Optimal landmark for chest compression during cardiopulmonary resuscitation derived from a chest computed tomography in arms-down position

Type of funding sources: Private hospital(s). Main funding source(s): The Faculty of Medicine, Chiang Mai University Fund

Recently evidence, compression at the maximal left ventricular diameter on sternum (LVmax) maximises cardiac output, stroke volume and rate of return of spontaneous circulation. However, there is insufficient evidence for the specific landmark on the chest for high-quality chest compression. Although cardiac arrest patients are usually in the arms-down position, previous studies used chest computed tomography (CCT) of the patient with arms-up position. It might alter the left ventricular position.

This study aimed to identify the landmark of LVmax and to propose the new hand placement to optimise the chest compression by using CCT in arms-down position.

A retrospective, cross-sectional study conducted at a university-based, tertiary care hospital between September 2016 and November 2020. We included adult patients who underwent CCT in arms-down position. We measured healthcare providers’ hand heel width and the cardiothoracic parameters in CCT to establish a new optimal landmark of chest compression. We defined the sternal notch as a reference point and measured the distance from the sternal notch to LVmax (DLVmax), to the lower half of sternum (DLH), and to the point of maximal force of hand which placed the palmar margin of the reference hand at the xiphisternal junction (lower end of the sternum).

A total of 39 patients were enrolled to measure the cardiothoracic parameters. There were 22 male (56.4%) and the median age was 67 years. DLVmax was neither different in inspiratory-hold nor expiratory-hold (mean ± standard deviation: 12.1 ± 1.9 cm and 12.9 ± 2.7 cm, p = 0.386). LVmax was located lower than the lower half of the sternum (Figure 1); the median of DLVmax and DLH were 12.6 cm (interquartile range: 10.6, 13.5 cm) and 10.0 cm (9.5, 11.0 cm), respectively (p <0.001). We found that the distance from the sternal notch to the point of maximal force of the left hand which the ulnar border located at the xiphisternal junction (DLU) was not significantly different from DLVmax (Figure 2); the median of DLVmax and DLU were 12.6 cm (10.6, 13.5 cm) and 11.3 cm (10.6, 12.5 cm), respectively (p 0.076).

The maximal left ventricular diameter on sternum (DLVmax) in the arms-down position was located lower than the lower half of the sternum (lower than the standard guideline recommendation). We propose that the new hand placement for chest compression is placing the left hand down and the hand’s border located at the xiphisternal junction while approach at left side of the patient.

Abstract Figure.