Ventilatory Parameters in Obstetric Patients With COVID-19 and Impact of Delivery: A Multicenter Prospective Cohort Study

Abstract

Background: Current evidence on obstetric patients requiring advanced ventilatory support and impact of delivery on ventilatory parameters is retrospective, scarce, and controversial.

Research question: What are the ventilatory parameters for obstetric patients with COVID-19 and how does delivery impact them? What are the risk factors for invasive mechanical ventilation (IMV) and for maternal, fetal, and neonatal mortality?

Study design and methods: Prospective, multicenter, cohort study including pregnant and postpartum patients with COVID-19 requiring advanced ventilatory support in the ICU.

Results: Ninety-one patients were admitted to 21 ICUs at 29.2 ± 4.9 weeks; 63 patients (69%) delivered in ICU. Maximal ventilatory support was as follows: IMV, 69 patients (76%); high-flow nasal cannula, 20 patients (22%); and noninvasive mechanical ventilation, 2 patients (2%). Sequential Organ Failure Assessment during the first 24 h (SOFA₂₄) score was the only risk factor for IMV (OR, 1.97; 95% CI, 1.29-2.99; P = .001). Respiratory parameters at IMV onset for pregnant patients were: mean ± SD plateau pressure (PP), 24.3 ± 4.5 cm H₂O; mean ± SD driving pressure (DP), 12.5 ± 3.3 cm H₂O; median static compliance (SC), 31 mL/cm H₂O (interquartile range [IQR], 26-40 mL/cm H₂O); and median Pao₂ to Fio₂ ratio, 142 (IQR, 110-176). Respiratory parameters before (< 2 h) and after (≤ 2 h and 24 h) delivery were, respectively: mean ± SD PP, 25.6 ± 6.6 cm H₂O, 24 ± 6.7 cm H₂O, and 24.6 ± 5.2 cm H₂O (P = .59); mean ± SD DP, 13.6 ± 4.2 cm H₂O, 12.9 ± 3.9 cm H₂O, and 13 ± 4.4 cm H₂O (P = .69); median SC, 28 mL/cm H₂O (IQR, 22.5-39 mL/cm H₂O), 30 mL/cm H₂O (IQR, 24.5-44 mL/cm H₂O), and 30 mL/cm H₂O (IQR, 24.5-44 mL/cm H₂O; P = .058); and Pao₂ to Fio₂ ratio, 134 (IQR, 100-230), 168 (IQR, 136-185), and 192 (IQR, 132-232.5; P = .022). Reasons for induced delivery were as follows: maternal, 43 of 71 patients (60.5%); maternal and fetal, 21 of 71 patients (29.5%); and fetal, 7 of 71 patients (9.9%). Fourteen patients (22.2%) continued pregnancy after ICU discharge. Risk factors for maternal mortality were BMI (OR, 1.10; 95% CI, 1.006-1.204; P = .037) and comorbidities (OR, 4.15; 95% CI, 1.212-14.20; P = .023). Risk factors for fetal or neonatal mortality were gestational age at delivery (OR, 0.67; 95% CI, 0.52-0.86; P = .002) and SOFA₂₄ score (OR, 1.53; 95% CI, 1.13-2.08; P = .006).

Interpretation: Contrary to expectations, pregnant patient lung mechanics were similar to those of the general population with COVID-19 in the ICU. Delivery was induced mainly for maternal reasons, but did not change ventilatory parameters other than Pao₂ to Fio₂ ratio. SOFA₂₄ score was the only risk factor for IMV. Maternal mortality was associated independently with BMI and comorbidities. Risk factors for fetal and neonatal mortality were SOFA₂₄ score and gestational age at delivery.

Keywords: critical care; delivery; mechanical ventilation; mortality; pregnancy.

Graphical abstract

Figure 1

Bar graph showing organ dysfunction during the first 24 h in the ICU and its corresponding ICU mortality among 91 pregnant or postpartum patients with COVID-19.

Figure 2

Bar graph showing type of respiratory support on admission for 91 pregnant or postpartum patients with COVID-19 and differences between survivors and nonsurvivors. ^aP = .71 for comparison of type of respiratory support on admission between SV and NonSV groups. HFNC = high-flow nasal cannula; IMV = invasive mechanical ventilation; NIMV = noninvasive mechanical ventilation; NonSV = nonsurvivors; NP = nasal prong; NRM = nonrebreathing mask; SV = survivor.

Figure 3

A-D, Box-and-whisker plots showing mechanical ventilation and oxygenation parameters over the first week after intubation for 47 patients admitted before delivery because of COVID-19 and differences between survivors and nonsurvivors. A, Plateau pressure. B, Driving pressure. C, Static compliance. D, Pao₂ to Fio₂ ratio. ^aDifference between survivors (blue) and nonsurvivors (red) (P < .05) that were significant for plateau pressure at days 2 and 7, and driving pressure at day 7. ^bDifferences in Pao₂ to Fio₂ ratio over the first week for the entire group (gray) (P = .000): post hoc Bonferroni significant differences between day 0 vs day 2 and day 0 vs day 7, P = 000.

Figure 4

A-D, Box-and-whisker plots showing mechanical ventilation and oxygenation parameters before (< 2 h) and after (< 2 h and 24 h) delivery among 47 patients with COVID-19 admitted before delivery. A, Plateau pressure. B, Driving pressure. C, Static compliance. D, Pao₂ to Fio₂ ratio. Comparisons of variables before (< 2 h) and after (< 2 h and 24 h) delivery: ^aD, Pao₂ to Fio₂ ratio = P = .022 for the entire group (P = .025 between before [< 2 h] and at 24 h of delivery in the post hoc Bonferroni analysis).