Initiation of Inhaled Nitric Oxide by Air Transport Team in Adult COVID-19 Respiratory Failure

Evaluation of Inhaled Nitric Oxide Generation Systems at Altitude

INTRODUCTION

Inhaled nitric oxide (INO) is a selective pulmonary vasodilator delivered from compressed gas cylinders filled to 2,200 psig (137.8 bar) with 800 ppm of NO in a balance of nitrogen. NO is currently FDA-approved for use in term or near-term infants with hypoxemia and signs of pulmonary hypertension in the absence of cardiac disease. INO has also been shown to improve oxygenation in adults with refractory hypoxemia. Current doctrine precludes the use of NO during military aeromedical transport owing to the requirement for large compressed gas cylinders. We performed a bench evaluation of 2 delivery systems that create NO from room air without the need for pressurized cylinders.

MATERIALS AND METHODS

We evaluated 2 portable nitric oxide INO generation systems (LungFit PH, Beyond Air Inc, Garden City, NJ and a prototype NO generator, Odic Inc, Littleton, MA) at ground level, 8,000, and 14,000 feet (2,437 and 4,267 meter) simulated altitude in an altitude chamber. The output from each device was injected into the inspiratory limb of the ventilator circuit that was attached to a test lung. A 731 ventilator (Zoll Medical, Chelmsford, MA) and T1 (Hamilton Medical, Reno, NV) were used employing 24 combinations of ventilator settings each repeated in duplicate. An INOmax DS IR was used to measure delivered INO and NO2 via a sampling line attached in the ventilator circuit inspiratory limb. A fast response oxygen analyzer (O2CAP, Oxigraf Inc, Sunnyvale, CA) was used to measure inspired FiO2. Target INO concentration was 20 ppm.

RESULTS

Across all ventilator settings, the LungFit device delivered INO was 19.8 ± 1.6 ppm, 16.1 ± 1.9 ppm, and 11.6 ± 1.7 ppm at ground level, 8,000 ft (2,437 meter), and 14,000 ft (4,267 meter), respectively. The Odic device delivered INO dose was 20.6 ± 1.4 ppm, 21.3 ± 5.5 ppm, and 20.4 ± 9.1 ppm at ground level, 8,000 ft (2,437 meter), and 14,000 ft (4,267 meter), respectively.

CONCLUSIONS

Both devices delivered a reliable INO dose at ground level. Altitude significantly affected INO delivery accuracy at 14,000 ft (4,267 meter) (P < 0.01) with both devices and at 8,000 ft (2,437 meter) (P < 0.01) with LungFit. Differences in INO dosage were not statistically significant with the Odic device at 8,000 ft (2,437 meter)(P > 0.05) although there were large variations with selected ventilator settings. With careful monitoring, devices creating INO from room air without cylinders could be used during aeromedical transport without the need for pressurized cylinders.

SIMULATED AEROMEDICAL EVACUATION EXACERBATES ACUTE LUNG INJURY VIA HYPOXIA-INDUCIBLE FACTOR 1Α-MEDIATED BNIP3/NIX-DEPENDENT MITOPHAGY

ABSTRACT

Background: With the advancement of medicine and the development of technology, the limiting factors of aeromedical evacuation are gradually decreasing, and the scope of indications is expanding. However, the hypobaric and hypoxic environments experienced by critically ill patients in flight can cause lung injury, leading to inflammation and hypoxemia, which remains one of the few limiting factors for air medical evacuation. This study aimed to examine the mechanism of secondary lung injury in rat models of acute lung injury that simulate aeromedical evacuation. Methods: An acute lung injury model was induced in SD rats by the administration of lipopolysaccharide (LPS) followed by exposure to a simulated aeromedical evacuation environment (equivalent to 8,000 feet above sea level) or a normobaric normoxic environment for 4 h. The expression of hypoxia-inducible factor 1α (HIF-1α) was stabilized by pretreatment with dimethyloxalylglycine. The reactive oxygen species levels and the protein expression levels of HIF-1α, Bcl-2-interacting protein 3 (BNIP3), and NIX in lung tissue were measured. Results: Simulated aeromedical evacuation exacerbated pathological damage to lung tissue and increased the release of inflammatory cytokines in serum as well as the reactive oxygen species levels and the protein levels of HIF-1α, BNIP3, and NIX in lung tissue. Pretreatment with dimethyloxalylglycine resulted in increases in the protein expression of HIF-1α, BNIP3, and NIX. Conclusion: Simulated aeromedical evacuation leads to secondary lung injury through mitophagy.

Unraveling the impact of nitric oxide, almitrine, and their combination in COVID-19 (at the edge of sepsis) patients: a systematic review

Introduction: During the coronavirus disease 2019 (COVID-19) pandemic, a large number of critically ill and severe COVID-19 patients meet the diagnostic criteria for sepsis and even septic shock. The treatments for COVID-19 patients with sepsis are still very limited. For sepsis, improving ventilation is one of the main treatments. Nitric oxide (NO) and almitrine have been reported to improve oxygenation in patients with "classical" sepsis. Here, we conducted a systematic review and meta-analysis to evaluate the efficacy and safety of NO, almitrine, and the combination of both for COVID-19 (at the edge of sepsis) patients. Method: A systematic search was performed on Embase, PubMed, the Cochrane Library, the Web of Science, Wanfang Data, and China National Knowledge Infrastructure. Randomized clinical trials, cohort studies, cross-sectional studies, case-control studies, case series, and case reports in COVID-19 patients with suspected or confirmed sepsis were performed. Study characteristics, patient demographics, interventions, and outcomes were extracted from eligible articles. Results: A total of 35 studies representing 1,701 patients met eligibility criteria. Inhaled NO did not affect the mortality (OR 0.96, 95% CI 0.33-2.8, I2 = 81%, very low certainty), hospital length of stay (SMD 0.62, 95% CI 0.04-1.17, I2 = 83%, very low certainty), and intubation needs (OR 0.82, 95% CI 0.34-1.93, I2 = 56%, very low certainty) of patients with COVID-19 (at the edge of sepsis). Meanwhile, almitrine did not affect the mortality (OR 0.44, 95% CI 0.17-1.13, low certainty), hospital length of stay (SMD 0.00, 95% CI -0.29-0.29, low certainty), intubation needs (OR 0.94, 95% CI 0.5-1.79, low certainty), and SAEs (OR 1.16, 95% CI 0.63-2.15, low certainty). Compared with pre-administration, the PaO2/FiO2 of patients with NO (SMD-0.87, 95% CI -1.08-0.66, I2 = 0%, very low certainty), almitrine (SMD-0.73, 95% CI-1.06-0.4, I2 = 1%, very low certainty), and the combination of both (SMD-0.94, 95% CI-1.71-0.16, I2 = 47%, very low certainty) increased significantly. Conclusion: Inhaled NO, almitrine, and the combination of the two drugs improved oxygenation significantly, but did not affect the patients' mortality, hospitalization duration, and intubation needs. Almitrine did not significantly increase the patients' SAEs. Well-designed high-quality studies are needed for establishing a stronger quality of evidence. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=367667, identifier CRD42022367667.

Inhaled Nitric Oxide in Acute Respiratory Distress Syndrome Subsets: Rationale and Clinical Applications

Acute respiratory distress syndrome (ARDS) is a life-threatening condition, characterized by diffuse inflammatory lung injury. Since the coronavirus disease 2019 (COVID-19) pandemic spread worldwide, the most common cause of ARDS has been the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Both the COVID-19-associated ARDS and the ARDS related to other causes-also defined as classical ARDS-are burdened by high mortality and morbidity. For these reasons, effective therapeutic interventions are urgently needed. Among them, inhaled nitric oxide (iNO) has been studied in patients with ARDS since 1993 and it is currently under investigation. In this review, we aim at describing the biological and pharmacological rationale of iNO treatment in ARDS by elucidating similarities and differences between classical and COVID-19 ARDS. Thereafter, we present the available evidence on the use of iNO in clinical practice in both types of respiratory failure. Overall, iNO seems a promising agent as it could improve the ventilation/perfusion mismatch, gas exchange impairment, and right ventricular failure, which are reported in ARDS. In addition, iNO may act as a viricidal agent and prevent lung hyperinflammation and thrombosis of the pulmonary vasculature in the specific setting of COVID-19 ARDS. However, the current evidence on the effects of iNO on outcomes is limited and clinical studies are yet to demonstrate any survival benefit by administering iNO in ARDS.