From the Journals

COVID-19 in pregnancy: Supplement oxygen if saturation dips below 94%


 

OBSTETRICS & GYNECOLOGY

Oxygen supplementation for pregnant women with COVID-19 should begin when saturations fall below 94%, according to physicians in the divisions of maternal-fetal medicine and surgical critical care at the University of Texas Medical Branch at Galveston.

This transmission electron microscope image shows SARS-CoV-2—also known as 2019-nCoV, the virus that causes COVID-19. isolated from a patient in the U.S., emerging from the surface of cells cultured in the lab. Courtesy NIAID-RML

That’s a bit higher than the 92% cut point for nonpregnant women, but necessary due to the increased oxygen demand and oxygen partial pressure in pregnancy. The goal is a saturation of 94%-96%, said Luis Pacheco, MD, a maternal-fetal medicine and critical care specialist at the university, and associates.

Most pregnant women with coronavirus disease 2019 (COVID-19) will have mild disease, but some might require respiratory support, so Dr. Pacheco and associates addressed the issue in a commentary in Obstetrics & Gynecology.

Women on respiratory support should lie prone if under 20 weeks’ gestation to help with posterior lung recruitment and oxygenation.

If conventional oxygen therapy isn’t enough, high-flow nasal cannula (HFNC) at 60 L/min and 100% oxygen should be the next step, not positive-pressure ventilation. Positive pressure, another option, kicks off aerosols that increase the risk of viral transmission to medical staff. “This makes high-flow nasal cannula the first-line option for patients not responding to conventional oxygen therapy but who are not yet candidates for endotracheal intubation,” the team said. If women do well, the fraction of inspired oxygen should be weaned before the nasal cannula flow is decreased.

However, if they continue to struggle with dyspnea, tachypnea, and oxygen saturation after 30-60 minutes on HFNC, it’s time for mechanical ventilation, and fast. “Delays in recognizing early failure of high-flow nasal cannula ... may result in life-threatening hypoxemia at the time of induction and intubation (especially in pregnant patients with difficult airway anatomy),” the authors said.

For birth, Dr. Pacheco and associates recommended controlled delivery, likely cesarean, if respiration continues to deteriorate despite intubation, especially after 28 weeks’ gestation, instead of waiting for fetal distress and an ICU delivery. A single course of steroids is reasonable to help fetal lung development beforehand, if indicated.

As for fluid strategy during respiratory support, pregnant women are at higher risk for pulmonary edema with lung inflammation, so the authors cautioned against giving maintenance fluids, and said “if daily positive fluid balances are present, combined with worsening respiratory status, the use of furosemide (10-20 mg intravenously every 12 hours) may be indicated.”

For women stable on conventional oxygen therapy or HFNC, they suggested daily nonstress tests starting at 25 weeks’ gestation instead of continuous monitoring, to minimize the COVID-19 transmission risk for staff.

The team cautioned against nebulized treatments and sputum-inducing agents when possible as this may aerosolize the virus.

There was no external funding for the report, and the authors didn’t have any relevant financial disclosures.

SOURCE: Pacheco LD et al. Obstet Gynecol. 2020 Apr 29. doi: 10.1097/AOG.0000000000003929.

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