摘要:

ObjectiveTo determine the effect of enteral tube feedings on the measurement of gastric intramucosal pH.DesignInterventional study.SettingTwo intensive care units of a university-affiliated teaching hospital.PatientsTwenty hemodynamically stable patients undergoing mechanical ventilation, with a nasogastric tonometer in situ, in whom enteral feeding was initiated.InterventionsThe baseline fasting gastric intramucosal pH and gastric fluid pH were determined in the study population. The patients then received enteral feedings for 2 hrs, after which the gastric intramucosal pH and gastric fluid pH measurements were repeated. The tube feedings were then withheld for 2 hrs. The data set was repeated 1 and 2 hrs after the feedings had been stopped. Finally, tube feedings were restarted and the data set was repeated after 4 hrs. All patients received a histamine-2 (H sub 2)-receptor antagonist-blocking agent during the study. To investigate the possibility that a direct reaction between gastric fluid and enteral feedings may generate CO sub 2, 30-mL aliquots of gastric fluid from an independent sample of 14 patients (seven receiving cimetidine) were mixed with 60 mL of enteral feeding in an airtight container; the PCO2of the gastric fluid before and after adding enteral feeding was measured tonometrically.Measurements and Main ResultsThe mean +/- SD gastric intramucosal pH decreased from 7.40 +/- 0.08 to 7.33 +/- 0.12 (p < .005), and from 7.38 +/- 0.07 to 7.31 +/- 0.1 (p < .005) after the first and second feeding challenges, respectively. The gastric intramucosal pH returned to the baseline value after 1 hr of fasting. The mean in vitro PCO2of the gastric fluid increased from 11.9 +/- 3.0 to 16.2 +/- 2.0 torr (1.6 +/- 0.4 to 2.1 +/- 0.27 kPa) (p = .003) after the addition of tube feedings in the samples from those patients who were not receiving H2receptor antagonists, but did not change significantly in those samples from the patients who were receiving H2receptor antagonists.ConclusionsEnteral feeding stimulates the secretion of hydrogen ions, which are then buffered by ionized bicarbonate secreted by the nonparietal gastric cells generating CO2. In addition, the enzymatic digestion of nutrients in the stomach may also generate CO2. The increased intraluminal CO2following enteral feeding results in a spuriously low gastric intramucosal pH reading. Our data suggest that tube feedings should be temporarily discontinued for at least 1 hr when measuring the gastric intramucosal pH. These data should, however, be used with caution when extrapolating to hemodynamically unstable patients. Furthermore, the consequences of frequent interruptions of enteral feeding need to be weighed against the possible benefits derived from the use of this monitoring tool.(Crit Care Med 1996; 24:1498-1500)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesTo investigate the clinical accuracy of infrared ear thermometer derived and equilibrated rectal temperatures in estimating core body temperature. The clinical bias (i.e., mean difference between body sites), and variability (SD of the differences) of simultaneous temperatures were compared with pulmonary artery temperatures. Clinical repeatability (pooled SD of triplicate reading differences) was also examined for three ear infrared thermometers.DesignProspective clinical study.SettingA multidisciplinary, adult intensive care unit.PatientsTwenty patients with an existing pulmonary artery catheter were studied in a multidisciplinary, adult intensive care unit.InterventionsA single operator using optimum ear infrared technique and masked to ear and rectal temperatures recorded triplicate measurements with each of three infrared ear thermometers, each over a 4-min period with each infrared thermometer, while an assistant recorded temperatures. Infrared and rectal temperatures were compared with a simultaneous pulmonary artery temperature.Measurements and Main ResultsInfrared ear thermometers and rectal thermometers were calibrated daily, and pulmonary artery catheters were calibrated on removal from the patient. Patients were grouped into afebrile and febrile groups, based on initial pulmonary artery temperature. Bias and variability were compared between thermometers using analysis of variance.Clinical bias, but not variability, was significantly different between three ear infrared thermometers (0.16 +/- 0.46 degrees C, 0.07 +/- 0.38 degrees C, and -0.22 +/- 0.47 degrees C). The repeatability was not different between ear infrared thermometers (range 0.13 degrees C to 0.14 degrees C). Rectal temperature had a significantly greater bias (average 0.3 degrees C), but less variability (average 0.2 degrees C). Bias was increased, and variability decreased for both rectal and infrared ear temperatures when pulmonary artery temperature was increased.ConclusionsThe three infrared ear thermometers studied provided a closer estimate of core body temperature than equilibrated rectal temperature. Clinical bias was greatest in febrile vs. afebrile intensive care unit patients.(Crit Care Med 1996; 24:1501-1506)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveThe use of the Pediatric Risk of Mortality (PRISM) score or other scoring systems in the intensive care unit (ICU) is of great importance for evaluating the efficacy and efficiency of a particular ICU. However, the PRISM score was developed and validated in the United States and subsequently validated in Europe, but has not been evaluated in a less affluent society. In general, scoring systems should be used only in populations similar to the reference population in which the prediction model was developed. We set out to determine the applicability of the PRISM score at Baragwanath Hospital, South Africa.DesignProspective, descriptive study.SettingTwenty-four-bed multidisciplinary ICU.PatientsWe analyzed 1,528 consecutive pediatric admissions from January 1989 to June 1994.InterventionsNone.Measurements and Main ResultsPRISM scores, Therapeutic Intervention Scoring System scores, demographic, and clinical data collected prospectively were entered and stored by means of a commercial software package at the time of admission of each patient. The prediction of actual mortality by PRISM scoring was evaluated by the Hosmer and Lemeshow goodness-of-fit test (chi2[8 degrees of freedom]). Receiver operating characteristic curves were constructed and compared with those curves from pediatric ICU populations in the United States and Europe. Individual receiver operating characteristic curves were constructed for surgical and nonsurgical patients, age categories, and diagnostic categories. Compared with European and American ICU populations, our patients were younger, were mostly nonsurgical emergency admissions, stayed longer in the ICU, and were more severely ill with a higher admission PRISM score and overall mortality rate. Respiratory and septic diagnoses predominated, with very few surgical cases admitted. The Hosmer and Lemeshow goodness-of-fit test showed a significant failure of the PRISM scoring system to accurately predict mortality over a wide range of expected mortality rates (chi2[8 degrees of freedom] = 465, p = 0). Similarly, receiver operating characteristic analysis indicated a poor predictive power (Az= 0.73 +/- 0.01 [SEM]), with an area under the curve significantly less than that for the PRISM reference population (p = 0). PRISM showed equally poor discriminatory function at all age groups and diagnostic categories.ConclusionsThe PRISM score needs to be recalibrated or recalculated for our patient population in view of the high discrepancy and poor discriminatory function shown. Part of the inaccuracy may derive from different demographic characteristics of our ICU population and a different pattern of diseases. It appears that PRISM is not population independent.(Crit Care Med 1996; 24:1507-1513)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo test the efficacy of a recombinant endotoxin neutralizing protein as compared with saline in rats with Escherichia coli sepsis.DesignProspective, controlled animal trial.SettingHospital animal research laboratory.SubjectsMale Wistar rats challenged with intraperitoneal E. coli, O18ac K1, and treated 1 hr later with ceftriaxone and gentamicin.InterventionsRecombinant endotoxin neutralizing protein, 50 mg/kg, was administered to rats 1, 2, or 3 hrs after E. coli challenge; saline was administered to control animals.Measurements and Main ResultsQuantitative bacteremia, 1 hr after challenge and before antibiotic administration, was not significantly different between treatment groups (range geometric mean 451 to 621 colony-forming units [cfu]/mL). The endotoxin concentration, measured immediately before recombinant endotoxin neutralizing protein administration, was significantly higher in animals sampled and treated at 2 hrs (geometric mean 260 EU/mL; 95% confidence interval 140 to 480 EU/mL), or 3 hrs (geometric mean 697 EU/mL; 95% confidence interval 307 to 1585 EU/mL) after E. coli challenge, compared with animals sampled and treated at 1 hr (geometric mean 17 EU/mL; 95% confidence interval 7 to 69 EU/mL). Survival rate was significantly greater in rats treated with recombinant endotoxin neutralizing protein at 1 hr (23/27; p < .001) or 2 hrs (8/30; p < .01) after E. coli challenge than in controls (1/32).ConclusionAdministration of recombinant endotoxin neutralizing protein delayed up to 2 hrs after challenge with E. coli improves survival in antibiotic-treated rats with Gram-negative sepsis.(Crit Care Med 1996; 24:1514-1517)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivePulmonary clearance of technetium-labeled human serum albumin was measured in order to investigate whether the surfactant layer is a rate-limiting factor for the permeability of the alveolar-capillary membrane for99mTc-labeled albumin.DesignProspective, randomized, controlled trial.SettingResearch laboratory.SubjectsNineteen white New Zealand adult rabbits.InterventionsThree groups of rabbits were studied: group 1 animals received natural surfactant after lung lavage; group 2 animals underwent lung lavage only; and group 3 animals were not lavaged and served as an untreated, healthy control group. All animals were ventilated with high pressures.Measurements and Main Resultssup 99m Tc-labeled albumin was nebulized into the inspiratory line of the breathing circuit with an air jet nebulizer. The clearance measurements were then immediately started. Gamma camera images were obtained in 1-min frames for 120 mins and stored in a 64 times 64 image matrix in a computer.In group 1 animals, surfactant restored blood gases to near normal, and all animals except one had bi-exponential clearance curves. The half-life of the fast compartment was 35.9 +/- 6.4 mins, and the half-life of the slow compartment was 847.5 +/- 143.5 mins. All group 2 animals also had bi-exponential clearance curves of the tracer (the half-lives of the fast and slow compartments were 14.6 +/- 6.7 and 459.8 +/- 167 mins, respectively). The half-lives of both the fast (p < .01) and slow (p < .01) components were significantly different between groups 1 and 2. Group 3 had a monoexponential half-life of 580 +/- 225 mins.ConclusionsThe use of99mTc-human serum albumin as a tracer molecule is possible and feasible. The clearance of this tracer is, in part, determined by the integrity of the pulmonary surfactant system, as it is with99mTc-diethylenetriamine pentaacetate.(Crit Care Med 1996; 24:1518-1523)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo document the effect of administering artificial surfactant into the trachea, either by instillation or aerosolization, on acute lung injury experimentally induced with kerosene in sheep.DesignRandomized, prospective, controlled study.SettingResearch laboratory.SubjectsSheep (n = 24), weighing 8.5 to 25.2 kg (average 16.6).InterventionsIn anesthetized, tracheally intubated sheep with pulmonary and femoral artery catheters inserted, lung injury was induced by instilling kerosene (0.3 mL/kg) into the trachea. After 15 mins of spontaneous breathing, mechanical ventilation was instituted with a uniform FIO2and a tidal volume of 10 mL/kg. Sheep were then assigned randomly to one of four regimens as follows: exogenous surfactant or saline (5 mL/kg each) was administered as a bolus intratracheally or by aerosolization for 6 hrs.Measurements and Main ResultsArterial and mixed venous blood gases, pH, airway pressure, and static respiratory system compliance were measured and compared between aerosol saline and aerosol surfactant and between bolus saline and bolus surfactant. For all variables except static respiratory system compliance, the hourly rate of change from 15 mins, 1 hr, and 6 hrs after kerosene instillation was determined for each animal, and group rank sums of hourly rates of change were compared. For static respiratory system compliance, the slope of the pressure-volume curve with volumes of 100, 200, 300, 400, and 500 mL was computed for each animal at baseline and at 3 and 6 hrs after kerosene instillation. Group rank sums for static respiratory system compliance at 3 and 6 hrs were compared. Also, the 3- and 6-hr static respiratory system compliance values at each of the volumes were compared. With saline, six of eight sheep died; with surfactant, no sheep died (p = .001). When compared with saline at 15 mins, 1 hr, and 6 hrs after kerosene instillation, surfactant, regardless of whether administered by aerosol or bolus, significantly increased rate of change of arterial oxygen saturation, mixed venous oxygen saturation, and Po2.ConclusionsIn the present animal study, artificial surfactant was an effective treatment for hydrocarbon aspiration. Aerosolized surfactant achieved results similar to instilled surfactant but at a lower total dose.(Crit Care Med 1996; 24:1524-1529)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesTo study the expression of preproendothelin-1 messenger RNA (mRNA) in tissue after Escherichia coli lipopolysaccharide challenge and to evaluate the possible effects of betamethasone both regarding endothelin-1 production as well as hemodynamic and vascular effects during E. coli lipopolysaccharide infusion in pigs in vivo.DesignProspective trial.SettingLaboratory at a university medical center.SubjectsTen domestic pigs, weighing 18 to 25 kg.InterventionsAnesthetized pigs were given continuous infusions of E. coli lipopolysaccharide (15 micro gram/kg/hr for 3 hrs), with or without prior treatment with betamethasone (0.5 mg/kg im 12 hrs before the start of the surgical preparation and 0.5/kg iv at the start of the preparation).Measurements and Main ResultsThe E. coli lipopolysaccharide infusion evoked the characteristic cardiovascular changes observed in septic shock: decreased mean arterial pressure and cardiac output; increased heart rate and increased pulmonary vascular resistance. Large increases in both arterial plasma concentrations of endothelin-1 like immunoreactivity, as well as preproendothelin-1 mRNA concentrations in tissues, were also observed during the E. coli lipopolysaccharide infusion. Treatment with betamethasone significantly attenuated the E. coli lipopolysaccharide-induced increase in endothelin-1 plasma concentrations, whereas the increased mRNA concentrations were only slightly affected. Furthermore, betamethasone treatment also affected cardiovascular parameters, with significant attenuation of the E. coli lipopolysaccharide-induced increase in heart rate and a higher cardiac output after 60 mins of the E. coli lipopolysaccharide infusion. The urine production, which was markedly decreased during the E. coli lipopolysaccharide infusion, was significantly higher in the betamethasone-treated group compared with the control group.ConclusionsThe present results indicate that the increased concentrations of endothelin-1-like immunoreactivity that are observed in septic shock may have negative effects on both cardiovascular parameters as well as renal function, which is in agreement with a possible role for endothelin-1 in the pathogenesis of septic shock.(Crit Care Med 1996; 24:1530-1536)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveIncreased release of intracellular calcium has been implicated in cell death and organ failure in endotoxemia and sepsis. We sought to test this hypothesis in a rat model of antibiotic-treated intraperitoneal sepsis with the use of dantrolene sodium, a specific inhibitor of intracellular calcium release.DesignA prospective, randomized controlled trial.SettingAn experimental animal laboratory in a university hospital.SubjectsTwo hundred fourteen male Sprague-Dawley rats.InterventionsRats were rendered septic by intraperitoneal implantation of sterile feces mixed with live Escherichia coli and allocated to control, vehicle, or dantrolene treatment. A separate group of rats had arterial catheters implanted to allow blood sampling for determination of circulating tumor necrosis factor (TNF)-alpha and lactate concentrations. Additional rats were randomized to receive vehicle or dantrolene after intravenous injection of endotoxin.Measurements and Main ResultsOver the 7-day study period, survival was significantly worse among rats that received dantrolene at a dose of 10 mg/kg, irrespective of whether treatment was started before or after induction of peritonitis. Mean whole blood lactate for each group peaked at 6 hrs after induction of infection. There were no significant differences in lactate concentration among the groups at any of the time points examined. Similarly, there were no differences among any of the groups for circulating concentrations of TNF-alpha. In rats challenged with endotoxin, dantrolene affected neither survival nor circulating concentrations of TNF-alpha.ConclusionsWe conclude that dantrolene decreases survival in bacterial sepsis and has no effect on survival in endotoxemia in rats. The importance of excessive intracellular calcium release in sepsis remains to be elucidated. (Crit Care Med 1996; 24:1537-1542)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo determine the tumor necrosis factor (TNF) receptor type involved in induction of E-selectin expression on vascular endothelial cells.DesignProspective, in vitro repeated-measures analysis of cellular responses.SettingResearch laboratory in an academic medical center.SubjectsCultured human umbilical vein endothelial cells.InterventionsHuman umbilical vein endothelial cells were incubated with recombinant human TNF (rhTNF) to induce the expression of E-selectin on their surfaces. To block rhTNF from binding to receptors, the cells were incubated with monoclonal antibodies against TNF receptors (anti-CD120a and anti-CD120b). TNF-induced E-selectin expression of the endothelial cells, with and without blocking antibodies, was then determined using indirect immunofluorescence and flow cytometry.Measurements and Main ResultsBlocking of either CD120a or CD120b receptors individually resulted in inhibition of TNF-induced E-selectin expression on human umbilical vein endothelial cells. When both antibodies were added, the inhibition of TNF-induced E-selectin expression was synergistic. Inhibition of E-selectin expression was dependent on both TNF concentrations and antibody concentrations.ConclusionsBoth CD120a and CD120b receptors are involved in TNF-induced E-selectin expression on human umbilical vein endothelial cells. Blocking of both or one receptor type can reduce or totally inhibit expression of E-selectin on human umbilical vein endothelial cells, but the response is dependent on both TNF and antibody concentrations.(Crit Care Med 1996; 24:1543-1546)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo evaluate the effects of monoclonal antibody to tumor necrosis factor (TNF)-alpha on the hemodynamic alterations and survival rate in rats subjected to intestinal ischemia/reperfusion.DesignProspective, randomized study.SettingAnimal laboratory of an institute for research in traumatology.SubjectsMale Sprague-Dawley rats, weighing 430 to 460 g.InterventionsAnesthetized rats underwent 75 mins of superior mesenteric artery occlusion followed by 6 hrs of reperfusion. The animals were treated intravenously with either TNF-alpha monoclonal antibody (TN3, 20 mg/kg) or the control protein (albumin, 20 mg/kg) 30 mins before the onset of ischemia.Measurements and Main ResultsPretreatment with TNF-alpha monoclonal antibody significantly attenuated the decreases in blood pressure and cardiac index (p < .01) compared with controls, for <or=to6 hrs after reperfusion. Stroke volume remained stable in the TNF-alpha monoclonal antibody-treated group and was significantly higher than in the control group at 0.5, 5, and 6 hrs after reperfusion (p < .05 at 0.5 and 5 hrs and p < .01 at 6 hrs). No differences in vascular resistance index values were observed between the two groups at any point in time (p < .05). After intestinal ischemia/reperfusion injury, both the portal and systemic TNF concentrations in the control animals were completely neutralized by TNF-alpha monoclonal antibody treatment. The 72-hr survival rate was significantly (p < .01) better in the treatment group (90%, 9/10) than in the control group (20%, 2/10).ConclusionsThese results suggest that intestinal ischemia/reperfusion injury can lead to increased TNF release into both the portal and the systemic circulation, which may be an important factor contributing to the development of hemodynamic dysfunction. Pretreatment with TNF-alpha monoclonal antibody significantly attenuates the cardiovascular consequences and improves the survival rate after acute intestinal ischemia/reperfusion injury.(Crit Care Med 1996; 24:1547-1553)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID