Monday, May 20, 2013
I have hypoventilation and increased CO2 at night (documented on a sleep study) due to a myopathy and weakened respiratory muscles. I was placed on a CPAP but am unable to tolerate it. I just cannot go to sleep with it on. It is very frustrating and I have given up on it. I don`t know what to do. On a muga scan last year, it showed decreasing rt heart function and stiffness of the ventricles. What are the effects of untreated hypoventilation on the heart? I really would like to prevent any further damage but just cannot tolerate the CPAP. Thanks.
Thank you for using NetWellness. We believe it is very important to treat hypoventilation during sleep in patients with neuromuscular disease as, if left untreated, it may result in respiratory insufficiency. This appears to have occurred in you and it is imperative that you follow up with a Sleep Specialist.
There are many reasons for intolerance to CPAP, including mask intolerance, mask leak, upper respiratory tract issues (congestion, sinusitis), pressure setting too high, and machine malfunction, to name a few. Having said that, it is likely that you need a different type of device other than CPAP to treat your hypoventilation in sleep.
There are various forms of noninvasive ventilation (NIV), one of them being CPAP, which stands for continuous positive airway pressure. CPAP delivers one constant pressure throughout the breathing cycle and thus works primarily to splint open the upper airway in patients with obstructive sleep apnea (OSA). This is the therapy you have recently been prescribed and it raises the question as to whether the sleep study may have also revealed OSA in addition to your hypoventilation. However, CPAP does not treat hypoventilation as it does not improve the depth of breathing.
A different type of NIV is typically used to treat hypoventilation, namely bilevel pressure support (commonly referred to by its trade name BiPAP and also known as bilevel pressure support). Bilevel positive airway pressure delivers a higher pressure during inspiration and lower pressure during exhalation, thus improving ventilation and helping to reduce the CO2 level. Because to the lower expiratory pressure, it allows the individual with neuromuscular weakness to breathe out easier against less resistance. As such, bilevel positive airway pressure is effective for treating hypoventilation and also better tolerated in patients with neuromuscular disease. When adjusted appropriately, it can also treat any coexisting OSA.
Your MUGA scan result is concerning and suggests that the hypoventilation and/or OSA are likely effecting your heart. This makes it all the more important to get these problems treated. OSA has been associated with both traditional hypertension (high blood pressure) and pulmonary hypertension (high blood pressure in the lungs and right heart) and the latter could lead to significant functional impairment.
Chronic hypoventilation from obesity hypoventilation syndrome (respiratory insufficiency due to obesity) has a strong association with progressive heart disease and the development of arrhythmias (abnormal heart rhythms), but the relationship with neuromuscular disease is less obvious, however, if recurrent and frequent falls in ones oxygen level during sleep occur, the same consequences could occur.
So in summary, you have significant health issues that need to be addressed appropriately and may require the help of more than one specialist. I strongly encourage you to follow up with a Sleep Specialist to discuss these issues. You should also be followed by a Neurologist. Once again, I thank you for using NetWellness.
Steven Kadiev, MBBCh
College of Medicine
The Ohio State University