Long Term Pulmonary Artery Pressure Monitoring in the Management of the Critically Ill

Detailed experience during prolonged pulmonary artery pressure monitoring (up to 19 days) in 86 seriously ill patients is reviewed. Strict adherence to a protocol developed for insertion and maintenance of Swan-Ganz catheters resulted in successful catheterization of the pulmonary artery in nearly 100% of patients with minimal morbidity. Several technical problems associated with the use of this catheter-monitoring system are described, excessive balloon inflation with resultant misleading, spuriously high pressure measurement being one of the most serious. Most technical problems are avoidable. In the majority of critically ill patients both central venous and pulmonary artery diastolic pressures proved to be in-accurate estimates of pulmonary artery wedge pressure (PAW). PAW was a useful adjunct in the assessment of intravascular volume and hemodynamic alterations in these patients. The Swan-Ganz catheter serves for other functions including collection of mixed venous blood for cardiac output determination and injection of contrast material for small vessel angiography. Measurement of pulmonary artery wedge pressures should be routinely included in the sequential hemodynamic evaluation of most patients sufficiently ill to be hospitalized in an intensive care unit.     

The pulmonary artery catheter in critical care

Pulmonary artery catheterization has been a routine part of care for critically ill patients over the past 25 years. Primary hemodynamic data regarding cardiac output and pulmonary pressures can be utilized to make diagnoses and guide therapy. Tissue oxygen delivery and utilization allow inferences about the efficiency of the cardiopulmonary system and the impact of disease and medical therapies on tissue metabolism. Goals of high level invasive monitoring of cardiopulmonary function with pulmonary artery catheterization are organ salvage and minimizing complications associated with critical illness. Optimizing renal perfusion and minimizing pulmonary congestion with precise volume titration are common reasons for performing pulmonary artery catheterization in the intensive care unit. Despite being reassuring to clinicians that hemodynamic therapy is optimal, multiple data from well conducted clinical studies have not demonstrated outcome benefits to patients related to pulmonary artery catheterization. Less invasive techniques to obtain data regarding hemodynamic function are now entering the clinical arena and are being actively investigated.     

Evaluation of pulmonary arterial catheter parameters utilizing intermittent pneumatic compression boots in congestive heart failure

The use of intermittent pneumatic compression boots to reduce the risk of deep venous thrombosis is contraindicated in patients with congestive heart failure (CHF) due to a theoretical increase in venous return to the heart and exacerbation of heart failure. This study evaluates intermittent pneumatic compression effects on pulmonary artery catheter parameters in CHF patients. We conducted a prospective within-patient study of CHF patients monitored by pulmonary artery catheterization. Hemodynamic variables were assessed with and without the use of intermittent pneumatic compression boots. A sample size of 18 patients was calculated a priori to obtain an 80 per cent power to detect a mean difference of 10 per cent. Twenty patients were studied; no patient suffered hemodynamic instability during the application of pneumatic compression; no statistically significant change in any hemodynamic parameters was noted. A trend toward decreasing mean arterial blood pressure (P = 0.057), pulmonary artery wedge pressure (P = 0.065), and systemic vascular resistance (P = 0.08) was observed. None were clinically significant. The application of intermittent pneumatic compression to the feet of patients in CHF does not significantly alter central hemodynamic parameters in CHF patients. This study suggests that intermittent pneumatic compression may be used in CHF patients for venous thromboembolic risk reduction.     

Poor correlation between pulmonary arterial wedge pressure and left ventricular end-diastolic volume after coronary artery bypass graft surgery

The authors studied 12 surgical patients in the intensive care unit post coronary artery bypass graft surgery and ten nonsurgical patients in the coronary care unit with chronic heart failure to determine the usefulness of the pulmonary arterial wedge pressure as an indicator of left ventricular preload. Left ventricular end diastolic volume was derived from concomitant determination of ejection fraction (gated blood pool scintigraphy) and stroke volume (determined from thermodilution cardiac output). In the nonsurgical patients, there was a significant correlation between changes in pulmonary arterial wedge pressure and left ventricular end-diastolic volume (P less than 0.05, r = 0.57). In the 12 patients studied during the first few hours after surgery, there was a poor correlation between changes in pulmonary wedge pressure (range = 4-32 mmHg) and left ventricular end-diastolic volume (range = 25-119 ml/m2), and a poor correlation between pulmonary arterial wedge pressures and stroke work index. In contrast, there was a good correlation between left ventricular end-diastolic volume and stroke work index. The poor correlation between the pulmonary arterial wedge pressure and left ventricular end-diastolic volume was not explained by changes in systemic or pulmonary vascular resistance. The altered ventricular pressure-volume relationship may reflect acute changes in ventricular compliance in the first few hours following coronary artery bypass graft surgery. While measurement of pulmonary arterial wedge pressure remains valuable in clinical management to avoid pulmonary edema, it cannot reliably be used as an index of left ventricular preload while attempting to optimize stroke volume in patients immediately following coronary artery bypass graft surgery.     

Laparoscopically assisted abdominal aortic aneurysm repair: First 20 cases

Purpose: Laparoscopic surgery decreases postoperative pain, shortens hospital stay, and returns patients to full functional status more quickly than open surgery for a variety of surgical procedures. This study was undertaken to evaluate laparoscopic techniques for application to abdominal aortic aneurysm (AAA) repair. Methods: Twenty patients who had AAAs that required a tube graft underwent laparoscopically assisted AAA repair. The procedure consisted of transperitoneal laparoscopic dissection of the aneurysm neck and iliac vessels. A standard endoaneurysmorrhaphy was then performed through a minilaparotomy using the port sites for the aortic and iliac clamps. Data included operative times, duration of nasogastric suction, intensive care unit days, and postoperative hospital days. Pulmonary artery catheters and transesophageal echocardiography were used in seven patients. For these patients data included heart rate, pulmonary artery systolic and diastolic pressures, mean arterial pressure, central venous pressure, pulmonary capillary wedge pressure, cardiac index, and end diastolic area. Data were obtained before induction, during and after insufflation, during aortic cross-clamp, and at the end of the procedure. Results: Laparoscopically assisted AAA repair was completed in 18 of 20 patients. Laparoscopic and total operative times were 1.44 ± 0.44 and 4.1 ± 0.92 hours, respectively. Duration of nasogastric suction was 1.3 ± 0.7 days. Intensive care unit stay was 2.2 ± 0.9 days. The mean length of hospital stay was 5.8 days excluding three patients who underwent other procedures. There were two minor complications, one major complication (colectomy after colon ischemia), and no deaths. For the eight patients who had intraoperative transesophageal echocardiographic monitoring, no changes were noted in heart rate, pulmonary artery systolic pressure, pulmonary capillary wedge pressure, and cardiac index. Pulmonary artery diastolic pressure and central venous pressure were greatest during insufflation without changes in end-diastolic area. Volume status, as reflected by end-diastolic area and pulmonary capillary wedge pressure, did not change. Conclusions: Laparoscopically assisted AAA repair is technically challenging but feasible. Potential advantages may be early removal of nasogastric suction, shorter intensive care unit and hospital stays, and prompt return to full functional status. The hemodynamic data obtained from the pulmonary artery catheter and transesophageal echocardiogram during pneumoperitoneum suggest that transesophageal echocardiography may be sufficient for evaluation of volume status along with the added benefit of detection of regional wall motion abnormalities and aortic insufficiency. Further refinement in technique and instrumentation will make total laparoscopic AAA repair a reality. (J Vasc Surg 1998;27:81-8.)     

The use of ketamine and midazolam for analgesia and sedation in ventilated patients subject to obligatory treatment with catecholamines

This study was undertaken to compare two regimens for analgesic sedation in intensive care patients with exogenous catecholamine therapy, giving special regard to catecholamine demand and hemodynamic parameters. A total of 20 ventilated patients in a surgical intensive care unit were investigated in a prospectively randomized design. Exogenous catecholamine therapy with epinephrine and/or norepinephrine was started at systolic pressure (SAP) less than 85 mmHg or mean arterial pressure (MAP) less than 65 mmHg to maintain cardiovascular function. For analgesic sedation, patients received bolus injections of about 0.2 mg/h fentanyl and 2.5 mg/h midazolam (fentanyl group, n = 10) or an infusion of about 50 mg/h ketamine and 2.5 mg/h midazolam by syringe pump (ketamine group, n = 10). Before the investigation, all patients received fentanyl and midazolam. The study period was 48 h. During the course of the study, mean catecholamine dosage increased significantly in the fentanyl group from 12.1 to 16.3 micrograms/min (+33%, P = 0.003). In the ketamine group, mean catecholamine dosage decreased from 43.9 to 38 micrograms/min (-13%, P = 0.19). No significant differences in group levels or time course were observed with regard to MAP, heart rate, cardiac index, pulmonary capillary wedge pressure, and shunt volume. Levels of pulmonary artery pressure (PAP) were comparable in both groups (ketamine group 29 mmHg, fentanyl group 26 mmHg). In time course, PAP increased by about 5 mmHg in the ketamine group but not in the fentanyl group (P = 0.009). The average central venous pressure (CVP) was 12 mmHg in both groups. At the end of the investigation, CVP decreased in the fentanyl group and increased in the ketamine group (P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Pulmonary artery catheterization by the percutaneous approach to the axillary vein

The choice of venous access can be difficult in patients under intensive care. The axillary vein appeared interesting to evaluate. This prospective study involved 63 punctures carried out in 59 patients during a 16 month period (14 females and 45 males; mean age: 54 +/- 4 yr). 34 patients were tracheostomized and under controlled respiration; some had coagulation abnormalities (8 cases). The other 29 patients were undergoing a preoperative haemodynamic study. Puncture of the axillary vein was carried out with the needle inserted at an angle of 30 degrees to the skin surface and directed parallel to the artery medial to its course. The Seldinger technique was used (catheter and guide wire). Overall success rate was 87.5%. In 73%, less than three attempts were required. After the catheter was set in place in the axillary vein, the mean time required to reach the pulmonary artery was 7 +/- 15 min (range: 20 s-45 min). Less than 1 min was needed in 60%. Extrasystoles were observed in 3.6%. The incidence of arterial puncture was 11% without any late complications. In every case, pulmonary artery and capillary wedge pressure curves were obtained, as well as cardiac output measurements. Mean duration of catheterization was 2 +/- 1.1 days in the preoperative haemodynamic group and 4 +/- 1.7 days in the other. No infectious complication was related to the catheterization. One thrombosis of the axillary and subclavian veins was noted (1.8%). The axillary vein appeared therefore to be useful for pulmonary artery catheterization. It is an alternative choice in patients under controlled ventilation and with coagulation problems.     

Cardiopulmonary hemodynamic changes during acute subdural hematoma evacuation

The aim of this study was to clarify the mechanism of hemodynamic changes leading to intraoperative hypotension during evacuation of acute subdural hematoma. To our knowledge, little data is available about the mechanism of hemodynamic changes during surgical interventions to decrease intracranial pressure after severe head injury. The influence of preoperative hypotension on intraoperative hypotension was examined. Hemodynamic studies (pulmonary artery catheterization) were carried out in 15 patients before and after acute subdural hematoma evacuation. All patients were assessed for hemodynamic parameters, evacuated hematoma volume, and intracranial pressure measurements. Comparison between just before and after evacuation of the hematoma showed that the mean arterial pressure, pulmonary arterial pressure, systemic vascular resistance, pulmonary vascular resistance, central venous pressure, and pulmonary capillary wedge pressure all decreased after hematoma evacuation. However, the cardiac index was unchanged after hematoma evacuation. Mean arterial blood pressure is dependent on the cardiac index and vascular resistance, so the decrease in arterial blood pressure during hematoma evacuation was the result of a decline in vascular resistance. The influence of preoperative blood pressure on intraoperative hemodynamic changes was analyzed by dividing the patients into two groups, the preoperative hypotension group and preoperative nonhypotension group. The decrease in mean arterial blood pressure was more marked in the preoperative hypotension group than in the preoperative nonhypotension group. Intraoperative hypotension during evacuation of acute subdural hematoma is caused by a decrease in vascular resistance. Preoperative hypotension is a also risk factor for intraoperative hypotension.     

Comparison of Dopamine and Dobutamine Following Coronary Artery Bypass Grafting

A prospective, randomized comparison of the hemodynamic effects of dopamine and dobutamine was performed in 20 patients following coronary artery bypass grafting. Approximately 6 hours postoperatively, when patients were hemodynamically stable, either dopamine or dobutamine was administered at 2.5, 5.0, and 7.5 μg per kilogram of body weight per minute. At 5.0 μg/kg, both drugs increased cardiac index without changing heart rate, mean arterial pressure, pulmonary capillary wedge pressure, or peripheral vascular resistance. At 7.5 μg/kg, dobutamine caused a further increase in cardiac index without changing the other variables. In contrast, increasing dopamine from 5.0 to 7.5 μg/kg/min caused significant increases in mean arterial pressure, pulmonary capillary wedge pressure, and pulmonary vascular resistance but no further increase in cardiac index. We conclude that dobutamine is preferable to dopamine in patients following coronary artery bypass grafting, since it produces consistent, dose-related increases in cardiac index without increases in heart rate, mean arterial pressure, pulmonary capillary wedge pressure, or pulmonary vascular resistance.     

吸入伊洛前列素行急性肺血管扩张试验在先天性心脏病合并重度肺动脉高压术前评估中的作用

目的 评价吸入伊洛前列素的急性肺血管扩张试验在先天性心脏病(CHD)肺动脉高压(PH)患者心脏外科手术适应证选择中的作用.方法 对2006年6月至2008年12月46例CHD合并重度PH患者的临床资料进行回顾性分析.其中男性15例,女性31例,平均年龄(12±9)岁.所有患者术前均接受心导管检查和吸入伊洛前列索试验,患者平均肺动脉压(mPAP)(80±13)mm Hg(1 mill Hg=0.133 kPa),平均肺小动脉阻力指数(PVRI)(17±10)wood·m2.将吸入伊洛前列素试验肺血管阳性反应定义为在体循环压力不变或上升的情况下,PVRI下降≥20%,并作为选择手术适应证的重要条件.药物试验阳性患者在心脏外科修补术后均放置肺动脉漂浮导管,监测术后肺动脉压力、阻力以及心功能状况.结果 46例患者中,药物试验阳性29例(63.1%),吸药后PVRI由(15±6)wood·m2降至(9-4-4)wood·m2,肺循环体循环阻力比(Rp/Rs)由0.7±0.2降至0.4±0.2(P值均<0.05).药物试验反应阴性者17例(36.9%),吸药后PVRI由(21±10)wood·m2降至(19±9)wood·m2(P<0.05),Rp/Rs由1.0±0.5降至0.9±0.5(P>0.05).23例患者接受了心脏外科手术治疗,全部存活.其中药物试验阳性组21例,术后mPAP降至(27±10)mm Hg.药物试验阴性组仅2例接受外科修补术,术后mPAP均>45 mm Hg.结论 吸入伊洛前列素试验阳性患者术后肺动脉压力和PVRI明显降低,可作为评价合并PH的CHD手术适应证的一种蕈要手段.     

Invasive and non-invasive determinants of pulmonary hypertension in patients with chronic heart failure.

BACKGROUND: In patients with chronic heart failure, pulmonary hypertension is an important predictive marker of adverse outcome. Its invasive and non-invasive determinants have not been evaluated. OBJECTIVE: This study was performed to evaluate hemodynamic determinants of pulmonary hypertension in chronic heart failure and to compare the predictive value of Doppler indices with that of invasively measured hemodynamic indices. METHODS: Right heart catheterization and transthoracic echo-Doppler were simultaneously performed in 259 consecutive patients with chronic heart failure (ejection fraction 24% +/- 7%) who were in sinus rhythm and receiving optimized medical therapy. Systolic pulmonary artery pressure (sPAP), cardiac index, transpulmonary gradient pressure, and pulmonary wedge pressure (PWP) were measured invasively. Left atrial and ventricular systolic and diastolic volumes, the ratio of maximal early to late diastolic filling velocities (E/A ratio), deceleration time (DT) and atrial filling fraction (AFF) of transmitral flow, systolic fraction of forward pulmonary venous flow (SFpvf), and mitral regurgitation were quantified by echo-Doppler. RESULTS: Patients with pulmonary hypertension had greater left atrial systolic and diastolic dysfunction, more left ventricular diastolic abnormalities, and greater hemodynamic impairment. The correlations between systolic left ventricular indices, mitral regurgitation, and sPAP were generally poor. Among invasive and non-invasive measurements, PWP (r = 0.89, p < 0.0001) and SFpvf (r = -0.68, p < 0.0001) showed the strongest correlation with sPAP. When we compared all patients with those without mitral regurgitation, the correlations between E/A ratio (r = 0.56 vs r = 0. 74, p < 0.002), SFpvf (r = -0.68 vs r = -0.84, p < 0.03), and systolic pulmonary artery pressure were significantly stronger. Multivariate analysis revealed that PWP was the strongest invasive independent predictor of systolic pulmonary artery pressure in patients with (R(2) = 0.87, p < 0.0001) and without (R(2) = 0.90, p < 0.0001) mitral regurgitation. A PWP > or= 18 mm Hg (odds ratio [95% CL], 142 (41-570) was strongly associated with systolic pulmonary hypertension. Among non-invasive variables DT, SFpvf, and AFF were identified as independent predictors of sPAP in patients with (R(2) = 0.56, p < 0.0001) and without (R(2) = 0.78, p < 0.0001) mitral regurgitation. A DT < 130 (odds ratio [95% CL], 3.5 (1.3-8.5), SFfvp < 40% (odds ratio [95% CL], 333 (41-1,007), and AFF < 30% (odds ratio [95% CL], 2 (1.3-7) most strongly predicted systolic pulmonary hypertension. CONCLUSIONS: The results of this study indicate that in patients with chronic heart failure, venous pulmonary congestion is an important determinant of systolic pulmonary artery hypertension. Hemodynamic and Doppler determinants showed similar predictive power in identifying systolic pulmonary artery hypertension.     

Intravascular fluid administration and hemodynamic performance during open abdominal surgery

We studied whether central hemodynamics measured by a pulmonary artery catheter can serve as a pharmacodynamic expression of fluid therapy in 10 patients undergoing open abdominal surgery. We examined how closely hemodynamic variables follow plasma dilution, which is an index of plasma volume expansion, during and after an IV infusion of 25 mL/kg of lactated Ringer's solution over 45 min. Pulmonary artery wedge pressure and central venous pressure responded to IV fluid with an increase that correlated with accompanying plasma dilution. Six of 10 patients showed a decrease in cardiac output that was probably secondary to an increase in peripheral vascular resistance (nonresponders), whereas the rest increased cardiac output (responders). Volume kinetic analysis suggested that 54% of the infused fluid resided in the central fluid space at the end of the infusion and 25% at the end of the study in the responders compared with 25% and 3%, respectively, in nonresponders. In conclusion, half of the patients undergoing open abdominal surgery responded to crystalloid fluid with a decrease in cardiac output. Pulmonary artery wedge pressure and central venous pressure responded more consistently to different degrees of plasma dilution, which can be simulated for various fluid regimens using volume kinetics.     

Fibrillation in patients subjected to coronary artery bypass grafting

OBJECTIVE: Atrial fibrillation is the most frequently encountered postoperative arrhythmic complication after coronary artery bypass grafting. Ischemic preconditioning has proved a potent endogenous factor in suppressing ischemia-reperfusion-induced arrhythmias. The protective effect of ischemic preconditioning on atrial fibrillation after coronary artery bypass grafting has not been studied. The purpose of the present study was to investigate whether ischemic preconditioning had an effect on postoperative atrial fibrillation in patients undergoing coronary artery bypass grafting. METHODS: Eighty-five patients undergoing coronary artery bypass grafting were randomized into ischemic preconditioning and control groups. Holter data from 24-hour electrocardiography were collected 1 day before the operation to the second postoperative day. Atrial fibrillation was registered as positive if any atrial fibrillation event occurred. RESULTS: The overall incidence of postoperative atrial fibrillation and sustained atrial fibrillation was 34.1% and 27.1%, respectively. The occurrence of atrial fibrillation was significantly lower in the ischemic preconditioning group (21.4% in patients undergoing ischemic preconditioning and 46.5% in control subjects, P =.015). Preoperative recent unstable angina did not influence the incidence of atrial fibrillation. Patients with atrial fibrillation had longer intensive care unit stays and compromised postoperative hemodynamic outcomes. Binary logistic regression analysis showed that ischemic preconditioning, preoperative mean heart rate, and postoperative pulmonary capillary wedge pressure were the independent predictors of atrial fibrillation. CONCLUSIONS: Postcoronary artery bypass grafting atrial fibrillation is associated with more complicated postoperative outcome. Higher preoperative heart rate and postoperative pulmonary capillary wedge pressure were the independent predictors of atrial fibrillation. Recent unstable angina is not related to the occurrence of postcoronary artery bypass grafting atrial fibrillation. Ischemic preconditioning significantly suppresses postcoronary artery bypass grafting atrial fibrillation, suggesting that ischemic preconditioning can be used as an effective prophylactic method for postoperative atrial fibrillation.     

Resting and exercise hemodynamics in pulmonary arterial hypertension

The normal mean pulmonary artery pressure (PAP) is 14 ± 3 mmHg. Precapillary pulmonary hypertension is defined as a mean PAP ≥ 25 mmHg at rest and a pulmonary capillary wedge pressure ≤ 15 mmHg as assessed by right heart catheterization. When performed in experienced centers, right heart catheter procedures in patients with pulmonary hypertension are associated with low morbidity and mortality rates. Right heart catheterization remains essential for the management of pulmonary arterial hypertension (PAH) as it confirms the diagnosis, determines the type of pulmonary hypertension, its severity, its vasoreactivity as well as response to therapeutic interventions. The hemodynamic severity largely influences patients' management including the choice of initial and subsequent therapies. Hemodynamic evaluation during exercise allows a precise characterization of the true resistive properties of pulmonary vessels through the assessment of the pressure-flow relationship. The significance of isolated pulmonary hypertension during exercise remains unknown. Indeed, roughly 50% of healthy subjects > 50 years old exhibit mean PAP > 30 mmHg during mild exercise. Isolated exercise-induced increases in mean PAP > 30 mmHg during exercise is thus no longer used to define pulmonary hypertension. More complex hemodynamic parameters allow partitioning of arterial and venous vascular resistance, as well as a better characterization of pulmonary artery compliance, right ventricle function and right ventriculo-arterial coupling. The clinical relevance of these subtle markers of pulmonary vascular abnormalities remains unknown.     

Hemodynamic monitoring in the critically ill: spanning the range of kidney function

Critically ill patients often have deranged hemodynamics. Physical examination, central venous pressure, and pulmonary artery occlusion pressure ("wedge") have been shown to be unreliable at assessing volume status, volume responsiveness, and adequacy of cardiac output in critically ill patients. Thus, invasive and noninvasive cardiac output monitoring is a core feature of evaluating and managing a hemodynamically unstable patient. In this review, we discuss the various techniques and options of cardiac output assessment available to clinicians for hemodynamic monitoring in the intensive care unit. Issues related to patients with kidney disease, such as timing and location of arterial and central venous catheters and the approach to hemodynamics in patients treated by long-term dialysis also are discussed.     

Predictive factors associated with the development of abdominal compartment syndrome in the surgical intensive care unit

HYPOTHESIS: Intraoperative and postoperative variables contribute to the development of abdominal compartment syndrome (ACS) in general surgical patients. DESIGN: Case-control cohort study of 44 patients admitted to the surgical intensive care unit from March 1, 1995, to January 1, 2001. Groups were matched with respect to age, sex, diagnosis, and procedure. Prospectively collected data included demographics, ventilatory parameters, fluid requirements, hemodynamic and oxygen-derived variables, length of stay, and mortality rates. Statistical analysis was done with the Fisher exact test and/or chi(2) analysis. Continuous variables were analyzed with multivariate and univariate analysis. Data are presented as mean +/- SD. Statistical significance is defined as P<.05. SETTING: Long Island Jewish Medical Center (New Hyde Park, NY) is a large tertiary teaching hospital. PATIENTS: Twenty-two patients admitted to the surgical intensive care unit who developed ACS, and 22 case-control patients without ACS. MAIN OUTCOME MEASURES: Identification of variables that predict the development of ACS. RESULTS: Twenty-two patients with episodes of ACS (group 1) were examined and contrasted with 22 matched patients without ACS (group 2). Using univariate analysis, the groups differed with respect to 24-hour fluid administration and balance, number of emergency procedures, peak airway pressure, central venous pressure, pulmonary artery occlusion pressure, lengths of stay in the hospital and intensive care unit, and mortality rates. With multivariate analysis, only 24-hour fluid balance and peak airway pressure (group 1 vs group 2: mean +/- SD, 15.9 +/- 10.3 L vs 7.0 +/- 3.5 L, and 57.9 +/- 11.9 mm Hg vs 32.2 +/- 7.1 mm Hg, respectively; P<.05) remained significantly different. The groups did not differ with regard to age, cardiac index, operative blood loss, duration of surgery, intraoperative fluid input, or balance. A predictive equation for ACS development was created: P = 1/(1 +e(-z)), where z= -18.6763 + 0.1671 (peak airway pressure) + 0.0009 (fluid balance). CONCLUSION: The results of this study indicate that 24-hour fluid balance and peak airway pressure are 2 independent variables predictive of the development of ACS in nontrauma surgical patients.     

Stroke volume variation as an indicator of fluid responsiveness using pulse contour analysis in mechanically ventilated patients

Assessment of cardiac performance and adequate fluid replacement of a critically ill patient are important goals of a clinician. We designed this study to evaluate the ability of stroke volume variation (SVV), derived from pulse contour analysis, and frequently used preload variables (central venous pressure and pulmonary capillary wedge pressure) to predict the response of stroke volume index and cardiac index to volume replacement in normoventilated cardiac surgical patients. We studied 20 patients undergoing elective coronary artery bypass grafting. After the induction of anesthesia, hemodynamic measurements were performed before (T1) and subsequent to volume replacement by infusion of 6% hydroxyethyl starch 200/0.5 (7 mL/kg) with a rate of 1 mL x kg(-1) x min(-1). Except for heart rate, all hemodynamic variables changed significantly (P < 0.01) after volume loading. Linear regression analysis between SVV at baseline (T1) and DeltaSVV after volume application showed a significant correlation (r = -0.97; P < 0.01), whereas linear regression analysis between SVV (T1) and percentage changes of stroke volume index (r = 0.19) and cardiac index (r = 0.17) did not reveal a significant relationship between variables. The results of our study suggest that SVV derived from pulse contour analysis cannot serve as an indicator of fluid responsiveness in normoventilated cardiac surgical patients.     

Mitral Valve Replacement with the Modified University of Cape Town (UCT) Prosthesis: Clinical and Hemodynamic Results

Mitral valve replacement with the modified University of Cape Town prosthesis was performed in 42 patients. In 35 the procedure was an isolated one, and the hospital mortality was 6%. The late survival rate was 60%, half of the late deaths being the result of thromboembolism or complications of anticoagulant therapy. The incidence of hemolysis was low, and hemodynamic results demonstrated improvement in cardiac index and lowering of pulmonary artery pressure, pulmonary artery wedge pressure, pulmonary arteriolar resistance, and transvalvular mean gradients. However, the calculated prosthetic valve orifice area was lower than the measured area. Because of complications of thromboembolism, the high incidence of late deaths, and high transvalvular gradients, this prosthetic valve is no longer used in patients requiring mitral valve replacement.     

Hemodynamic status following regional and general anesthesia for carotid endarterectomy

We prospectively studied 23 patients undergoing carotid endarterectomy under regional (n = 13) or general (n = 10) anesthesia to determine the hemodynamic basis of increased frequency in the need for postoperative vasopressor support when regional anesthesia was used. Anesthesia and postoperative care were conducted without reference to hemodynamic data from pulmonary artery catheterization. Although mean arterial pressure was similar in the two groups postoperatively, 11 of the 13 patients undergoing regional anesthesia and 3 of the 10 patients undergoing general anesthesia required phenylephrine postoperatively. No patient required therapy postoperatively to reduce a systolic pressure exceeding 160 mm Hg. Mean arterial pressure remained below the preoperative baseline value in both groups (p < 0.05 with general anesthesia; p = 0.06 with regional anesthesia) during follow-up. In the general anesthesia group, systemic vascular resistance declined significantly below baseline (p < 0.05) following the operation, accompanied by a decline in mean arterial pressure (p < 0.05) and a higher cardiac output. Intraoperative fluid requirements were greater during general anesthesia than during regional anesthesia (p < 0.01). Pulmonary artery occlusion pressure was lower postoperatively than at baseline in both groups (p < 0.05). Pulmonary artery occlusion pressure was higher in the general anesthesia group despite the greater use of phenylephrine in the regional anesthesia group.     

Utility and application of pulmonary artery catheterization in aortic and aortoiliac disease

To determine how useful pulmonary artery catheterization is in abdominal aortic surgery and which patients are most likely to benefit from the procedure, the author studied 28 patients with aneurysms and 22 with obstructive disease. Patients with multiple risk factors, except those with leaking aneurysms, were assessed before operation by pulmonary artery catheterization and volume loading (15 ml of 5% albumin/kg over 12 hours). All patients who underwent operation were assessed and monitored by pulmonary artery catheterization, beginning immediately postoperatively. In 26 patients the procedure made a substantial contribution to assessment or care of their condition, not suggested by the usual clinical and technical modalities. In four patients the proposed surgery was affected; it was cancelled in one, delayed in two and replaced by a lesser procedure in one. Two other patients, thought to have unacceptable cardiac function, were considered suitable for operation after catheterization was done. Eleven patients with suboptimal cardiac index and 2 with volume overload were recognized early after surgery. Two patients with oliguria following repair of a ruptured aneurysm had optimal cardiac indices and renal perfusion assured by pulmonary artery catheterization, which helped to identify unsuspected pulmonary hypertension in three patients, bleeding in one and intestinal infarction in one. Twenty-seven patients were challenged before surgery with 5% albumin and their response was analyzed. In 7 there was no response to the colloid challenge and they suffered much more morbidity than the 20 patients who had a positive hemodynamic response to challenge.(ABSTRACT TRUNCATED AT 250 WORDS)