CPAP Cuts Lung Complications After Heart Surgery

[roster]

CPAP Cuts Lung Complications After Heart Surgery
By John Gever, Senior Editor, MedPage Today
Published: May 06, 2009
Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston. Earn CME/CE credit
for reading medical news



WHEELING, W.Va., May 6 -- Providing continuous positive airway pressure (CPAP) after cardiac surgery reduced lung complications and ICU readmissions by half in a large randomized trial.

Of 232 heart surgery patients given nasal CPAP for at least six hours after extubation, 12 developed pulmonary complications, compared with 25 of 236 patients receiving 10 minutes of positive airway pressure every four hours (P=0.03), reported Alexander Zarbock, M.D., of the University of Muenster in Germany, and colleagues in the May issue of CHEST.

Seven patients receiving CPAP versus 14 treated with intermittent airway pressure were readmitted to the ICU (P=0.03), the researchers added. Action Points
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Explain to interested patients that continuous positive airway pressure is an effective treatment for sleep apnea and may have benefits for patients with other conditions as well.


Note that CPAP involves wearing a face mask at night that provides pressure in the nose and/or mouth to improve oxygen supply.


Explain that this study was a randomized trial, the strongest form of medical evidence.
"Noninvasive respiratory support with nasal CPAP is a useful tool to reduce pulmonary morbidity following elective cardiac surgery," Dr. Zarbock and colleagues concluded.

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The idea to use CPAP for this purpose came from research showing that pulmonary atelectasis is an important contributor to respiratory problems following extubation, the researchers said.


CPAP has previously shown good results in other hospital patients, but studies in cardiac surgery patients used relatively low pressures and did not examine clinical outcomes, they said.


The current study used pressure of 10 cm H2O, sufficient to keep tracheal pressure positive during the whole respiratory cycle.


Of 468 patients included in the data analysis, 176 were extubated immediately after surgery, and the remainder in the ICU after a mean of six hours of mechanical ventilation.


In the CPAP group, airway pressure was applied for a mean of 9.1 hours.


The study's primary endpoints were pulmonary complications, defined as hypoxemia (PaO2/FIO2 ratio less than 100), pneumonia, or reintubation.


PaO2/FIO2 ratios among the patients extubated in the operating room were initially lower than in those who stopped mechanical ventilation in the ICU, but quickly became similar.


But the mean ratios remained significantly lower in the patients receiving intermittent airway pressure compared with the CPAP group -- about 270 versus 325 after four hours (P<0.05).


Although the total number of pulmonary complications differed significantly between groups, numbers of individual types of such complications were too small to permit meaningful comparisons.


There was no significant difference in rates of cardiac complications such as myocardial infarction or arrhythmia: 66 total in the CPAP group and 76 in the control group.


Readmissions and pulmonary complications appeared somewhat more common in patients extubated in the operating room than in the ICU in both treatment groups.


Dr. Zarbock and colleagues noted that they had excluded patients with pre-existing pulmonary diseases such as COPD, as well as those with left ventricular impairment. As a result, the results cannot be generalized to all cardiac surgery patients.


Nevertheless, they said, a priori considerations suggest that high-risk patients may actually benefit more from CPAP.


They also noted that nasal CPAP is technically simple to apply and inexpensive compared with other noninvasive ventilation technologies.


"Therefore, nasal CPAP can be recommended as a useful tool to prevent postoperative pulmonary complications in patients recovering from cardiac surgery," Dr. Zarbock and colleagues wrote.



External funding sources for the study were not reported.

No potential conflicts of interest were reported.




Primary source: CHEST
Source reference:
Zarbock A, et al "Prophylactic nasal continuous positive airway pressure following cardiac surgery protects from postoperative pulmonary complications: a prospective, randomized, controlled trial in 500 patients" CHEST 2009; 135: 1252-59.
http://www.medpagetoday.com/Surgery/Tho ... ent=Group1

[Gerald]

Rooster.......

Interesting article......I wonder if the application of CPAP therapy simply helped some undiagnosed OSA folks....who had their stress reduced by CPAP?

Gerald

[roster]

Rooster.......

Interesting article......I wonder if the application of CPAP therapy simply helped some undiagnosed OSA folks....who had their stress reduced by CPAP?

Gerald

Gerald,

I wondered the same thing.

I am now so suspicious of so many different types of studies because they don't control for undiagnosed sleep apnea.

Regards,

[Catnap]

Very interesting stuff! The consideration of undiagnosed OSA is an important one, especially with what's known about its connection to heart disease, the reason for the patients being in the OR to begin with. Would also be interested to know how they are defining the "high-risk patients" for whom CPAP should be recommended -- again wondering if current, but undiagnosed, OSA might be what caused the extra problems that landed the patient in the high-risk category.

[tdm5032c]

I will comment on my own personal experience here. I had open heart surgery and had lung complications afterward, mostly due to being on and off the heart/lung bypass machine during the surgery itself. I had a collapsed lung afterward. For three days after the surgery, the hospital didn't want me to use my CPAP machine. That is until they woke me up from a nap to check my blood oxygen level and found it to be 62 percent. After that they made sure I had my CPAP machine and made sure I used it anytime I slept, even for a nap. The next day my lung function was better and they were able to finally remove the drain tubes. I really do believe that them finally letting me use my machine helped tremendously and I may have prevented these problems.

[roster]

..... For three days after the surgery, the hospital didn't want me to use my CPAP machine. ........

Such ignorance about sleep apnea spanning from coast to coast still amazes me.

Glad you made it through.