Prone positioning is an effective intervention for improving oxygenation and survival in ARDS. Although logistically challenging, it may be safely performed during ECMO support[59–61] and throughout pregnancy.[18,62] We use prone positioning for pregnant patients with moderate to severe ARDS (Pao2/FIO2 ratio <150 to 200) despite optimizing ventilation, including patients on ECMO. The exclusion criteria for prone positioning are similar as for nonpregnant patients, though the process may be more onerous in the third trimester. Additionally, in the presence of an acutely nonreassuring fetal heart rate tracing, prone positioning may be inadvisable. Alternatively, for pregnant patients on ECMO who may benefit from prone positioning but have contraindications or in settings with resource and personnel constraints that render proning impractical, other authors have suggested lateral decubitus positioning.[16,63]
An experienced team is required for successful prone positioning during pregnancy, especially during ECMO support. For these patients, at least 4 team members are required when prone positioning or repositioning to supine (ie, perfusionist, respiratory therapist, ICU nurse, and obstetric nurse). A mechanical lift greatly improves safety and convenience. Relevant consultants are also notified before positioning in the event of maternal decompensation or nonreassuring fetal status (ie, obstetrics or maternal-fetal medicine, obstetric anesthesiology, and neonatology). Figure 2 demonstrates our approach to prone positioning for ventilated and sedated pregnant patients, which involves an "A" frame configuration for patient cushioning. We have had success using several different materials for constructing an "A" frame, including rolled blankets or proprietary padding products such as Convoluted Pad (Span-America Medical Systems) or Z Flo Fluidized Positioner (Molnlycke Health Care). The upper and lateral parts of the body are supported by the 2 limbs of the "A," and the horizontal bar of "A" supports the pelvis below the anterior superior iliac spines. The size of the triangle in the "A-frame" is adjusted to provide enough space for the abdomen to rest without touching the bed, to avoid compression of the aorta and inferior vena cava by the gravid uterus. The fetal heart rate monitor is placed between the bed and the abdomen. Whenever feasible and required, a tocodynamometer is used with an elastic belt. Both lower limbs are supported adequately to limit hip flexion and so facilitate blood flow via femoral cannulas. The head is turned to 1 side and the arm on the same side is placed in swimmer's position. The fetal heart rate monitor and the tocodynamometer are disconnected from the monitoring base station when patients are moved between prone and supine positions.
Cushioning for prone positioning during pregnancy. A, Aerial view of the patient, resting on an "A" frame configuration of cushions. The pelvis and upper body are supported by 2 limbs of the "A," and the pelvis is supported by a horizontal cushion. The abdomen is free in the hollow of the "A" frame, and there is space to insert a fetal heart rate monitor and a tocodynamometer. B, Lateral view of patient on the "A" frame. The head is turned to 1 side, with ipsilateral arm in swimmers' position. Cushions support the lower extremities to facilitate cannula flow by avoiding excessive hip flexion.
In our institutional proning protocol, patients are placed for a goal of 16 hours in prone position and repositioned supine for 8 hours though, in practice, it may be necessary to return to supine position sooner if the fetus is challenging to continuously monitor while prone. Other concerns that may prompt early return to supine positioning include frequent uterine contractions, new or worsening nonreassuring fetal heart tracing, and deteriorating maternal hypoxemia or hemodynamics. Daily prone positioning sessions are planned until there ceases to be improvement in maternal blood gas measurements, chest radiography, or lung compliance, or if there is evidence of pressure injury.
Anesth Analg. 2022;135(2):277-289. © 2022 International Anesthesia Research Society