Severity of illness and risk of death associated with pulmonary artery catheter use.

Chittock OR, et al: Crit Care Med 2004; 32:911-915.

Reviewer: Michael H. Wall, MD
University of Texas
Southwestern Medical Center at Dallas
Dallas, TX

Abstract: This observational cohort study of 7310 consecutive patients admitted to a large Canadian academic medical center ICU from 1988 to 1998 examined the association between the use of the pulmonary artery catheter (PAC) in critically ill patients with a higher versus lower severity of illness. The ICU is a 21-bed multidisciplinary medical/surgical/trauma unit. The unit did not care for cardiology or post-cardiac surgical patients. All of the data was prospectively collected by a single trained data collector. All cause mortality was the primary outcome variable for the entire population in association with PAC use. This outcome was also analyzed in 4 groups based on Acute Physiology and Chronic Health Evaluation (APACHE) II score 25th percentiles. The PAC was used in 28% of all patients. Using both unadjusted univariate and adjusted multivariable analysis (data shown), PAC use was not associated with mortality differences overall [odds ratio (OR) 1.05 (95% confidence interval (95% CI) 0.92 - 1.21] or in the second highest severity of illness group (APACHE II score 25 - 31: OR 1.0, 95% CI 0.80 - 1.24). The use of the PAC was associated with higher mortality in the two lowest severity of injury groups (APACHE II < 18: OR 2.47, 95% CI 1.27 - 4.81 and APACHE II 18 - 24: OR 1.64, 95% CI 1.24 - 2.17). Finally, use of PAC was associated with a lower mortality in the most severely ill group (APACHE II > 31: OR 0.8, 95% CI 0.64 - 1.00).

The authors point out that the major limitation of this study is that it is an observational cohort design and not a prospective randomized trial, so that unknown sources of bias may have influenced the outcome of the study. Also, several things were not controlled (transfusion, insulin/glucose management, nutritional support, etc.) which may have influenced outcomes.

Comments: The debate surrounding the use of the PAC continues. Two previous observational trials^1,2 showed that there was an association between PAC use and increased mortality. However, two recent prospective trials evaluating the use of PAC in high risk geriatric patients³ and patients with sepsis or ARDS⁴ showed no differences in mortality, length of hospital stay between groups managed with or without a PAC. Further, utilization of goal-directed therapy in sepsis (central venous oxygen saturation > 70%) showed significantly decreased mortality and less severe organ dysfunction.⁵ The use of central venous oxygen saturation > 70% has been recommended by the Surviving Sepsis Campaign Guidelines for management of sepsis.⁶ Finally, there is one study⁷ that used goal-directed therapy (mixed venous oxygen sat > 70%) in cardiac surgery patients that showed decreased morbidity and hospital length of stay.

This excellent study suggests that PAC use may be harmful in less severely ill patients (APACHE II < 24) but may be beneficial in the patients who are most severely ill (APACHE II > 31). I do not think the PAC itself causes mortality: but how the PAC is used may affect mortality. Several important questions need to be answered: 1) Which data should be used from the PAC (filling pressures, cardiac output/index, oxygen delivery, mixed venous oxygen saturation)? 2) How should this data be used or what should be "optimized"? 3) How should these endpoints be "optimized" (blood, crystalloid, colloid, vasoactive drugs, etc.)? and as this study points out, 4) Which patients should have a PAC placed? Prospective trials evaluating the use of PAC, controlling the severity of illness, and utilizing goal-directed therapy (central venous oxygen saturation > 70%, etc.) need to be performed in critically ill patients and in patients undergoing cardiac surgery. Until these trials are completed, the use of PAC and endpoints of resuscitation remain controversial.

References

1. Connors AF Jr, Speroff T, Dawson NV, et al: The effectiveness of right heart catheterization in the initial care of critically ill patients. JAMA 1996; 276:889-897
2. Polanczyk CA, Rohde LE, Goldman L, et al: Right heart catheterization and cardiac complications in patients undergoing noncardiac surgery: An observational study. JAMA 2001; 286:309-314
3. Sandham JD, Hull RD, Brant RF, et al: A randomized, controlled trial of the use of pulmonary-artery catheters in high-risk surgical patients. N Engl J Med 2003; 348:5-14
4. Warszawski J, Anguel N, et al: Early use of the pulmonary artery catheter and outcomes in patients with shock and acute respiratory distress syndrome: a randomized controlled trial. JAMA 2003; 290:2713-2720
5. Rivers E, Nguyen B, Havstad S, et al: Early goal-directed therapy in the treatment of severe sepsis and septic shock. N Engl J Med 2001 345:1368-1377
6. Dellinger RP, Carlet JM, Masur H, et al: Surviving sepsis campaign guidelines for management of severe sepsis and septic shock. Crit Care Med 2004; 32:858-873
7. Polonen P, Ruokonen E, Hippelainen M, et al: A prospective, randomized study of goal-oriented hemodynamic therapy in cardiac surgical patients. Anesth Analg 2000; 90:1052-105

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Table of Contents:

• President's Message
• Fellow/Faculty Recruitment Reception
• Letters to the Editor


• PRO/CON: Transesophageal Echocardiography (TEE) should be used routinely in all high risk noncardiac surgery
• Pro - Feroze Mahmood, MD
• Con - John E. Ellis, MD


• Literature Reviews
  • Mitral valve surgery for chronic ischemic mitral regurgitation (Mark A. Chaney, MD)
  • Plasma B-type natriuretic peptide levels predict postoperative atrial fibrillation in patients undergoing cardiac surgery (Mohammed M. Minhaj, MD)
  • Severity of illness and risk of death associated with pulmonary artery catheter use (Michael H. Wall, MD)
  • Cardiac replacement with a total artificial heart as a bridge to transplantation (K.W. Tim Park, MD)

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