The effectiveness of right heart catheterization in the initial care of critically ill patients. SUPPORT Investigators

Early continuous noninvasive haemodynamic monitoring after severe blunt trauma

BACKGROUND

Invasive haemodynamic parameters obtained by pulmonary artery (PA) catheterization from survivors' patterns were reported to provide criteria for therapeutic goals in high-risk elective surgery and accidental injuries. This approach is limited because PA catheterization requires critical care conditions; however, noninvasive methods can provide early information anywhere in the hospital.

OBJECTIVES

To evaluate the feasibility of using noninvasive haemodynamic monitoring of patients with severe blunt trauma immediately after emergency department (ED) admission and to describe the early time course of haemodynamic events in survivors and nonsurvivors of blunt trauma.

SETTING

A large, academic, level-I trauma centre.

DESIGN

Prospective, descriptive haemodynamic study.

PATIENTS AND METHODS

38 severely injured patients, 22 (58%) survivors and 16 (42%) nonsurvivors, with ISS > 15 were monitored by: (a) an improved thoracic bioelectric impedance device that estimated cardiac output noninvasively and continuously, (b) simultaneous arterial oxygen saturation by pulse oximetry, (c) noninvasive blood pressure measurement and (d) transcutaneous oxygen and carbon dioxide sensors. The patients were monitored as soon as possible upon arrival at the ED and continued during the first 24 h or more after admission. When the patient reached the ICU, monitoring by PA catheterization was undertaken to validate the noninvasive methods and for continued diagnostic evaluations.

RESULTS

Cardiac output estimations by thermodilution and bioimpedance were well correlated; r = 0.91. Survivors started with high cardiac index (CI) values that subsequently rose to over 4 L/min/m2; arterial oxygen saturation (SaO2), transcutaneous oxygen tension and transcutaneous-oxygen-tension-to-inspired-fraction-of-oxygen-concentr ati on (PtcO2/FiO2) values were normal in survivors and higher than those of the nonsurvivors. In the 1st h after admission, nonsurvivors' blood pressures were higher than normal and higher than that of the survivors, but in the 2nd and 3rd h, both groups were in the normal range; thereafter, nonsurvivors' values were lower than survivors' and often lower than normal.

CONCLUSIONS

The noninvasive haemodynamic monitoring system provides reasonably accurate, continuous, on-line, real-time display of haemodynamic data that show marked differences in the early patterns of survivors and nonsurvivors. The study suggests noninvasive monitoring may be used for early detection and correction of posttraumatic circulatory deficits.

Supportive therapy of the sepsis syndrome

Adequate volume loading may be the most important step in the treatment of patients with septic shock. Techniques allowing us to achieve and tightly control volume loading and regional perfusion are considered to be helpful. An elevated oxygen delivery may be beneficial in some patients but the increase of oxygen delivery should be guided by the measurement of parameters assessing global and regional oxygenation. Forcing an increase in oxygen delivery by the use of very high dosages of catecholamines can be harmful. Vasopressors should be used for achieving an adequate perfusion pressure. For norepinephrine, no negative effects on regional perfusion have been demonstrated. Epinephrine and dopamine should be avoided because they seem to redistribute blood flow away from the splanchnic region. There are no convincing data yet to support the routine use of low dose dopamine or dopexamine in patients with sepsis. Neither low dose dopamine nor dopexamine has been proven to prevent renal failure in septic patients. Furthermore, there is evidence that low dose dopamine may reduce mucosal perfusion in the gut in some patients. There is some suggestion that dopexamine can improve splanchnic perfusion but since these effects remain somewhat controversial, there is no reason for a general recommendation for dopexamine in septic patients.

Continuous cardiac output and mixed venous oxygen saturation monitoring

Continuous assessment of cardiac output and SVO2 in the critically ill may be helpful in both the monitoring variations in the patient's cardiovascular state and in determining the efficacy of therapy. Commercially available continuous cardiac output (CCO) monitoring systems are based on the pulsed warm thermodilution technique. In vitro validation studies have demonstrated that this method provides higher accuracy and greater resistance to thermal noise than standard bolus thermodilution techniques. Numerous clinical studies comparing bolus with continuous thermodilution techniques have shown this technique similarly accurate to track each other and to have negligible bias between them. The comparison between continuous thermal and other cardiac output methods also demonstrates good precision of the continuous thermal technique. Accuracy of continuous oximetry monitoring using reflectance oximetry via fiberoptics has been assessed both in vitro and in vivo. Most of the studies testing agreement between continuous SVO2 measurements and pulmonary arterial blood samples measured by standard oximetry have shown good correlation. Continuous SVO2 monitoring is often used in the management of critically ill patients. The most recently designed pulmonary artery catheters are now able to simultaneously measure either SVO2 and CCO or SVO2 and right ventricular ejection fraction. This ability to view simultaneous trends of SVO2 and right ventricular performance parameters will probably allow the clinician to graphically see the impact of volume loading or inotropic therapy over time, as well as the influence of multiple factors, including right ventricular dysfunction, on SVO2. However, the cost-effectiveness of new pulmonary artery catheters application remains still questionable because no established utility or therapeutic guidelines are available.

Three-dimensional echocardiographic determination of left ventricular volumes and function by multiplane transesophageal transducer: dynamic in vitro validation and in vivo comparison with angiography and thermodilution

The goal of this study was to validate 3-dimensional echocardiography by multiplane transesophageal transducer for the determination of left ventricular volumes and ejection fraction in an in vitro experiment and to compare the method in vivo with biplane angiography and the continuous thermodilution method. In the dynamic in vitro experiment, we scanned rubber balloons in a water tank by using a pulsatile flow model. Twenty-nine measurements of volumes and ejection fractions were performed at increasing heart rates. Three-dimensional echocardiography showed a very high accuracy for volume measurements and ejection fraction calculation (correlation coefficient, standard error of estimate, and mean difference for end-diastolic volume 0.998, 2.3 mL, and 0.1 mL; for end-systolic volume 0.996, 2.7 mL, and 0.5 mL; and for ejection fraction 0.995, 1.0%, and -0.4%, respectively). However, with increasing heart rate there was progressive underestimation of ejection fraction calculation (percent error for heart rate below and above 100 bpm 0.59% and -8.6%, P < .001). In the in vivo study, left ventricular volumes and ejection fraction of 24 patients with symmetric and distorted left ventricular shape were compared with angiography results. There was good agreement for the subgroup of patients with normal left ventricular shape (mean difference +/-95% confidence interval for end-diastolic volume 5.2+/-6.7 mL, P < .05; for end-systolic volume -0.5+/-8.4 mL, P = not significant; for ejection fraction 2.4%+/-7.2%, P = not significant) and significantly more variability in the patients with left ventricular aneurysms (end-diastolic volume 23.1+/-56.4 mL, P < .01; end-systolic volume 5.6+/-41.0 mL, P = not significant; ejection fraction 4.9%+/-16.0%, P < .05). Additionally, in 20 critically ill, ventilated patients, stroke volume and cardiac output measurements were compared with measurement from continuous thermodilution. Stroke volume as well as cardiac output correlated well to thermodilution (r = 0.89 and 0.84, respectively, P < .001), although both parameters were significantly underestimated by 3-dimensional echocardiography (mean difference +/-95% confidence interval = -6.4+/-16.0 mL and -0.6+/-1.6 L/min, respectively, P < .005).

Continuous noninvasive measurement of aortic blood flow in critically ill patients with a new esophageal echo-Doppler system

PURPOSE

Determination of aortic blood flow (ABF) using esophageal Doppler has been proposed as a low invasive hemodynamic monitoring method. The esophageal echo-Doppler Dynemo 3000 (Sometec Inc., Paris, France) system, recently available on the market, is an original device measuring simultaneously, and at the same anatomic level, aortic diameter, and blood flow velocity. Until now, this material has been used exclusively for peroperative monitoring. The objectives of the study were to assess the feasibility and reliability of use for continuous measurements of ABF in hemodynamically compromised intensive care unit patients; and to compare ABF values and its change induced by preload manipulation with the cardiac output (CO) values measured simultaneously by the standard thermodilution method.

MATERIALS AND METHODS

Sixty simultaneous measurements of ABF and CO were performed in 22 intensive care unit patients. In 16 hypovolemic patients, Doppler and thermodilution measurements were repeated after fluid replacement.

RESULTS

Applicability of the method was 84.6% (failure of the echo-Doppler method in 4 of 26 eligible patients). Coefficient of variation of echo-Doppler-derived ABF was 3.25 +/- 2.26%. Interobserver variability was 3.3 +/- 1.6%. Close linear relationship was found between ABF and CO (r = 0.92). Average ABF/CO ratio was 73 +/- 10%, but significant variation was observed after fluid replacement.

CONCLUSIONS

The echo-Doppler Dynemo 3000 system allows reliable continuous measurements of ABF in intensive care unit patients, both easily and safely.

Benefits, risks and alternatives of pulmonary artery catheterization

Twenty-five years after the introduction of the pulmonary artery catheter in clinical practice, its effectiveness in improving patient outcome is seriously questioned. Experts still recommend to use pulmonary artery catheters in selected critically ill patients, although evidence supporting these recommendations is lacking. The risks and the unclear benefits associated with this procedure should prompt the search for alternative, noninvasive monitoring techniques.

A firm trial of interdisciplinary rounds on the inpatient medical wards: an intervention designed using continuous quality improvement

OBJECTIVES

In August 1993 a group of house staff and nursing staff at MetroHealth Medical Center formed a quality improvement team to evaluate the process of medical care on the inpatient wards. Using standard continuous quality improvement (CQI) methods, a team of medical interns, nurses, and other health professionals involved in patient care on the medicine inpatient service designed interdisciplinary, daily work rounds to improve the care of patients on the inpatient wards.

METHODS

The authors conducted a randomized, controlled firm trial of the impact of interdisciplinary rounds on the inpatient medicine services. The trial lasted 6 months (November 1993-April 1994) and included 1,102 admissions randomly assigned to experimental or control teams by the pre-existing firm system. Of the 1,102 admissions included in the study, 535 were randomized to medical services with traditional rounds and 567 to medical services with interdisciplinary rounds. The outcomes studied included length of stay (LOS), total hospital charges, provider satisfaction, and ancillary service efficiency.

RESULTS

Unadjusted analysis for log-transformed data showed lower length of stay and total charges for the interdisciplinary group. The mean LOS for interdisciplinary rounds was 5.46 days, compared with 6.06 days for traditional care (P = 0.006), whereas mean total charges were $6,681 and $8,090 (P = 0.002) for the two groups, respectively. After multivariate regression analysis using a propensity score that included gender, age, marital status, admission source, diagnosis-related group (DRG) weight, and primary diagnosis by International Classification of Diseases, Ninth Revision (ICD-9) cluster, these differences remained statistically significant.

CONCLUSIONS

Previous studies of interdisciplinary teams have failed to show statistically significant cost savings. This study involving more patients shows both cost and LOS decreases with the use of interdisciplinary teams. At the end of the 6-month trial, interdisciplinary rounds were instituted on all medicine inpatient services.

Oxygen delivery and outcome

Perioperative haemodynamic optimization of high-risk surgical patients seems to be associated with a reduction in morbidity and mortality. There is, however, no evidence to support the use of treatment directed at achieving survivor values of oxygen delivery and consumption in critically ill patients after admission to intensive care. Mitochondrial dysfunction may be responsible for the inability of patients dying of sepsis to increase oxygen consumption and thus may explain why therapies directed at reducing mortality through increasing oxygen delivery have not been successful. In response to the recent controversy surrounding the risks versus benefits of pulmonary artery catheterization, current research is focusing on the development and evaluation of noninvasive methods to assess the adequacy of resuscitation.

The surgeon's use of transesophageal echocardiography

Transesophageal echocardiography has become an instrumental diagnostic modality for the accurate evaluation of cardiac and aortic anatomy and function. Multiplanar technology has facilitated improved visualization of structures and enhanced TEE over TTE in many situations. Care of the trauma patient and critically ill patient is improved with the appropriate and timely performance of TEE. Education, certification, credentialing, and determination of competency are areas that need to be addressed continually in the future.

A future role for the pulmonary artery catheter?

Either a moratorium prohibiting, or a prospective, randomized clinical trial on pulmonary artery catheter use has been proposed. Expert opinion regarding both this suggestion and on the therapeutic efficacy of interventions guided by pulmonary artery catheters in a variety of clinical settings has included (in my view incorrectly) physician prerogative and perceived threats to therapeutic freedom. The legitimate concerns of worsened patient outcome secondary to pulmonary artery catheter use and demonstrably inadequate intellectual preparation of practitioners and allied healthcare professionals, which may exacerbate these deficiencies, have also been discussed. The future of the pulmonary artery catheter is questioned; physicians must evaluate the available information and, more importantly, critique their current practice, before employing this technology.

The effectiveness of early endoscopy for upper gastrointestinal hemorrhage: a community-based analysis

OBJECTIVES

The effectiveness of upper endoscopy in unselected patients with upper gastrointestinal hemorrhage has not been well studied. This study was undertaken to identify factors associated with the performance of early endoscopy (ie, within 1 day of hospitalization) and, after adjusting for these factors, to determine associations between early endoscopy and in-hospital mortality, length of stay, and performance of surgery.

METHODS

Subjects in this observational cohort study were 3,801 consecutive admissions with upper gastrointestinal hemorrhage to 30 hospitals in a large metropolitan region. Demographic and clinical data were abstracted from hospital records. A multivariable model based on factors that potentially could relate to the decision to perform endoscopy was developed to determine the propensity (0 to 100%) for early endoscopy in each patient.

RESULTS

Early endoscopy was performed in 2,240 patients (59%), and although it was not associated with mortality after adjusting for severity of illness among all patients, it was associated with a higher risk of death for patients in the lowest propensity group. Early endoscopy was associated with a lower likelihood of upper gastrointestinal surgery in all patients and in the two highest propensity groups and with a shorter length of stay in the entire cohort and in all subgroups.

CONCLUSIONS

In the absence of specific contraindications, early endoscopy should be considered because of associated reductions in length of stay and surgical intervention. Further studies are needed to identify subgroups in whom the procedure may be associated with adverse effects on survival.

Measurement of gastric mucosal carbon dioxide tension by saline and air tonometry

PURPOSE

This study compares the balloon air tonometry method of measuring gastric mucosal CO2 to standard saline tonometry. Also, this study investigates the effect of histamine-2 receptor blockade on the precision of tonometric measures of gastric mucosal PCO2 (PtCO2).

MATERIALS AND METHODS

We obtained hourly measurements of PtCO2 from two gastric tonometers inserted orally in 19 healthy volunteers. One tonometer measured PtCO2 by the intermittent saline method, whereas the other measured PtCO2 using a newer continuous air method. Subjects received intravenous 5% dextrose during the first 6 hours of the experiment followed by a continuous infusion of a solution of ranitidine in 5% dextrose for another 6 hours. The ranitidine infusion was titrated to maintain gastric fluid pH > or = 4.

RESULTS

Comparison of air to saline tonometry yielded a bias of -1.3 mm Hg with a limit of agreement of 6.6 mm Hg under optimal conditions of optimal gastric fluid pH (gastric fluid pH > or = 5.0). Measures of PtCO2 were lower with ranitidine for either group, 45.3 +/- 1.3 mm Hg versus 39.7 +/- 0.5 mm Hg for saline (P < .01) and 45.9 +/- 1.0 versus 41.3 +/- 0.5 for air (P < .01). The mean PCO2 gap (PtCO2-P(arterial)CO2) at gastric fluid pH > or = 5.0 was 1.4 mm Hg, with a standard deviation of 2.7 mm Hg. A span of three standard deviations yields a normal limit for PCO2 gap of 9.5 mm Hg.

CONCLUSION

Measures of PtCO2 with the air tonometer method are similar to those obtained with saline tonometry. The reliability of PtCO2 measurements with either method improved with the use of ranitidine to maintain gastric fluid pH > or = 5.

Clinicians' abilities to estimate cardiac index in ventilated children and infants

OBJECTIVES

To evaluate the ability of clinicians involved in the provision of paediatric intensive care to estimate cardiac index in ventilated children, based on physical examination and clinical and bedside laboratory data.

METHODS

Clinicians were exposed to all available haemodynamic and laboratory data for each patient, allowed to make a physical examination, and asked to first categorize cardiac index as high, high to normal, low to normal, or low, and then to quantify this further with a numerical estimate. Cardiac index was measured simultaneously by femoral artery thermodilution (coefficient of variation 5.37%). One hundred and twelve estimates were made by 27 clinicians on 36 patients (median age 34.5 months).

RESULTS

Measured cardiac index ranged from 1.39 to 6.84 1/min/m2. Overall, there was poor correlation categorically (kappa statistic 0.09, weighted kappa 0.169) and numerically (r = 0.24, 95% confidence interval 0.06 to 0.41), although some variation was seen among the various levels of seniority.

CONCLUSION

Assuming that objective measurement, and hence manipulation, of haemodynamic variables may improve outcome, these findings support the need for a safe, accurate, and repeatable technique for measurement of cardiac index in children who are critically ill.

Routine pulmonary artery catheterization does not reduce morbidity and mortality of elective vascular surgery: results of a prospective, randomized trial

OBJECTIVE

The authors determined whether the preoperative placement of a pulmonary artery catheter (PAC) with optimization of hemodynamics results in outcome improvement after elective vascular surgery.

SUMMARY BACKGROUND DATA

The PAC commonly is used not only in patients who are critically ill, but also perioperatively in major elective surgery. Few prospective studies exist documenting its usefulness.

METHODS

One hundred four consecutive patients were randomized to have a PAC placed the morning of operation (group I) or to have a PAC placed only if clinically indicated (group II). Group I patients were resuscitated to preestablished endpoints before surgery and kept at these points both intraoperatively and postoperatively. Group II patients received standard care.

RESULTS

There was one death in each group. An intraoperative or postoperative complication developed in 13 patients in group I versus 7 patients in group II (p = not significant). Group I patients received more fluid than did group II patients (5137 +/- 315 mL vs. 3789 +/- 306 mL; p < 0.003). There was no significant difference in either overall or surgical intensive care unit length of stay. Only one patient in group II required a postoperative PAC.

CONCLUSIONS

Routine PAC use in elective vascular surgery increases the volume of fluid given to patients without demonstrable improvement in morbidity or mortality.

A prospective randomized trial of preoperative "optimization" of cardiac function in patients undergoing elective peripheral vascular surgery

BACKGROUND

Previous investigations have suggested that preoperative invasive hemodynamic monitoring with "optimization" of cardiovascular function may favorably affect the outcome among patients undergoing peripheral vascular surgery. The purpose of this study was to evaluate the effect of preoperative optimization of hemodynamic parameters on outcome in patients undergoing aortic reconstruction (AR) or limb salvage procedures (LSP) in a randomized, prospective clinical trial.

METHODS

All 72 patients who consented to participate in this study were admitted to the intensive care unit at least 12 hours before operation for placement of a pulmonary artery catheter (PAC). Patients who were randomized to the treatment group (n = 32) were "optimized" by adjusting their hemoglobin concentration, oxygen saturation (SaO2), cardiac output, or afterload until the mixed venous O2 saturation (SvO2) was at least 65%. The control group (n = 40) underwent placement of a PAC and had oxygen transport parameters measured without any attempt to optimize SvO2.

RESULTS

There were no significant differences between the treatment and control groups with respect to age, gender, type of operation, initial Acute Physiology and Chronic Health Evaluation (APACHE) II score, SvO2, pulmonary artery occlusion pressure, or cardiac index. All treatment patients achieved an SvO2 of at least 65% before operation. Comparing the treatment and control groups, postoperative cardiovascular complications occurred in 25% versus 27%, intraoperative complications in 28% versus 20%, and death in 9% versus 5%, respectively. None of these differences was statistically significant as a whole or within the subgroups undergoing AR or LSP.

CONCLUSIONS

These data suggest that preoperative optimization of cardiovascular function by using achievement of SvO2 above 65% as the end point does not result in any reduction of intraoperative or perioperative cardiac complications in patients undergoing PVS. Further studies with alternative assessments and manipulation of different cardiopulmonary parameters may yield additional information.