Hemodynamic and oxygen transport effects of dobutamine in critically ill general surgical patients

The effects of dobutamine on hemodynamic and oxygen transport were evaluated in 43 studies on 34 critically ill general (noncardiac) surgical patients. Dobutamine, beginning at a low dose (2.5 micrograms/kg X min) significantly increased cardiac index (CI), oxygen delivery (DO2), and oxygen consumption (VO2), while decreasing mean arterial pressure, pulmonary artery and wedge pressures, and systemic and pulmonary vascular resistances; blood gases, pH, and pulmonary shunt were not significantly changed. These effects were seen in postoperative and septic patients, as well as in patients with normal, low, and high control CI. These responses were poor in terminally ill and hypovolemic patients; however, when the latter were given additional fluids, their responses were markedly improved. The hemodynamic effects of dobutamine are well known, but the DO2 and VO2 effects, which suggest improved tissue perfusion, have not been appreciated.     

Hemodynamic, blood volume, and oxygen transport responses to albumin and hydroxyethyl starch infusions in critically ill postoperative patients

Hemodynamic, plasma volume, and oxygen transport effects were measured after administration of 500 ml of 5% albumin or 6% hydroxyethyl starch (HES) in hypovolemic postoperative patients using a prospectively randomized crossover design. Both agents produced marked and significant improvement in plasma volume and flow as well as small transient increases in arterial and venous pressures, urine output, colloidal osmotic pressure (COP), and oxygen transport. The authors conclude that HES is a safe, inexpensive, effective plasma expander that has hemodynamic effects similar to those of other colloids. It was apparent from these and other studies that clinically stable postoperative patients may have appreciable blood volume deficits. Routine vital signs correlated poorly with the preinfusion control hemodynamic values or the changes in blood volume status after volume loading. Normal cardiac output, central venous pressure (CVP), and pulmonary arterial wedge pressure (WP) values are commonly seen in critically ill postoperative patients who, nevertheless, may be hypovolemic. Measurement of changes in these variables after a fluid challenge is a useful way to assess plasma volume status.     

Tissue blood flow and oxygen transport in critically ill patients.

The theoretical and practical solutions to the problems of increasing oxygen transport are well understood. Unfortunately the quantitation of hypoxia, both as an absolute deficit and as a precise method of prognosis is not yet available. This may well be because regional hypoxia in a vital tissue cannot be mirrored in a total body measurement. In the low-flow state, oxygen delivery can be maintained by redistribution of cardiac output, reduction of oxygen uptake by ischemic tissue by reducing work load, by increasing oxygenation of the blood, or by decreasing the affinity of oxygen for hemoglobin. The latter provides for more oxygen to be delivered by a given amount of oxyhemoglobin before the tension falls to deleterious regions (about 20 torr). There is some evidence that pharmacologic doses of methylprednisolone may be beneficial in this respect.     

Hemodynamic patterns in shock and critically ill patients.

Nine variables were studied in 56 patients to analyze hemodynamic patterns of critically ill and shock patients. The variables were central venous pressure, mean arterial pressure, heart rate, cardiac index, left ventricular stroke work, strok index, total peripheral resistance, arteriovenous oxygen difference, and oxygen consumption. We observed six patterns; three with low cardiac index (hypodynamic) and three with high cardiac index (hyperdynamic). Group IA: Low cardiac index with increased central venous pressure and arteriovenous oxygen differences associated with myocardial infarction, cardiac insufficiency, and postoperative cardiac surgery: Group IB: Low cardiac index with normal arteriovenous oxygen difference associated with myocardial infarction or hypovolemia. Group IC: Low cardiac index and decreased arteriovenous oxygen difference in patients with hypodynamic septic shock. Group IID: High cardiac index and increased arteriovenous oxygen difference in patients with sepsis and stable hemodynamic conditions. Groups IIE and IIF: Increased cardiac index and normal or increased arteriovenous oxygen difference in septic patients, who were hemodymamically unstable or in shock. These hemodynamic observations were found to be useful for understanding physiological compensations, for deciding on therapy, and in evaluating the effectiveness of therapy.     

Hemodynamic response of restoring sinus rhythm in critically ill patients with atrial fibrillation

BackgroundElectrical cardioversion (ECV) is the recommended treatment for atrial fibrillation (AFib) in critically ill patients, despite lacking data showing hemodynamic benefits of restoring sinus rhythm in this setting. The aim of this study was to assess the hemodynamic effect of successful ECV in a cohort of hemodynamically unstable critically ill patients.Methods and resultsThis study included 66 successful ECV performed in hemodynamically unstable critically ill patients with new-onset AFib. The primary outcome was the requirement of norepinephrine and inotropes 6 h after successful ECV in relation to baseline. Baseline norepinephrine dose was 0.19 ± 0.02 μg/kg/min, and 67% of patients were treated with positive inotropic drugs. Six hours after ECV, 33 patients (50%) were considered hemodynamic non-responders. Overall, the mean norepinephrine dose at 6 h was 0.17 ± 0.02 μg/kg/min (P = 0.051 compared to baseline) and 61% of patients were on inotropes (P = 0.13 compared to baseline). During the 6-hour period after ECV the mean norepinephrine dose temporary increased to 0.20 ± 0.02 μg/kg/min (P = 0.033 compared to baseline).ConclusionsECV is associated with a large proportion of hemodynamic non-responders and a numerically modest, non-significant hemodynamic improvement in critically ill patients with new-onset AFib.     

Hemodynamic responses to amiodarone in critically ill patients receiving catecholamine infusions

The hemodynamic response after an iv loading dose of amiodarone for resistant supraventricular tachyarrhythmias was studied in ten critically ill patients receiving a catecholamine infusion for shock. A loading dose of amiodarone, 3.7 to 5.0 mg/kg, was infused over 2 h while the catecholamine infusion dose requirements were monitored. There was a significant decrease in heart rate (mean 16%, p less than .01), and an increase in stroke volume index (mean 29%, p less than .01) and left ventricular stroke work index (mean 34%, p less than .01). Cardiac index, oxygen availability index, and mean arterial pressure were not changed significantly. The reported adrenoreceptor antagonism of amiodarone did not change catecholamine dose requirements in this study. In nine of ten patients, sinus rhythm was achieved and maintained. The loading dose of amiodarone had no significant acute effect on plasma digoxin concentrations. Despite good arrhythmia control, mortality was high.     

Intrahospital transport of critically ill patients

Severe complications sometimes occur in critically ill patients during intrahospital transport. Possible causes may be inadequate ventilation, insufficient monitoring, interrupted application of vasoactive drugs, or disconnections and accidental extubation. We constructed a transport unit equipped with a respirator; capnometer; monitor to measure ECG, arterial and intracranial pressures, and temperature; and two syringe pumps that can be connected easily to the patient's bed. Gas is supplied by cylinders with oxygen and air. Electrical power is supplied by two accumulators connected to recharger and transformer devices that deliver 220 V (110 V). Since this transfer unit was introduced, we have had no unanticipated problems during intrahospital ICU patient transport.     

Optimal oxygen delivery in critically ill patients

Standard hemodynamic support in septic shock is to increase pulmonary capillary wedge pressure to above 15 mmHg by volume replacement and to give inotropic support if the mean arterial pressure (MAP) is not adequate. In an attempt to decrease mortality in critically ill patients, oxygen delivery (DO₂) was increased by switching inotropic support from dobutamine alone or in combination with norepinephrine to dopamine alone, or by adding dopexamine, prostacyclin, or hypertonic saline to the treatment. DO₂ increased significantly in all patients, but the increase in DO₂ was accompanied by only a 10% increase in oxygen consumption (VO₂). The increase in VO₂ was similar in survivors and nonsurvivors and in patients with and without septic shock. The results indicate that if adequate volume and inotropic support is provided for critically ill patients, the detectable oxygen debt is small and has little effect on patient outcome. When DO₂ is adequate, factors other than a tissue oxygen deficit seem to determine patient outcome.     

Lipolytic response to metabolic stress in critically ill patients

OBJECTIVE: To measure whole-body lipolysis and fatty acid re-esterification in critically ill patients. DESIGN: The rates of appearance of glycerol and palmitic acid in blood plasma were measured by infusing stable isotope tracers [2H5]glycerol and [1-13C]palmitic acid, respectively. Energy expenditure was measured by indirect calorimetry. SETTING: Medical ICU of The University of Texas Medical Branch Hospital, a university-based referral center. PATIENTS: Five uninjured critically ill patients. Four patients were hospitalized because of respiratory insufficiency and one because of myocardial infarction. Three patients died during their hospitalization. INTERVENTIONS: Metabolic studies were performed in each patient after an overnight (12-hr) fast. MEASUREMENTS AND MAIN RESULTS: Mean +/- SE glycerol and fatty acid rates of appearance were 4.5 +/- 1.0 and 11.5 +/- 0.8 mumol/kg.min, respectively. The ratio of fatty acid to glycerol rate of appearance was 2.9 +/- 0.5. Resting energy expenditure was 132 +/- 6% of predicted. CONCLUSIONS: An accelerated rate of lipolysis is part of the metabolic response to severe stress, regardless of its etiology. Because the rate of fatty acid release far exceeded energy requirements, fatty acids that were not oxidized as fuel were re-esterified to triglyceride, presumably in the liver.     

Hemodynamic assessment of critically ill patients using echocardiography Doppler

PURPOSE OF REVIEW: The evaluation of hemodynamic status in critically ill patients is a leading recommended indication of transesophageal echocardiography in the intensive care unit. Advantages and diagnostic yield of transesophageal echocardiography in this setting are particularly relevant when considering limitations and questioned prognostic impact of pulmonary artery catheterization. RECENT FINDINGS: Recent clinical studies have been performed to validate and assess the value of transesophageal echocardiography in determining cardiac output, cardiac preload dependence, right ventricular function, and left ventricular filling pressure. In addition, diagnostic capacity and therapeutic impact of transesophageal echocardiography have been widely reported in various intensive care unit settings. SUMMARY: Transesophageal echocardiography appears well suited for the determination of cardiac index and to track its variations after therapeutic interventions. Although repeated measurements of left ventricular end-diastolic dimension allows to accurately track preload variations, a single determination is not reliable to predict fluid responsiveness in intensive care unit patients. Identification of preload dependence in hemodynamically unstable patients currently tends to rely mainly on dynamic parameters that use cardiopulmonary interactions under mechanical ventilation. Transesophageal echocardiography also allows to adequately assess right ventricular function and left ventricular filling pressure using combined Doppler modalities. Adequate education and training of intensivists and anesthesiologists is crucial to further develop the use of transesophageal echocardiography in the intensive care unit setting. Despite the absence of randomized controlled studies documenting transesophageal echocardiography benefits on patient outcome, present evidence and experience strongly recommend a larger use of echocardiography Doppler for a comprehensive functional hemodynamic assessment of critically ill patients with circulatory failure.     

Intrahospital transport of critically ill patients.

Intrahospital transport of critically ill patients must be considered as part of the critical care continuum. The level of care provided must be commensurate with the severity of illness. These transfers are intensive in terms of utilization of personnel and resources. Advance preparation and optimal coordination of the transport process go a long way toward safer transfers of the critically ill.     

儿科危重病人院间转运

危重病人的院间转运越来越受到重视,本文综述了转运中的风险评估和降低转运过程中不良影响的措施等,达到提高转运质量和效果的目的 .     

Bioelectrical impedance spectroscopy to estimate fluid balance in critically ill patients

Fluid management is a crucial issue in intensive-care medicine. This study evaluated the feasibility and reproducibility of bioimpedance spectroscopy to measure body-water composition in critically ill patients, and compared fluid balance and daily changes in total body water (TBW) measured by bioimpedance. This observational study included 25 patients under mechanical ventilation. Fluid balance and bioimpedance measurements were recorded on 3 consecutive days. Whole-body bioimpedance spectroscopy was performed with exact or ideal body weights entered into the device, and with or without ICU monitoring. Reproducibility of bioimpedance spectroscopy was very good in all conditions despite ICU monitoring and mechanical ventilation. Bioimpedance measurements using an ideal body weight varied significantly, making the weighing procedure necessary. Comparison of fluid balance and daily changes in body weight provided the best correlation (ρ = 0.74; P < 0.0001). Daily changes in TBW were correlated with fluid balance (Spearman coefficient ρ = 0.31; P = 0.003) and this correlation was improved after exclusion of patients with a SOFA score >10 (ρ = 0.36; P = 0.05) and with extracorporeal circulation (ρ = 0.50; P = 0.005). Regardless of the technique used to estimate volume status, important limits of agreement were observed. Non-invasive determination of body-water composition using bioimpedance spectroscopy is feasible in critically ill patients but requires knowledge of the patient’s weight. The best method to assess volume status after fluid resuscitation and the value gained from information about body composition provided by bioimpedance techniques needs further evaluation.     

HDL-cholesterol level and cortisol response to synacthen in critically ill patients

Objective To explore the relationship between cholesterol levels and the adrenal cortisol response to synacthen in critically ill patients.Design Prospective observational study.Patients Critically ill patients with multiple organ dysfunction syndrome (MODS) with possible adrenal dysfunction defined as unexplained hypotension, ongoing inotropic support, unexplained fever, unexplained hyponatraemia or a combination of these symptoms.Measurements HDL-cholesterol levels (HDL), total cholesterol levels (TC), and triglycerides (TG) before administration of synacthen. LDL-cholesterol was calculated using the Friedewald formula. Basal cortisol and response to 250 g synacthen intravenously was measured. A cortisol rise of 0.25 mol/l in a 30-min or 60-min blood sample after synacthen infusion was defined as a proper adrenal response.Results Patients with a proper response to synacthen showed higher HDL-cholesterol levels than patients without that response (P=0.02). Severity of disease as measured by APACHE II or SOFA was not a confounder. LDL-cholesterol levels were extremely low in both responders and non-responders and were not associated with the absolute rise in cortisol. In linear and logistic regression analysis HDL-cholesterol was the sole predictor of cortisol response.Conclusions Adrenal cortisol response to a classic 250-g synacthen test relates in critically ill patients to HDL-cholesterol levels. LDL and TC levels did not show such a relation. These findings are in concordance with known biochemical pathways of cortisol production.     

急诊危重患者转运的安全护理

转运是急诊危重患者抢救不可分割的重要组成部分,是救治过程不可忽略的重要环节。急诊危重患者安全转运关键在于掌握转运的指征、转运前的风险评估、转运人员的组成、转运的急救器械和药品的准备、转运前的预防处理、转运途中的观察与抢救、搬运方法是否正确、抢救预案是否有效实施及严格交接班等。     

Erythropoietin response is blunted in critically ill patients

Objectives: Critically ill patients often develop anaemia which can be related to a number of factors. However, the exact causes of anaemia in many patients remain unexplained. We hypothesized that the relationship between erythropoietin (EPO) and haematocrit may be altered in critically ill patients. Design: Serum concentrations of EPO were serially determined by the ELISA method in 36 critically ill, non-hypoxaemic patients who stayed more than 7 days in the Intensive Care Unit, including 22 patients with sepsis and 14 without. Eighteen ambulatory patients with iron-deficiency anaemia served as a control group. Setting: Two University Hospital Intensive Care Departments. Results: A significant inverse correlation between serum EPO and haematocrit levels was found in the control patients (r = −0.81, p < 0.001), but not in the critically ill patients (r = −0.09, NS), except in a subgroup of non-septic patients without renal failure (r = −0.61, p < 0.01). Conclusions: EPO levels can be inappropriately low in critically ill patients, so that EPO deficiency may contribute to the development of anaemia in these patients. This phenomenon is observed not only in the presence of acute renal failure, but also in the presence of sepsis. Received: 4 March 1996 Accepted: 7 November 1996