International retrieval of adults on extracorporeal membrane oxygenation support.

A retrieval service was established in New South Wales to provide mobile extracorporeal membrane oxygenation support to patients with severe, acute cardiac or respiratory failure. This service has also retrieved four adult patients from Nouméa, New Caledonia to Sydney on extracorporeal membrane oxygenation support, which are the first international retrievals of this type from Australia. We discuss our experience with these patients, three of whom survived to hospital discharge. However, one patient referred from New Caledonia died before extracorporeal membrane oxygenation could be established.

Retrieval of critically ill adults using extracorporeal membrane oxygenation: an Australian experience.

PURPOSE: A retrieval program was developed in New South Wales (NSW), Australia to provide extracorporeal membrane oxygenation support (ECMO) for the safe transport of adults with severe, acute respiratory or cardiac failure. We describe the development and results of this program and the impact of the 2009 H1N1 epidemic on this service. METHODS: An observational study of all patients who were retrieved on ECMO support in NSW, from March 1, 2007 to June 1, 2010, was carried out. RESULTS: Forty adult patients were retrieved on ECMO support (median age 34 years). The indications for retrieval were respiratory in 38 patients (of whom 16 were confirmed or suspected H1N1 cases) and cardiac in 2 patients. Two other patients died after referral but before ECMO support could be established. Patients were transported by road (n = 26, 65%), medical retrieval jet (n = 10, 25%) and helicopter (n = 4, 10%). The median retrieval distance was 250 km (range 12-1,960 km). Thirty-four patients (85%) survived to hospital discharge. Survival for respiratory indications was 87% (33/38 patients) and 50% (1/2 patients) for cardiac indications. There were no deaths or major morbidity associated with these retrievals. CONCLUSIONS: Patients with very severe respiratory failure, which was considered to preclude conventional ventilation for safe transfer to tertiary centres, were managed by an ECMO referral and retrieval program in NSW and had a high rate of survival. This program also enhanced the capacity of the state to respond to a surge in demand for ECMO support due to the H1N1 epidemic, although the role of ECMO in respiratory failure is not yet well defined.

A comparison between direct and calculated oxygen saturation in intensive care.

We investigated the discrepancy between calculated and spectrophotometrically determined oxygen saturation, and the corresponding effect of this difference on calculated oxygen uptake in 46 arterial-venous sample pairs from 28 critically ill patients. The range of discrepancy between the two methods showed limits of agreement (mean +/- 2SD) of -2.26 to +0.70% for arterial samples, and -5.52 to +4.96% for the corresponding venous samples. The effect of this variation on oxygen uptake showed limits of agreement of -43.2 to 36.0 ml/min when the discrepancy between oxygen uptake, calculated using the direct measure of saturation, was compared to that using the derived value. Multiple regression analysis showed that PCO2, temperature and 2,3 diphosphoglycerate were significantly related to saturation discrepancy with an R-squared value of 0.64 (P < 0.0001) for a subgroup of 25 venous samples. The precision of the PO2 electrode was also found to be a major contributory component to the discrepancies, particularly at venous PO2 values. Thus the use of calculated oxygen saturation may result in clinically significant inaccuracies in the assessment of some oxygen flux variables.

Intensive care treatment of patients with bleeding esophageal varices: results, predictors of mortality, and predictors of the adult respiratory distress syndrome.

OBJECTIVES: To determine the factors predicting mortality from bleeding esophageal varices and to examine the possibility of an association between the development of adult respiratory distress syndrome (ARDS) and the use of ethanolamine oleate as an esophageal variceal sclerosant. DESIGN: Retrospective review. SETTING: ICU in a teaching hospital. PATIENTS: A total of 101 patients with endoscopically confirmed bleeding esophageal varices were admitted on 124 occasions from 1985 to 1990. Mean age was 50 +/- 13.5 (SD) yrs. There were 62 males and 39 females. Using the Child-Pugh classification, 21.8% patients were class A, 38.6% class B, and 39.6% class C. Mean ICU and hospital lengths of stay were 5.4 +/- 5.1 and 19.6 +/- 16.1 days, respectively. Mean Acute Physiology and Chronic Health Evaluation (APACHE II) score on admission was 16.5 +/- 7.6. INTERVENTIONS: Endoscopic variceal sclerotherapy was performed in 99 (79.8%) of 124 ICU admissions in the 101 patients. Esophageal balloon tamponade was performed in 64 (51.6%) and a vasopressin infusion was administered in 47 (37.9%) of the 124 ICU admissions. A variety of factors was studied to find predictors of mortality and the development of ARDS. RESULTS: Forty-eight (48.5%) of the 101 patients died during the hospital stay. Independent predictors of mortality (by stepdown logistic regression) were total volume of ethanolamine oleate injected during sclerotherapy, multiple blood transfusions, Glasgow Coma Scale score, International normalized ratio for prothrombin test, and the presence of circulatory shock on ICU admission. Age, sex, Child-Pugh score, APACHE II score, serum bilirubin, albumin, and creatinine concentrations, use of esophageal balloon tamponade or vasopressin infusion, sepsis, pneumonia, congestive cardiac failure, aspiration, and ARDS were not statistically independent predictors of outcome. There was no difference in the mortality rates for the various causes of liver disease. Pulmonary complications occurred in 44 (43.6%) patients; sepsis occurred in 31 (25%) patients. ARDS developed in 14 patients (11.3% admissions, 13.9% patients). Statistically independent predictors of ARDS were sepsis, low plasma albumin concentration, use of esophageal balloon tamponade, and more than one sclerotherapy session. The volume and type of sclerosant used were not statistically independent predictors. CONCLUSIONS: Outcome is poor for patients with bleeding esophageal varices requiring ICU admission and is related to the severity of liver failure, the degree of blood loss, and failure of therapy to stop the bleeding. The findings do not support an association between the use of the sclerosant ethanolamine and the development of ARDS.

Thrombocytopenia post liver transplantation. Correlations with pre-operative platelet count, blood transfusion requirements, allograft function and outcome.

This study reports that thrombocytopenia is a universal phenomenon post hepatic transplantation. In 53 consecutive adult patients undergoing liver transplantation the platelet count fell by a mean of 63% (157 x 10(9)/l to 50 x 10(9)/l). The platelet count reached a nadir at Day 5 post-transplant but returned to pre-operative levels by Day 14. Non-parametric regression analysis found that pre-operative platelet count, blood transfusion requirements and maximum post-operative ALT values were independent predictors of the percentage fall in platelet count. No correlation was seen with length of graft cold ischaemic time or the use of University of Wisconsin (UW) solution. The nadir day correlated with maximum post-operative bilirubin and ALT, graft ischaemic time and use of UW solution. Maximum post-operative ALT was also an independent predictor of nadir platelet count. It was observed that patients who did not survive the hospital admission had lower post-operative platelet counts and these did not return to pre-operative levels by Day 14. The percentage fall in platelet count was an independent predictor of survival. Severe thrombocytopenia was associated with cerebral haemorrhage in 3 patients. This report provides evidence that allograft dysfunction (maximum post-operative bilirubin and/or AST/ALT) was the most consistent independent predictor of the nadir platelet count, nadir day and percentage fall in platelet count post liver transplantation although the exact mechanism(s) of the platelet changes remain uncertain.

Alterations in anion gap following cardiopulmonary bypass.

OBJECTIVES: To evaluate the changes in the anion gap and their relation to hyperlactatemia and alterations in plasma proteins after cardiopulmonary bypass. DESIGN: Prospective study. SETTING: Cardiothoracic intensive therapy unit. PATIENTS: One hundred eleven consecutive patients after cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: Data were collected before cardiopulmonary bypass and every 6 hrs for 24 hrs after cardiopulmonary bypass. Results were analyzed for the entire cohort and for hyperlactatemic subgroups. The major finding of this study was that the anion gap decreased significantly at all sampling periods relative to precardiopulmonary bypass values, despite the presence of clinically important hyperlactatemia. No correlation between the decrease in plasma protein concentrations and the decrease in anion gap could be demonstrated. CONCLUSIONS: The decrease in anion gap after cardiopulmonary bypass appears to represent a balance between the influences of increased serum chloride and lactate concentrations and reduced plasma protein concentrations. This analysis demonstrates the limitations of the anion gap in the evaluation of a metabolic acidosis after cardiopulmonary bypass.

Use of the cell saver during elective abdominal aortic aneurysm surgery--influence on transfusion with bank blood. A retrospective survey.

One hundred and two patients undergoing elective abdominal aortic aneurysm repair and admitted to ICU at RPAH in 1989/90 were studied. In forty patients a cell saver was used during the operative procedure (Group CS) while in the remaining sixty-two patients intraoperative blood loss was drained and discarded conventionally (Group NCS). Preoperative ASA grade and postoperative APACHE score were similar in these two groups. The amount of bank blood transfused intraoperatively was less in Group CS than in Group NCS (0.6 +/- 0.2 vs 3.3 +/- 0.3 units) (mean +/- SEM) (P less than 0.0001). The total amount of bank blood transfused during hospital admission was also less in Group CS (1.5 +/- 0.4 vs 4.8 +/- 0.4 units, P less than 0.0001). Of Group CS, 22 patients (55%) received no bank blood compared to two patients (3%) in Group NCS. There was no difference between the groups with respect to postoperative haemoglobin and creatinine levels. ICU stay was similar in both groups. We conclude that use of the cell saver reduces perioperative bank blood transfusion in elective abdominal aortic surgery.