Impact of Trendelenburg positioning on functional residual capacity and ventilation homogeneity in anaesthetized children

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Adrian Regli,¹ Walid Habre¹ Sonja Saudan ¹ Chantal Mamie¹ Britta S. von Ungern-Sternberg¹
1 Paediatric Anaesthesia Unit, Geneva Children’s Hospital, Geneva, Switzerland

Purpose of Study

Trendelenburg positioning, as defined by head-down tilt, is routinely used in anaesthesia when inserting a central venous catheter to enhance the calibre of the jugular or sub-clavian veins and to prevent an air embolism. We investigated the impact of Trendelenburg positioning on functional residual capacity (FRC) and ventilation homogeneity as well as the potential reversibility of these changes by repositioning and/or a recruitment manoeuvre in children with congenital heart disease.

Method

We assessed FRC and ventilation homogeneity in 20 anaesthetised children (3 months to 8 years) who required central venous catheterization before undergoing cardiac surgery. Functional residual capacity was assessed 1) in the supine position, 2) in the Trendelenburg position, 3) after repositioning supine and 4) after a recruitment manoeuvre. The recruitment manoeuvre to total lung capacity consisted of was performed by manually elevating the airway pressure to 37-40 cmH2O of peak inspiratory pressure for 10 consecutive breaths.

Result

The Trendelenburg position led to a significant decrease in FRC (median [range] -12 (6-21) %) and increase in lung clearance index (12 (2-19) %). Baseline values were not reached after repositioning supine but also required a standardised recruitment manoeuvre in all children.

Conclusion

The Trendelenburg position led to a significant decrease in FRC and ventilation homogeneity. These changes in lung function were not restored following simple supine repositioning suggesting airway closures necessitating a recruitment maneouvre. Therefore, anaesthetists must be aware of the impact of head-down tilt positioning on lung volume and gas exchange and consider a recruitment manoeuvre to restore baseline lung volumes

Time of Presentation
1530