(Negative-pressure pulmonary edema accompanied by hemorrhage as a manifestation of upper airway obstruction during extubation is an uncommon problem that is potentially life-threatening.This is not uncommon after OSA surgery.
Dr.Thomas, the senior anesthetist shares his experience of this fatal condition during sleep apnea surgery.)
ENT surgeons dealing with airway surgery should have an understanding of acute negative-pressure pulmonary edema (NPPE) and its treatment. It is frequently under diagnosed and potentially lethal. Rapid diagnosis and treatment is necessary to achieve early resolution and avoid significant patient morbidity.
It occurs most frequently in patients with laryngospasm after procedures performed under general anesthesia, during extubation.I have come across few patients in my series of sleep apnea surgery over the last few years, hence thought of writing about it.
Negative-pressure pulmonary edema is a complication of acute airway obstruction, resulting from attempted inspirations against a closed glottis or other obstruction. A large, negative intrathoracic pressure is generated, which shifts fluid from the pulmonary vessels into the interstitium.
The pathogenesis of NPPE is multifactorial, and the highly negative intrathoracic pressure associated with upper airway obstruction plays an important role.
There are two types of NPPE: type 1, which is followed by sudden and intense obstruction, such as post extubation laryngospasm and type 2, which develops after surgical release of chronic airway obstruction, such as resection of laryngeal tumors, adenoids/tonsils (adenotonsillectomy), or intrathoracic goiters.
Early diagnosis of negative-pressure pulmonary edema and immediate initiation of treatment are vital for a favorable patient outcome. Signs and symptoms of negative-pressure pulmonary edema include shortness of breath (dyspnea), tachypnea, cyanosis, pink frothy sputum, hemoptysis, and decreased oxygen saturation.
A chest radiograph shows diffuse interstitial and alveolar infiltration and pulmonary edema. There will be bilateral pulmonary infiltrates consistent with pulmonary edema. Bilateral rhonchi and rales will be heard at the base of the lungs.
The differential diagnosis of the chest radiograph includes acute respiratory distress syndrome, and without clinical history can be confused, as in this case. Auscultation reveals pulmonary rales and rhonchi. Negative-pressure pulmonary edema can be misdiagnosed as fluid overload, aspiration, or even bronchospasm.7
Relief of the airway obstruction is the first step in the treatment of negative-pressure pulmonary edema. It is important to maintain a supportive airway and then reverse the hypoxic state. Supplemental oxygen is given to the patient since the primary goal of treating negative-pressure pulmonary edema is adequate oxygen saturation. A small dose of succinylcholine chloride may be given by anesthesiologists to treat laryngospasm as required by the particular clinical situation. Small doses of Lasix are given IV. CPAP therapy also helps.