Pulmonary Dead Space Fraction and Pulmonary Artery Systolic Pressure as Early Predictors of Clinical Outcome in Acute Lung Injury

doi:10.1378/chest.07-0409

Chest

Volume 132, Issue 3, September 2007, Pages 836-842

https://doi.org/10.1378/chest.07-0409 Get rights and content

Study objective

The primary objective of this study was to test whether an elevated systolic pulmonary artery (PA) pressure or an elevated pulmonary dead space fraction (Vd/Vt) in early acute lung injury (ALI) is associated with poor clinical outcomes in the era of lung-protective ventilation.

Design

Prospective observational cohort study.

Setting

ICUs of a university hospital.

Patients

Forty-two patients with ALI receiving mechanical ventilation.

Measurements

PA pressure was measured noninvasively using transthoracic echocardiography. Vd/Vt was measured by volumetric capnography (NICO Cardiopulmonary Management System; Novametrix; Wallingford, CT).

Main results

There was no difference in the mean systolic PA pressure in patients who died compared to those who survived (43 ± 9 mm Hg vs 41 ± 9 mm Hg, p = 0.54) [mean ± SD]. In contrast to the PA systolic pressure, Vd/Vt was significantly higher in patients who died compared to those who survived (0.61 ± 0.09 vs 0.53 ± 0.10, p = 0.02). Similarly, Vd/Vt was higher in patients with < 7 ventilator-free days during the first 28 days after enrollment compared to those with > 7 ventilator-free days (0.61 ± 0.08 vs 0.52 ± 0.11, p = 0.008).

Conclusion

In the era of lung-protective ventilation, systolic PA pressure early in the course of ALI is elevated but not predictive of outcome. However, elevated Vd/Vt in early ALI is associated with increased mortality and with fewer ventilator-free days.

Section snippets

Study Design and Patient Selection

This was a prospective observational cohort study conducted in the ICU of a tertiary care university hospital. The protocol was approved by the Institutional Committee on Human Research, and informed consent was obtained from the patients or their surrogates. All patients with ALI admitted to the adult ICU of Moffitt-Long Hospital at the University of California San Francisco between December 2004 and May 2006 were eligible for the study. Inclusion criteria were age ≥ 18 years, positive

Baseline Characteristics

A total of 42 patients with ALI were enrolled in the study (23 women and 19 men; mean age, 62 ± 17 years). Of the 42 patients enrolled, 15 patients (36%) died and 27 patients (64%) survived. The demographics, etiology of ALI, and comorbidities are summarized in Table 1. Baseline physiologic variables are summarized in Table 2. Systolic PA pressure measurements were successfully obtained in 39 of the 42 patients. Three patients had an incomplete tricuspid regurgitation jet despite agitated

Discussion

Abnormalities of pulmonary blood flow and progressive and irreversible obstruction of the microvasculature³⁵ resulting in pulmonary hypertension⁶⁷⁸ are one of the hallmarks of ALI, first described by Zapol and Snider²⁸ in 1977. Several subsequent studies⁹¹⁰¹¹ using right-heart catheterization in patients with ARDS have confirmed that PA hypertension is common and can be associated with poor prognosis. However, these early studies examined PA pressure at varying points after the onset of ARDS,

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This research was supported in part by National Heart, Lung, and Blood Institute grants HL74005 and HL58156, and also KL2RR024130 from the National Center for Research Studies.

The authors have no conflicts of interest to disclose.

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Chest

ORIGINAL RESEARCHCRITICAL CARE MEDICINEPulmonary Dead Space Fraction and Pulmonary Artery Systolic Pressure as Early Predictors of Clinical Outcome in Acute Lung Injury

Study objective

Design

Setting

Patients

Measurements

Main results

Conclusion

Section snippets

Study Design and Patient Selection

Baseline Characteristics

Discussion

Chest

Am J Med

J Am Coll Cardiol

Am J Cardiol

Chest

Chest

Chest

Chest

The acute respiratory distress syndrome

N Engl J Med

Incidence and outcomes of acute lung injury

N Engl J Med

Early bedside detection of pulmonary vascular occlusion during acute respiratory failure

Am Rev Respir Dis

Alterations of the gas exchange apparatus in adult respiratory insufficiency associated with septicemia

Am Rev Respir Dis

The pulmonary vascular lesions of the adult respiratory distress syndrome

Am J Pathol

Effects of dopamine on cardiopulmonary function and left ventricular volumes in patients with acute respiratory failure

Am Rev Respir Dis

Pulmonary and systemic haemodynamic disorders in the adult respiratory distress syndrome

Intensive Care Med

Pulmonary hypertension in acute respiratory failure

Crit Care Med

Hemodynamic profile in severe ARDS: results of the European Collaborative ARDS Study

Intensive Care Med

Pulmonary dead-space fraction as a risk factor for death in the acute respiratory distress syndrome

N Engl J Med

The American-European Consensus Conference on ARDS: definitions, mechanisms, relevant outcomes, and clinical trial coordination

Am J Respir Crit Care Med

Physiologically based indices of volumetric capnography in patients receiving mechanical ventilation

Eur Respir J

ORIGINAL RESEARCH
CRITICAL CARE MEDICINE
Pulmonary Dead Space Fraction and Pulmonary Artery Systolic Pressure as Early Predictors of Clinical Outcome in Acute Lung Injury