The biochemical effects of restricting chloride-rich fluids in intensive care.

OBJECTIVE: To determine the biochemical effects of restricting the use of chloride-rich intravenous fluids in critically ill patients. DESIGN: Prospective, open-label, before-and-after study. SETTING: University-affiliated intensive care unit. PATIENTS: A cohort of 828 consecutive patients admitted over 6 months from February 2008 and cohort of 816 consecutive patients admitted over 6 months from February 2009. INTERVENTIONS: We collected biochemical and fluid use data during standard practice without clinician awareness. After a 6-month period of education and preparation, we restricted the use of chloride-rich fluids (0.9% saline [Baxter, Sydney, Australia], Gelofusine [BBraun, Melsungen, Germany], and Albumex 4 [CSL Bioplasma, Melbourne, Australia]) in the intensive care unit and made them available only on specific intensive care unit specialist prescription. MEASUREMENTS AND MAIN RESULTS: Saline prescription decreased from 2411 L in the control group to 52 L in the intervention group (p < .001), Gelofusine from 538 to 0 L (p < .001), and Albumex 4 from 269 to 80 L (p < .001). As expected, Hartmann's lactated solution prescription increased from 469 to 3205 L (p < .001), Plasma-Lyte from 65 to 160 L (p < .05), and chloride-poor Albumex 20 from 87 to 268 L (p < .001). After intervention, the incidence of severe metabolic acidosis (standard base excess <-5 mEq/L) decreased from 9.1% to 6.0% (p < .001) and severe acidemia (pH <7.3) from 6.0% to 4.9% (p < .001). However, the intervention also led to significantly greater incidence of severe metabolic alkalosis (standard base excess >5 mEq/L) and alkalemia (pH >7.5) with an increase from 25.4% to 32.8% and 10.5% to 14.7%, respectively (p < .001). The time-weighted mean chloride level decreased from 104.9 ± 4.9 to 102.5 ± 4.6 mmol/L (p < .001), whereas the time-weighted mean standard base excess increased from 0.5 ± 4.5 to 1.8 ± 4.7 mmol/L (p < .001), mean bicarbonate from 25.3 ± 4.0 to 26.4 ± 4.1 mmol/L (p < .001) and mean pH from 7.40 ± 0.06 to 7.42 ± 0.06 (p < .001). Overall fluid costs decreased from $15,077 (U.S.) to $3,915. CONCLUSIONS: In a tertiary intensive care unit in Australia, restricting the use of chloride-rich fluids significantly affected electrolyte and acid-base status. The choice of fluids significantly modulates acid-base status in critically ill patients.

Decreased catecholamine degradation associates with shock and kidney injury after cardiac surgery.

Enzymatic pathways involving catechol-O-methyltransferase (COMT) catabolize circulating catecholamines. A G-to-A polymorphism in the fourth exon of the COMT gene results in a valine-to-methionine amino acid substitution at codon 158, which leads to thermolability and low ("L"), as opposed to high ("H"), enzymatic activity. We enrolled 260 patients postbypass surgery to test the hypothesis that COMT gene variants impair circulating catecholamine metabolism, predisposing to shock and acute kidney injury (AKI) after cardiac surgery. In accordance with the Hardy-Weinberg equilibrium, we identified 64 (24.6%) homozygous (LL), 123 (47.3%) heterozygous (HL), and 73 (28.1%) homozygous (HH) patients. Postoperative catecholamines were higher in homozygous LL patients compared with heterozygous HL and homozygous HH patients (P < 0.01). During their intensive care stay, LL patients had both a significantly greater frequency of vasodilatory shock (LL: 69%, HL: 57%, HH: 47%; P = 0.033) and a significantly longer median duration of shock (LL: 18.5 h, HL: 14.0 h, HH: 11.0 h; P = 0.013). LL patients also had a greater frequency of AKI (LL: 31%, HL: 19.5%, HH: 13.7%; P = 0.038) and their AKI was more severe as defined by a need for renal replacement therapy (LL: 7.8%, HL: 2.4%, HH: 0%; P = 0.026). The LL genotype associated with intensive care and hospital length of stay (P < 0.001 and P = 0.002, respectively), and we observed a trend for higher mortality. Cross-validation analysis revealed a similar graded relationship of adverse outcomes by genotype. In summary, this study identifies COMT LL homozygosity as an independent risk factor for shock, AKI, and hospital stay after cardiac surgery. (ClinicalTrials.gov number, NCT00334009).

Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia.

BACKGROUND: Cardiac arrest outside the hospital is common and has a poor outcome. Studies in laboratory animals suggest that hypothermia induced shortly after the restoration of spontaneous circulation may improve neurologic outcome, but there have been no conclusive studies in humans. In a randomized, controlled trial, we compared the effects of moderate hypothermia and normothermia in patients who remained unconscious after resuscitation from out-of-hospital cardiac arrest. METHODS: The study subjects were 77 patients who were randomly assigned to treatment with hypothermia (with the core body temperature reduced to 33 degrees C within 2 hours after the return of spontaneous circulation and maintained at that temperature for 12 hours) or normothermia. The primary outcome measure was survival to hospital discharge with sufficiently good neurologic function to be discharged to home or to a rehabilitation facility. RESULTS: The demographic characteristics of the patients were similar in the hypothermia and normothermia groups. Twenty-one of the 43 patients treated with hypothermia (49 percent) survived and had a good outcome--that is, they were discharged home or to a rehabilitation facility--as compared with 9 of the 34 treated with normothermia (26 percent, P=0.046). After adjustment for base-line differences in age and time from collapse to the return of spontaneous circulation, the odds ratio for a good outcome with hypothermia as compared with normothermia was 5.25 (95 percent confidence interval, 1.47 to 18.76; P=0.011). Hypothermia was associated with a lower cardiac index, higher systemic vascular resistance, and hyperglycemia. There was no difference in the frequency of adverse events. CONCLUSIONS: Our preliminary observations suggest that treatment with moderate hypothermia appears to improve outcomes in patients with coma after resuscitation from out-of-hospital cardiac arrest.

Circadian pattern of activation of the medical emergency team in a teaching hospital.

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.

Features and outcome of patients receiving multiple Medical Emergency Team reviews.

BACKGROUND AND OBJECTIVES: There is no information on the clinical features and outcome of patients receiving multiple Medical Emergency Team (MET) reviews. Accordingly, we studied the characteristics and outcome of patients receiving one MET call and compared them with those receiving multiple MET reviews. DESIGN: Retrospective observational study using prospectively collected data. SETTING: Tertiary hospital. PATIENTS: Cohort of 1664 patients receiving 2237 MET reviews over a 2-year period. MEASUREMENTS AND MAIN RESULTS: We retrieved information about patient demographics, reasons for MET review, procedures performed by the MET and hospital outcome. We found that 1290 (77.5%) patients received a single MET review and 374 (22.5%) received multiple MET reviews (mean 2.5 reviews, median 2.0). Multiple MET reviews were more likely to be in surgical patients (p < 0.001) and to be due to arrhythmias (p = 0.016). Multiple MET review patients were more likely to be admitted for gastrointestinal diseases (p < 0.001), had a 50% longer hospital stay (p < 0.001) and a 34.6% increase in hospital mortality (p < 0.001) compared to single MET review patients. Their odds ratio (OR) for mortality was 2.14 (95% C.I.: 1.62-2.83; p < 0.001). After exclusion of patients with not for resuscitation (NFR) orders, the OR for mortality was 2.92 (95% C.I.: 2.10-4.06; p < 0.001). The in-hospital mortality of patients subject to multiple MET reviews who were not designated NFR was 34.1%, but only 9.7% of these deaths occurred within 48 h of the initial MET review. CONCLUSION: In our hospital, one fifth of patients receiving MET calls are subject to multiple MET calls. Such patients have identifiable features and have an increased risk of morbidity and mortality. Within any rapid response system, such patients should be recognized as a higher risk group and receive specific additional attention.

Post-hypoxic myoclonic status: the prognosis is not always hopeless.

A 67-year-old woman abruptly developed acute pulmonary oedema, severe bradycardia and then cardiac arrest while in hospital 6 days after an elective hernia repair. She was resuscitated, intubated and transferred to the intensive care unit. Within 24 hours, she began to display repetitive, generalised myoclonic jerks that failed to respond to therapy with conventional anticonvulsants; an electroencephalogram confirmed myoclonic status. After administration of levetiracetam was begun on Day 3, myoclonic jerks reduced, and there was gradual clinical improvement. By Day 6 after the arrest, the patient was alert and oriented (Glasgow Coma Score, 15/15). Although she died on Day 11 after massive haemoptysis and cardiac arrest, this patient demonstrates the possibility of reasonable neurological recovery despite early onset of myoclonic status.

Life-threatening respiratory failure from H1N1 influenza 09 (human swine influenza).

We present the first six cases of H1N1 influenza 09 (confirmed by a polymerase chain reaction test from nasopharyngeal swabs) in patients requiring admission to intensive care in Australia (in three hospitals in the north-western suburbs of Melbourne). These cases highlight the small but significant risk of life-threatening respiratory failure associated with H1N1 influenza 09 infection.

Interventions to circumvent intensive care access block: a retrospective 2-year study across metropolitan Melbourne.

OBJECTIVES: To measure the prevalence of interventions used to circumvent intensive care access block and to estimate the attributable mortality and additional hospital bed-days associated with them. DESIGN AND SETTING: Retrospective observational study of 11 adult public hospital intensive care units (ICUs) in Melbourne, Victoria, July 2004 - June 2006. MAIN OUTCOME MEASURES: Prevalence of five interventions in response to access block; attributable fatalities and/or increased length of stay associated with each. RESULTS: 21 896 ICU admissions and 3039 inhospital deaths (13.9%) were screened. All hospitals reported ICU access block. There were 6787 interventions for access block (mean, 9.3/day) -- 4070 (18.6% of admissions) instances of after-hours step-down from an ICU to a low-acuity ward; 1115 (5.1%) delays in an emergency department > 8 hours; 895 (4.1%) postponed major surgeries; 487 (2.2%) interhospital transfers; and 220 (1.0%) instances of premature cessation of intensive care. Based on published risk estimates, these interventions may have resulted in 91.1 (95% CI, 34.7-147.2) attributable deaths and 4368 (95% CI, 333-10 050) additional hospital bed-days each year. CONCLUSIONS: Intensive care access block is frequent, and measures to circumvent it increase mortality and length of stay. Further study of the health and financial implications of access block are warranted.

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.