Reference Levels for Central Venous Pressure and Pulmonary Artery Occlusion Pressure Monitoring in the Lateral Position

Objective To investigate reference levels for central venous pressure or pulmonary artery occlusion pressure monitoring in a lateral position. Design Retrospective observational study. Setting A tertiary university hospital. Participants A total of 204 adults who underwent chest computed tomography scan in the 90° lateral position from November 2006 to February 2015. Interventions None. Measurements and Main Results Distances from the mid-sternum to the uppermost and lowermost blood levels of both atria were measured. Ratios of the distance from the bottom of the thorax to the uppermost and the lowermost blood levels of both atria to the largest diameter of the thorax were calculated. There were significant differences between the distances from the mid-sternum to the uppermost and the lowermost blood levels of the right atrium and those of the left atrium in the right and left lateral positions, respectively. There were significant differences in the uppermost (3.3±0.1 cm; 95% confidence interval [CI] 3.1-3.5) and the lowermost (4.4±0.1 cm; 95% CI 4.2-4.7) blood levels of the right atrium between the right and left lateral positions. Although the uppermost (1.5±0.1 cm; 95% CI 1.3-1.8) and the lowermost (0.4±0.1 cm; 95% CI 0.2-0.6) blood levels of the left atrium between the right and left lateral positions showed differences, their extent was smaller than the right atrium. The uppermost and the lowermost blood levels of the right atrium lay lower than those of the left atrium in the 90° right lateral position. In contrast, in the 90° left lateral position, the uppermost and the lowermost blood levels of the right atrium lay higher than those of the left atrium. Conclusions When monitoring the central venous pressure and pulmonary artery occlusion pressure with patients in the lateral position, changes in the blood level of both atria should be considered when releveling the reference transducer.