Biomedical subjects
Publications and source records attributed to D Ernest.
Psittacosis is a systemic disease that causes fever, headache and pneumonia. Although potentially serious, it is rarely fatal unless respiratory or renal failure occurs. In this case report we describe a case of psittacosis with an unusual clinical picture for this disease and where, despite multi-organ failure, the patient survived.
OBJECTIVE: To determine ICU registrars' level of awareness regarding measurement of intra-abdominal pressure (IAP), features of intra-abdominal hypertension (IAH), and management of abdominal compartment syndrome (ACS). METHODS: We surveyed 40 Australasian ICU registrars attending a post-graduate teaching course in 2004. The survey questions explored clinical experience and understanding of IAP, methods of measurement of IAP, diagnosis and causes of IAH and management of ACS in critically ill patients. RESULTS: The survey recorded a 90% response rate. Ninety two percent of the ICU registrars had used IAP in their clinical practice; 52% of those with experience in IAP measurement had only employed it infrequently. While 90% affirmed their knowledge that IAP can rise due to intraperitoneal pathology, causation of IAH by retroperitoneal conditions was poorly understood. Ninety two per cent correctly said that ACS should be treated by abdominal decompression. Only 70% of our respondents felt confident not to perform a computed tomography (CT) scan of the abdomen before treating a patient with ACS. The majority understood the need for, and the modes of, therapy for ACS; but 33 % erroneously said that they would treat IAP > 30 mmHg regardless of organ dysfunction and another 22 % were unsure of the threshold of therapy for ACS. CONCLUSIONS: ICU registrars in Australasia appreciate the techniques for, and significance of, IAP measurements and recognise and treat ACS appropriately. Retroperitoneal causes of IAH and the threshold for treatment for ACS were not well understood by the respondents.
This report describes a fatal case of the propofol infusion syndrome in an adult patient being sedated for a closed head injury using high doses of propofol. The features of circulatory collapse, metabolic acidosis, mild rhabdomyolysis and renal impairment are consistent with the syndrome and not readily attributable to alternative aetiologies. Potential mechanisms for the syndrome may relate to antagonism of beta-receptors, impaired myocardial oxygen utilization and a specific disruption to fatty-acid oxidation. This is the first published Australian case of the propofol infusion syndrome in an adult and should serve as an additional case report to the existing literature highlighting this potentially fatal syndrome in adults.
OBJECTIVE: To determine the relative distribution of fluid within the extracellular fluid volume (ECFV) and the effect on oxygen delivery after infusing either normal saline or 5% albumin in cardiac surgical patients. DESIGN: Prospective, randomized, unblinded, interventional study. SETTING: Cardiac surgical intensive care unit in a 450-bed teaching hospital. PATIENTS: Postoperative cardiac surgical patients (n = 40). INTERVENTIONS: Infusion of either normal saline or 5% albumin to a hemodynamic end point determined by the patient's clinician. MEASUREMENTS AND MAIN RESULTS: Plasma volume (PV), ECFV, cardiac index, and arterial oxygen content were measured immediately before (baseline) and after each fluid infusion. PV and ECFV were measured by dilution of (131)I-albumin and [(35)S]sodium sulfate, respectively. Interstitial fluid volume (ISFV) was calculated as ECFV - PV. Baseline values for PV, ISFV, ECFV, and oxygen delivery index did not differ between treatment groups. Infusion of normal saline and 5% albumin increased PV by 9 +/- 23% and 52 +/- 84% of the volume infused, respectively (p <.05), whereas there was no significant difference between saline and albumin in the change in ISFV per volume infused. Only 5% albumin significantly increased cardiac index, although oxygen delivery did not change significantly after either infusion. CONCLUSIONS: In postoperative cardiac surgical patients, infusion of 5% albumin is approximately five times as efficient as a PV expander but has comparable effects on changes in ISFV and oxygen delivery relative to normal saline.
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We analyzed tissue samples from bottlenose dolphins (Tursiops truncatus) that had stranded on beaches in Texas and Florida over a 1-year period starting in September 1991. The concentrations of 10 elements plus methyl mercury (MeHg) were determined in brain, kidney, and liver, and we examined these results for differences based upon age, site, sex, and tissue type. A strong inverse relationship between total mercury (Hg) and the percentage that was MeHg was found in liver, kidney, and brain tissue, presumably due to demethylation of MeHg. A threshold concentration was found for total Hg in brain tissue, indicating that most Hg was present as MeHg up to about 8 years of age. Increases in total Hg after this age were accompanied by an increase in the ratio of total Hg to MeHg, indicating demethylation. Strong relationships were found between total Hg in liver and age and between total Hg and selenium in liver, which have been observed before in many fish- and squid-eating marine mammals. The only difference based on sex of the animals was observed for MeHg, which was higher in females and contrary to the pattern often observed for organic contaminants. Several elements (copper, Hg, lead, zinc) exhibited intersite differences, which were not consistent. Bottlenose dolphin from Florida exhibited the highest levels of MeHg and total Hg, while animals from Texas exhibited the highest levels of lead, copper, and zinc. The essential elements copper and zinc were expected to be the same for the Texas and Florida animals; however, observed differences may indicate population differences in basic physiological levels, dietary intake, or health status.
Contamination of marine invertebrates by aromatic compounds (ACs) can occur from a variety of environmental sources, both natural and anthropogenic. Invertebrate species bioaccumulate ACs because they metabolize and eliminate them at a much slower rate than do vertebrates, such as fish. We have developed a high-performance liquid chromatography (HPLC) UV fluorescence screening method that measures ACs in invertebrate tissues. Screening methods have proven to be useful in response to environmental emergencies (e.g., oil spills) and in environmental monitoring because they are more rapid and less expensive than detailed analyses. This method was validated using three species of bivalves and lobster hepatopancreas and tail muscle as test samples. The AC screening method at naphthalene, phenanthrene, and benzo[a]pyrene wavelength pairs showed good correlation to GC/MS results. The method was also used successfully in response to the North Cape oil spill, off Narragansett, Rhode Island.http://link.springer-ny. com/link/service/journals/00244/bibs/37n2p220.html
OBJECTIVE: To determine the relative distribution of fluid within the extracellular fluid volume (ECFV) after infusing either normal saline or 5% albumin in septic, critically ill patients. DESIGN: Prospective, randomized, unblinded, interventional study. SETTING: Intensive care unit in a 450-bed, tertiary care, teaching hospital. PATIENTS: Septic, critically ill patients (n = 18). INTERVENTIONS: Infusion of either normal saline or 5% albumin to a hemodynamic end point determined by the patient's clinician. MEASUREMENTS AND MAIN RESULTS: Plasma volume (PV), ECFV, cardiac index, and arterial oxygen content were measured immediately before (baseline) and after each fluid infusion. PV and ECFV were measured by dilution of 131I-albumin and 35S sodium sulfate, respectively. Interstitial fluid volume (ISFV) was calculated as ECFV - PV. Baseline values for PV, ISFV, ECFV, and oxygen delivery index did not differ between treatment groups. Infusion of normal saline increased the ECFV by approximately the volume infused, and the expansion of the PV to ISFV was in a ratio of 1:3. Infusion of 5% albumin increased the ECFV by double the volume infused, with both the PV and ISFV expanding by approximately equal amounts. Oxygen delivery index did not increase after either infusion due to the effect of hemodilution. CONCLUSION: Expansion of the ECFV in excess of the volume of 5% albumin infused suggests that fluid may move from the intracellular fluid volume to the ECFV in septic patients who receive this fluid.
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The bronchial circulation, as opposed to the pulmonary circulation, is the likely source of the edema and inflammatory cells that contribute to airflow obstruction and airway narrowing associated with asthma and pulmonary edema. The purpose of this study was to understand the mechanism of edema formation and inflammation in airway walls. Therefore, we sought first to determine the normal bronchial venous drainage pathways. In anesthetized, ventilated, open-chest sheep we measured the relative distribution of 51Cr-labeled red blood cells to the right and left ventricles after injection into the bronchial artery (n = 7). Using this information, we then studied the kinetics of leukocytes in the bronchial vascular bed. We measured the extraction of 111In-labeled neutrophils during their first pass through the microvasculature after injection into the bronchial artery or right ventricle (n = 6). In the first set of experiments, we found > 85% of the systemic blood flow to the lung returns to the left ventricle. In the second set of experiments, we found that extraction of neutrophils in the bronchial vasculature (50-60%) was less (P < 0.05) than that in the pulmonary vasculature (80%). This finding may be explained by differences in the anatomy and/or hydrodynamic dispersal forces between the pulmonary and bronchial vascular beds or may reflect sequestration of neutrophils within the pulmonary microvasculature while traversing bronchial-to-pulmonary anastomotic pathways.
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To test whether endogenous endothelial nitric oxide (NO) influences baseline bronchial vascular tone and mediates acetylcholine (ACh)-induced bronchial vascular dilation and/or modulates bronchoconstriction in ovine airways, we studied anesthetized ventilated open-chest sheep and measured bronchial blood flow (Qbr) and pulmonary resistance (RL). In six sheep we measured the response of Qbr and RL to the dose of ACh required to produce 50% of the maximal increase in Qbr at baseline during infusion of the NO synthase inhibitor NG-nitro-L-arginine (L-NNA; 10(-2) M). Infusion of L-NNA decreased both the baseline Qbr (28 +/- 13 to 8 +/- 2 ml/min, P < 0.01) and the change in Qbr (delta Qbr) from the baseline value (84 +/- 42 to 33 +/- 18 ml/min, P < 0.05). There was no difference in baseline RL or in the response of RL to ACh at any time. In another six sheep, phenylephrine (5 x 10(-6) to 5 x 10(-7) M) decreased baseline Qbr (22 +/- 6 to 10 +/- 3 ml/min, P < 0.05) but not delta Qbr (62 +/- 13 to 66 +/- 21 ml/min, not significant). Infusion of L-NNA in these sheep decreased the baseline Qbr to a similar extent (11 +/- 5 ml/min) and also decreased delta Qbr (42 +/- 16 ml/min, P < 0.05). We conclude that endogenous endothelial NO influences baseline vascular tone and ACh-induced vasodilation of the ovine bronchial vasculature but has no effect on baseline RL or ACh-induced bronchoconstriction.
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.
OBJECTIVE: To investigate the feasibility of predicting gentamicin dosing requirements during continuous arteriovenous hemodiafiltration (CAVHD). DESIGN: Prospective study. SETTING: General intensive therapy unit in a university teaching hospital. PATIENTS: Five adult patients with acute renal failure in whom both dialytic and gentamicin therapy were indicated. MEASUREMENTS AND MAIN RESULTS: CAVHD clearance and total body clearance of gentamicin were estimated from serial gentamicin concentrations in the blood and the combined ultrafiltrate and dialysate. Results (mean +/- SD) were: CAVHD clearance of gentamicin 5.2 +/- 1.8 mL/min; total body clearance of gentamicin 20.5 +/- 6.9 mL/min; ultrafiltrate flow rate 7.0 +/- 2.4 mL/min (420 +/- 146 mL/hr). CAVHD clearance of gentamicin was small and represented approximately 25% of total body clearance of gentamicin, although significant interpatient variation existed in these measurements and in the proportion of total gentamicin clearance attributable to CAVHD. CAVHD clearance of gentamicin was related to the ultrafiltrate flow rate (r2 = .81). CONCLUSIONS: CAVHD clearance of gentamicin may be predicted for variable ultrafiltrate flow rates. However, due to its minor and variable contribution to total body clearance of gentamicin, prediction of gentamicin dosing requirements based on estimates of CAVHD clearance of gentamicin would be precluded and close monitoring of circulating gentamicin concentrations during CAVHD is necessary.
Plasma and extracellular fluid (ECF) volume measurements may provide valuable complementary data to the hemodynamic measurements currently used to compare fluid infusions in critically ill patients. To assess the reproducibility of plasma and extracellular fluid volume measurements in critically ill patients, we injected 131I-labeled albumin (10 microCi) and 35S-sodium sulfate (50 microCi), respectively, into 15 stable patients on two occasions 150 min apart. Plasma was sampled at 20, 30, and 40 min after each injection and the volume of distribution of each radioisotope was calculated from the extrapolated zero time counts. We found that plasma and ECF volume did not differ significantly between the first (42.4 +/- 4.7 ml/kg and 186 +/- 39 ml/kg) and second (42.8 +/- 5.5 ml/kg and 193 +/- 48 ml/kg) measurements. Specifically, the mean difference between the two measurements was 0.4 +/- 3.2 ml/kg and 7 +/- 17 ml/kg respectively. We conclude that measurements of plasma and ECF volume are reproducible over 150 min in stable critically ill patients.
Acute adrenal insufficiency due to bilateral adrenal haemorrhage is an important clinical diagnosis and its association with heparin-induced thrombocytopaenia is infrequent. We report on a patient in whom life threatening acute adrenal insufficiency occurred consequent to such an association. The clinical manifestations simulated septic shock, highlighting the need to consider specifically acute adrenal insufficiency in such settings, and institute therapy promptly prior to obtaining results of confirmatory tests.
The clearance of vancomycin during therapy with continuous arteriovenous hemodiafiltration (CAVHD) has been measured in vivo. Vancomycin clearances (n = 16) were 0.636 +/- 0.269 L/h (10.5 +/- 4.46 ml/min). Effective drug clearances were proportional to ultrafiltrate volumes, reflecting convective clearance. Clearances of vancomycin on CAVHD were approximately twice the values seen with continuous arteriovenous hemofiltration. These data allow construction of a dosing schedule for vancomycin therapy in patients receiving renal support via CAVHD.
We report the results of continuous arteriovenous haemodiafiltration (CAVHD) treatment in 12 critically ill intensive care patients with acute renal failure (eight males, four females - mean age 60.9 years - range 47 to 76) (APACHE II score 28.8, range 18-37). All patients were oligoanuric or had a rising creatinine (greater than or equal to 100 microM/L per day). Vascular access was obtained by Scribner shunt or wide-bore femoral arterial and venous cannulae. At the beginning of CAVHD therapy the mean plasma urea was 38 mM/L (SE 4.5, 95% confidence interval (CI) 25.1 to 75.6 mM/L) and the mean creatinine was 604 microM/L (SE 70, 95% CI 450-756 microM/L). After 72 hours of therapy, despite oligoanuria, urea concentration had fallen to a mean of 15.7 mM/L (SE 2.4, 95% CI 12.5-22.9 mM/L) and the creatinine concentration to 297 microM/L (SE 25, 95% CI 243-351 microM/L), respectively. The mean ultrafiltrate volume was 441 mL/hr (SE 33, 95%, range 50-1050 mL/hr). There were no complications related to the extracorporeal circuit, the filter, anticoagulant therapy, electrolyte status or changes in patients' haemodynamic state. Excellent biochemical control of azotaemia was uniformly achieved during CAVHD therapy. Five patients (41.6%) survived to be discharged from the Intensive Care Unit. CAVHD is a simple, safe and effective continuous renal replacement therapy. CAVHD offers technical advantages over alternative therapy while providing equivalent or better biochemical control of azotaemia and volume status in critically ill patients with acute renal failure.