Inhaled Nitric Oxide for High Amplitude Pulmonary Edema (HAPE)

Overview

High Altitude Pulmonary Edema (HAPE) is a critical, non-cardiogenic pulmonary edema that manifests in high-altitude conditions, marked by the rapid onset of symptoms such as dyspnea, cough, frothy sputum, and cyanosis. It represents a significant cause of mortality among high-altitude illnesses due to its swift progression and elevated fatality rates if not addressed promptly. The pathophysiological mechanisms underlying HAPE include excessive hypoxic pulmonary vasoconstriction, increased permeability of the pulmonary vasculature, impaired clearance of fluid from the lungs, and systemic fluid retention. A pivotal factor in HAPE is pulmonary arterial hypertension (PAH), characterized by a progressive rise in pulmonary arterial pressure and resistance, which can ultimately lead to right heart failure. Recent developments in the management of HAPE have introduced inhaled nitric oxide (iNO) as a selective pulmonary vasodilator, which effectively lowers pulmonary arterial pressure and enhances oxygenation without inducing systemic hypotension. The INOwill N300 device, created by Nanjing Novlead Biotech, is a portable iNO delivery system that produces nitric oxide gas on-site, thereby obviating the need for gas cylinders. This device also facilitates real-time monitoring of nitric oxide, nitrogen dioxide, and oxygen concentrations, ensuring safe and effective treatment. This innovative strategy shows potential for improving clinical outcomes in patients with HAPE while addressing logistical challenges encountered in high-altitude environments.

This study utilized the inaugural nitric oxide therapeutic device sanctioned by the State Drug Administration, which possesses independent intellectual property rights (INOwill N300, Nanjing Novlead Biotechnology Co., LTD.). The device is compact and generates nitric oxide gas upon activation, eliminating the need for cylinders for the storage and transport of nitric oxide. It employs an electrochemical catalytic reduction method to produce nitric oxide gas in real-time and automatically administers the gas to the respiratory circuit at a predetermined concentration, based on flow monitoring. The phase change sensor sampling technology enables real-time monitoring of the concentrations of nitric oxide, nitrogen dioxide, and oxygen at the patient end of the respiratory circuit, thereby ensuring the safety of clinical interventions. The primary aim of this investigation was to assess the efficacy of inhaled nitric oxide (iNO) in the management of mild to moderate high altitude pulmonary edema (HAPE) in comparison to a control group. Key parameters evaluated included the onset time of changes in oxygenation, the duration until symptom resolution (as measured by the Lake Louise Acute Mountain Sickness score), the time required for improvement in imaging indicators, and the proportions of patients categorized as cured, effective, ineffective, or experiencing severe HAPE by days 3 to 7 of treatment. Additionally, the length of hospital admission or stay was recorded for patients receiving iNO therapy for high altitude pulmonary edema. This study aimed to elucidate the impact of iNO on enhancing oxygenation and pulmonary circulation in patients with high altitude pulmonary edema relative to the control group.