Question: A couple of questions in regards to CPAP use for acute pulmonary edema. I wondered if the medical directive intended for CPAP use in other cases of acute pulmonary edema other than the situation arising from heart failure. For example secondary drowning several hours after initial insult or inhalation injuries in the absence of facial or thorax burns that could be seen with chemicals or fire? It would be reasonable to assume that these insults would cause trauma to the lung tissue and increase the risks for developing pneumothorax as a complication, however in instances like this would CPAP be recommended, beneficial or allowed. Second part would be the use of CPAP for those with complex medical issues such as those patients with Hx of asthma, COPD and CHF. If you where to treat with CPAP for say evidence of acute pulmonary edema and crackles resolved, but wheezes remained would there be benefit to consider ventolin for bronchoconstriction via MDI or neb through the CPAP device? Typically ventolin is not considered in these instances but auscultation in the prehospital setting has limitations and with complex medical histories cardiac asthma and COPD exacerbation may also be part of the overall medical situation. I thank you for your comments and insights.
Thanks for your questions: interesting discussion and thoughts surrounding the possible expanded use of CPAP.
As CPAP is a relatively new technology (especially in the prehospital field), the evidence supporting its use is limited mostly to the patients with severe pulmonary edema as well as impending ventilatory failure for COPD (as listed in your indications under the current medical directive).
While near drowning may make sense from a physiology point of view (and other forms of non cardiac pulmonary edema), at this time there is a lack of evidence to support the use of CPAP for these conditions.
In your example of thermal injury, we agree that the potential tissue destruction that could have resulted from the inhalational exposure would be one factor to consider as a contraindication for CPAP, however, rarely does direct thermal injury happen at the alveolar level without concurrent significant upper airway injury (which would be a contraindication as listed in your medical directive).
In terms of your second question, we would suggest that the optimal management strategy would be to make a decision as to the likely etiology of the severe shortness of breath your patient is experiencing. Is it acute pulmonary edema or is it bronchoconstriction such as in severe COPD?
If it is felt that acute pulmonary edema is the likely cause, then CPAP would be indicated along with Nitroglycerin (NTG) as per the Acute Pulmonary Edema Medical Directive. Remember however that it has been our teaching at SWORBHP that if a patient with pulmonary edema is improving with CPAP, there is no need to keep removing the mask to administer NTG especially given the physical difficulty of administering a spray of NTG sublingually when high flow oxygen is also being applied.
If the suspected cause of the respiratory distress is bronchoconstriction, then we would suggest that CPAP could be applied as per the Bronchoconstriction Medical Directive, and the use of bronchodilators such as Salbutamol may be administered in-line via MDI where possible to ease the bronchoconstriction.
The SWORBHP medical directors would however not support treating suspected pulmonary edema with CPAP and then using a bronchodilator simply due to the fact the patient has wheezes as your question seems to suggest. Bronchodilators simply have no role in the therapy of acute pulmonary edema.