摘要:

Objective:The role of the splanchnic circulation in the development of the metabolic acidosis of cardiopulmonary bypass (CPB) is not fully understood. New quantitative methods of acid-base balance now offer the ability to define this phenomenon more accurately. Accordingly, we studied acid-base changes across the splanchnic circulation during CPB and defined and quantified the factors that contributed to acid-base balance.Design:Prospective cohort study.Setting:Tertiary institution.Patients:Ten patients undergoing CPB for coronary artery bypass surgery.Interventions:Sampling of arterial and hepatic venous blood at four time intervals: postinduction, on CPB during cooling and rewarming, and at skin closure.Measurements:Measurement of serum Na+, K+, Mg++, Ca++, Cl−, HCO3−, and phosphate concentrations, arterial and hepatic venous blood gases and serum albumin, and lactate and pyruvate concentrations at each collection point. Analysis of findings according to quantitative physicochemical principles.Main Results:All patients developed a mild metabolic acidosis with a decrease in median serum bicarbonate concentration from 24.97 mEq/L after induction to 22.29 mEq/L at cooling and 22.23 mEq/L at rewarming (p< .05). Before CPB, the pH decreased by 0.0275 (p< .05) across the splanchnic circulation, representing an increase of 2.26 nmol/L of hydrogen ions. Nevertheless, the splanchnic circulation induced a metabolic alkalosis, with a median transsplanchnic increase in the base excess of 1.50 mEq/L (p< .05). This change was largely due to a decrease in serum chloride and lactate concentration across the splanchnic circulation (p< .05). The acidifying effect of the splanchnic circulation was therefore the result of cell respiration with a median increase in carbon dioxide tension of 5.75 mm Hg (p< .05), causing the strong ion difference effective to increase by 1.94 mEq/L (p< .05). There were no other anions or acids added to the circulation by splanchnic organs (no change in strong ion gap). During and after CPB the splanchnic metabolic alkalinizing effect continued and the respiratory acidifying effect was reduced. This caused the splanchnic circulation to be pH neutral at these times.Conclusions:Using quantitative biophysical methods it can be demonstrated that the splanchnic circulation does not contribute to the metabolic acidosis of CPB, and that it continues to have a metabolic alkalinizing effect involving significant lactate extraction. However, its respiratory acidifying effect continues, although at a reduced rate.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objectives:The exposure to intense physical and psychological stress during intensive care can result in posttraumatic stress disorder (PTSD) in survivors. Cortisol is a biological stress mediator that can have a protective effect during severe stress. The administration of stress doses of hydrocortisone during treatment in the intensive care unit could theoretically result in a lower incidence of PTSD. We tested this hypothesis in survivors of septic shock.Design:A retrospective case-controlled analysis.Setting:A 20-bed multidisciplinary intensive care unit of a tertiary-care university hospital.Patients:We identified 27 patients who received standard therapy for septic shock. These patients served as controls and were compared with an equal number of patients who received hydrocortisone in addition to standard treatment. These patients were selected from our database with regard to age (±4 yrs), gender, and cause of septic shock to be as similar as possible with control patients.Interventions:Patients from the hydrocortisone group had received stress doses of hydrocortisone (100 mg bolus, followed by 0.18 mg/kg/hr) in addition to standard treatment. Patients from the control group received standard protocol-driven treatment only. PTSD was diagnosed with the Posttraumatic Stress Syndrome-10 inventory, a self-report scale for diagnosis of PTSD. Health-related quality of life was measured using the Medical Outcomes Study Short-Form Survey (Medical Outcomes Trust, Boston, MA), which consists of 36 questions.Measurements and Main Results:Patients who received hydrocortisone during septic shock had a significantly lower incidence of PTSD than patients who received standard treatment only (5 of 27 vs. 16 of 27;p= .01) and had significantly higher scores on the mental health index of the Medical Outcomes Study Short-Form health-related quality-of-life questionnaire (68 vs. 44 points;p= .009).Conclusions:Data from this study support the hypothesis that the administration of stress doses of hydrocortisone in doses equivalent to the maximal endocrine secretion rate during septic shock reduces the incidence of PTSD and improves emotional well-being in survivors. This hypothesis should be tested in a prospective randomized trial.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To determine whether the energy expenditure of mechanically ventilated multiple trauma patients correlates with the severity of injury and illness indices before important systemic infection has complicated the clinical course, and to compare the energy expenditure with the energy expenditure expected from the Harris-Benedict equation adjusted with correction factors for trauma.Design:Prospective, clinical study.Setting:General intensive care unit of a university teaching hospital.Patients:Immediate multiple trauma adult patients who required mechanical ventilation.Interventions:Metabolic cart connected to the ventilator.Measurements and Main Results:Data on admission to the emergency department and during the first 24 hrs of intensive care unit admission were collected for computation of severity of injury and illness indices, respectively. Resting and total energy expenditures were derived at least 48 hrs after intensive care unit admission by continuous indirect calorimetry. Predicted basal energy expenditure was obtained using the Harris-Benedict equation and predicted total energy expenditure was calculated using the Harris-Benedict value adjusted with correction factors for trauma. Twenty-six multiple trauma adult patients completed the study. No statistically significant correlations were observed between both the resting energy expenditure and the total energy expenditure and the Injury Severity Score, Revised Trauma Score, Simplified Acute Physiologic Score II, Acute Physiology and Chronic Health Evaluation II score, and Glasgow Coma Scale score. A regression model of total energy expenditure was developed with the following variables: Harris-Benedict equation, heart rate, and minute ventilation (p= .01; r2= .74). The resting energy expenditure/predicted basal energy expenditure ratio was 1.17 ± 0.2 and the total energy expenditure/predicted total energy expenditure ratio was 0.76 ± 0.1.Conclusions:In mechanically ventilated multiple trauma patients the energy expenditure is not correlated to the severity of injury and illness indices but is dependent on the Harris-Benedict equation in addition to heart rate and minute ventilation. Furthermore, this patient population is characterized by a moderate state of hypermetabolism, and the Harris-Benedict prediction modified with correction factors for trauma systematically overestimates the total energy expenditure.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:The use of bicarbonates in the treatment of severe diabetic ketoacidosis remains controversial, especially regarding the benefit/risk ratio. The aim of this study was to assess the efficacy of bicarbonate therapy during severe diabetic ketoacidosis (pH <7.10).Design:Retrospective study.Setting:The emergency unit of a teaching hospital.Patients:The records of 39 patients consecutively admitted for severe diabetic ketoacidosis were analyzed (pH <7.10). The patients were divided into two groups: group 1 (n = 24; patients with bicarbonate treatment) and group 2 (n = 15; patients without bicarbonate treatment).Interventions:None.Measurements and Main Results:We compared two groups of patients presenting with severe diabetic ketoacidosis (pH values between 6.83 and 7.08) treated with or without bicarbonate. A group of 24 patients received 120 ± 40 mmol sodium bicarbonate. The two groups were similar at admission with regard to clinical and biological parameters. No difference could be demonstrated between the two groups concerning the clinical parameters or the normalization time of biochemical parameters. If the number of patients with hypokalemia was comparable between the two groups, the potassium supply was significantly more important in group 1 compared with group 2 (366 ± 74 mmol/L vs. 188 ± 109 mmol/L, respectively;p< .001).Conclusions:Data from the literature and this study are not in favor of the use of bicarbonate in the treatment of diabetic ketoacidosis with pH values between 6.90 and 7.10.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To compare semicontinuous cardiac output (CCO) with bolus cardiac output (BCO), in the immediate postoperative period after valvular surgery, under hypothermic cardiopulmonary bypass with two CCO pulmonary artery catheters, based on the pulsed warm thermodilution technique, i.e., Opti-Q from Abbott or IntelliCath from Baxter-Edwards (Abbott and Baxter groups, respectively).Design:Prospective study.Setting:University hospital.Patients:Forty-four adult patients scheduled for mitral and/or aortic valve surgery were randomized into two groups. Tricuspid or pulmonary valvulopathy diagnosed by echocardiography was excluded.Interventions:Cardiac output was measured every 20 mins during the 3 postoperative hrs. BCO was the mean of three boluses (10 mL) of an ice-cold saline solution injected within 3 secs. CCO was the mean of two CCO values obtained in normal mode immediately before and after BCO measurements.Measurements and Main Results:Two groups of 22 patients underwent 198 pairs of cardiac output measurements. The mean difference or bias was calculated as the difference between BCO and CCO, and precision was the SD of the mean bias. The limits of agreement were defined as bias ± 2 SD. A two-sample Wilcoxon's test was used for comparison of bias and precision in sinus and non-sinus rhythm, and stable and unstable mean arterial pressure in each group and between the two pulmonary artery catheters. The coefficient of correlation was also calculated. Bias ± precision was 0.066 ± 0.526 L/min, r2= .83, for the Abbott group, and 0.015 ± 0.490 L/min, r2= .85 (not significant), for the Baxter group. There was no significant difference within and between groups for bias and precision in sinus and non-sinus rhythm, nor in stable and unstable mean arterial pressure.Conclusions:The study, during the immediate postoperative period in valvular surgery under hypothermic cardiopulmonary bypass, showed a satisfactory correlation between CCO and BCO with the two systems.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objectives:To determine hemodynamic response to amrinone in patients after cardiac surgery, in relation to the postoperative cardiac function, which was indicated by the required doses of catecholamines.Design:Prospective clinical study.Setting:Surgical intensive care unit in a university hospital.Patients:Fourteen patients who required a low-to-moderate dose of dopamine and dobutamine (group L) and 14 patients who required a high dose of dopamine and dobutamine (group H) after cardiac valve replacement.Interventions:A loading dose of amrinone (0.75 mg/kg) was administered during a 15-min period and the continuous infusion was followed incrementally by doses of 5, 10, and 20 μg/kg/min every 60 mins on the first postoperative day.Measurements and Main Results:Hemodynamic variables were determined by the radial and pulmonary artery catheters at a dose of 0, 5, 10, and 20 μg/kg/min. Two-way repeated-measures analysis of variance showed significant interaction in the two groups in cardiac index and mean systemic arterial pressure. Cardiac index increased in a dose-dependent manner in group L but was unchanged in group H. Systemic vascular resistance index decreased in a dose-dependent manner in both groups. The mean systemic arterial pressure decreased in group L at a dose of 5 μg/kg/min and returned to the baseline level at doses of 10 and 20 μg/kg/min. On the other hand, the mean systemic arterial pressure significantly decreased in group H at a dose of 20 μg/kg/min.Conclusions:The inotropic effects of amrinone after cardiac valve replacement may be associated with the postoperative myocardial reserve, which was indicated by the required doses of catecholamines, although a similar vasodilative effect was observed in both groups.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:Whether right ventricular systolic time intervals accurately reflect right ventricular function in patients with acute respiratory failure was determined by assessing the correlation between right ventricular systolic time intervals and the right ventricular end-systolic pressure-volume relationship.Design:A prospective study.Setting:A surgical intensive care unit in a university hospital.Patients:Twenty patients with acute respiratory failure.Measurements and Main Results:Right ventricular systolic time intervals were determined by the simultaneous graphic display of the electrocardiogram, the phonocardiogram, and the pulmonary artery pressure curve and were expressed as a ratio of the pre-ejection period/right ventricular ejection time. The total electromechanical systole was measured from the onset of the electrocardiographic wave complex to the pulmonic component of the second heart sound. Right ventricular ejection time was measured from the rapid upstroke of the pulmonary artery pressure curve to the dicrotic notch. Right ventricular ejection fraction, from which right ventricular end-systolic volume was derived, was measured by the thermodilution technique. Pulmonary artery dicrotic notch pressure was used as an estimate of right ventricular end-systolic pressure. Data were collected at the baseline and after one or two alterations in preload, to define the right ventricular end-systolic pressure-volume relationship line. There was an inverse correlation between the pre-ejection period/right ventricular ejection time ratio and the slope of the right ventricular end-systolic pressure-volume relationship line (r2= .67;p< .0001). When patients were divided into two groups, based on the pre-ejection period/right ventricular ejection time ratio, the slope of the right ventricular end-systolic pressure-volume relationship line was lower in the group with a high pre-ejection period/right ventricular ejection time ratio (p< .0001). No difference in other hemodynamic data, between the two groups, was noted.Conclusions:These data suggest that right ventricular systolic time intervals reflect right ventricular performance accurately in patients with acute respiratory failure.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To present results of electrophysiologic investigations of the visual toxicity observed during the early stage of methanol poisoning.Design:Retrospective, clinical study.Setting:A 7-bed intensive care unit in a university hospital.Patients:Nineteen patients admitted with a diagnosis of acute methanol poisoning.Interventions:Visual evoked potentials were obtained within the first 48 hrs after admission; a clinical follow-up examination was performed in 11 patients, and 12 patients were followed up by visual evoked potentials beyond the same delay. Correlations between the occurrence of an optic neuropathy and clinical, biological, and electrophysiological data were studied.Measurements and Main Results:A significant correlation was found between arterial pH and blood formate concentration (r2= 0.58,p= .003), between blood formate and bicarbonate concentrations (r2= 0.36,p= .02), and between delay from ingestion and blood formate concentration (r2= 0.44,p= .017). Clinical outcome was correlated not only with the bicarbonate (p= .007), formate (p= .018), and methanol (p= .03) concentrations and arterial pH (p= .004) but also with a well-defined electrophysiologic pattern during the acute stage. An index of global cortical functioning ≥3 was associated with death, whereas a global cortical functioning index ≤2 was associated with survival (p= .0058). Moreover, a statistically significant difference in long-term visual impairment was found between the subgroup with abnormal wave III morphology or a global cortical functioning index of 1-2 and the subgroup with normal wave III morphology and a global cortical functioning index <1 (p= .015).Results of the electrophysiologic studies were expressed as retinal dysfunction and optic nerve injury. Five patients had normal findings on electrophysiologic examination. Ten patients had early signs of retinal dysfunction that were fully reversed in the eight patients who were followed. Ten patients had persistent electrophysiologic signs of optic neuropathy.Conclusions:Although reversible retinal dysfunction is evident in the early stage of human methanol poisoning, its absence does not preclude development of optic neuropathy. The occurrence of optic neuropathy and early electrophysiologic data are correlated.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To determine the spatial distribution of pulmonary blood flow in three groups of piglets: partial liquid ventilation in normal piglets, partial liquid ventilation during acute lung injury, and conventional gas ventilation during acute lung injury.Design:Prospective randomized study.Setting:A university medical school laboratory approved for animal research.Subjects:Neonatal piglets.Interventions:Regional pulmonary blood flow was studied in 21 piglets in the supine position randomized to three different groups: a normal group that received partial liquid ventilation (Normal-PLV) and two acute lung injury groups that received an oleic acid-induced lung injury: partial liquid ventilation during acute lung injury (OA-PLV) and conventional gas ventilation during acute lung injury (OA-Control). Acute lung injury was induced by infusing oleic acid (0.15 mL/kg iv) over 30 mins. Partial liquid ventilation was instituted with perflubron (LiquiVent, 30 mL/kg) after 30 mins in the Normal-PLV and OA-PLV groups.Measurements and Main Results:Arterial and venous blood gases, hemodynamics, and pulmonary mechanics were measured every 15 mins throughout the hour-long study. Pulmonary blood flow was assessed by fluorescent microsphere technique at baseline and after 30, 45, and 60 mins. In the Normal-PLV piglets, pulmonary blood flow decreased from baseline (before injury or partial liquid ventilation) in the most dependent areas of the lung (F ratio = 3.227;p< .001). In the OA-PLV piglets, pulmonary blood flow was preserved over time throughout the lung (F ratio = 1.079;p= .38). In the OA-Control piglets, pulmonary blood flow decreased in the most dependent areas of the lung and increased from baseline in less dependent slices over time (F ratio = 2.48;p= .003).Conclusions:The spatial distribution of regional pulmonary blood flow is preserved during partial liquid ventilation compared with gas ventilation in oleic acid-induced lung injury.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:High-frequency oscillation studies have shown that ventilation at high end-expiratory lung volumes combined with small volume cycles at high rates best preserves exogenous surfactant and gas exchange in lavaged lungs. We investigated whether surfactant composition and gas exchange can also be preserved by conventional modes of mechanical ventilation, which combine high levels of positive end-expiratory pressure (PEEP) with small pressure amplitudes.Design:Prospective, randomized, nonblinded, controlled study.Setting:Research laboratory.Subjects:Thirty male Sprague-Dawley rats.Interventions:Rats were lung-lavaged and treated with exogenous surfactant (100 mg/kg). After 5 mins, four different ventilator settings (FIO2= 1.0) were applied for 3 hrs in four groups of rats [peak inspiratory pressure (cm H2O); static PEEP (cm H2O); inspiratory/expiratory ratio; frequency], as follows: 26/2/1:2/30 (group 26/2), 26/6/1:2/30 (group 26/6), 20/10/1:2/30 (group 20/10-static), and 20/6/7:3/130, creating an auto PEEP of 4 cm H2O (group 20/10-auto).Measurements and Main Results:In all groups, PaO2increased immediately to prelavage values after surfactant therapy. In group 26/2, PaO2deteriorated to postiavage values within 30 mins when PEEP was decreased to 2 cm H2O, whereas PaO2remained stable for 3 hrs in the other groups. The PaCO2increased in groups 26/2 and 20/10-static; PaCO2could not be reduced by increasing ventilation frequency to 130 in group 20/10-static. Groups 26/6 and 20/10-auto remained normocapnic. Bronchoalveolar lavage protein concentration was higher in groups 26/2 and 26/6 compared with groups 20/10-static and 20/10-auto. There was significantly more conversion of surface active large aggregates into nonactive small aggregates in group 26/2 compared with groups 20/10-static and 20/10-auto.Conclusions:We conclude that exogenous surfactant composition is preserved by conventional modes of mechanical ventilation that use small pressure amplitudes, and adequate oxygenation is maintained by high end-expiratory pressure levels. Effective carbon dioxide removal can be achieved by applying a ventilation mode that creates auto PEEP and not by a mode that applies the same level of PEEP by static PEEP only.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID