Prone equals prone? Impact of positioning techniques on respiratory function in anesthetized and paralyzed healthy children

Abstract

Objectives: Although the prone position is effectively used to improve oxygenation, its impact on functional residual capacity is controversial. Different techniques of body positioning might be an important confounding factor. The aim of this study was to determine the impact of two different prone positioning techniques on functional residual capacity and ventilation distribution in anesthetized, preschool-aged children. Design: Functional residual capacity and lung clearance index, a measure of ventilation homogeneity, were calculated using a sulfur-hexafluoride multibreath washout technique. After intubation, measurements were taken in the supine position and, in random order, in the flat prone position and the augmented prone position (gel pads supporting the pelvis and the upper thorax). Setting: Pediatric anesthesia unit of university hospital. Patients and participants: Thirty preschool children without cardiopulmonary disease undergoing elective surgery. Measurements and results: Mean (range) age was 48.5 (24-80) months, weight 17.2 (10.5-26.9) kg, functional residual capacity (mean ± SD) 22.9 ± 6.2 ml.kg -1 in the supine position and 23.3 ± 5.6 ml.kg -1 in the flat prone position, while lung clearance indices were 8.1 ± 2.3 vs. 7.9 ± 2.3, respectively. In contrast, functional residual capacity increased to 27.6 ± 6.5 ml.kg -1 (p< 0.001) in the augmented prone position while at the same time the lung clearance index decreased to 6.7 ± 0.9 (p< 0.001). Conclusions: Functional residual capacity and ventilation distribution were similar in the supine and flat prone positions, while these parameters improved significantly in the augmented prone position, suggesting that the technique of prone positioning has major implications for pulmonary function.

The Prone Position During Surgery and its Complications: A Systematic Review and Evidence-Based Guidelines

“…7 Lung volume and oxygenation increase due to improved ventilation/perfusion ratio in both adults and pediatric demographics. 7,15 Obese patients are at particular risk of increased abdominal pressure, increased venous pressure in the head, and decreased cardiac output and reduced end organ blood flow. 1,16 However, with proper supportive padding, these patients have better oxygenation in supported prone position versus supine position, as mediastinal contents fall anteriorly facilitating ventilation.…”

Anaesthesia for scoliosis correction surgery complicated by severe recalcitrant bradycardia upon prone positioning in an adolescent with Prader-Willi syndrome

“…Patients with scoliosis are particularly difficult to position optimally because of anatomical distortion. A study by Von Ungern-Sternberg et al 16 compared the effects of "flat" and "augmented" prone positioning in children. The "augmented" prone position involved the use of supports for the pelvis and upper thorax.…”

Impact of anaesthesia on lung function in children

“…Therefore, additional confounding factors, such as changes in ventilation distribution or differences in positioning techniques, might be important. In our recent study, we demonstrated that the augmented prone position (gel pads supporting the shoulders and the pelvis), in contrast to the flat prone position, increases FRC and thus could help to optimise respiratory function in paralysed, mechanically ventilated, healthy children [9].…”