CPAP Safe for Obesity Hypoventilation Syndrome With Apnea

Ingrid Hein

September 14, 2017

MILAN — Most patients with obesity hypoventilation syndrome and sleep apnea can safely switch to continuous positive airway pressure (CPAP) ventilation therapy after at least 3 months of bilevel positive airway pressure (BiPAP) therapy, new research shows.

"We were astonished," said lead investigator María Paola Arellano-Maric, MD, from Pontifical Catholic University of Chile in Santiago. "We all felt pretty neutral on this when we started, but our results were very positive."

Noninvasive BiPAP ventilation provides a higher pressure for inhalation and a lower pressure for exhalation. With CPAP, pressure is consistent.

There has been a belief that "if you have a pressure gradient for inhalation and exhalation, it's more comfortable for the patient, but our patients didn't find that," Dr Arellano-Maric explained here at the European Respiratory Society International Congress 2017.

She and her colleagues demonstrated that once patients were stabilized after using BiPAP for at least 3 months, most could be safely switched to CPAP. The patients "didn't have any respiratory insufficiency under CPAP," she reported.

For their study, the team recruited 42 stable patients with obesity hypoventilation syndrome who had been receiving noninvasive ventilation at home for an average of 34 months (interquartile range, 13.7 - 57.4 months).

All 19 women and 23 men had severe obstructive sleep apnea and 52.3% had chronic obstructive pulmonary disease (COPD) classified as GOLD stage I or II. Average body mass index (BMI) in the study cohort was 45.1 kg/mg², and 83% of the patients were current or ex smokers.

Every patient spent one night in the hospital receiving automatic positive airway pressure (APAP) so that the proper amount of pressurized air could be determined.

If blood gases, polysomnography, and lung function were adequate, patients were sent home with a CPAP machine. "Surprisingly, the pressure for many was about 14 centimeters of water," Dr Arellano-Maric reported. "That was high. We were worried they wouldn't be able to sleep."

After 3 weeks, each patient returned to the hospital to undergo whole-night polysomnography. "One after the other, the patients told us they were sleeping better," she said.

After 6 weeks of home CPAP, daytime levels of partial pressure of carbon dioxide in arterial blood were 45 mm Hg or less in 30 of the 42 patients (71%; 95% confidence interval [CI], 55% - 84%).

Guidelines Do Not Recommend CPAP Selection

Current guidelines do not recommend auto-titrating CPAP machines for patients such as the ones in this study because initial treatment with CPAP often fails, and there is a "lack of studies on switching," Dr Arellano-Maric explained.

The patients in this study were started on BiPAP for a variety of reasons: they failed initial CPAP therapy (37.5%), they experienced acute hypercapnic respiratory failure (31.0%), their clinician preferred BiPAP (21.4%), their BMI was at least 50 kg/m² (4.8%), and they could not tolerate CPAP (2.4%). In 4.7% of the cases, the reason was not known.

"We think that switching after about 6 months is feasible for these patients," she said.

CPAP Cheaper

Further investigation into the safety and efficacy of switching to CPAP is needed, particularly because of cost considerations. A CPAP machine costs around €1000 (~US$1200), whereas a BiPAP machine costs around €8000 (~US$9500), she noted.

With the rising epidemic of obesity around the world, cost-effective therapies are an essential consideration for patient care. In Germany, where this study was performed, "they do not have a huge preoccupation with lowering health costs," she explained. "But in South America or Eastern Europe, it is going to be huge to learn that they can start with noninvasive ventilation and, after 3 to 6 months, try to switch to CPAP."

This finding could have a positive impact on healthcare resources and on the ability of patients with obesity hypoventilation syndrome and sleep apnea to purchase ventilation machines. "If the time with BiPAP was shorter, they could rent that machine and then purchase the CPAP," Dr Arellano-Maric said.

Patients Preferred CPAP

The investigators were surprised to find that 24 patients (57%) expressed a preference for CPAP therapy, despite high pressure levels (mean, 13.8 mbar). In a follow-up questionnaire, they reported that it was easier to keep the mask on with the continuous airflow, and they didn't have to adjust the mask as much during the night, which improved sleep quality.

Patients reported that "their partners also liked it better because they were fussing less with the mask at night and it was quieter," Dr Arellano-Maric told Medscape Medical News. Because six of 10 patients with obesity hypoventilation syndrome sleep with a partner, according to a recent study (Sleep Health. Published online July 25, 2017), their preferences can have an effect on adherence.

In fact, compliance was better with CPAP than with BiPAP (95% vs 87%).

This study shows that we can give these people cheaper yet similar treatment, said Dragoş Bumbăcea, MD, PhD, from the University of Medicine and Pharmacy in Bucharest, Romania, where "people have to pay for their machines."

He said he has already done some switches. In one case, "the patient couldn't afford to go with BiPAP anymore, so we had two possibilities: CPAP or nothing," he told Medscape Medical News. So "we have seen that it works."

The evidence needs to be more conclusive, so more studies are needed. This study included patients with COPD, which could have introduced bias, Dr Bumbăcea explained. It also "included patients who wanted to try switching even when they had APAP titration; that might have added some noise to the results."

European Respiratory Society (ERS) International Congress 2017: Abstract OA4427. Presented September 12, 2017.

Follow Medscape Pulmonary Medicine on Twitter @MedscapeLung and Ingrid Hein @ingridhein

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