Analysis of the oxygen administration in patients hospitalised in Internal Medicine wards and intensive care unit in Hacettepe University

Aim: Oxygen is widely used for the prevention and treatment of hypoxia. The primary aim of this study was to determine the frequency of oxygen usage among patients in the Internal Medicine (IM) wards and intensive care unit (ICU). The secondary aims of this study were to define oxygen support methods, investigate the inappropriate usage of oxygen, grouping patients based on their SpO2 values into <94%, 94%-98%, >98%, and investigate the correlation between SpO2/FiO2 and PaO2/FiO2. Material and Method: This is a prospective, observational study. We recruited 143 patients who were inpatient during March 1-31, 2022 and receiving oxygen. We have documented admission data, and modified early warning score (MEWS). Oxygen support data was collected in the first 24 hours and recorded in 6 hours quartiles. In every quartile, oxygen support system was noted and average of oxygenation parameters were recorded. Oxygenation parameters were calculated as 24 hour average. Oxygen flow rate greater than 6 L/min in nasal cannula, different than 5-10 L/min in simple face mask, and application of simple face mask in chronic obsructive lung disease (COPD) exacerbation were marked as inappropriate usage. SpO2/FiO2 and PaO2/FiO2 relationship was analyzed in ICU patients. Results: Among the 20% of 397 patients in wards, and 50% of 124 patients in ICU received oxygen (mean age 65, 55% male). Reason of oxygen need was respiratory failure for 98 (69%) patients, hypervolemia for 22 (15%) patients, and septic shock for 18 (13%) patients. Oxygen support type was nasal cannula in 51%, simple face mask in 21%, and high flow nasal cannula (HFNC) in 4%. Invasive mechanical ventilation (İMV) was applied to 18% of the patients, and 6% them received non-invasive mechanical ventilation (NIMV) as oxygen support. Nasal oxygen was not used greater than 6 L/min flow rate in any case. Among simple face mask applications, 46% were <5 L/min and 5% of them were >10 L/min. Application of simple face mask rate in COPD exacerbation was 15%. SpO2 value was less than 94% in 46% of the patients, between 94%-98% in 49% of the patients, and greater than 98% in 5% of the patients. Among 62% of the COPD exacerbation patients, SpO2 value was greater than 92%. MEWS score was noted to be high among the group with SpO2 <94%. A strong correlation was shown between SpO2/FiO2 and PaO2/FiO2 (r=0,87 p<0,001) among ICU patients. Conclusion: The rate of oxygen usage was 20% among patients that were hospitalized in the IM wards, and 50% in the ICU. More than half of the simple face mask applications were inappropriate. The SpO2 value was greater than 94% in more than half of patients who were on oxygen, and greater than 92% in more than half of COPD exacerbation patients. Strong correlation between SpO2/FiO2 and PaO2/FiO2 suggests that SpO2/FiO2, a non-invasive method, can be considered as a candidate for the replacement of PaO2/FiO2. Keywords: oxygen saturation, oxygen therapy, oxygen administration & dosage