Non-invasive measurement of intrapulmonary shunt during inert gas rebreathing.

We tested the agreement between non-invasive measurement of intrapulmonary shunt, using oxygen uptake and pulmonary capillary blood flow measurement obtained by nitrous oxide rebreathing, with that measured using mixed venous blood sampling. Nine patients were recruited pre- and post-cardiac surgery resulting in 20 sets of measurements overall. Mean shunt fraction was 12.5%, and bias between methods (+/-95% confidence limits) was -0.7% (+/-0.8%). The standard deviation of the difference was 1.7% with limits of agreement between the two methods of +2.6% and -3.9%. Correlation coefficient r was 0.90. Agreement with the invasive standard was less accurate and precise where cardiac output was measured by bolus thermodilution (mean bias +1.6%, standard deviation of the difference 2.2%, limits of agreement between the two methods of +5.8% and -2.8%, r = 0.86). Good agreement was demonstrated between the non-invasive method and the invasive reference standard.

Fencl-Stewart analysis of acid-base changes immediately after liver transplantation.

OBJECTIVE: The Fencl-Stewart approach to acid-base physiology allows detailed, quantitative insights into acid-base disorders. We tested the hypothesis that this type of analysis would reveal complex acid-base changes in patients after liver transplantation that differed from those in a general intensive care unit population. METHODS: Data were collected retrospectively on patients on admission to the ICU after liver transplantation between 2001 and 2003 and prospectively on a convenience group of general ICU patients in 2001. RESULTS: Data were collected from 100 ICU patients and 83 liver transplant patients. Values for most clinical chemistry variables differed between the two groups, with considerable variation within the groups. All acid- base variables differed between the control and transplant groups (P < 0.005). Overall, the transplant group had metabolic acidosis (mean base excess +/-SD, -4.5 +/-3.1mmol/L) due to both a sodium chloride effect on base excess (-4.0 +/-4.1 mmol/L) and an other ion effect on base excess (-6.3 +/-4.2 mmol/L). The sodium chloride effect was mainly due to increased chloride concentration. All estimates of other anions (anion gap, corrected anion gap, strong ion gap, and the other ion effect on base excess) suggested that other anions play an important role in the acid-base status of patients after liver transplantation. These effects on base excess were partly offset by a greater metabolic alkalosis in the transplant group caused by a marked effect of decreased albumin on base excess (5.8 +/-1.5 mmol/L). CONCLUSIONS: The Fencl-Stewart approach allowed us to quantitatively assess the factors contributing to patients' acid-base status. We found complex acid-base changes in patients immediately after liver transplantation.

Postoperative complications and mortality in older patients having non-cardiac surgery at three Melbourne teaching hospitals.

OBJECTIVE: To determine the incidence of postoperative complications, including 30-day mortality rate, and need for intensive care unit (ICU) admission in older patients after non-cardiac surgery. DESIGN AND SETTING: Prospective observational study of all patients aged 70 years or older having elective and non-elective, non-cardiac surgery, and staying at least 1 night after surgery in one of three Melbourne teaching hospitals, June to September 2004. MAIN OUTCOME MEASURES: Postoperative complications and 30-day mortality rate. RESULTS: 1102 consecutive patients were audited in mid 2004; 70% had pre-existing comorbidities. The 30-day mortality rate was 6%; 19% had postoperative complications; and 20% of patients spent at least 1 night in ICU. On multivariate analysis, preoperative factors associated with 30-day mortality included age (odds ratio [OR], 1.09 per year over 70 years; 95% CI, 1.04-1.13; P < 0.001); increasing severity of systemic disease (American Society of Anesthesiologists physical status classification) (OR, 2.53; 95% CI, 1.65-3.86; P < 0.001); and albumin level < 30 g/L (OR, 2.23; 95% CI, 1.09-4.57; P = 0.03). Postoperative factors associated with 30-day mortality were unplanned ICU admission (OR, 3.95; 95% CI, 1.63-9.55; P = 0.003); sepsis (OR, 2.75; 95% CI, 1.17-6.47; P = 0.02); and acute renal impairment (OR, 2.40; 95% CI, 1.06-5.41; P = 0.04). Thoracic surgery was the only surgical specialty significantly associated with mortality (OR, 3.96; 95% CI, 1.44-9.10; P = 0.008) in the multivariate analysis. CONCLUSION: Older patients having surgery had high rates of comorbidities and postoperative complications, placing considerable demands on critical care services. Patient factors were often stronger predictors of mortality than the type of surgery.

Implementing a research governance framework for clinical and public health research.

Research conduct in Australia and worldwide is mostly unaudited. The purpose of good research governance is to ensure integrity in research through accountability, transparency and responsibility. Institutional responsibility for research governance has been adopted by Monash University's Department of Epidemiology and Preventive Medicine, providing clear lines of accountability for researchers as well as support and guidance. A research audit tool has been developed, identifying areas where practice could be improved especially among less experienced researchers; the most common adverse findings concerned research protocols and procedure manuals. The need for participant confidentiality, privacy and data security was found to be understood, and adhered to widely by all researchers. An evaluation of the effect of audit on researchers found that the process was well accepted.

Natural justice and human research ethics committees: an Australia-wide survey.

OBJECTIVE: To determine how familiar human research ethics committees (HRECs) are with the principles of natural justice and whether they apply these principles. DESIGN AND SETTING: A postal survey conducted between April and September 2002 of the Chairs of all HRECs registered with the Australian Health Ethics Committee of the National Health and Medical Research Council (NHMRC) in 2001. MAIN OUTCOME MEASURES: HRECs' reported familiarity with, and application of, three principles of natural justice: (1). the hearing rule, requiring a decision maker to allow a person affected by a decision to present his or her case; (2). the rule against bias, requiring a decision maker to be unbiased in the matter to be decided; and (3). the evidence rule, requiring that a decision be based on the evidence provided, and not irrelevant issues. RESULTS: From 201 Chairs of HRECs Australia-wide, we received 110 completed questionnaires (55% response rate). About 33% of respondents were very familiar with the principles of natural justice, and 25% completely unfamiliar. Most respondents felt that natural justice should be, and usually is, applied by HRECs. In cases of possible positive bias of an HREC member towards a research proposal, 70% of respondents said they would exclude the member from decision making. In cases of possible negative bias, 43% said they would exclude the HREC member. CONCLUSION: The degree of familiarity with principles of natural justice varies widely among Chairs of HRECs. While many respondents felt that HRECs usually apply natural justice, responses to questions about bias suggest that HRECs do not always exclude members with possible bias, contrary to NHMRC guidelines.