Chest
Volume 135, Issue 5, May 2009, Pages 1252-1259
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Original Research
Cardiothoracic Surgery
Prophylactic Nasal Continuous Positive Airway Pressure Following Cardiac Surgery Protects From Postoperative Pulmonary Complications: A Prospective, Randomized, Controlled Trial in 500 Patients

https://doi.org/10.1378/chest.08-1602Get rights and content

Background

Continuous positive airway pressure is a noninvasive respiratory support technique that may prevent pulmonary complications following cardiac surgery. This study was conducted to determine the efficacy of prophylactic nasal continuous positive airway pressure (nCPAP) compared with standard treatment. The primary end points were pulmonary adverse effects defined as hypoxemia (Pao2/fraction of inspired oxygen [Fio2] <100), pneumonia, and reintubation. The secondary end point was the readmission rate to the ICU or intermediate care unit (IMCU).

Methods

We prospectively randomized 500 patients scheduled for elective cardiac surgery. Following extubation either in the operating room (early) or in the ICU (late), patients were allocated to standard treatment (control) including 10 min of intermittent nCPAP at 10 cm H2O every 4 h or prophylactic nCPAP (study) at an airway pressure of 10 cm H2O for at least 6 h.

Results

Prophylactic nCPAP significantly improved arterial oxygenation (Pao2/Fio2) without altering heart rate and mean arterial BP. Pulmonary complications including hypoxemia (defined as Pao2/Fio2 <100), pneumonia, and reintubation rate were reduced in study patients compared to controls (12 of 232 patients vs 25 of 236 patients, respectively; p = 0.03). The readmission rate to the ICU or IMCU was significantly lower in nCPAP-treated patients (7 of 232 patients vs 14 of 236 patients, respectively; p = 0.03).

Conclusions

The long-term administration of prophylactic nCPAP following cardiac surgery improved arterial oxygenation, reduced the incidence of pulmonary complications including pneumonia and reintubation rate, and reduced readmission rate to the ICU or IMCU. Thus noninvasive respiratory support with nCPAP is a useful tool to reduce pulmonary morbidity following elective cardiac surgery.

Section snippets

Patients

The ethics committee of Heinrich Heine University of Düsseldorf approved the protocol, and written informed consent was obtained from the patients before surgery. The study was conducted in accordance with the principles outlined in the Declaration of Helsinki.

All patients electively scheduled for coronary bypass surgery or heart valve replacement were eligible to participate in the study. Patients were excluded for one of the following reasons: no consent was obtained, age < 18 years,

Results

Five hundred patients were enrolled in the study during 1 year, of whom 32 were excluded for the following reasons: rethoracotomy due to bleeding (13), perioperative left ventricular failure with catecholamine treatment (11); perioperative myocardial ischemia (3); mechanical ventilation > 18 h (3); and insufficient documentation (2).

Accordingly, 468 patients were left for analysis (Fig 1). There were no statistical differences regarding demographic and surgical procedure data between the

Discussion

Hypoxemia after cardiac surgery is a common complication15, 16 and frequently caused by the impairment of the pulmonary ventilation perfusion ratio due to atelectasis.17 Atelectatic lung areas decrease FRC and increase right-left shunt6 even after uncomplicated cardiac surgery, and nonventilated lung areas may engage up to 20% of the total lung volume17 thus causing postoperative hypoxemia.15

A variety of factors have been identified that promote atelectasis, including operation-induced trauma

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    The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/site/misc/reprints.xhtml).

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