Graeme K Hart

Critical care services and 2009 H1N1 influenza in Australia and New Zealand

BACKGROUND Planning for the treatment of infection with the 2009 pandemic influenza A (H1N1) virus through health care systems in developed countries during winter in the Northern Hemisphere is hampered by a lack of information from similar health care systems. METHODS We conducted an inception-cohort study in all Australian and New Zealand intensive care units (ICUs) during the winter of 2009 in the Southern Hemisphere. We calculated, per million inhabitants, the numbers of ICU admissions, bed-days, and days of mechanical ventilation due to infection with the 2009 H1N1 virus. We collected data on demographic and clinical characteristics of the patients and on treatments and outcomes. RESULTS From June 1 through August 31, 2009, a total of 722 patients with confirmed infection with the 2009 H1N1 virus (28.7 cases per million inhabitants; 95% confidence interval [CI], 26.5 to 30.8) were admitted to an ICU in Australia or New Zealand. Of the 722 patients, 669 (92.7%) were under 65 years of age and 66 (9.1%) were pregnant women; of the 601 adults for whom data were available, 172 (28.6%) had a body-mass index (the weight in kilograms divided by the square of the height in meters) greater than 35. Patients infected with the 2009 H1N1 virus were in the ICU for a total of 8815 bed-days (350 per million inhabitants). The median duration of treatment in the ICU was 7.0 days (interquartile range, 2.7 to 13.4); 456 of 706 patients (64.6%) with available data underwent mechanical ventilation for a median of 8 days (interquartile range, 4 to 16). The maximum daily occupancy of the ICU was 7.4 beds (95% CI, 6.3 to 8.5) per million inhabitants. As of September 7, 2009, a total of 103 of the 722 patients (14.3%; 95% CI, 11.7 to 16.9) had died, and 114 (15.8%) remained in the hospital. CONCLUSIONS The 2009 H1N1 virus had a substantial effect on ICUs during the winter in Australia and New Zealand. Our data can assist planning for the treatment of patients during the winter in the Northern Hemisphere.

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 patients 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.

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

ObjectiveTo 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. DesignProspective, controlled before-and-after trial. SettingUniversity-affiliated hospital. PatientsConsecutive patients admitted to hospital for major surgery during a 4-month control phase and during a 4-month intervention phase. InterventionsIntroduction 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 ResultsWe 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). ConclusionsThe 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.

Hypoglycemia and Outcome in Critically Ill Patients

OBJECTIVE To determine whether mild or moderate hypoglycemia that occurs in critically ill patients is independently associated with an increased risk of death. PATIENTS AND METHODS Of patients admitted to 2 hospital intensive care units (ICUs) in Melbourne and Sydney, Australia, from January 1, 2000, to October 14, 2004, we analyzed all those who had at least 1 episode of hypoglycemia (glucose concentration, <81 mg/dL). The independent association between hypoglycemia and outcome was statistically assessed. RESULTS Of 4946 patients admitted to the ICUs, a cohort of 1109 had at least 1 episode of hypoglycemia (blood glucose level, <81 mg/dL). Of these 1109 patients (22.4% of all admissions to the intensive care unit), hospital mortality was 36.6% compared with 19.7% in the 3837 nonhypoglycemic control patients (P<.001). Even patients with a minimum blood glucose concentration between 72 and 81 mg/dL had a greater unadjusted mortality rate than did control patients (25.9% vs 19.7%; unadjusted odds ratio, 1.42; 95% confidence interval, 1.12-1.80; P=.004.) Mortality increased significantly with increasing severity of hypoglycemia (P<.001). After adjustment for insulin therapy, hypoglycemia was independently associated with increased risk of death, cardiovascular death, and death due to infectious disease. CONCLUSION In critically ill patients, an association exists between even mild or moderate hypoglycemia and mortality. Even after adjustment for insulin therapy or timing of hypoglycemic episode, the more severe the hypoglycemia, the greater the risk of death.

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 &agr; 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.

Very old patients admitted to intensive care in Australia and New Zealand: a multi-centre cohort analysis.

IntroductionOlder age is associated with higher prevalence of chronic illness and functional impairment, contributing to an increased rate of hospitalization and admission to intensive care. The primary objective was to evaluate the rate, characteristics and outcomes of very old (age ≥ 80 years) patients admitted to intensive care units (ICUs).MethodsRetrospective analysis of prospectively collected data from the Australian New Zealand Intensive Care Society Adult Patient Database. Data were obtained for 120,123 adult admissions for ≥ 24 hours across 57 ICUs from 1 January 2000 to 31 December 2005.ResultsA total of 15,640 very old patients (13.0%) were admitted during the study. These patients were more likely to be from a chronic care facility, had greater co-morbid illness, greater illness severity, and were less likely to receive mechanical ventilation. Crude ICU and hospital mortalities were higher (ICU: 12% vs. 8.2%, P < 0.001; hospital: 24.0% vs. 13%, P < 0.001). By multivariable analysis, age ≥ 80 years was associated with higher ICU and hospital death compared with younger age strata (ICU: odds ratio (OR) = 2.7, 95% confidence interval (CI) = 2.4 to 3.0; hospital: OR = 5.4, 95% CI = 4.9 to 5.9). Factors associated with lower survival included admission from a chronic care facility, co-morbid illness, nonsurgical admission, greater illness severity, mechanical ventilation, and longer stay in the ICU. Those aged ≥ 80 years were more likely to be discharged to rehabilitation/long-term care (12.3% vs. 4.9%, OR = 2.7, 95% CI = 2.6 to 2.9). The admission rates of very old patients increased by 5.6% per year. This potentially translates to a 72.4% increase in demand for ICU bed-days by 2015.ConclusionsThe proportion of patients aged ≥ 80 years admitted to intensive care in Australia and New Zealand is rapidly increasing. Although these patients have more co-morbid illness, are less likely to be discharged home, and have a greater mortality than younger patients, approximately 80% survive to hospital discharge. These data also imply a potential major increase in demand for ICU bed-days for very old patients within a decade.

Blood glucose concentration and outcome of critical illness: the impact of diabetes.

Objective:To study the impact of diabetes mellitus on the relationship between glycemia and mortality in critically ill patients. Design:Retrospective observational study. Setting:Intensive care units of two university hospitals. Patients:Cohort of 4946 critically ill patients including 728 patients with diabetes mellitus. Intervention:None. Measurements and Main Results:We assessed and compared the relationship between glycemia during intensive care unit stay and mortality in diabetic and nondiabetic patients. There were 125,036 blood glucose measurements (5.7 measurements/day on average). Intensive care unit mortality increased significantly with increasing mean blood glucose concentration in nondiabetes mellitus patients but not in diabetes mellitus patients. Nondiabetes mellitus patients with a time-weighted glucose concentration (GluTw) between 8.0 and 10.0 mmol/L were found to be 1.74 times more likely to die in intensive care unit as diabetes mellitus patients in the same range (odds ratio = 1.74 [1.13–2.68] p = 0.01). They were also more than three times more likely to die in the intensive care unit compared with diabetes mellitus patients when the Glutw was between 10.0 and 11.1 mmol/L (odds ratio = 3.34 [1.35–8.23] p = 0.009). Using multivariate logistic regression analysis, hyperglycemia was strongly and independently associated with outcome in nondiabetic patients (p < 0.001) but showed no significant association with outcome in diabetic patients. Conclusions:Unlike nondiabetic patients, diabetic patients show no clear association between hyperglycemia during intensive care unit stay and mortality and markedly lower odds ratios of death at all levels of hyperglycemia. These findings suggest that, in critically patients with diabetes mellitus, hyperglycemia may have different biological and/or clinical implications. LEARNING OBJECTIVESOn completion of this article, the reader should be able to: Explain the impact of blood glucose monitoring on outcomes. Describe the impact of the diagnosis of diabetes on outcomes in patients with hyperglycemia. Use this information in a clinical setting. Dr. French has disclosed that he was the recipient of grant/research funds from Novartis and is currently receiving grant/research funds from Novartis, Wyeth, Lilly, and Takeda. Dr. French has disclosed that he was a consultant/advisor for Wyeth. The remaining authors have disclosed that they have no financial relationships with or interests in any commercial companies pertaining to this educational activity. All faculty and staff in a position to control the content of this CME activity have disclosed that they have no financial relationship with, or financial interests in, any commercial companies pertaining to this educational activity. Lippincott CME Institute, Inc., has identified and resolved all faculty conflicts of interest regarding this educational activity. Visit the Critical Care Medicine Web Site (www.ccmjournal.org) for information on obtaining continuing medical education credit.

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

IntroductionIt 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.MethodWe 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.ResultsBefore 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.ConclusionIntroduction 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.

Percutaneous versus surgical tracheostomy: A randomized controlled study with long-term follow-up*

Objective:To compare the safety, availability, and long-term sequelae of percutaneous vs. surgical tracheostomy. Design:Prospective, randomized, controlled study. Setting:Combined medical/surgical intensive care unit in a tertiary referral hospital. Patients:Two hundred critically ill mechanically ventilated patients who required tracheostomy. Interventions:Tracheostomy by either percutaneous tracheostomy or surgical tracheostomy performed in the intensive care unit. Measurements and Main Results:The primary outcome measure was the aggregate incidence of predefined moderate or severe complications. The secondary outcome measures were the incidence of each of the components of the primary outcome. Long-term follow-up included clinical assessment, flow volume loops, and bronchoscopy. Both groups were well matched for age, gender, admission Acute Physiology and Chronic Health Evaluation II score, period of endotracheal intubation, reason for intubation, and admission diagnosis. There was no statistical difference between groups for the primary outcome. Bleeding requiring surgical intervention occurred in three percutaneous tracheostomy patients and in no surgical tracheostomy patient (p = .2). Postoperative infection (p = .044) and cosmetic sequelae (p = .08) were more common in surgical tracheostomy patients. There was a shorter delay from randomization to percutaneous tracheostomy vs. surgical tracheostomy (p = .006). Long-term follow-up revealed no complications in either group. Conclusions:Both percutaneous tracheostomies and surgical tracheostomies can be safely performed at the bedside by experienced, skilled practitioners.

Relative hyperlactatemia and hospital mortality in critically ill patients: a retrospective multi-centre study

IntroductionHigher lactate concentrations within the normal reference range (relative hyperlactatemia) are not considered clinically significant. We tested the hypothesis that relative hyperlactatemia is independently associated with an increased risk of hospital death.MethodsThis observational study examined a prospectively obtained intensive care database of 7,155 consecutive critically ill patients admitted to the Intensive Care Units (ICUs) of four Australian university hospitals. We assessed the relationship between ICU admission lactate, maximal lactate and time-weighted lactate levels and hospital outcome in all patients and also in those patients whose lactate concentrations (admission n = 3,964, maximal n = 2,511, and time-weighted n = 4,584) were under 2 mmol.L-1 (i.e. relative hyperlactatemia).ResultsWe obtained 172,723 lactate measurements. Higher admission and time-weightedlactate concentration within the reference range was independently associated with increased hospital mortality (admission odds ratio (OR) 2.1, 95% confidence interval (CI) 1.3 to 3.5, P = 0.01; time-weighted OR 3.7, 95% CI 1.9 to 7.00, P < 0.0001). This significant association was first detectable at lactate concentrations > 0.75 mmol.L-1. Furthermore, in patients whose lactate ever exceeded 2 mmol.L-1, higher time-weighted lactate remained strongly associated with higher hospital mortality (OR 4.8, 95% CI 1.8 to 12.4, P < 0.001).ConclusionsIn critically ill patients, relative hyperlactataemia is independently associated with increased hospital mortality. Blood lactate concentrations > 0.75 mmol.L-1 can be used by clinicians to identify patients at higher risk of death. The current reference range for lactate in the critically ill may need to be re-assessed.