Israel Medical Association Journal

Background: At the beginning of the coronavirus disease 2019 (COVID-19) pandemic, many patients presented with acute hypoxemic respiratory failure, requiring ventilatory support. One treatment method was the addition of a reservoir mask to a high flow nasal cannula (HFNC) (dual oxygenation).

Objectives: To evaluate the clinical outcomes of combining reservoir mask on top of a high-flow nasal cannula.

Methods: A retrospective cohort of adult patients who were admitted due to COVID-19 during the first year of the pandemic to Rambam Health Care Campus. The primary endpoint was 30-day mortality. Secondary endpoints were incidence of invasive positive pressure ventilation initiation and admission to the intensive care unit (ICU). Patients who received positive pressure ventilation for reasons other than hypoxemic respiratory failure or who were transferred to another facility while still on HFNC were excluded.

Results: The final analysis included 333 patients; 166 were treated with dual oxygenation and 167 with HFNC only (controls). No significant differences in baseline characteristics were noted between the groups. The dual oxygenation group was slightly older (69.2 ± 14.8 years vs. 65.6 ± 15.5 years, P = 0.034). The 30-day mortality (24.1% vs. 36.5%, P = 0.013), rates of invasive positive pressure ventilation (47% vs. 59.3%, P = 0.024), and ICU admissions (41.6% vs. 52.7%, P = 0.042) were all significantly lower in the dual oxygenation group.

Conclusions: The addition of reservoir masks to HFNC may improve the oxygenation and overall prognosis in patients with severe hypoxemia due to COVID-19.

For most passengers, even those with respiratory disease, air travel is safe and comfortable. Some travelers may experience hypoxia at sea level but may not need supplemental oxygen during air travel in a hypobaric hypoxic environment. For some individuals compensatory pulmonary mechanisms may be inadequate, causing profound hypoxia. In addition, venous thromboembolism/pulmonary emboli may occur, especially during long haul flights. With adequate screening, patients at risk can be identified, therapeutic solutions can be proposed for the flight, and most can travel can continue safely with supplemental oxygen and other preventive measures.

Background: Accurate pulse oximetry reading at hospital admission is of utmost importance, mainly for patients presenting with hypoxemia. Nevertheless, there is no accepted or evidence-based protocol for such structured measuring.

Objectives: To devise and assess a structured protocol intended to increase the accuracy of pulse oximetry measurement at hospital admission.

Methods: The authors performed a prospective comparison of protocol-based pulse-oximetry measurement with non-protocol based readings in consecutive patients at hospital admission. They also calculated the relative percentage of improvement for each patient (before and after protocol implementation) as a fraction of the change in peripheral capillary oxygen saturation (SpO₂) from 100%.

Results: A total of 460 patients were recruited during a 6 month period. Implementation of a structured measurement protocol significantly changed saturation values. The SpO₂ values of 24.7% of all study participants increased after protocol implementation (ranging from 1% to 21% increase in SpO₂ values). Among hypoxemic patients (initial SpO₂ < 90%), protocol implementation had a greater impact on final SpO₂ measurements, increasing their median SpO₂ readings by 4% (3–8% interquartile range; P < 0.05). Among this study population, 50% of the cohort improved by 17% of their overall potential and 25% improved by 50% of their overall improvement potential. As for patients presenting with hypoxemia, the median improvement was 31% of their overall SpO₂ potential.

Conclusions: Structured, protocol based pulse-oximetry may improve measurement accuracy and reliability. The authors suggest that implementation of such protocols may improve the management of hypoxemic patients.

Objectives: To investigate the effect of hypoxemia and nocturnal glucose homeosatsis in non-diabetic patients with sleep apnea.

Methods: Seven non-diabetic patients with moderate to severe sleep apnea were connected to a continuous glucose-monitoring sensor while undergoing overnight polysomnography. Mean SpO₂ and percentage of time spent at SpO₂ < 90% were recorded. The correlation between mean glucose levels, the difference between consecutive mean glucose measurements (glucose variability) and the corresponding oxygen saturation variables were determined in each patient during REM[1] and non-REM sleep.

Results: No consistent correlation was found for the individual patient between oxygen saturation variables and glucose levels during sleep. However, a lower mean SpO₂ correlated with decreased glucose variability during sleep (r = 0.79, P = 0.034). This effect was primarily evident during REM sleep in patients with significant, compared to those with mild, oxygen desaturations during sleep (> 30% vs. < 10% of sleeping time spent with SpO₂ < 90%) (P = 0.03).

Conclusions: Severe nocturnal hypoxemia in non-diabetic patients with moderate to severe sleep apnea might affect glucose regulation primarily during REM sleep.

Objectives: To suggest a simple outpatient technique for evaluating the response of arterial oxygen saturation to exercise for use as a marker of disease severity.

Patients and methods: Ninety-six patients with various degrees of COPD¹ were divided into three groups: mild (forced expiratory volume in 1 sec >65%), moderate (FEV1² between 50 and 65%), and severe (FEV1 <50%). Using continuous oximeter recording we measured oxygen saturation during 15 steps of climbing, and quantified  oxygen desaturation by measuring the “desaturation area”, defined as the area under the curve of oxygen saturation from the beginning of exercise through the lowest desaturarion point and until after recovery to the baseline level of oxygen percent saturation. Desaturation was correlated to spirometry, lung gas volumes, blood gas analysis, and 6 min walking distance.

Results A good correlation was found between severity of COPD and baseline SaO2³, lowest SaO2, recovery time, and desaturation area.  A negative correlation was found between desaturation area and FEV1 (r=-0.65), FEV1/forced vital capacity (r=-0.58), residual volume to total lung capacity (r=0.52), and diffusing lung capacity for carbon monoxide (r=-0.52). In stepwise multiple regression analysis only FEV1 correlated significantly to desaturation area.  A good correlation was noted between 6 min walking distance and desaturation area with the 15 steps technique (r=0.56).

Conclusions: In patients with severe COPD, arterial hypoxemia during exercise can be assessed by simple 15 steps oximetry. This method can serve both as a marker for disease severity and to determine the need for oxygen supplementation.

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COPD = chronic obstructive pulmonary disease

FEV1 = forced expiratory volume in 1 sec

SaO2 = arterial oxygen saturation