Oxygen as an Essential Medicine: Under- and Over-Treatment of Hypoxemia in Low- and High-Income Nations

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To the Editor:In a recent issue of Critical CareMedicine, Helmerhorst et al (1) made two important points. First, hyperoxia is associated with significant morbidity and mortality. Second, an intervention with minimal cost, involving training and provider feedback, decreased improper use of oxygen by 25% (p < 0.0001), ensuring that 63% of patients received appropriate therapy (SpO2, 92–95%). This modest intervention resulted in a significant decrease in hospital mortality and mechanical ventilation time.However, in low-income nations, undertreatment of hypoxemia, as opposed to the “more is better” scenario addressed by Helmerhorst et al (1), is still a problem. A single study found that the point prevalence of undiagnosed hypoxemia was 9% among 109 inpatient adults in Zambia (2). In 2015, the Lancet Commission on Global Surgery found that 24% of developing country hospitals lack oxygen, and 70% of operating theaters do not have pulse oximeters (3). Our group sought to determine the occurrence rate of hypoxemia and associated mortality among all inpatient adults in a low-income setting.We conducted a prospective single-center observational study in one of Rwanda’s two public tertiary care hospitals, with 12,000 annual admissions (4). We screened all adult inpatients (age, > 15 yr) every day for 4 weeks in 2014 with an Acare/Lifebox oximeter (Acare Technology Co., Ltd., Taipei, Taiwan). Hypoxemia was defined as oxygen saturation less than 90% or receiving oxygen supplementation.During the 4 weeks of the study, 1,046 adult patients were admitted to the hospital (4). one hundred twenty-six patients (12.0%) were hypoxemic on one or more days with an inpatient mortality rate of 49.2%. Median age was 49 years (interquartile range [IQR], 34–65 yr). Mortality was worse with worsening hypoxemia. As hypoxemia increased from mild, moderate, to severe, corresponding mortality rates increased from 30.8% to 40.7% to 57.4% (estimated PaO2-to-FIO2 ratio between 200 and 300; 100–200; < 100), respectively. While 111 patients (88.1%) received adequate oxygen at least 1 day, 76 (60.3%) of hypoxemic patients either received no oxygen therapy or inadequate oxygen therapy on at least 1 day (SpO2, < 90%). Median time from admission to hypoxemia was 1 day (IQR, 1–3 d).Oxygen has been listed as one of the World Health Organization’s Essential Medicines since the first online edition was published in 2002 (5); however, very little research exists on hypoxemia in adult populations. In our study of inpatient adults, hypoxemia occurred at epidemic proportions. Although 85.7% of hypoxemic patients were in hospital wards outside the ICU, their 49.2% mortality rate was almost identical to the mortality of our ICU patients (47.1%) (4).It is possible that hypoxemia is simply a marker of severe disease; however, our data raise the question of whether consistent oxygen therapy at all levels of the health system could make an impact on mortality. While Helmerhort et al (1) study rightly emphasizes that more oxygen is not always better, “some” oxygen to address hypoxemia is almost certainly beneficial. Helmerhort et al (1) trial indicates that simple, low-cost educational and behavioral interventions are capable of improving oxygen use where oxygen is available and hyperoxia a common occurrence. For much of the world, making oxygen consistently available and educating on the need to avoid hypoxemia remain the priority.

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