Relationship of pulmonary artery catheter use to mortality and resource utilization in patients with severe sepsis*

Pulmonary Artery Catheter in Patients with Severe Acute Pancreatitis: A Single-Center Retrospective Study

OBJECTIVE

It is still uncertain what effects pulmonary artery catheter (PAC)-guided resuscitation has on outcomes for patients with severe acute pancreatitis (SAP). Therefore, we aimed to investigate the effect of PAC on hospital mortality in patients with SAP.

METHODS

We collected the data of patients with a diagnosis of SAP from January 10, 2017, to July 30, 2019. Patients were divided into a PAC group and a control group. The primary outcome measured was the day-28 mortality. Secondary outcomes included day-90 mortality, duration of ICU and hospital stay, ventilation days, usage of renal support and vasoactive agents, incidences of acute abdominal compartment syndrome, infusion volumes, and fluid balance and hemodynamic characteristics measured by the PAC. Kaplan-Meier analysis was applied to estimate survival outcomes. Complications related to PAC were also analyzed.

RESULTS

There was no significant difference between the PAC group and the control group for day-28 mortality (22.7% vs. 30%, odds ratio, 0.69; 95% CI 0.31-1.52; P = 0.35). The duration of ICU stay in the PAC group was shorter (P = 0.00), and the rate of dependence on renal support treatment was lower in the PAC group than in the control group (P = 0.03). There was no difference in other secondary outcomes and no significant difference in the survival curve between the two groups (log-rank P = 0.72, X² = 0.13). However, SAP patients inserted PAC within 24 h ICU admission showed that duration of renal support therapy in PAC patients within 24 h ICU admission (mean days, 1.60; standard deviation, 0.14) was shorter than those with 24-72 h ICU admission (mean days, 2.94; standard deviation, 0.73; P = 0.03). The organ failure rates (1 organ, 2 organs and 3 organs) were all lower in PAC patients within 24 h ICU admission than with 24-72 h ICU admission (P = 0.02, P = 0.02, P = 0.048, respectively).

CONCLUSION

In patients with severe acute pancreatitis, PAC-guided fluid resuscitation shortened the duration of ICU stay, and patients in the PAC group had a lower rate of dependence on renal support, while no benefit in terms of mortality was observed. However, SAP patients inserted PAC within 24 h ICU admission showed shorter duration of renal support therapy and lower organ failure rates than those with 24-72 h ICU admission, indicating that early use of PAC, especially within 24 h, might be better for SAP patients.

Reliability of Pulse Contour Cardiac Output Analysis in a Piglet Model of Multi-step Intra-abdominal Hypertension

BACKGROUND

Pulse contour cardiac output (PCCO) analysis is a minimally invasive technique for continuous cardiac output (CO) measurement monitoring. PCCO requires calibration by transpulmonary thermodilution (TPTD). Studies showed good agreement between PCCO, TPTD CO and CO measured by pulmonary artery thermodilution (PATD) during stable hemodynamics. However, data are limited in patients with intra-abdominal hypertension (IAH). The objective is to compare the agreement between PCCO, TPTD CO, and PATD CO in a piglet model of multi-step IAH.

MATERIALS AND METHODS

Ten female domestic piglets were enrolled in this study. IAH was induced by stepwise carbon dioxide inflation into peritoneal cavity in anesthetized piglets. Following baseline registrations, intra-abdominal pressure (IAP) was increased and maintained at each IAP plateau of 10, 20, 30, and 40 mmHg for 15 min before CO measurements. CO was measured by PATD and simultaneously by 2 femoral artery PCCO catheters. One PCCO catheter was recalibrated by TPTD at each IAP plateau while the other was only calibrated at baseline.

RESULTS

In pooled data of different IAP stages, TPTD CO and recalibrated PCCO (R-PCCO) showed excellent correlation (r² = 0.94 and 0.93) and small bias (-0.09 and -0.09 L/min), respectively, compared with PATD CO. However, PCCO without recalibration (NR-PCCO) were not accurate during IAH (r² = 0.58, bias: +0.32 L/min). When IAP increased to 30 mmHg, NR-PCCO failed to agree with PATD CO (r² = 0.47, bias: +0.52 L/min). On the contrary, a clinically accepted agreement between TPTD CO, R-PCCO, and PATD CO was observed at different IAP stages.

CONCLUSIONS

TPTD CO and R-PCCO agreed with PATD CO in this piglet model of multi-step IAH. On the contrary, NR-PCCO failed to agree with PATD CO when IAP increased to 30 mmHg or more. PCCO analysis needs recalibration in this condition.

To Swan or Not to Swan: Indications, Alternatives, and Future Directions

The pulmonary artery catheter (PAC) has revolutionized bedside assessment of preload, afterload, and contractility using measured pulmonary capillary wedge pressure, calculated systemic vascular resistance, and estimated cardiac output. It is placed percutaneously by a flow-directed balloon-tipped technique through the venous system and the right heart to the pulmonary artery. Interest in the hemodynamic variables obtained from PACs paved the way for the development of numerous less-invasive hemodynamic monitors over the past 3 decades. These devices estimate cardiac output using concepts such as pulse contour and pressure analysis, transpulmonary thermodilution, carbon dioxide rebreathing, impedance plethysmography, Doppler ultrasonography, and echocardiography. Herein, the authors review the conception, technologic advancements, and modern use of PACs, as well as the criticisms regarding the clinical utility, reliability, and safety of PACs. The authors comment on the current understanding of the benefits and limitations of alternative hemodynamic monitors, which is important for providers caring for critically ill patients. The authors also briefly discuss the use of hemodynamic monitoring in goal-directed fluid therapy algorithms in Enhanced Recovery After Surgery programs.

Cardiac power output accurately reflects external cardiac work over a wide range of inotropic states in pigs

BACKGROUND

Cardiac power output (CPO), derived from the product of cardiac output and mean aortic pressure, is an important yet underexploited parameter for hemodynamic monitoring of critically ill patients in the intensive-care unit (ICU). The conductance catheter-derived pressure-volume loop area reflects left ventricular stroke work (LV SW). Dividing LV SW by time, a measure of LV SW min^- 1 is obtained sharing the same unit as CPO (W). We aimed to validate CPO as a marker of LV SW min^- 1 under various inotropic states.

METHODS

We retrospectively analysed data obtained from experimental studies of the hemodynamic impact of mild hypothermia and hyperthermia on acute heart failure. Fifty-nine anaesthetized and mechanically ventilated closed-chest Landrace pigs (68 ± 1 kg) were instrumented with Swan-Ganz and LV pressure-volume catheters. Data were obtained at body temperatures of 33.0 °C, 38.0 °C and 40.5 °C; before and after: resuscitation, myocardial infarction, endotoxemia, sevoflurane-induced myocardial depression and beta-adrenergic stimulation. We plotted LVSW min^- 1 against CPO by linear regression analysis, as well as against the following classical indices of LV function and work: LV ejection fraction (LV EF), rate-pressure product (RPP), triple product (TP), LV maximum pressure (LVP_max) and maximal rate of rise of LVP (LV dP/dt_max).

RESULTS

CPO showed the best correlation with LV SW min^- 1 (r² = 0.89; p < 0.05) while LV EF did not correlate at all (r² = 0.01; p = 0.259). Further parameters correlated moderately with LV SW min^- 1 (LVP_max r² = 0.47, RPP r² = 0.67; and TP r² = 0.54). LV dP/dt_max correlated worst with LV SW min^- 1 (r² = 0.28).

CONCLUSION

CPO reflects external cardiac work over a wide range of inotropic states. These data further support the use of CPO to monitor inotropic interventions in the ICU.

Swan, Ganz, and Their Catheter: Its Evolution Over the Past Half Century

Jeremy Swan and William Ganz developed their eponymous pulmonary artery (PA) catheter in the 1970s and, in the process, revolutionized measurement of cardiac output, pressures within the left side of the heart, and resistance in systemic and pulmonary circulations. Their invention enabled diagnostic measurements at the bedside and contributed to the birth of critical care medicine; technologic advances preceding the PA catheter generally could not be used at the bedside and required patients to be stable enough to be taken to the catheterization laboratory. Swan and Ganz worked in the same department but had quite dissimilar backgrounds and personalities. This article describes their lives and careers, the state of intensive care before and after their catheter was introduced, and the natural life cycle the PA catheter faced as new, less invasive technology arrived to replace it.

Is hemodynamic transesophageal echocardiography needed for patients with left ventricular assist device?

BACKGROUND

Interventions in patients with a left ventricular assist device (LVAD) in the intensive care unit (ICU) are typically performed based on the results of conventional monitoring, such as vital signs and Swan-Ganz catheter (SGC) and LVAD parameters. These variables might not always accurately reflect a patient's cardiac function, volume status, and interventricular septal configuration, however. To assess the accuracy of standard monitoring, we performed routine continuous hemodynamic transesophageal echocardiography (hTEE) to evaluate cardiac function, volume status, and septal position.

METHODS

Between 2011 and 2015, 93 HeartMate II LVADs were implanted. The study group comprised 30 patients with an SGC in place who were monitored routinely by hTEE in the ICU every 1 to 3 hours until extubation. A total of 147 hTEE studies were analyzed retrospectively to observe differences between conventional monitoring and hTEE.

RESULTS

Among the 30 patients studied, 26 (87%) had at least 1 disagreement between conventional monitoring and hTEE findings. In 22 patients (73%), at least 1 of the hTEE studies was abnormal whereas conventional parameters were normal. Abnormal hTEE findings included a shift in the interventricular septum in 19 patients (63%), abnormal ventricular volume status in 22 patients (73%), and right ventricular failure in 9 patients (30%). Based on conventional monitoring, none of the patients required an LVAD speed change, whereas hTEE showed that 14 patients (47%) needed an LVAD speed adjustment.

CONCLUSIONS

Conventional monitoring in the ICU might not provide an accurate representation of cardiac function, ventricular volume status, or septal position in patients with LVAD. Continuous monitoring with hTEE in patients with an LVAD may help guide optimal intervention in the ICU setting during the early postoperative period.

The Routine Use of the Pulmonary Artery Catheter Should Be Abandoned

The pulmonary artery catheter (PAC) is the most common method of measuring cardiac output in cardiac surgery. However, its use has always been questioned in terms of survival benefit, specifically with regard to the accuracy of its measurements and its invasive nature, with the potential for serious complications. In this review we aimed to develop a clear understanding of the pitfalls of the use of PAC, and discuss its risks and available alternatives. We conclude that there is no indication for the routine use of PAC such that clinicians should carefully consider the clinical risks and benefits on a patient by patient basis.

The Use of Pulmonary Artery Catheter in Sepsis Patients: A Literature Review

This article was to review the literature regarding the use of the pulmonary artery catheter (PAC) in the management of patients with sepsis and septic shock. A PubMed search was conducted in order to identify publications evaluating the use of PAC as a tool for management and therapeutic guidance in patients with sepsis. The bibliographies of all identified publications were reviewed for additional relevant references. Much information is identified in the literature regarding the indications for pulmonary artery catheterization in the assessment and treatment of patients with sepsis. Although the PAC has been widely used for many years, there is no clear benefit with regard to outcome, and there is controversy regarding its use. It is not clear that use of the PAC contributes to reduced morbidity and mortality in patients with sepsis. The role of the PAC is becoming less clear, as newer, non-invasive techniques are developed for hemodynamic assessment of sepsis patients. Large, well-designed clinical trials are needed to better assess the role and potential benefit from use of the PAC in sepsis.

The Pulmonary Artery Catheter in Anesthesia Practice in 2007: An Historical Overview With Emphasis on the Past 6 Years

The pulmonary artery catheter has been widely used in anesthesiology and critical care medicine. Until recently, only retrospective or relatively weak prospective studies examining its effect on outcome had been performed. Over the past 6 years, however, a number of well-designed prospective trials and statistically sound retrospective studies have been completed. All of these show no benefit and some even reveal a potential for increased morbidity. Reasons for this device's inability to improve outcome are numerous, including wrong patient selection and misinterpretation, but the most impressive and convincing evidence is that filling pressures measured from the catheter, particularly the pulmonary artery “wedge” pressure, have no physiologic value. The wedge pressure has been shown to not correlate with other accepted methods of determining left ventricular filling or volume or intravascular volume and also does not help to generate cardiac function curves. Therefore, knowledge of it may actually lead to incorrect management more frequently than not.

Manual hyperinflation combined with expiratory rib cage compression for reduction of length of ICU stay in critically ill patients on mechanical ventilation

OBJECTIVE

Although manual hyperinflation (MH) is widely used for pulmonary secretion clearance, there is no evidence to support its routine use in clinical practice. Our objective was to evaluate the effect that MH combined with expiratory rib cage compression (ERCC) has on the length of ICU stay and duration of mechanical ventilation (MV).

METHODS

This was a prospective randomized controlled clinical trial involving ICU patients on MV at a tertiary care teaching hospital between January of 2004 and January of 2005. Among the 49 patients who met the study criteria, 24 and 25 were randomly assigned to the respiratory physiotherapy (RP) and control groups, respectively. Of those same patients, 6 and 8, respectively, were later withdrawn from the study. During the 5-day observation period, the RP patients received MH combined with ERCC, whereas the control patients received standard nursing care.

RESULTS

The two groups were similar in terms of the baseline characteristics. The intervention had a positive effect on the duration of MV, as well as on the ICU discharge rate and Murray score. There were significant differences between the control and RP groups regarding the weaning success rate on days 2 (0.0% vs. 37.5%), 3 (0.0% vs. 37.5%), 4 (5.3% vs. 37.5%), and 5 (15.9% vs. 37.5%), as well as regarding the ICU discharge rate on days 3 (0% vs. 25%), 4 (0% vs. 31%), and 5 (0% vs. 31%). In the RP group, there was a significant improvement in the Murray score on day 5.

CONCLUSIONS

Our results show that the use of MH combined with ERCC for 5 days accelerated the weaning process and ICU discharge.

The pulmonary artery catheter

The pulmonary artery catheter (PAC) has been widely used for monitoring of critically ill patients over the years, but with advances in less invasive monitoring techniques, notably echocardiography, there are fewer indications for PAC insertion. Nevertheless, the PAC provides simultaneous monitoring of pulmonary artery pressures, cardiac filling, cardiac output and mixed venous oxygen saturation, and still has an important role in complex cases. Adequate and continued training are required to ensure that PAC-derived data are correctly interpreted and applied.

Review article: closed-loop systems in anesthesia: is there a potential for closed-loop fluid management and hemodynamic optimization?

Closed-loop (automated) controllers are encountered in all aspects of modern life in applications ranging from air-conditioning to spaceflight. Although these systems are virtually ubiquitous, they are infrequently used in anesthesiology because of the complexity of physiologic systems and the difficulty in obtaining reliable and valid feedback data from the patient. Despite these challenges, closed-loop systems are being increasingly studied and improved for medical use. Two recent developments have made fluid administration a candidate for closed-loop control. First, the further description and development of dynamic predictors of fluid responsiveness provides a strong parameter for use as a control variable to guide fluid administration. Second, rapid advances in noninvasive monitoring of cardiac output and other hemodynamic variables make goal-directed therapy applicable for a wide range of patients in a variety of clinical care settings. In this article, we review the history of closed-loop controllers in clinical care, discuss the current understanding and limitations of the dynamic predictors of fluid responsiveness, and examine how these variables might be incorporated into a closed-loop fluid administration system.

Pulmonary artery catheters: evolving rates and reasons for use

OBJECTIVE

Randomized trials have demonstrated risks and failed to establish a clear benefit for the use of the pulmonary artery catheter. We assessed rates of pulmonary artery catheter use in multiple centers over 5 yrs, variables associated with their use, and how these variables changed over time (2002-2006).

DESIGN

A multicenter longitudinal study using the Hamilton Regional Critical Care Database. A two-level multiple logistic regression analysis was used to determine significant variables associated with pulmonary artery catheter use and whether these varied over time.

SETTING

Academic intensive care units in Hamilton, Canada.

PATIENTS

We identified patients from five intensive care units who received a pulmonary artery catheter within the first 2 days of intensive care unit admission.

INTERVENTIONS

Pulmonary artery catheter use over a 5-yr period.

MEASUREMENTS AND MAIN RESULTS

Among 15,006 patients, 1,921 (12.8%) had a pulmonary artery catheter. Adjusted rates of pulmonary artery catheter use decreased from 16.4% to 6.5% over 5 yrs. Determinants of pulmonary artery catheter use included Acute Physiology and Chronic Health Evaluation II score (odds ratio [OR], 1.05; confidence interval [CI], 1.04-1.06; p < .0001), elective surgical status (OR, 2.82; CI, 2.29-3.48; p < .0001), postabdominal aortic aneurysm repair (OR, 10.91; CI, 8.24-14.45; p < .0001), cardiogenic shock (OR, 5.31; CI, 3.35-8.42; p < .0001), sepsis (OR, 2.83; CI, 1.94-4.13; p < .0001), vasoactive infusion use (OR, 4.04; CI, 3.47-4.71; p < .0001), and mechanical ventilation (OR, 2.21; CI, 1.86-2.63; p < .0001). Physician's base specialty and local intensive care unit were also associated with pulmonary artery catheter use (p < .0001). The determinants of pulmonary artery catheter use did not change over time.

CONCLUSIONS

We observed a >50% reduction in the rate of pulmonary artery catheter use over 5 yrs. Patient factors predicting pulmonary artery catheter use were illness severity, specific diagnoses, and the need for advanced life support. Nonpatient factors predicting pulmonary artery catheter use were intensive care unit and the attending physician's base specialty.

Pulse pressure variation: where are we today?

In the present review we will describe and discuss the physiological and technological background necessary in understanding the dynamic parameters of fluid responsiveness and how they relate to recent softwares and algorithms' applications. We will also discuss the potential clinical applications of these parameters in the management of patients under general anesthesia and mechanical ventilation along with the potential improvements in the computational algorithms.

Cardiac output assessed by invasive and minimally invasive techniques

Cardiac output (CO) measurement has long been considered essential to the assessment and guidance of therapeutic decisions in critically ill patients and for patients undergoing certain high-risk surgeries. Despite controversies, complications and inherent errors in measurement, pulmonary artery catheter (PAC) continuous and intermittent bolus techniques of CO measurement continue to be the gold standard. Newer techniques provide less invasive alternatives; however, currently available monitors are unable to provide central circulation pressures or true mixed venous saturations. Esophageal Doppler and pulse contour monitors can predict fluid responsiveness and have been shown to decrease postoperative morbidity. Many minimally invasive techniques continue to suffer from decreased accuracy and reliability under periods of hemodynamic instability, and so few have reached the level of interchangeability with the PAC.

Changing paradigms in surgical resuscitation

Patients undergoing emergency surgery typically require resuscitation, either because they are hemorrhaging or because they are experiencing significant internal fluid shifts. Intravascular hypovolemia is common at the time of anesthesia induction and can lead to hemodynamic collapse if not promptly treated. Central pressure monitoring is associated with technical complications and does not improve outcomes in this population. Newer modalities are in use, but they lack validation. Fluid resuscitation is different in bleeding and septic patients. In the former group, it is advisable to maintain a deliberately low blood pressure to facilitate clot formation and stabilization. If massive transfusion is anticipated, blood products should be administered from the outset to prevent the coagulopathy of trauma. Early use of plasma in a ratio approaching 1:1 with red blood cells (RBCs) has been associated with improved outcomes. In septic patients, early fluid loading is recommended. The concept of "goal-directed resuscitation" is based on continuing resuscitation until venous oxygen saturation is normalized. In either bleeding or septic patients, however, the most important goal remains surgical control of the source of pathology, and nothing should be allowed to delay transfer to the operating room. We review the current literature and recommendations for the resuscitation of patients coming for emergency surgery procedures.

The epidemiology of, and risk factors for, mortality from severe sepsis and septic shock in a tertiary-care university hospital setting

This study investigated the clinical characteristics of, and outcomes and risk factors for hospital mortality of 390 patients admitted with severe sepsis or septic shock in an intensive care unit (ICU). Prospectively collected data from patients collected between 1 July 2004 and 30 June 2006 were analysed. Overall hospital mortality was 49.7% and comorbidities were found in 40.3% of patients, the most common of which was haematological malignancy. The respiratory tract was the most common site of infection (50%). Hospital-acquired infections accounted for 55.6% of patients with Gram-negative bacteria predominant (68%). Multivariate analysis showed that acute respiratory distress syndrome, pulmonary artery catheter placement, comorbidities, hospital-acquired infection, APACHE II score and maximum LOD score, were independent risk factors for hospital mortality. In conclusion, severe sepsis and septic shock are common causes of ICU admission. Patients with risk factors for increased mortality should be carefully monitored and aggressive treatment administered.

A critical appraisal of propensity-score matching in the medical literature between 1996 and 2003

Propensity-score methods are increasingly being used to reduce the impact of treatment-selection bias in the estimation of treatment effects using observational data. Commonly used propensity-score methods include covariate adjustment using the propensity score, stratification on the propensity score, and propensity-score matching. Empirical and theoretical research has demonstrated that matching on the propensity score eliminates a greater proportion of baseline differences between treated and untreated subjects than does stratification on the propensity score. However, the analysis of propensity-score-matched samples requires statistical methods appropriate for matched-pairs data. We critically evaluated 47 articles that were published between 1996 and 2003 in the medical literature and that employed propensity-score matching. We found that only two of the articles reported the balance of baseline characteristics between treated and untreated subjects in the matched sample and used correct statistical methods to assess the degree of imbalance. Thirteen (28 per cent) of the articles explicitly used statistical methods appropriate for the analysis of matched data when estimating the treatment effect and its statistical significance. Common errors included using the log-rank test to compare Kaplan-Meier survival curves in the matched sample, using Cox regression, logistic regression, chi-squared tests, t-tests, and Wilcoxon rank sum tests in the matched sample, thereby failing to account for the matched nature of the data. We provide guidelines for the analysis and reporting of studies that employ propensity-score matching.

Pulmonary artery catheters: state of the controversy

Since 1970, pulmonary artery catheters (PACs) have been used in clinical practice to monitor the hemodynamic status of critically ill and injured patients. This technology was introduced and commercialized without considerable testing to determine safety and efficacy. After years of common clinical use, investigators identified potential increases in mortality associated with PAC use. For the past decade, investigators have studied various patient populations to elucidate the safety and efficacy of the PAC. This article reviews the historical context of PAC use, findings from recent clinical trials intended to determine safety and efficacy, issues with reliability and validity of PAC use, and complications associated with PAC use. Data from recent clinical trials do not support routine use of PACs, and the authors suggest that PAC-guided therapy should be the focus of study in future trials.

Pulse contour cardiac output analysis in a piglet model of severe hemorrhagic shock

OBJECTIVE

Pulse contour cardiac output (PCCO) analysis is a technique for continuous cardiac output (CO) monitoring through an arterial catheter after calibration by transpulmonary thermodilution (TPTD). Studies in adults show good correlation with pulmonary artery thermodilution (PATD) CO. Data are limited in children and patients with hemodynamic instability. The objective was to determine whether TPTD CO and PCCO analysis correlate with PATD CO in a piglet model of severe hemorrhagic shock. Mixed venous oxygen saturation (SVO2) was also compared with PATD CO.

DESIGN

Prospective animal study.

SETTING

University animal research laboratory.

SUBJECTS

Domesticated piglets, 24-37 kg.

INTERVENTIONS

Hemorrhagic shock was created by graded hemorrhage in anesthetized piglets. Hemorrhage was initiated to achieve mean arterial pressure plateaus of 60, 50, 40, 30, and 20 mm Hg.

MEASUREMENTS AND MAIN RESULTS

CO was measured by PATD and simultaneously with two femoral artery PCCO catheters. At each mean arterial pressure plateau, one PCCO catheter was recalibrated by TPTD; the other catheter was not recalibrated during hemorrhage. TPTD CO, PCCO measurements from each catheter, and SVO2 were compared with PATD CO at each mean arterial pressure level. TPTD CO and recalibrated PCCO showed excellent correlation (r2 = .96 and .97) and small bias (+0.11 and +0.14 L/min), respectively, compared with PATD. Without recalibration, PCCO measurements were not accurate during rapid hemorrhage (r2 = .22). SVO2 decline did not correlate as well with PATD CO (r2 = .69).

CONCLUSIONS

TPTD CO and recalibrated PCCO analysis correlate well with PATD CO in this severe hemorrhagic shock model. The mean difference is small (<0.15 L/min) and is not clinically significant. With rapid changes in blood pressure or intravascular volume, PCCO is not accurate unless recalibrated by TPTD CO. SVO2 did not correlate well with CO in this model.

Hemodynamic evaluation and monitoring in the ICU

Hemodynamic monitoring, a cornerstone in the management of the critically ill patient, is used to identify cardiovascular insufficiency, its probable cause, and response to therapy. Still it is difficult to document the efficacy of monitoring because no device improves outcome unless coupled to a treatment that improves outcome. Several clinical trials have consistently documented that preoptimization for high-risk surgery patients treated in the operating room and early (< 12 h) goal-directed resuscitation in septic patients treated in the emergency department reduce morbidity, mortality, and resource use (costs) when the end points of resuscitation were focused on surrogate measures of adequacy of global oxygen delivery (Do2). The closer the resuscitation is to the insult, the greater the benefit. When resuscitation was started after ICU admission in high-risk surgical patients, reduced length of stay was also seen. The focus of these monitoring protocols is to establish a mean arterial pressure > 65 mm Hg and then to increase Do2 to 600 mL/min/m2 within the first few minutes to hours of presentation. To accomplish these goals, hemodynamic monitoring focuses more on measures of cardiac output and mixed venous oxygen saturation to access adequacy of resuscitation efforts than on filling pressures. Although these protocols reduce mortality and morbidity is selected high-risk patient groups, the widespread use of monitoring-driven treatment protocols has not yet happened, presumably because all studies have been single-center trials using a single, proprietary blood flow-monitoring device. Multicenter trials are needed of early goal-directed therapies for all patients presenting in shock of various etiologies and when the protocol and not the monitoring device is the primary variable.

Systematic review of randomized clinical trials on the use of hydroxyethyl starch for fluid management in sepsis

Background

Patients with sepsis typically require large resuscitation volumes, but the optimal type of fluid remains unclear. The aim of this systematic review was to evaluate current evidence on the effectiveness and safety of hydroxyethyl starch for fluid management in sepsis.

Methods

Computer searches of MEDLINE, EMBASE and the Cochrane Library were performed using search terms that included hydroxyethyl starch; hetastarch; shock, septic; sepsis; randomized controlled trials; and random allocation. Additional methods were examination of reference lists and hand searching. Randomized clinical trials comparing hydroxyethyl starch with other fluids in patients with sepsis were selected. Data were extracted on numbers of patients randomized, specific indication, fluid regimen, follow-up, endpoints, hydroxyethyl starch volume infused and duration of administration, and major study findings.

Results

Twelve randomized trials involving a total of 1062 patients were included. Ten trials (83%) were acute studies with observation periods of 5 days or less, most frequently assessing cardiorespiratory and hemodynamic variables. Two trials were designed as outcome studies with follow-up for 34 and 90 days, respectively. Hydroxyethyl starch increased the incidence of acute renal failure compared both with gelatin (odds ratio, 2.57; 95% confidence interval, 1.13–5.83) and crystalloid (odds ratio, 1.81; 95% confidence interval, 1.22–2.71). In the largest and most recent trial a trend was observed toward increased overall mortality among hydroxyethyl starch recipients (odds ratio, 1.35; 95% confidence interval, 0.94–1.95), and mortality was higher (p < 0.001) in patients receiving > 22 mL·kg^-1 hydroxyethyl starch per day than lower doses.

Conclusion

Hydroxyethyl starch increases the risk of acute renal failure among patients with sepsis and may also reduce the probability of survival. While the evidence reviewed cannot necessarily be applied to other clinical indications, hydroxyethyl starch should be avoided in sepsis.

Clinical relevance of data from the pulmonary artery catheter

The usefulness of parameters measured using the pulmonary artery catheter has been challenged because no benefit in patient outcome has been observed in clinical trials. However, technological advances have been made, including continuous measurement of cardiac output (CO), mixed venous saturation (SvO₂), and right ventricle end-diastolic volume (CEDV) have been made. Pulmonary artery occlusion pressure (PAOP), CEDV and right atrial pressure (RAP) are not good predictors of fluid load responsiveness except when very low. Despite this methodological limitation, variation of these parameters during fluid loading remains a good indicator of fluid challenge tolerance. Accuracy of continuous thermodilution and SvO₂ measurement has been demonstrated in vitro and at bedside. A decrease in SvO₂ is a global index of an inadequate oxygen delivery (DO₂)/oxygen requirement relationship. In this setting, a therapeutic decision to improve determinants of SvO₂ should be considered with the help of all other PAC parameters. Technological improvement transforms PAC in a real time integrated physiological device and allows one to observe the impact of therapeutic intervention. What we need now is a clinical trial with a PAC-guided treatment algorithm taking into account the above integrated PAC parameters.

Which cardiac surgical patients can benefit from placement of a pulmonary artery catheter?

The use of pulmonary artery catheters (PACs) during cardiac surgery varies considerably depending on local policy, ranging from use in 5–10% of the patient population to routine application. However, as in other clinical fields, recent years have witnessed a progressive decline in PAC use. One of the reasons for this is probably the increasing use of transoesophageal echocardiograpy, even though careful analysis of the information provided by PAC and transoesophageal echocardiograpy indicates that the two tools should be considered subsidiary rather than alternatives. The principal categories of cardiac patients who can benefit from PAC monitoring are those with present and those with possible haemodynamic instability. On this basis we can identify five groups: patients with impaired left ventricular systolic function; those with impaired right ventricular systolic function; those with left ventricular diastolic dysfunction; those with an acute ventricular septal defect; and those with a left ventricular assist device. This review highlights the specific role of PAC-derived haemodynamic data for each category.

Which general intensive care unit patients can benefit from placement of the pulmonary artery catheter?

From the report by Connors and coworkers in 1996 until now, much effort has been directed at demonstrating the safety and/or effectiveness of strategies based on pulmonary artery catheter (PAC) data. Although studies have failed to demonstrate a clear benefit of PAC use, neither have any corroborated the initial report of PAC-induced mortality. With this in mind, it is important to clarify the indications for PAC, taking into account the development of new technologies to measure cardiac output and stroke volume. The present review focuses on safety and effectiveness data, with a special focus on reasonable indications for PAC use in the intensive care unit. The PAC has evolved since its initial presentation, and it now offers numerous parameters in addition to cardiac output and pressure measurement, such as mixed oxygen saturation and right ventricular ejection fraction. Because many techniques may be used to measure cardiac output, the indications for PAC use have become founded on other parameters that are useful in more specific situations, essentially involving the right circulation.

Sepsis in 2003: are we still in the middle of nowhere?

PURPOSE OF REVIEW

Although enthusiasm of intensivists has been raised during the last 2-3 years due to several successful clinical trials, severe sepsis and septic shock still have an increasing incidence with more or less unchanged mortality. Within the last 12 months, the progress in sepsis research covering definitions, epidemiology, pathophysiology, diagnosis, standard and adjunctive therapy, as well as experimental approaches is encouraging. In this review, state-of-the-art publications of 2003 are presented to elucidate the possible impact on clinical routine.

RECENT FINDINGS

The rationale for using a new definition based on the PIRO system has been widely acknowledged, although it is not yet applicable in clinical practice. This includes genomic information for stratifying subgroups of patients, and a broader field of laboratory diagnostics due to clinical studies and basic research on the cellular mechanisms of inflammation and organ dysfunction. Early diagnosis is important for a fast implementation of specific therapies, and it has been confirmed that the time until the start of therapy has an impact on patient outcome. Thorough data analysis of successful trials with activated protein C has revealed encouraging details on long-term outcome and subgroup effects. Together with new findings on low-dose hydrocortisone, this stresses the relevance of adjunctive therapy in severe sepsis and septic shock.

SUMMARY

Scientific progress in areas of sepsis has been continuing throughout 2003, although the challenges are still enormous. The identification of more specific markers and new therapeutic approaches will hopefully improve the diagnosis, monitoring of therapy, and outcome in the septic patient.

Monitoring oxygen transport and tissue oxygenation

PURPOSE OF REVIEW

To review recent publications in the field of oxygen delivery and tissue oxygenation. With few exceptions, we restricted our selection to clinical studies published in the English literature.

RECENT FINDINGS

No major breakthroughs have occurred in the past decade in the diagnosis or treatment of tissue hypoxia. There is renewed interest in goal-directed resuscitation when applied early in the course of treatment. Monitoring metabolic markers of tissue hypoxia continues to hold great clinical interest, in particular, tissue PCO2, near infrared spectroscopy, base deficit and blood lactate concentration. Technical issues, however, seem to restrict the widespread use of many of these techniques.

SUMMARY

There is an urgent need to develop methods to accurately and rapidly identify patients with tissue hypoxia. Perhaps the combination of gastric tonometry, near-infrared spectroscopy, urinary PO2 and continuous measures of mixed (or central) venous O2 saturation may provide the answer. An even more formidable task is that of developing effective therapy to correct tissue hypoxia while avoiding harm to the patient.

Hemodynamic monitoring over the past 10 years

Changes in hemodynamic monitoring over the past 10 years have followed two paths. First, there has been a progressive decrease in invasive monitoring, most notably a reduction in the use of the pulmonary artery catheter because of a presumed lack of efficacy in its use in the management of critically ill patients, with an increased use of less invasive monitoring requiring only central venous and arterial catheterization to derive the same data. Second, numerous clinical trials have documented improved outcome and decreased costs when early goal-directed protocolized therapies are used in appropriate patient populations, such as patients with septic shock presenting to Emergency Departments and high-risk surgical patients before surgery (pre-optimization) and immediately after surgery (post-optimization). Novel monitoring will be driven more by its role in improving outcomes than in the technical abilities of the manufacturers.

Pulmonary artery catheter use is associated with reduced mortality in severely injured patients: a National Trauma Data Bank analysis of 53,312 patients

OBJECTIVE

To evaluate the association between pulmonary artery catheter (PAC) use and mortality in a large cohort of injured patients. We hypothesized that PAC use is associated with improved survival in critically injured trauma patients.

DESIGN

Retrospective database analysis.

SETTING

A total of 268 level 1 trauma centers from across the United States.

PATIENTS

A total of 53,312 patients admitted to the intensive care units of the trauma centers participating in the National Trauma Data Bank maintained by the American College of Surgeons.

MEASUREMENTS AND MAIN RESULTS

The National Trauma Data Bank was queried to identify patients aged 16-90 yrs with complete data on base deficit, and Injury Severity Score (n=53,312). Patients were initially divided into two groups: those managed with a PAC (n=1,933) and those managed without a PAC (n=51,379). Chi-square and Student's t-test analysis were utilized to explore group differences in mortality. In a second analysis, groups were stratified by base deficit, Injury Severity Score, and age to further explore the influence of injury severity on PAC use and mortality. In addition, a logistic regression model was developed to assess the relationship between PAC use and mortality after adjusting for differences in age, mechanism, injury severity, injury pattern, and co-morbidities. Overall, patients managed with a PAC were older (45.8+/-21.3 yrs), had higher Injury Severity Score (28.4+/-13.5), worse base deficit (-5.2+/-6.5), and increased mortality (PAC, 29.7%; no PAC, 9.8%; p<.001). However, after stratification for injury severity, PAC use was associated with a survival benefit in four subgroups of patients. Each of these groups had advanced age or increased injury severity. Specifically, patients aged 61-90 yrs, with arrival base deficit worse than -11 and Injury Severity Score of 25-75, had a decrease in the risk of death with PAC use (odds ratio, 0.33; 95% confidence interval, 0.17-0.62). Three additional groups had a similar decrease in the risk of death with PAC use: odds ratio, 0.60 (95% confidence interval, 0.43-0.83), 0.82 (95% confidence interval, 0.44-1.52), and 0.63 (95% confidence interval, 0.40-0.98). Logistic regression analysis demonstrated a decreased mortality when a PAC was used in the management of patients with the following severe injury characteristics: Injury Severity Score of 25-75, base deficit of less than -11, or age of 61-90 yrs (odds ratio, 0.593; 95% confidence interval, 0.437-0.805).

CONCLUSIONS

Trauma patients managed with a PAC are more severely injured and have a higher mortality. However, severely injured patients (Injury Severity Score, 25-75) who arrive in severe shock, and older patients, have an associated survival benefit when managed with a PAC. This is the first study to demonstrate a benefit of PAC use in trauma patients.

A review of the application of propensity score methods yielded increasing use, advantages in specific settings, but not substantially different estimates compared with conventional multivariable methods

OBJECTIVE

Propensity score (PS) analyses attempt to control for confounding in nonexperimental studies by adjusting for the likelihood that a given patient is exposed. Such analyses have been proposed to address confounding by indication, but there is little empirical evidence that they achieve better control than conventional multivariate outcome modeling.

STUDY DESIGN AND METHODS

Using PubMed and Science Citation Index, we assessed the use of propensity scores over time and critically evaluated studies published through 2003.

RESULTS

Use of propensity scores increased from a total of 8 reports before 1998 to 71 in 2003. Most of the 177 published studies abstracted assessed medications (N=60) or surgical interventions (N=51), mainly in cardiology and cardiac surgery (N=90). Whether PS methods or conventional outcome models were used to control for confounding had little effect on results in those studies in which such comparison was possible. Only 9 of 69 studies (13%) had an effect estimate that differed by more than 20% from that obtained with a conventional outcome model in all PS analyses presented.

CONCLUSIONS

Publication of results based on propensity score methods has increased dramatically, but there is little evidence that these methods yield substantially different estimates compared with conventional multivariable methods.

Charlson Index is associated with one-year mortality in emergency department patients with suspected infection

OBJECTIVES

A patient's baseline health status may affect the ability to survive an acute illness. Emergency medicine research requires tools to adjust for confounders such as comorbid illnesses. The Charlson Comorbidity Index has been validated in many settings but not extensively in the emergency department (ED). The purpose of this study was to examine the utility of the Charlson Index as a predictor of one-year mortality in a population of ED patients with suspected infection.

METHODS

The comorbid illness components of the Charlson Index were prospectively abstracted from the medical records of adult (age older than 18 years) ED patients at risk for infection (indicated by the clinical decision to obtain a blood culture) and weighted. Charlson scores were grouped into four previously established indices: 0 points (none), 1-2 points (low), 3-4 points (moderate), and > or =5 points (high). The primary outcome was one-year mortality assessed using the National Death Index and medical records. Cox proportional-hazards ratios were calculated, adjusting for age, gender, and markers of 28-day in-hospital mortality.

RESULTS

Between February 1, 2000, and February 1, 2001, 3,102 unique patients (96% of eligible patients) were enrolled at an urban teaching hospital. Overall one-year mortality was 22% (667/3,102). Mortality rates increased with increasing Charlson scores: none, 7% (95% confidence interval [CI] = 5.4% to 8.5%); low, 22% (95% CI = 19% to 24%); moderate, 31% (95% CI = 27% to 35%); and high, 40% (95% CI = 36% to 44%). Controlling for age, gender, and factors associated with 28-day mortality, and using the "none" group as a reference group, the Charlson Index predicted mortality as follows: low, odds ratio of 2.0; moderate, odds ratio of 2.5; and high, odds ratio of 4.7.

CONCLUSIONS

This study suggests that the Charlson Index predicts one-year mortality among ED patients with suspected infection.

Systemic coagulation changes caused by pulmonary artery catheters: laboratory findings and clinical correlation

BACKGROUND

A higher rate of pulmonary embolism has been associated with pulmonary artery (PA) catheters; however, no mechanism has been described. Conventional tests of coagulation reveal no changes related to PA catheterization. The purpose of this study was to determine whether PA catheterization resulted in a hypercoagulable state detectable by thrombelastography (TEG).

METHODS

ANIMAL

Healthy, anesthetized, swine (n = 19) underwent PA catheterization. Samples were drawn from 7F femoral arterial catheters before and two hours after PA catheterization, at 5 mL/min, and analyzed (native whole blood, n = 15, kaolin activated blood, n = 4) by TEG (Hemoscope, Niles, IL) at precisely two minutes. Human: An IRB-approved prospective, observational trial was conducted in critically ill patients (n = 19). Samples were drawn from 22-gauge radial artery catheters, before and three hours after PA catheterization. Kaolin-activated TEG samples were analyzed at precisely five minutes. Data are mean +/- SE; Groups were compared with analysis of variance and significance was assessed at the 95% confidence interval.

RESULTS

In both animals and patients, PA catheterization truncated R times (time to initial fibrin formation). In swine, the R times were 17.6 +/- 1.3 minutes (native) and 3.8 +/- 0.4 (kaolin) before PA catheterization, and decreased to 6.3 +/- 1.0 minutes (p = 0.002) and 1.9 +/- 0.5 minutes (p = 0.010) afterward. There were no changes in pH or temperature during the experiment. In patients, 4 of 19 were excluded for protocol violations. The R time was 6.3 +/- 1.0 minutes (kaolin) before and 3.0 +/- 0.3 minutes after catheterization (p = 0.003). No changes were observed in conventional coagulation parameters, temperature or pH.

CONCLUSION

In healthy swine, and critically ill patients, PA catheters may enhance thrombin formation and fibrin polymerization, indicating a systemic hypercoagulable state. This may explain why PA catheters are associated with an increased risk of pulmonary emboli.

Use of the pulmonary artery catheter is not associated with worse outcome in the ICU

STUDY OBJECTIVES

In critically ill patients, the impact of pulmonary artery catheter (PAC) use on outcome is debatable. We investigated the epidemiology of PAC use in European ICUs and its relation to outcome.

DESIGN

International cohort, observational study.

SETTING

One hundred ninety-eight European ICUs participating in the Sepsis Occurrence in Acutely Ill Patients Study.

PATIENTS

All 3,147 adult patients admitted to one of the participating ICUs between May 1, 2002, and May 15, 2002.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Patients were classified according to whether or not they had a PAC at any time during their ICU stay, and were followed up until death, hospital discharge, or for 60 days. Propensity score case matching was performed, and matched pairs were examined for baseline characteristics and outcome. Of 3,147 patients, 481 patients (15.3%) had a PAC. Patients with a PAC were older, had a higher incidence of heart failure, a lower incidence of cancer, and were more commonly surgical admissions. Fluid balance was comparable between the two groups. ICU and hospital mortality rates were higher in patients with a PAC (28.1% vs 16.8% and 32.5% vs 22.5%, respectively; p < 0.001). However, PAC use was not an independent risk factor for 60-day mortality in multivariate analysis, and in 453 propensity-matched pairs ICU and hospital mortality rates were comparable between groups (26.7% vs 26.3% and 31.4% vs 32.8%, p = not significant). Survival to 60 days was similar between the two matched groups (log rank = 0.02; p = 0.894).

CONCLUSIONS

This observational study suggests that PAC use is not associated with increased mortality in this heterogeneous population.

Let us use the pulmonary artery catheter correctly and only when we need it

OBJECTIVE

To clarify the issues related to the use of the pulmonary artery catheter within a rational clinical perspective.

RESULTS

Barriers include a) increased patient risk of pulmonary artery catheter placement; b) ability to measure similar variables via central venous catheterization, echocardiography, or other less invasive techniques; c) increased cost; d) inaccurate measurements; e) incorrect interpretation and application of pulmonary artery catheter-derived variables; and f) lack of proven benefit of pulmonary artery catheter use in the overall management of patients.

INTERPRETATION

a) The risks are mainly due to insertion of a central catheter, not a pulmonary artery catheter; b) continuous monitoring of left ventricular filling pressures, pulmonary vascular pressures, and mixed venous oxygen saturation is a unique feature; c) additional costs are minimal relative to the cost of intensive care; d) measurement errors require ongoing programmatic educational efforts; e) pulmonary artery catheter-derived data need to be used within the context of a defined treatment protocol; and f) no monitoring device, no matter how simple or sophisticated, will improve patient-centered outcomes unless coupled with a treatment that, itself, improves outcome.

CONCLUSION

A treatment protocol for the use of pulmonary artery catheter-derived variables is proposed that could serve as a basis for a prospective clinical trial.

Management of severe sepsis and septic shock

PURPOSE OF REVIEW

Severe sepsis and septic shock are common and deadly conditions for which the epidemiology, pathogenesis, and management continue to evolve. Recent publications (2003 and early 2004) have been systematically reviewed for important new original research and scholarly reviews, with an emphasis on clinical advances in adults.

RECENT FINDINGS

Important new epidemiologic studies establish the increasing frequency (nearly 9% per year) and falling mortality rates associated with sepsis. Sepsis definitions were reviewed by a group of experts, and the principal features of the 1991 consensus conference definitions were supported, with a new framework for evaluation of sepsis proposed. New research and thoughtful reviews continue to elucidate the pathogenesis of sepsis, with emphasis on innate immunity and time-based changes in immune status, varying from hyperreactive immunity and inflammation to immune depression with enhanced risk for nosocomial infections. A comprehensive evidence-based approach to the management of severe sepsis is presented in an important document developed by representatives from many critical care and infectious disease societies. Management includes early targeted resuscitation, broad empiric antibiotic coverage and source control, effective shock evaluation and treatment, adjuvant therapy with recombinant human activated protein C and moderate-dose hydrocortisone in selected patients, and comprehensive supportive care. Recently published multicenter clinical trials for novel agents have been disappointing, particularly for a nitric oxide synthase inhibitor that effectively supported blood pressure but increased mortality.

SUMMARY

The works reviewed reflect the advances in the care of patients with sepsis.