摘要:

Objective:The intraoperative development of metabolic acidosis is frequently attributed to hypovolemia, tissue hypoperfusion, and lactic acidosis. In this study, dilutional acidosis was evaluated as a possible mechanism for the routine development of intraoperative acidosis in noncardiac, nonvascular surgery patients.Design:Prospective, observational study.Setting:University-affiliated Veteran's Affairs Medical Center and a staff model, health maintenance organization hospital.Patients:Twelve patients undergoing prolonged surgical procedures expected to last ≥4 hrs were enrolled in the study.Interventions:Perioperative management was based on the judgment of the attending anesthesiologist and surgeon without knowledge of the study's intent.Measurements and Main Results:Arterial blood gas parameters, serum electrolytes, and urine electrolytes were measured pre- and postoperatively. Pulmonary artery catheters were placed for hemodynamic measurement and oxygen delivery calculations. Plasma volume was measured both pre- and postoperatively, using the Evans blue dye dilution technique.Although significant changes in lactate level (1.1 ± 0.6-1.8 ± 1.0) occurred, the change was not large enough to explain the degree of change in base excess (0.8 ± 2.3 to −2.7 ± 2.9). Chloride levels significantly increased (106 ± 3-110 ± 5) with a correlation (r2= .92;p< .0001) between the degree of change in chloride and the degree of change in base excess. Plasma volume did not change. Furthermore, a correlation between the volume of normal saline administered and the change in base excess was found (r2= .86;p< .0001), although no correlation was found with Ringer's lactate solution. An even stronger correlation was noted when the total chloride amount administered was compared with the change in base excess (r2= .93;p< .0001).Conclusions:In this patient population, a common source of increasing base deficit is related to chloride administration. The largest source of chloride is usually normal saline. Classically, dilutional acidosis would explain the predominance of this acidotic change; however, no increase in plasma volume occurred. The absence of plasma volume change would suggest that the mechanism postulated to result in dilutional acidosis is incomplete. The common treatment of administering more fluid for intraoperative acidosis may be inappropriate, may have caused the acidosis, and may further exacerbate the acidosis. Chloride levels should be assessed whenever a metabolic acidosis is seen perioperatively.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:Although invasive monitoring has not been effective in late stages after organ failure has occurred, early postoperative monitoring revealed differences in survivor and nonsurvivor patterns and provided goals for improving outcome. We searched for the earliest divergence of survivor and nonsurvivor circulatory changes as an approach to earlier preventive therapy. The aim was to describe the intraoperative time course of circulatory dysfunction in survivors and nonsurvivors among high-risk elective surgery patients using both the thermodilution pulmonary artery catheter (PAC) and multicomponent noninvasive monitoring.Design:Prospective intraoperative description of circulatory dysfunction.Setting:University-run county hospital.Patients:Two hundred nine consecutively monitored high-risk elective surgery patients.Measurements and Main Results:We evaluated the data of high-risk elective surgery patients using both PAC and multicomponent noninvasive monitoring. The latter consisted of the following: a) an improved bioimpedance method for estimating cardiac output; b) the standard pulse oximetry to screen for pulmonary problems; c) transcutaneous oxygen and carbon dioxide tension sensors to evaluate tissue perfusion; and d) routine noninvasive blood pressure and heart rate. The current noninvasive impedance cardiac output estimations closely approximated those of the thermodilution method; r2= .74,p< .001; the precision and bias was −0.124 ± 0.75 L/min/m2.Outcome measures included intraoperative description of circulatory patterns of high-risk surgical patients who survived compared with nonsurvivors.Hypotension, low cardiac index, arterial hemoglobin desaturation, low transcutaneous oxygen, high transcutaneous carbon dioxide tensions, low oxygen delivery, and low oxygen consumption developed intraoperatively gradually over time; the abnormalities were more pronounced in the nonsurvivors than in the survivors.Conclusions:The survivors had slightly higher mean arterial pressure, cardiac index, and mixed venous oxygen saturation, as well as significantly higher oxygen delivery, oxygen consumption, transcutaneous oxygen tension, and transcutaneous oxygen tension/FIO2ratios, than did the nonsurvivors. The data suggest that blood flow, oxygen delivery, and tissue oxygenation of the nonsurvivors became inadequate toward the end of the operation. Noninvasive monitoring provides similar information to that of the PAC; both approaches revealed low-flow and poor tissue perfusion that were worse in the nonsurvivors. The continuous on-line real-time displays of hemodynamic trends facilitate early recognition of acute circulatory dysfunction.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To determine whether inhaled nitric oxide (NO) improves right ventricular function in mechanically ventilated patients with severe chronic obstructive pulmonary disease (COPD).Design:Open, prospective, controlled trial.Setting:General intensive care unit of a community hospital.Patients:Twelve patients with acute respiratory failure caused by acute exacerbation of COPD requiring mechanical ventilation.Interventions:Insertion of a pulmonary artery catheter modified with a rapid response thermistor and a radial arterial catheter. Nitric oxide was then administered to the patient via a T piece placed between the Y piece of the ventilator and the endotracheal tube.Measurements and Main Results:Hemodynamic and gasometric variables were recorded before NO inhalation, during administration of inhaled NO (20 ppm, 20 mins), and 20 mins after NO discontinuation. Inhaled NO reduced pulmonary artery pressure from 26 ± 6 to 22 ± 5 mm Hg (p= .0004), but arterial oxygenation, cardiac output, and right ventricular ejection fraction remained unmodified (41% ± 9% vs. 41% ± 8%; not significant). Calculated pulmonary vascular resistance decreased from 453 ± 233 to 348 ± 108 dyne·sec/cm5·m2(p= .02), and right ventricular volumes did not change. Subsequently, right ventricular end-systolic pressure/volume ratio decreased from 0.52 ± 0.22 to 0.44 ± 0.19 mm Hg/mL/m2(p= .01). No significant correlation was observed between the changes of pulmonary artery pressure (or pulmonary vascular resistance) and changes of right ventricular ejection fraction.Conclusion:Inhalation of NO does not seem to improve either right ventricular function or arterial oxygenation in patients with acute respiratory failure caused by acute exacerbation of COPD.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To determine the acute hemodynamic effect of hypertonic saline and/or colloid solutions as volume resuscitation in postoperative mitral valve repair patients.Design:Prospective, randomized trial.Setting:Postoperative cardiac intensive care unit of Broussais Hospital.Patients:Twenty-six patients who underwent mitral valve repair were prospectively studied. Two patients were excluded during the study.Interventions:During the immediate postoperative period, when wedge pressure decreases to <8 mm Hg, patients were randomly assigned to receive 250 mL of either hypertonic saline 7.2%-hydroxyethyl starch 6% (molecular weight, 200,000; hydroxyethylation ratio, 0.5) solution (HS-HES group), hypertonic saline 7.2% solution (HS group), or hydroxyethyl starch 6% solution (HES group). The infusion was completed within 15 mins. No additional volume was infused throughout the study.Measurements and Main Results:Standard hemodynamic measurements and echocardiographic data demonstrated that HS-HES and HS induced a higher increase in left ventricular end-diastolic area than HES. In the HS-HES and HS groups, systemic vascular resistances decreased significantly and end-systolic area tended to decrease. In the HES group, systemic vascular resistances did not change and end-systolic area tended to increase. Accordingly, ejection fraction increased significantly by 21% and 18% with HS-HES (from 50.5 ± 5.5 to 61.2 ± 4.8) and HS (from 49.7 ± 3.6 to 58.8 ± 3.3), respectively, and did not change with HES. A major increase in cardiac index was observed after hypertonic solutions infusion, from 2.9 ± 0.3 to 4.1 ± 0.4 L/min/m2in the HS-HES group and from 2.7 ± 0.3 to 3.8 ± 0.4 L/min/m2in the HS group. Then, cardiac index progressively returned to baseline values within the 3 hrs after the infusion. No significant difference was observed between HS-HES and HS. In these groups, plasma sodium increased significantly after the infusion and remained higher than baseline values throughout the study. Adverse events were observed only with hypertonic solution administration: hypotensive episodes, sudden increases in pulmonary capillary wedge pressure, and ventricular arrhythmias. These side effects are likely attributable to a too-high dose and/or rate of infusion. All patients included in the study were discharged from the hospital before the 10th postoperative day.Conclusion:We conclude that in patients who have undergone mitral valve repair, postoperative infusion of hypertonic saline solutions increases left ventricular preload and left ventricular ejection fraction. The use of these hypertonic solutions may be of interest in patients with valvular cardiomyopathy. A titrated dose and a low rate of infusion may substantially improve the safety.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To assess the effects of dopexamine on splanchnic blood flow and splanchnic oxygen uptake in septic patients.Design:A prospective, controlled trial.Setting:A ten-bed intensive care unit (ICU) in a university hospital.Patients:Twelve patients with severe sepsis (according to the criteria of the 1992 American College of Chest Physicians/Society of Critical Care Medicine consensus conference) being stabilized by volume loading and treated to an elevated oxygen delivery by dobutamine infusion.Interventions:Infusion of increasing dosages of dopexamine (0.5, 1.0, 2.0, and 4.0 μg/kg/min).Measurements and Main Results:Systemic and splanchnic hemodynamic and oxygen transport parameters as well as gastric mucosal pH (pHi) were measured. A hepatic venous catheter technique with indocyanine green dye dilution was used to determine splanchnic blood flow. Dopexamine increased global and splanchnic oxygen delivery without affecting oxygen consumption (&OV0312;O2). Splanchnic blood flow increased proportionally to cardiac output, indicating that there was no selective effect of dopexamine on the splanchnic flow. Dopexamine decreased pHi in a dose-dependent fashion in all 12 patients.Conclusions:In hemodynamically stable, hyperdynamic septic patients being treated with dobutamine, dopexamine has no selective effect on splanchnic blood flow. In fact, a decreased pHi suggests a harmful effect on gastric mucosal perfusion.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To test the sepsis marker procalcitonin (PCT) for its applicability to discriminate between septic and nonseptic causes of acute respiratory distress syndrome (ARDS).Design:Prospective study, assessing the course of PCT serum levels in early (within 72 hrs after onset) ARDS. The three other inflammation markers neopterin, interleukin-6 (IL-6), and C-reactive protein (CRP) were tested in parallel.Setting:Twenty-four-bed medical intensive care unit of a 1,990-bed primary hospital, providing health care for an estimated 39,000 patients.Patients:Twenty-seven patients, 18 male and nine female, aged 16-85 yrs, with early ARDS of known cause (17 with septic and ten with nonseptic ARDS) were enrolled in a prospective study between May 1994 and May 1995.Interventions:Serum samples were drawn every 4-6 hrs for measurement of PCT, neopterin, IL-6, and CRP concentrations. Blood cultures, tracheal aspirates, and urine samples were obtained every 12-24 hrs. In 24 of 27 patients, bronchoscopic cultures were also obtained. Clinical sepsis criteria as defined by the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference were checked daily.Measurements and Main Results:Assessment of inflammation marker serum levels in septic vs. nonseptic ARDS. PCT serum levels were significantly higher (p< .0005) in the patients with septic ARDS than in patients with nonseptic ARDS within 72 hrs after onset of ARDS. There was no overlap between the two groups. Also, neopterin allowed a differentiation (p< .005), although a substantial overlap between serum levels of septic and nonseptic patients was observed. No discrimination could be achieved by determination of CRP and IL-6 levels.Conclusion:PCT determination in early ARDS could help to discriminate between septic and nonseptic underlying disease.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objectives:To determine whether glycolate, a toxic metabolite of ethylene glycol that is chemically similar to lactate, can cause artifactual elevation of measured L-lactate concentrations.Design:Prospectivein vitrostudy.Setting:Intensive care unit and chemical pathology laboratory in a university-affiliated hospital.Subjects:Heparinized normal human blood and four commercially available L-lactate analyzers.Interventions:Four analyzers were tested, three of which used L-lactate oxidase and one of which used L-lactate dehydrogenase. Glycolic acid (10 g/L) in saline was added to blood in a series of aliquots. Corresponding plasma L-lactate concentrations and blood pH, PCO2, and hemoglobin concentrations were measured and base excess was calculated initially and after the addition of each aliquot. One of the two L-lactate oxidase-type analyzers, which was found to show interference, was then used to measure plasma L-lactate and glucose concentrations in blood with glycolic, oxalic, or formic acid added until the base excess was reduced by >15 mmol/L.Measurements and Main Results:Artifactual plasma L-lactate elevations were observed in two analyzers, both of the L-lactate oxidase type. Small concentrations of glycolic acid (causing reductions of base excess of 2-5 mmol/L) were accompanied by artifactual plasma L-lactate elevations of 4-8 mmol/L. Artifactual plasma L-lactate elevations increased with further glycolic acid-induced reductions in base excess. Oxalate and formate did not interfere with plasma L-lactate measurements, and measured plasma glucose concentrations were unaffected by all three acids.Conclusions:Glycolate causes large artifactual elevations in plasma L-lactate measurements by two analyzers in common use, with potential for misdiagnosis of lactic acidosis in ethylene glycol poisoning. A possible cause of the interference is incomplete specificity of the analytical reagent L-lactate oxidase, allowing cross-reaction with glycolate.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:Postoperative pulmonary hypertension increases the mortality risk in cardiac surgery. We have used central venous prostaglandin E1(PGE1) and left atrial norepinephrine (NE) infusion to wean from cardiopulmonary bypass (CPB) patients with refractory postoperative pulmonary hypertension.Design:Observational, nonrandomized study.Setting:Department of Cardiac Surgery in a university hospital.Patients:We studied 10 nonconsecutive American Society of Anesthesiologists III and New York Heart Association class III-IV patients with postoperative pulmonary hypertension and low cardiac output syndrome preventing separation from CPB.Interventions:Patients received right atrial PGE1(31.5 ± 6.26 ng/kg/min) and left atrial NE (0.11 ± 0.02 μg/kg/min) infusion. Hemodynamic data were obtained before CPB (T0), after CPB under maximal inotropes and vasodilator infusion (T1), 10 mins (T2) and 12 hrs (T3) after PGE1and NE infusion, and 48 hrs after withdrawal of PGE1and NE (T4).Measurements and Main Results:All patients were successfully weaned from CPB and survived. The biatrial infusion of PGE1and NE caused a dramatic reduction in mean pulmonary artery pressure (from 42.8 ± 5.1 mm Hg at T1 to 28.5 ± 2.6 mm Hg at T2 and 20.5 ± 2.0 mm Hg at T4), pulmonary vascular resistance index (from 1158 ± 269 dyne·sec/cm5·m2at T1 to 501 ± 99 dyne·sec/cm5·m2at T2 and 246 ± 50 dyne·sec/cm5·m2at T4), and pulmonary-to-systemic vascular resistance index ratio (from 0.61 ± 0.17 at T1 to 0.20 ± 0.04 at T2 and 0.11 ± 0.03 at T4). Cardiac index increased from 1.7 ± 0.2 L/min/m2at T1 to 2.3 ± 0.2 L/min/m2at T2 and 2.9 ± 0.1 L/min/m2at T4.Conclusions:In patients with refractory postoperative pulmonary hypertension, the combined administration of low-dose PGE1in the right atrium and NE in the left atrium is an effective means to wean patients from cardiopulmonary bypass.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To determine whether human vascular endothelial cells produce tumor necrosis factor-α (TNF-α) after stimulation with proinflammatory cytokines and bacterial lipopolysaccharides (LPS).Design:Prospective,in vitrorepeated-measurements analysis of cellular responses.Setting:Research laboratory in an academic medical center.Subjects:Human umbilical vein endothelial cells (HUVECs).Interventions:HUVECs were incubated with interferon-γ (IFN-γ), interleukin-1β (IL-1β), and LPS, or their different combinations for 2 to 48 hrs.Measurements and Main Results:TNF-α was measured by time-resolved immunofluorometric assay. Unstimulated HUVECs did not produce detectable amounts of TNF-α, but IFN-γ, IL-1β, and LPS when added together induced TNF-α production of HUVECs in a time-dependent manner. Immunofluorescent staining confirmed that the TNF-α was produced by endothelial cells. IFN-γ, IL-1β, or LPS alone did not induce TNF-α production, whereas IFN-γ and IL-1β in combination were able to induce TNF-α production to some extent, and the production could be further increased with LPS. TNF-α messenger RNA expression was detected with reverse transcriptase-coupled polymerase chain reaction in stimulated, but not in unstimulated, HUVECs.Conclusions:HUVECs are capable of producing TNF-α after proinflammatory cytokine stimulation and may therefore contribute to the increased amount of TNF-α found in pathologic states such as septic shock.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:Core temperature measurement using a pulmonary artery (PA) catheter is considered the gold standard for measuring temperatures in critically ill patients. The objective of this study was to compare oral and tympanic temperature measurements (in both the oral and core equivalence modes) against PA core temperature measurements to determine which method was the most accurate and reliable in the absence of a PA catheter.Design:Prospective, descriptive comparative analysis.Patients:Convenience sample of 102 critically ill orally intubated patients with a PA catheter in place.Setting:A 24-bed medical/surgical/trauma intensive care unit in a university-affiliated medical center.Interventions:Four experienced intensive care unit nurses were trained in the use of temperature measurement with the oral, tympanic (both core and oral equivalence modes were used), and PA core methods. Simultaneous temperature measurements were then taken once in each subject using each method. The potential covariates that were analyzed were mean blood pressure, patient acuity using the Simplified Acute Physiology Score II, age, sex, ambient room temperature, and ventilator circuit temperature.Measurements and Main Results:The training period indicated that it took more time to train experienced nurses in the use of tympanic thermometry than oral thermometry. Descriptive statistics were the following: core, x = 37.33 (SD = 0.89); oral, x = 37.18 (SD = 0.92); tympanic oral, x = 36.80 (SD = 0.93); and tympanic core, x = 37.12 (SD = 1.0). Bias averages were calculated and were significantly different from 0 for all three methods (oral-PA core, −0.15 [SD = 0.36]; tympanic core-PA core, −0.11 [SD = 0.57], tympanic oral-PA core, −0.52 [SD = 0.53]), indicating that there is some degree of decreased accuracy associated with each method when compared with PA core. However, scatter plots using the Bland and Altman methodology (Altman DG, Bland JM: Practical Statistics for Medical Research. London, Chapman and Hall, 1991) illustrate that the greatest variability is associated with the tympanic method.Conclusions:Temperature measurement is an important piece of clinical data in a critically ill patient population. We found oral thermometry to be the most accurate and reproducible method when a PA core measurement was not available.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID