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Biomedical subjects

B D Schouten

Publications and source records attributed to B D Schouten.

14 recordsLinked to original sources
PubMed1999

Predicting infection in localized intraabdominal fluid collections: value of pH and pO2 measurements.

PURPOSE: To evaluate the use of pH, pO2, and the subjective opinion of the radiologist compared with bacterial culture in accurate diagnoses of bacterial infection in intraabdominal fluid collections. MATERIALS AND METHODS: Prospectively, 79 patients who were suspected of having an intraabdominal fluid collection underwent diagnostic fluid aspiration. The aspirate was cultured and measured for pH and pO2. A pH < or = 7.1 and a PO2 < or = 49 mm Hg were threshold values used to separate infected from sterile fluid collections. RESULTS: pH alone had a 92% sensitivity and 79% specificity, whereas PO2 alone had a 51% sensitivity and 79% specificity. pH or pO2 combined yielded a 92% sensitivity and 60% specificity. The radiologist's opinion produced a 83% sensitivity and 92% specificity. pH and the radiologist's opinion combined produced a 78% sensitivity and 96% specificity. pH or the radiologist's opinion combined had a 95% sensitivity and a 63% specificity. CONCLUSION: pH is the most sensitive indicator of infection and the radiologist's opinion is the most specific. We recommend proceeding to drainage if the radiologist believes the collection to be infected and performing pH analysis if not. If the pH < or = 7.04, proceed to drainage. If neither of the above criteria are met, drainage could be delayed, pending the results of culture.

Abdominal Abscess↗
PubMed1998

Evaluation of a ventilation strategy to prevent barotrauma in patients at high risk for acute respiratory distress syndrome. Pressure- and Volume-Limited Ventilation Strategy Group.

BACKGROUND: A strategy of mechanical ventilation that limits airway pressure and tidal volume while permitting hypercapnia has been recommended for patients with the acute respiratory distress syndrome. The goal is to reduce lung injury due to overdistention. However, the efficacy of this approach has not been established. METHODS: Within 24 hours of intubation, patients at high risk for the acute respiratory distress syndrome were randomly assigned to either pressure- and volume-limited ventilation (limited-ventilation group), with the peak inspiratory pressure maintained at 30 cm of water or less and the tidal volume at 8 ml per kilogram of body weight or less, or to conventional ventilation (control group), with the peak inspiratory pressure allowed to rise as high as 50 cm of water and the tidal volume at 10 to 15 ml per kilogram. All other ventilatory variables were similar in the two groups. RESULTS: A total of 120 patients with similar clinical features underwent randomization (60 in each group). The patients in the limited-ventilation and control groups were exposed to different mean (+/-SD) tidal volumes (7.2+/-0.8 vs. 10.8+/-1.0 ml per kilogram, respectively; P<0.001) and peak inspiratory pressures (23.6+/-5.8 vs. 34.0+/-11.0 cm of water, P<0.001). Mortality was 50 percent in the limited-ventilation group and 47 percent in the control group (relative risk, 1.07; 95 percent confidence interval, 0.72 to 1.57; P=0.72). In the limited-ventilation group, permissive hypercapnia (arterial carbon dioxide tension, >50 mm Hg) was more common (52 percent vs. 28 percent, P=0.009), more marked (54.4+/-18.8 vs. 45.7+/-9.8 mm Hg, P=0.002), and more prolonged (146+/-265 vs. 25+/-22 hours, P=0.017) than in the control group. The incidence of barotrauma, the highest multiple-organ-dysfunction score, and the number of episodes of organ failure were similar in the two groups; however, the numbers of patients who required paralytic agents (23 vs. 13, P=0.05) and dialysis for renal failure (13 vs. 5, P= 0.04) were greater in the limited-ventilation group than in the control group. CONCLUSIONS: In patients at high risk for the acute respiratory distress syndrome, a strategy of mechanical ventilation that limits peak inspiratory pressure and tidal volume does not appear to reduce mortality and may increase morbidity.

Barotrauma↗
PubMed1998

Predicting the need for reoperation for abdominal infection.

Abdominal infection complicating abdominal operation is a serious clinical problem that is subject to diagnostic delay, which is a risk factor for adverse outcomes. Clinical examination and laboratory and imaging modalities become more accurate at achieving a diagnosis once the patient becomes sicker from infection but cannot reliably predict the need for reoperation early in the postoperative course. The Abdominal Reoperation Predictive Index scoring system synthesizes common sense and objective measurements in an attempt to predict the need for reintervention before it is too late. We encourage other centers to test this predictor in their own patient populations.

Abdomen↗
PubMed1995

Inhibition of human group II phospholipase A2 by C-reactive protein in vitro.

Endotoxin or cytokine-induced expression of a secretory non-pancreatic phospholipase A2 (sPLA2) has been implicated in the pathogenesis of multisystem organ dysfunction or failure in patients with septic shock. Circulating sPLA2 levels increase as much as 1000-fold during the course of septic shock. However, the mode of regulation of the activity of this lipolytic enzyme is unknown, since circulating inhibitors have not been identified. We investigated the potential inhibitory activity of the acute phase reactant, C-reactive protein (CRP), a phospholipid-binding protein whose expression increases as much as 1000-fold during severe infections. Serum CRP and sPLA2 profiles were highly concordant in patients with septic shock. In studies in vitro, human CRP inhibited hydrolysis of PC-lyso-PC (2:1) multilamellar liposomes by human recombinant sPLA2 in a dose-dependent manner, with an apparent IC50 of 50 micrograms/ml CRP and maximal inhibition at 100 micrograms/ml. Inhibition of sPLA2 activity by CRP was substrate concentration-dependent, and increasing substrate concentrations reversed the inhibitory effect of CRP using the PC-lyso-PC system. Preincubation of CRP with phosphorylcholine led to a concentration-dependent loss of CRP-induced inhibition of substrate hydrolysis. These observations are consistent with a substrate-depletion model of inhibition of sPLA2 activity by CRP.

C-Reactive Protein↗
PubMed1995

Survival of acute myelogenous leukemia patients requiring intubation/ventilatory support.

A 5-y (1987-1992) retrospective chart review assessed the survival of patients with acute myelogenous leukemia (AML) who required intubation/ventilatory support in the intensive care unit (ICU). Thirty-two patients were identified, average age 52 +/- 19 (range 14-82) y. Seven patients had undergone bone marrow transplantation for AML 2 weeks to 4 months prior to admission. Of the remaining 25 patients, 16 received chemotherapy prior to admission, 6 started or continued chemotherapy in the ICU, and 3 patients did not receive any chemotherapy. The Apache II score, which quantifies illness severity, on admission to the ICU was 32.5 +/- 8.8. The average length of stay was 7.4 d. Twenty-nine patients had diffuse pulmonary infiltrates on admission, 2 patients had large pleural effusions, and 1 patient had severe bronchospasm with a clear chest X-ray. The average PaO2/FiO2, when first stabilized on mechanical ventilation, was 204 +/- 83. Of the 32 patients, 28 died in the ICU, and 3 died shortly after withdrawal of aggressive therapy and discharge to the ward. A single patient survived the hospital admission but died 4 months later at home. The observed vs. the predicted ICU mortality determined by Knaus' method, was significantly greater even for those with lower Apache II scores. Acute myelogenous leukemia patients had a greater mortality than 2 other intubated patient populations in our ICU admitted during the same time period, a group of 126 consecutive admissions and 53 patients with connective tissue disease. The latter 2 control groups only included patients requiring mechanical ventilation. We conclude that AML patients who require ventilatory support for acute respiratory failure rarely survive their ICU admission.

APACHE↗
PubMed1994

Steroids, APACHE II score, and the outcome of abdominal infection.

OBJECTIVE: To compare the outcome of abdominal infection in patients with or without previous systemic glucocorticoid therapy and to determine the effect of steroid administration on the relationship between APACHE II (Acute Physiology and Chronic Health Evaluation) scores and mortality. HYPOTHESIS: Steroid therapy leads to greater mortality and relatively lower APACHE II scores. DESIGN: Prospective cohort study. SETTING: University hospital. PATIENTS: Two hundred ninety-seven consecutive adult patients with abdominal infection treated by surgical or percutaneous drainage. Treatment was at the clinician's discretion. Seventy-one patients received systemic steroid therapy. OUTCOME MEASURES: APACHE II score, clinical course, and death in hospital; relationship between APACHE II score and mortality in the steroid and no steroid groups. RESULTS: Thirty-three patients receiving steroid therapy (46%) died vs 55 (24%) of 226 patients not receiving steroid therapy. The APACHE II score (P < .0001) and steroid administration (P = .04) were each independently associated with death. Steroid-treated patients had the same probability of dying as "nonsteroid" patients with an APACHE II score a mean of 3.7 points higher (95% confidence limits, 0.03 and 7.7). The confidence that 2, 3, or 4 extra APACHE II points is the appropriate correction for steroid-treated patients is 80%, 60%, or 40%, respectively. CONCLUSIONS: Patients receiving steroid therapy appear to be at higher risk of dying of abdominal infection than predicted by APACHE II scores. The number of patients receiving cancer chemotherapy was too small to determine whether this was an additional risk factor. In the design of clinical trials stratified by APACHE II scores, steroid-treated patients should either be excluded or assigned two extra APACHE II points.

Abdomen↗
PubMed1994

Deferoxamine induces hypotension in experimental gram-negative septicemia.

Multiple organ system failure may result from tissue damage caused by activated neutrophils or endotoxin. A significant part of this tissue damage is due to peroxidation induced by oxygen-free radicals and requires iron as a co-factor. Iron chelation has been shown to prevent tissue damage in some models. This experiment was carried out to determine whether iron chelation with deferoxamine (DFO) would prevent lung damage in a swine model of Gram-negative septicemia. Fifteen animals were randomized to control, Pseudomonas aeruginosa infusion at a rate of 2 x 10(7) colony forming units/20 kg/min (septic group), or Pseudomonas infusion combined with DFO pretreatment at a dose of 80 mg/kg/h (septic-treated group). Three of six septic-treated animals became severely hypotensive and died during the course of the experiment as opposed to none of six septic animals. Surviving septic-treated animals were significantly hypotensive (60 +/- 24 mmHg mean arterial pressure) compared to septic (122 +/- 9 mmHg) and control (109 +/- 8 mmHg) animals. DFO did not improve respiratory function (e.g., pO2) or morphology in septic animals. We conclude that iron-chelation therapy with DFO at the above dosage results in a significant deterioration in cardiovascular function in septic swine. Lung damage was not prevented.

Animals↗
PubMed1992

Serum phospholipase A2 enzyme activity and immunoreactivity in a prospective analysis of patients with septic shock.

Massive elevations of serum phospholipase A2 activity have been documented in patients with septic shock. Serum PLA2 activity correlated to the degree and duration of circulatory collapse, while purified native PLA2 reproduced hypotension in experimental animals. In a prospective study of patients with septic shock, we have determined the relationship of PLA2 enzyme activity to PLA2 immunoreactivity using radiolabelled E. coli phospholipid substrate and an ELISA specific for group II human nonpancreatic PLA2. In all patients, there was a clear concordance of the two assays. Maximal PLA2 concentration was increased a mean of 554-fold over normal levels. We found no evidence to support the presence of activating or inhibitory proteins. These data confirm that the observed increase in serum PLA2 activity in septic shock is due to intravascular release of group II nonpancreatic PLA2.

Antibodies, Monoclonal↗
PubMed1991

Pneumonia complicating abdominal sepsis. An independent risk factor for mortality.

Nosocomial pneumonia (NP) is associated with a significant mortality, 66% in a previous retrospective study of NP complicating intra-abdominal sepsis (IAS). We prospectively compared the outcome of NP complicating IAS with that of recurrent IAS (R-IAS) in the absence of NP. Data were collected prospectively on 300 patients with IAS; 34 patients who presented with pneumonia were excluded from the analysis (44% mortality). One hundred seventy-one patients with no NP and no R-IAS (group 1) had a hospital mortality of 20% (34 patients); 36 without NP in whom R-IAS developed (group 2) had a 17% mortality (six patients); and 47 with NP but no R-IAS (group 3) had a 53% mortality (25 patients). Finally, 12 patients who had both NP and R-IAS suffered a 75% mortality (nine patients). We examined the relationships among the following putative risk factors and mortality: APACHE (acute physiology and chronic health evaluation) II score (at initial presentation with IAS), the need for mechanical ventilatory assistance following initial treatment for peritonitis, steroid requirement, generalized peritonitis vs abscess, and the need for surgical as opposed to percutaneous treatment. Using mortality as the dependent variable, group 2 vs 3 as the explanatory variable, and the risk factors as confounders, logistic regression analysis indicated that the group difference was significant after controlling for confounders. We conclude that NP complicating IAS is an independent risk factor associated with a significant mortality compared with R-IAS. These data challenge the notion that death in IAS is usually due to recurrent or persistent intra-abdominal infection.

Abdomen↗
PubMed1990

PC-based system for collection and analysis of physiological data.

A personal computer based system for data acquisition and analysis appropriate to physiological experiments is described in detail. The system is independent of the details of the analog signal generation. The software, written in C, is modular and easily portable to other PC systems. The system is capable of: (a) sampling many analog signals at an appropriate rate (100 Hz), (b) storing large quantities of digitized data, (c) analysing digitized waveforms to obtain signal parameters, and (d) storing signal parameters in a format suitable for statistical analysis. Computer processed cardiopulmonary data are compared with data derived from standard ICU equipment.

Algorithms↗
PubMed1989

Cardiopulmonary responses to Pseudomonas septicemia in swine: an improved model of the adult respiratory distress syndrome.

Bacteremia with resultant damage to multiple organ systems remains a serious problem in intensive care of human patients. We have developed a clinically relevant swine model of sepsis-induced adult respiratory distress syndrome (ARDS). Twenty-three animals were given various doses of Pseudomonas aeruginosa intravenously. Low cardiac output septic shock was prevented with massive fluid infusion. It was found that a dose of 1.0 X 10(7) colony forming units per 20 kg/min for 2 hours reliably produced respiratory failure in a setting of hyperdynamic sepsis which meets the diagnostic criteria of human ARDS.

Animals↗
PubMed1988

APACHE II score and abdominal sepsis. A prospective study.

Therapeutic trials for intra-abdominal sepsis require pretreatment stratification; physiologic scoring has been recently proposed for this purpose. We have prospectively tested the validity of one such scoring system, namely, the Acute Physiology and Chronic Health Evaluation (APACHE II). As part of a larger database, we correlated APACHE II scores with mortality in 100 patients hospitalized for generalized peritonitis or abdominal abscess. Use of steroids was recorded because of our suspicion that steroids increase mortality but blunt the physiologic response to sepsis. Thirty-one patients died, including 12 of 19 patients receiving steroids. Stepwise discriminant analysis revealed that the APACHE II score and steroid use were each independently associated with the rate of mortality. We report a prospective validation of pretreatment APACHE II scoring in abdominal sepsis. Steroid use is an independent risk factor.

Abscess↗
PubMedDate not supplied

Is outpatient surgery safe for the higher risk patient?

The trend toward outpatient surgery led to this study to determine the safety of elective outpatient laparoscopic surgery for the higher risk patient. One hundred consecutive higher risk patients from all patients scheduled for elective outpatient laparoscopic surgery were studied prospectively in a 256-bed community hospital. Seventeen percent of patients required admission. In each instance the need was readily evident in the perioperative observation period. Eighty-three percent of patients were stable and were successfully treated as outpatients. No patient who remained stable decompensated later, and none required readmission to treat complications resulting from outpatient status. The 2% readmission rate (for unrelated reasons) was comparable to the 2% readmission rate for low-risk patients. It was concluded that routine outpatient laparoscopic surgery is safe for elective higher risk patients. Problems requiring admission are readily evident during the period of observation and no patient who remains stable decompensates later.

Adult↗