Negative Pressure Pulmonary Edema in the PACU
Jennifer Nopoulos, MSNEd, RN, CPAN
Pulmonary edema from heart failure is a common pathology familiar to almost every RN, as opposed to Negative Pressure Pulmonary Edema (NPPE), with its unique characteristics and relative exclusivity to the post anesthesia unit. After nine years of ICU experience including CCRN certification, I had never heard of this problem until orienting to the PACU and have since cared for two patients with NPPE.
Thankfully not common, NPPE is not the result of cardiac or pulmonary pathology, in fact it most commonly occurs in younger, healthy male patients, as these patients can forcefully inhale to extremely high negative pressures (OpenAnesthesia, 2010, Lemyze & Mallat, 2014). It is caused by the inspiratory efforts (essentially suction) against an obstructed airway, laryngospasm being the most common etiology (Lemyze & Mallat, 2014). Other less common causes include foreign body in the airway, inflammation of the upper airway, suctioning, difficulty placing the artificial airway, head and neck tumors, infections or fluid collections, large body mass, and biting or other obstruction of the airway (Raj, Priti, Quari, & Jha, 2016).
Due to fluid and pressure changes within the cardio-pulmonary structures, fluid now moves from the higher pressure capillaries to the lower pressure lung interstitium and alveolar spaces, resulting in the signs and symptoms of classic pulmonary edema (Raj et al., 2016, Lemyze & Mallat, 2014). These signs and symptoms include agitation, elevated heart and respiratory rates, decreased O2 saturation, frothy sputum or hemoptysis, crackles upon auscultation, and x-ray findings consistent with pulmonary edema (Raj et al., 2016).
Treatment should begin with ensuring a patent airway, often as simple as a jaw thrust, chin lift maneuver, up to re-intubation if necessary. If laryngospasm is suspected, suctioning to remove secretions and positive pressure ventilation should be initiated (Bitner, 2020). Once the airway is secured, supplemental O2 and frequent monitoring is continued. Diuretics can be used but their efficacy is debated (Raj el al., 2016, Bitner 2020), and they may cause hypovolemia and decreased perfusion (Lemyze & Mallat, 2014). Many authors suggest the use of non-invasive continuous airway pressure (CPAP or BiPAP) if the patient’s specific surgery or co-morbidities do not include contraindications to this therapy (Bitner, 2020).
Resolution of symptoms, with stable vital signs and O2 saturation is expected within 12-24 hours and is facilitated by early recognition and prompt appropriate treatment in the PACU. (Lemyze & Mallat, 2014). In my experience, my first older patient had symptom resolution with supplemental oxygen and time. The second, younger patient was given, but did not respond to, diuretics but did respond well to non-invasive positive pressure ventilation (BiPAP), was admitted for observation overnight, and discharged the following day without sequela.