Accidental prolonged aerosol exposure to 1.5% glycine solution via inhalation

ABSTRACT

Background: Glycine is an endogenous, non-essential, simple amino acid produced in the human body. A 1.5% solution is commonly used for irrigation in gynecologic and urologic procedures as it is a sterile, clear, non-irritating liquid. It is neutral, mildly acidic and nonpyrogenic, and as it is produced by the human body it does not cause allergic reactions. If an excessive amount is absorbed during a procedure it can result in electrolyte abnormalities, such as hyponatremia or hypocalcemia. It can also result in transient vision disturbances, changes in heart rate, hypotension, hyperammonemia, or encephalopathy. Glycine has been used as a diluent in certain inhaled therapies for COVID-19 infections, such as epoprostenol. We describe a case where a 1.5% glycine solution was inadvertently used for humidified oxygen via high flow nasal cannula as opposed to distilled water. Case report The patient was a 70-year-old male who was admitted to the hospital for hypoxia related to a COVID-19 infection with O2 saturations in the 70-80% range. He was placed on high flow nasal cannula to improve his oxygen levels. During his inpatient stay it was discovered that a 3-L bag of 1.5% glycine solution had been connected to the high flow nasal cannula instead of distilled water. This ran from Friday evening to the following Monday morning before the error was discovered. There was only 100mL of the glycine solution remaining in the bag when it was found. The patient continued to do well and had no new complaints during his stay. The case was called to the regional poison center which recommended monitoring electrolytes, watching for any possible respiratory symptoms and continuing supportive care. Initial lab work on admission showed a chemistry panel of Na 146, K 3.6, Cl 102, CO2 25.3, BUN 9, Cr 0.70, Glucose 106, Ca 9.3. Repeat lab work immediately after the mistake was found showed Na 137, K 4.8 Cl 100, CO2 28, BUN 15, Cr 0.70, Glucose 129, Ca 9.0. On recommendations from poison control, electrolytes were monitored with repeat lab work 10 h after discontinuation of the glycine solution, showing Na 135, K 4.3, Cl 97, CO2 26.8, Glucose 175, Ca 9.2. The patient did not develop any new complaints, had no reported altered mental status, epistaxis, nasal irritation or other symptoms related to the inhalation. He was eventually discharged home on oxygen for his persistent hypoxia related to his COVID-19 lung infection. Discussion(s) This case demonstrates that prolonged continuous inhalational exposure to a 1.5% glycine irrigation solution does not result in any mucosal irritation, metabolic or systemic toxic reactions, even though its pH is reportedly between 4.5 and 6.5. Thus, glycine solutions up to this concentration appear to be safely tolerated for its increasing use as an excipient for aerosolized medications. Conclusion(s) We describe a case where 1.5% glycine solution was inadvertently used in place of distilled water for humidified oxygen via high flow nasal cannula for approximately 3 days in a patient being treated for COVID-19 related pneumonia with no notable adverse effects.