摘要:

ObjectivePatients in the intensive care unit (ICU) undergo acute increases in metabolic and cardiopulmonary demands in response to routine care interventions, such as chest physical therapy. This study examined whether the short-acting drug, propofol, could blunt the responses to chest physical therapy.DesignProspective, randomized, crossover (placebo vs. drug) study.SettingUniversity hospital surgical ICU.PatientsPostoperative ICU patients being ventilated in the synchronized intermittent mandatory ventilation mode.InterventionsTwo groups of 16 patients were studied. Each patient received two successive sessions of chest physical therapy. In random fashion, one was preceded by the administration of placebo and the other by an intravenous bolus of propofol (0.75 mg/kg in one group and 0.35 mg/kg in the other group). Each session was preceded and followed by a period of rest.Measurements and Main ResultsThe increases in oxygen uptake, CO2elimination, oxygen delivery, heart rate, and systolic blood pressure associated with chest physical therapy were attenuated with the low dose and suppressed with the high dose of propofol. The PaCO2concentration was slightly increased during both placebo and drug administration.ConclusionsPropofol, in the doses administered in this study, significantly reduced the hemodynamic and metabolic stresses caused by chest physical therapy.(Crit Care Med 1996; 24:612-617)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesTo evaluate the training of clinical staff in the use of interhospital transfer guidelines and to examine the underlying decision-making behavior in organizing patient transfers between hospitals.DesignProspective assessment of clinical scenarios, given before (time 1), immediately after (time 2), and 3 months after (time 3) a program informing clinical staff about the use of interhospital transfer guidelines.SettingThree emergency departments and one intensive care unit at three hospitals and a medical retrieval service in Sydney, Australia.SubjectsPhysicians, nurses, and a paramedic working in critical care areas and at a medical retrieval service.InterventionsFifteen minutes of training in the use of interhospital transfer guidelines, conducted by a trained nurse.Measurements and Main resultsA questionnaire containing clinical scenarios was administered to clinical staff. There was a significant difference in mean scores for selecting the appropriate escort levels across time (F2,78 equals 24.2; p less than .01) and for participant's experience with interhospital transfer (F sub 2,39 equals 4.63; p equals .02). Significant improvement in mean scores occurred between time 1 (7.55 plus minus 1.84) and time 2 (9.48 plus minus 1.47) (t41equals minus 6.21; p less than .01). The improvement in selecting appropriate escorts was maintained at time 3 (mean score 9.86 plus minus 2.01). The error rate for inappropriate assignment of low levels of escorts decreased from 35% (time 1) to 10% (time 2) and 14% (time 3). Using conjoint analysis, there were large variations in the decision-making behavior between each time period. The relative importance of each factor in influencing the decision to organize an escort at time 3 were as follows: treatment (43%); physiology (29%); patient age (24%); and diagnosis (4%). The decision-making model observed at time 3 had a high predictive value (87%) as compared with the model at time 1 (48%).ConclusionClinical staff can make informed and appropriate decisions by using standardized guidelines when organizing interhospital transfers.(Crit Care Med 1996; 24:618-622)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo examine if either nociceptive somatic nerve stimulation or skeletal muscle injury modified systemic hemodynamics and oxygen transport and utilization after resuscitation from hemorrhage in anesthetized pigs.DesignProspective, randomized, controlled laboratory study.SettingAnimal laboratory.SubjectsTwenty isoflurane-anesthetized and mechanically ventilated large white pigs.InterventionsThree groups of animals were instrumented with femoral arterial and thermodilution pulmonary artery catheters. One group of animals had bilateral brachial nerve electric stimulation before hemorrhage (brachial nerve stimulation plus hemorrhage, n equals 7). The second group of animals had bilateral hindlimbs skeletal muscle injury induced by firing a captive-bolt handgun with standard charges before hemorrhage (skeletal muscle injury plus hemorrhage, n equals 6). The third group had neither insult before hemorrhage (control, n equals 7). Controlled bleeding was initiated to reduce the cardiac index and systemic oxygen delivery (DO2) by 50% in all animals. Animals were then left for 30 mins before resuscitation. All animals were resuscitated with 4.5% human serum albumin at 45 mL/kg and observed for 2 hrs.Measurements and Main ResultsPlasma volume, systemic hemodynamics, and oxygen transport variables were measured and calculated after resuscitation. Similar increases of plasma volume and supranormal cardiac index were observed in all groups immediately after resuscitation. The brachial nerve stimulation and hemorrhage group maintained higher heart rate, cardiac index, DO2, and oxygen consumption (VO2) than the hemorrhage group. In contrast, the skeletal muscle injury and hemorrhage group had lower systemic mean arterial pressure and vascular resistance, and a tendency for decrease in VO2, than the hemorrhage group, although heart rate, cardiac index, and DO2were similar in both groups. Hemorrhage increased the arterial plasma lactate concentration, which was later normalized in all groups 60 mins after resuscitation.ConclusionsNeither nociceptive brachial nerve stimulation nor skeletal muscle injury attenuated the increases in plasma volume, cardiac index, or the repayment of systemic oxygen debt after resuscitation from hemorrhage. Brachial nerve stimulation was associated with augmented cardiac index, systemic DO2, and increased VO sub 2 requirements related to increased sympathetic nervous system activation. Skeletal muscle injury produced early systemic arterial hypotension and vasodilation, and a decrease in VO2that was suggestive of pathologic supply dependency on systemic DO2.(Crit Care Med 1996; 24:623-630)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo compare inferior vena cava-right atrial extracorporeal bypass with intraluminal atriocaval shunting during hepatic vascular isolation.DesignProspective, randomized, controlled animal study.SettingUniversity research laboratory.SubjectsAdult mongrel dogs (n equals 5) weighing 20 to 27 kg.InterventionsAnesthetized dogs underwent laparotomy and sternotomy for vascular isolation. For atriocaval shunting, 20- and 24-Fr intraluminal shunts were inserted into the inferior vena cava via right atriotomy. For extracorporeal bypass, each animal underwent inferior vena cava, portal vein, and right atrial cannulation for venovenous bypass, utilizing a centrifugal pump. Hemodynamic data were recorded at baseline and at intervals after caval occlusion, Pringle maneuver, and caval occlusion with Pringle maneuver.Measurements and Main ResultsIsolated Pringle maneuver and caval occlusion with Pringle maneuver produced significant reductions in mean arterial pressure (MAP) and cardiac output, irrespective of pulmonary artery occlusion pressure. Extracorporeal bypass, including both caval and portal venous return, produced significant increases in MAP and cardiac output during caval occlusion with Pringle maneuver, while atriocaval shunting and extracorporeal bypass without portal venous return did not improve MAP or cardiac output.ConclusionVenovenous extracorporeal bypass with portal return, acting as a right ventricular assist device, is superior to intraluminal atriocaval shunting in maintaining hemodynamic stability during hepatic vascular isolation.(Crit Care Med 1996; 24:631-634)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Objectivesa) To determine the significance of stress-induced alterations in intestinal permeability by measuring the transmucosal flux of formyl-methionyl-leucyl-phenylalanine (f-MLP), a ubiquitous neutrophilic chemoattractant present in the human and rodent colon; and b) to determine whether stress and/or diet influence(s) bacterial adherence-induced changes in epithelial permeability by affecting the production of secretory immunoglobulin A (IgA), the main immune mechanism preventing bacterial adherence.DesignProspective, randomized, controlled study.SettingUniversity animal research laboratory.SubjectsFemale Fischer rats.InterventionsRats were randomly assigned to four groups of seven animals each. Groups of animals were assigned to receive saline or dexamethasone (0.8 mg/kg ip) and were either starved (5% dextrose in water ad libitum) or fed (water and rat chow) for 48 hrs.Measurements and Main ResultsMucosal barrier function was evaluated by measuring secretory IgA, bacterial adherence to the intestinal mucosa, and transepithelial electrical resistance, a measure of tight junction permeability. The f-MLP permeation across the mucosa was also determined in segments with significant permeability changes. Results indicate that starvation in dexamethasone-treated rats significantly impairs secretory IgA, promotes bacterial adherence to the mucosa, and results in increased intestinal permeability to f-MLP. These effects are significantly attenuated by the feeding of rat chow.ConclusionsAlterations in intestinal barrier function are characterized by depressed IgA, bacterial adherence to the intestinal mucosa, and permeation of clinically relevant proinflammatory luminal macromolecules (f-MLP). Enteral stimulation with food-stuffs is a necessary protective measure to prevent altered epithelial barrier function during glucocorticoid stress.(Crit Care Med 1996; 24:635-641)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo assess the effects of lidocaine on the hemodynamic and inflammatory responses to Escherichia coli endotoxemia in rabbits.DesignProspective, randomized, controlled experimental study.SettingUniversity laboratory.SubjectsTwenty-seven female Japanese rabbits, anesthetized with urethane and ventilated mechanically.InterventionsAnimals were randomly assigned to one of three groups: a) endotoxemic control group (n equals 9), receiving intravenous Escherichia coli endotoxin (0.5 mg/kg bolus) via the mesenteric vein; b) laparotomy control group (n equals 9), treated identically to the endotoxemic control group, except for substitution of 0.9% saline for endotoxin; and c) lidocaine-treated group (n equals 9), treated identically to the endotoxemic controls and additionally, intravenous lidocaine (3 mg/kg bolus, followed by infusion at 2 mg/kg/hr) was administered immediately after endotoxin.Measurements and Main ResultsWe compared hemodynamics, blood gases, and microscopic findings of lung tissue obtained at necropsy in each group. Laparotomy alone had a minimal effect on the parameters and findings. Endotoxin injection decreased mean systolic arterial pressure from 135 plus minus 6 (SD) to 95 plus minus 25 mm Hg (p less than .05) and increased the mean base deficit from minus 1.2 plus minus 1.8 to minus 14.4 plus minus 4.2 mmol/L (p less than .05), and caused the infiltration of neutrophils into the lungs. Lidocaine administration abolished the hypotension and attenuated the increase of base deficit to minus 9.5 plus minus 2.1 mmol/L (p less than .05) and the cellular infiltration in comparison with endotoxemic controls.ConclusionsLidocaine attenuated the hemodynamic and inflammatory responses to endotoxemia in rabbits. Findings suggest that lidocaine administration may prevent the development of hypotension and metabolic acidosis during endotoxemia.(Crit Care Med 1996; 24:642-646)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesTo examine the mechanism of cardiac assist with systolic jet ventilation, specifically effects on loading conditions and left ventricular pressure-volume function. Both systolic and diastolic jet ventilation were compared in the absence and presence of heart failure.DesignProspective, two-factor, repeated-measures study.SettingAnimal laboratory.SubjectsTen anesthetized, closed-chest dogs.InterventionsThe measurement protocol consisted of two phases: a) apnea, randomized jet ventilation (systole- and diastole-synchronized); b) postjet ventilation apnea, before and after heart failure, induced with a propranolol-imipramine-plasma expansion treatment.Measurements and Main ResultsSystolic or diastolic jet ventilation was associated with mean airway pressures of approximate 7 mm Hg and intrapleural pressures of approximate 3 mm Hg in both heart conditions. In normal hearts, jet ventilation (either mode) decreased transmural left ventricular end-diastolic pressure by 40% to 60% (p less than .05), left ventricular end-diastolic volume 25 plus minus 8%, and stroke volume by 28% to 30%. Heart failure was associated with decreases (41 plus minus 6%) in end-systolic pressure-volume function (i.e., pressure change/volume change or elastance), transmural left ventricular end-systolic pressure (22 plus minus 3%), and stroke volume (16 plus minus 4%), and increased transmural left ventricular end-diastolic pressure (139 plus minus 6%). Application of jet ventilation (either mode) during heart failure did not affect stroke volume but significantly (p less than .05) attenuated transmural left ventricular end-diastolic pressure by 30% to 40%, left ventricular end-diastolic volumes by 33 plus minus 9%, and transmural left ventricular end-systolic pressure by 11% to 19% (p less than .05). After jet ventilation, left ventricular elastance was decreased 36 plus minus 8% in normal hearts and 35 plus minus 11% in failing hearts. Stroke volume, however, returned to baseline levels because of increases in transmural left ventricular end-diastolic pressure in both heart conditions, and also in failing hearts, because transmural left ventricular end-systolic pressure remained decreased approximate 30% (p less than .05).ConclusionsJet ventilation did not decrease stroke volume in failing hearts because of the afterload-reducing benefit (decreased transmural left ventricular end-systolic pressure) of increased intrapleural pressure in dilated ventricles. Moreover, jet ventilation did not have positive effects on myocardial function and had negative effects on left ventricular elastance in the postjet ventilation period in both normal and failing hearts. Cardiac assist by jet ventilation was not cycle specific, suggesting no selective benefit of jet ventilation over conventional positive-pressure ventilation during heart failure. These studies demonstrate a negative inotropy associated with jet ventilation that, during heart failure, may compromise the general benefit of positive-pressure-mediated increases in intrapleural pressure.(Crit Care Med 1996; 24:647-657)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo evaluate the effect of jet ventilation on tracheal stenosis in dogs and plastic models.DesignProspective, randomized trial in dogs, and multitrial tests in tracheal stenosis models.SettingAnimal laboratory in a university setting.InterventionsTracheal stenosis was surgically created around the middle of the trachea. Conventional mechanical ventilation and jet ventilation were compared at the same value of PaCO2in dogs and at the same tidal volume in tracheal stenosis models.SubjectsTwelve mongrel dogs and four types of plastic models with combinations of short or long stenosis and fluid or nonfluid stenosis.Measurements and Main ResultsCanine Studies. Mean peak airway pressure values at the distal and proximal portion of the stenosis, and the end-expiratory pressure at the distal portion of the stenosis, were significantly higher during conventional mechanical ventilation than during jet ventilation. The mean values of arterial pressure, pulmonary arterial pressure, central venous pressure, and cardiac output did not change significantly between conventional mechanical ventilation and jet ventilation, except for the pulmonary artery occlusion pressure value.Plastic Mold Studies. Peak airway pressure and end-expiratory airway pressure at the poststenotic trachea during jet ventilation with the model lung were significantly lower than during conventional mechanical ventilation. The difference in peak airway pressure and end-expiratory airway pressure values between jet ventilation and conventional mechanical ventilation increased more in short stenosis and nonfluid stenosis.ConclusionsThe jet flow that struck the portion of the stenosed wall reversed direction, even during early expiration. Therefore, the expiration during jet ventilation was facilitated more by the reversed flow than by the expiration during conventional mechanical ventilation. This reversed flow may provide lower end-expiratory airway pressure at the poststenotic portion with jet ventilation than with conventional mechanical ventilation.We conclude that jet ventilation was a useful method of ventilation in cases with tracheal stenosis, especially nonfluid and short stenosis.(Crit Care Med 1996; 24:658-662)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo test the effects of three hemoglobin solutions on liver function and hepatic morphology after resuscitation from severe hemorrhagic shock.DesignProspective study.SettingLaboratory.SubjectsThirty-three beagle dogs.InterventionHemorrhagic shock was induced in anesthetized dogs by removal of blood at a rate of 2 mL/kg/min until systolic blood pressure (BP) reached 50 mm Hg. BP was maintained at this level for 2 hrs by further withdrawing 5 to 10 mL aliquots whenever BP increased more than 50 mm Hg. Resuscitation was then initiated with autologous whole blood (n equals 7), 4% pyridoxalated-hemoglobin-polyoxyethylene conjugate (4% PHP [n equals 6]), 8% pyridoxalated-hemoglobin-polyoxyethylene conjugate (8% PHP [n equals 9]), or 8% stroma-free hemoglobin (n equals 7). Four dogs were managed identically but were not resuscitated. Gross necropsy and histologic examination of the liver were performed on all dogs after 7 days, or earlier if death occurred.Measurements and Main ResultsIn vitro interferences of PHP and stroma-free hemoglobin with liver function tests were determined and recommendations for interpretation of results from blood samples containing PHP and stroma-free hemoglobin were made. Blood was collected before, during, and after resuscitation from hemorrhagic shock. The dogs were then awakened and survivors were monitored daily with blood sampling until they were killed and necropsy was performed.After 7 days, the survival rate following hemorrhagic shock was 100% for whole blood and 4% PHP, 86% for stroma-free hemoglobin, and 33% for 8% PHP. Of the resuscitated dogs not surviving 7 days, all but one died within 27 hrs from coagulopathy. All dogs not resuscitated died within 1.75 hrs after 2 hrs of shock. Bilirubin, alkaline phosphatase, and lactic dehydrogenase concentrations could not be measured due to interferences of stroma-free hemoglobin and PHP. Aspartate (AST) and alanine (ALT) aminotransferase concentrations could be measured after dilution to overcome the interferences. Significant increases in AST and ALT values in all groups 24 hrs after resuscitation were attributed to hypoxic hepatocellular damage associated with the severity of the shock model rather than to the resuscitation fluid. Liver histology showed no changes attributed to toxic damage of hepatocytes in dogs resuscitated with stroma-free hemoglobin or PHP. However, the histologic changes, particularly hepatocellular hydropic changes, were less severe in dogs resuscitated with 4% PHP than in other groups.ConclusionMorphologic studies at necropsy and liver function tests in dogs receiving hemoglobin solutions, compared with autologous blood, support the conclusion that the PHP and stroma-free hemoglobin solutions tested did not produce hepatic toxicity when used as resuscitation fluids in this model of severe shock.(Crit Care Med 1996; 24:663-671)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo evaluate and compare the predictive powers of clinical examination, electroencephalography (EEG), and studies of short-latency somatosensory evoked potentials in determining the prognosis in anoxic coma.DesignProspective case series of patients in anoxic coma, whose prognoses were uncertain based on previously established clinical criteria. The clinical features, EEG, and somatosensory evoked potentials results were correlated with outcome.SettingA 40-bed intensive care unit in a university teaching hospital.PatientsThirty-four consecutive patients admitted over a 2-yr period with anoxic coma as the principal diagnosis.InterventionsNone.Measurements and Main ResultsTwenty-seven (79%) patients never recovered consciousness and seven (21%) patients made a good recovery. One of six patients whose pupillary reflexes were present but whose other cranial nerve reflexes were absent on day 1 recovered, but none of the seven patients with these features still present on day 3 survived. None of the patients with motor responses of extension to painful stimuli or worse on days 1 or 3 recovered. The EEGs were classified into benign, uncertain, and malignant categories. The results of both EEG and somatosensory evoked potentials studies were strongly associated with outcome. With malignant EEG, the sensitivity was 74%, the specificity was 71%, and the positive predictive value was 9% for prediction of no recovery (death or persistent vegetative state). However, two patients with an initially malignant EEG eventually made a good recovery. The sensitivity for low amplitude or absent somatosensory evoked potentials for prediction of no recovery was 66%. There were no falsely pessimistic predictions with somatosensory evoked potentials, as all 18 patients with absent or low-amplitude responses had no recovery (specificity and positive predictive value were 100%). EEG and somatosensory evoked potentials studies were complementary to clinical examination in the determination of prognosis. Using a combined clinical and electrophysiologic approach, 63% of patients who had no recovery could be identified by day 3. Repeat EEG and somatosensory evoked potentials studies were of value in patients whose prognoses were uncertain, as their evolution invariably correlated with outcome.ConclusionsBased on the present data and a literature review, we propose that clinical examination combined with the results of EEG and somatosensory evoked potentials can be used to establish an early, definitive prognosis in a significant proportion of patients in anoxic coma. On day 3 or thereafter, patients with motor response of extension to pain or worse and malignant EEG, or those patients with flexor posturing or worse and bilaterally absent cortical somatosensory evoked potentials invariably have poor outcome. However, some patients with initially malignant EEG and normal somatosensory evoked potentials may recover and should be supported until their prognoses become more definitive.(Crit Care Med 1996; 24:672-678)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID