyperglycemia in different time periods were 3.3, 2.7, 9.9, and 2.6% in each hospital. In all four hospitals, the average blood glucose value from 5:30 am to 6:30 am was significantly lower than the 24-hr average. CONCLUSIONS: Blood glucose values and the incidence of hyperglycemia have a circadian rhythm in critically ill patients. Morning blood glucose may not be an accurate surrogate of blood glucose control over the daily cycle.

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PubMed2006

Patient monitoring and the timing of cardiac arrests and medical emergency team calls in a teaching hospital.

OBJECTIVE: To describe the timing of cardiac arrest detection in relation to episodes of Medical Emergency Team (MET) review and routine nursing observations. DESIGN AND SETTING: Retrospective observational study in a university-affiliated hospital. PATIENTS: 279 cardiac arrests involving ward patients MEASUREMENTS AND RESULTS: Cardiac arrests were allocated to one of 24 1-h intervals (24:00-00:59, 01:00-01:59, etc.). The actual hourly rate of cardiac arrests was related to the expected average hourly rate. Peak levels of cardiac arrest detection occurred during times of routine overnight nursing clinical observations between 02:00 and 03:00 (OR 3.06) and 06:00-07:00 (OR 1.95). The lowest level of cardiac arrest detection occurred between 20:00 and 21:00 (OR 0.42). After introduction of the MET there were 162 cardiac arrests, 28% of which occurred shortly after an initial MET call. The odds ratio for risk of cardiac arrest during periods of lowest MET activation (24:00-08:00) when compared with periods of highest MET activation (16:00-24:00) was 2.26. CONCLUSIONS: Cardiac arrest detection in our hospital is episodic with peak levels corresponding to periods of overnight routine nursing observations following a period when patient review is likely to be low. After the introduction of the MET there was an inverse link between detection of cardiac arrests and levels of MET activation over the 24-h period. Increased overnight utilization and earlier MET activation may further reduce the incidence of cardiac arrests at our hospital.

Chi-Square Distribution↗

PubMed2006

Blood glucose on day of intensive care unit admission as a surrogate of subsequent glucose control in intensive care.

PURPOSE: The aim of the study was to test whether the mean of the highest and lowest glucose values on day 1 (Glu(1)) is a useful surrogate marker of mean blood glucose during the totality of intensive care unit (ICU) stay (Glu(tot)). MATERIALS AND METHODS: Glu(tot) values were extracted from electronically stored biochemical databases (point-of-care laboratory) and Glu(1) values from electronically stored prospectively collected patient databases in ICUs of 4 hospitals from January 2000 to October 2004. Statistical assessment of relationship between Glu(1) and Glu(tot) was done. RESULTS: There were 197227 blood glucose measurements for 8039 patients. The average of all blood glucose measurements was 8.22 +/- 2.75 mmol/L. The difference between the average of all glucose values (N = 197227) and average of Glu(1) (n = 8039) was 0.17 mmol/L. This difference in each hospital was also small (0.26, -0.13, 0.12, and 0.37 mmol/L, respectively). CONCLUSIONS: Glu(1) was a good predictor of Glu(tot) across all study hospitals. This observation makes it possible to use Glu(1) as a surrogate of glucose control during ICU stay and opens the door to understanding ICU glucose control across the whole of Australia and New Zealand.

APACHE↗

PubMed2006

Variability of blood glucose concentration and short-term mortality in critically ill patients.

BACKGROUND: Intensive insulin therapy may reduce mortality and morbidity in selected surgical patients. Intensive insulin therapy also reduced the SD of blood glucose concentration, an accepted measure of variability. There is no information on the possible significance of variability in glucose concentration. METHODS: The methods included extraction of blood glucose values from electronically stored biochemical databases and of data on patient's characteristics, clinical features, and outcome from electronically stored prospectively collected patient databases; calculation of SD of glucose as a marker of variability and of several indices of glucose control in each patient; and statistical assessment of the relation between these variables and intensive care unit mortality. RESULTS: There were 168,337 blood glucose measurements in the study cohort of 7,049 critically ill patients (4.2 hourly measurements on average). The mean +/- SD of blood glucose concentration was 1.7 +/- 1.3 mM in survivors and 2.3 +/- 1.6 mM in nonsurvivors (P < 0.001). Using multiple variable logistic regression analysis, both mean and SD of blood glucose were significantly associated with intensive care unit mortality (P < 0.001; odds ratios [per 1 mM] 1.23 and 1.27, respectively) and hospital mortality (P < 0.001 and P = 0.013; odds ratios [per 1 mM] 1.21 and 1.18, respectively). CONCLUSIONS: The SD of glucose concentration is a significant independent predictor of intensive care unit and hospital mortality. Decreasing the variability of blood glucose concentration might be an important aspect of glucose management.

Adult↗

PubMed2005

Long term effect of a medical emergency team on cardiac arrests in a teaching hospital.

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.

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PubMed2005

Intensive insulin therapy in postoperative intensive care unit patients: a decision analysis.

RATIONALE: Intensive insulin therapy (IIT) may reduce mortality in mechanically ventilated postoperative patients. OBJECTIVES: To assess the risks and benefits of IIT in different institutions. DESIGN: Retrospective, blinded-to-outcome selection of patient cohorts from four hospitals. METHODS: Selection of a cohort of patients with clinical features similar to those reported in a recent study of IIT and of all mechanically ventilated postoperative patients from each hospital. Retrieval of information on glucose control. Assessment of risks and benefits and final outcomes. MEASUREMENTS AND MAIN RESULTS: We selected 783 consecutive patients with similar clinical and demographic features to the IIT trial control group and four general cohorts for a total of 4,150 consecutive mechanically ventilated postoperative patients. In these patients, glucose levels were measured 212,663 times for a mean value of 8.22 +/- 2.7 mmol/L (148 +/- 49 mg/dl). Intensive care unit (ICU) mortality varied from 2.2 to 13.6%. The incidence of hypoglycemia (defined as < 2.2 mmol/L) varied from 1.4 to 2.7%. Assuming a beneficial effect of IIT as reported, the number needed to treat to save one life varied from 38 in one ICU to 125 in another, whereas the rate of hypoglycemia (number needed to harm) varied from 7 to 13. CONCLUSIONS: The number needed to treat to prevent an ICU death and the associated risk of hypoglycemia (number needed to harm) with IIT vary widely according to baseline mortality, case mix, and case selection. Rational decision analysis in individual ICUs should take these factors into account.

Critical Care↗

PubMed2005

Interfacing clinical practice and error prevention.

Medication error is a major source of preventable harm to patients in hospitals and is an area in which, it is suggested, information technology will have a positive impact. This paper presents findings from part of a study that examined current information utilisation patterns during nursing medication rounds. Nursing working patterns in medication administration are poorly understood despite being one of the most likely sources of medication error. Methods used were drawn from principles of Human Computer Interaction (HCI), using a semi-structured observational tool for analysing system requirements and data elements. Results from this study indicated that clinical and contextual factors impact on nursing patterns of information handling in many ways, including documentation quality, location of information sources and current patterns of computer utilization. Numerous extraneous interruptions also impact on the ability of nurses to assimilate and use clinical information effectively. These results were used to develop a conceptual framework for interfacing error prevention in clinical practice. These insights into the human factors that are the reality of clinical practice allow us to design and develop effective information technology systems to help prevent nursing medication administration errors.

Humans↗

PubMed2004

Early and exclusive use of norepinephrine in septic shock.

BACKGROUND: The timing and use of norepinephrine (noradrenaline) (NE) in septic shock remain a matter of controversy. AIM: To study the outcome of septic patients treated with early and exclusive NE. SETTING: Tertiary Intensive Care Unit. PATIENTS: 142 patients with septic shock. INTERVENTION: Exclusive NE infusion within 24 hours of admission to ICU. METHODS AND MAIN RESULTS: Retrospective analysis of data from a unit database identified 142 patients. Their median admission simplified acute physiology score (SAPS II) score was 46 [38, 56] with 98 (69%) receiving mechanical ventilation. Mean arterial pressure (MAP) at the start of NE infusion was 60 [58, 68]mmHg. NE infusion was started at a median of 1.3 [0.3, 5.0]h after ICU admission. Restoration and maintenance of target MAP was achieved initially in all patients and, in 61.3%, within 30 min. The median peak dose of NE was 0.28 [0.14, 0.61]microg/(kg min) and the duration of infusion was 88 [42, 175]h. SAPS II predicted mortality was 40.8%, however, only 34.5% (P = 0.27) died. Among the most severely ill patients (SAPS II score >56) actual mortality was 50.0% versus 74.7% predicted (P = 0.07). CONCLUSIONS: Early and exclusive use of NE in hyperdynamic septic shock achieved a stable MAP >75 mmHg in all patients. Survival compared favorably with that predicted by illness severity scores.

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PubMed2004

Prospective controlled trial of effect of medical emergency team on postoperative morbidity and mortality rates.

OBJECTIVE: To determine whether the introduction of an intensive care unit-based medical emergency team, responding to hospital-wide preset criteria of physiologic instability, would decrease the rate of predefined adverse outcomes in patients having major surgery. DESIGN: Prospective, controlled before-and-after trial. SETTING: University-affiliated hospital. PATIENTS: Consecutive patients admitted to hospital for major surgery during a 4-month control phase and during a 4-month intervention phase. INTERVENTIONS: Introduction of a hospital-wide intensive care unit-based medical emergency team to evaluate and treat in-patients deemed at risk of developing an adverse outcome by nursing, paramedical, and/or medical staff. MEASUREMENTS AND MAIN RESULTS: We measured incidence of serious adverse events, mortality after major surgery, and mean duration of hospital stay. There were 1,369 operations in 1,116 patients during the control period and 1,313 in 1,067 patients during the medical emergency team intervention period. In the control period, there were 336 adverse outcomes in 190 patients (301 outcomes/1,000 surgical admissions), which decreased to 136 in 105 patients (127 outcomes/1,000 surgical admissions) during the intervention period (relative risk reduction, 57.8%; p <.0001). These changes were due to significant decreases in the number of cases of respiratory failure (relative risk reduction, 79.1%; p <.0001), stroke (relative risk reduction, 78.2%; p =.0026), severe sepsis (relative risk reduction, 74.3%; p =.0044), and acute renal failure requiring renal replacement therapy (relative risk reduction, 88.5%; p <.0001). Emergency intensive care unit admissions were also reduced (relative risk reduction, 44.4%; p =.001). The introduction of the medical emergency team was also associated with a significant decrease in the number of postoperative deaths (relative risk reduction, 36.6%; p =.0178). Duration of hospital stay after major surgery decreased from a mean of 23.8 days to 19.8 days (p =.0092). CONCLUSIONS: The introduction of an intensive care unit-based medical emergency team in a teaching hospital was associated with a reduced incidence of postoperative adverse outcomes, postoperative mortality rate, and mean duration of hospital stay.

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PubMed2002

A phase II randomized, controlled trial of continuous hemofiltration in sepsis.

OBJECTIVE: To study the effect of early and continuous venovenous hemofiltration (CVVH) on the plasma concentrations of several humoral mediators of inflammation and subsequent organ dysfunction in septic patients. DESIGN: Randomized, controlled trial. SETTING: Intensive care unit of a tertiary hospital. PATIENTS: Twenty-four patients with early septic shock or septic organ dysfunction. INTERVENTIONS: Random allocation to receive 48 hrs of isovolemic CVVH at 2 L/hr of fluid exchange or no hemofiltration. MEASUREMENTS AND MAIN RESULTS: We measured the plasma concentrations of complement fractions C3a and C5a, interleukins 6, 8, and 10, and tumor necrosis factor alpha at baseline and 2, 24, 26, 48, and 72 hrs. A multiple organ dysfunction score (MODS) was calculated daily for each patient until death or discharge from the intensive care unit. The concentrations of most mediators decreased between baseline and 72 hrs. Some significant falls in concentration could be identified between specific time points, but CVVH was not associated with an overall reduction in any plasma cytokine concentrations. There was also no difference between the mean cumulative MODS for control survivors (43.3 +/- 19.7) and CVVH survivors (33.2 +/- 19.0; p = .30), and no difference between the average MODS calculated for all controls (4.1 +/- 1.9) and all CVVH subjects (3.3 +/- 1.7; p = .26). CVVH did not improve oxygenation, lower the platelet count, or reduce the duration of vasopressor support and mechanical ventilation. CONCLUSIONS: Early use of CVVH at 2 L/hr did not reduce the circulating concentrations of several cytokines and anaphylatoxins associated with septic shock, or the organ dysfunction that followed severe sepsis. CVVH using current technology cannot be recommended as an adjunct to the treatment of septic shock unless severe acute renal failure is present.

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