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Hand placement during chest compressions in parturients: a pilot study to identify the location of the left ventricle using transthoracic echocardiography

https://doi.org/10.1016/j.ijoa.2020.05.003Get rights and content

Highlights

  • Transthoracic echocardiography in parturients at 30–34 weeks’ gestation.

  • The location of the left ventricle (LV) was evaluated.

  • The left ventricle was ∼6 cm cranial to the distal tip of the xiphoid process.

  • No lateral displacement of the LV was seen.

  • Potential implications for chest compressions during cardiopulmonary resuscitation.

Abstract

Background

Current guidelines for maternal cardiopulmonary resuscitation recommend the hands be placed on the lower half of the sternum for compressions. We sought to evaluate the effect of the gravid uterus and left uterine displacement on the position of the left ventricle (LV) using transthoracic echocardiography.

Methods

We enrolled 20 women in the third trimester of a singleton pregnancy. Transthoracic echocardiography images in the supine and left lateral position, using a 30° wedge, were acquired. Parasternal long and short axis views of the LV were obtained at the lower half of the sternum and at the ideal imaging window (best image of mid-LV at 90° transducer orientation) The primary aim was to evaluate the distance between the distal end of the xiphoid and the location of the best imaging window of the LV.

Results

The cohort included women without prior anatomical cardiac disease. The LV was best visualized 5.8 (±2) cm cranial to the distal end of the xiphoid in the supine position and 6.1 (±2) cm in the lateral position (P=0.6), using the left parasternal border as a reference. No lateral cardiac displacement was evidenced in either position.

Conclusions

This pilot study used transthoracic echocardiography to document the position of the LV during the third trimester of pregnancy. The LV was located approximately 6 cm cranial to the distal tip of the xiphoid process. Further validation is required before recommending changes in hand placement during maternal cardiopulmonary resuscitation.

Introduction

Cardiac arrest during pregnancy is a rare event. Recent reports estimate its incidence in pregnancy to be between 1:12 000 and 1:36 000.1, 2 Maternal survival after cardiac arrest can be higher than 50% if there are timely and structured resuscitative efforts.2 Effective chest compression is one of the few interventions that improves the outcome of cardiopulmonary resuscitation (CPR).3 Current American Heart Association (AHA) guidelines recommend that the hands be placed on the lower half of the sternum for compressions during pregnancy, with manual uterine displacement to alleviate vena cava compression.4, 5 Hand placement on the lower half of the sternum is recommended because this anatomic landmark is easily identifiable and ensures consistent application by rescuers. To guarantee forward blood flow, the chest should ideally be compressed in the location that exerts the most pressure over the left ventricle (LV).

In pregnant women, the heart is rotated to the left and the diaphragm is pushed cephalad in the third trimester.6, 7 An older iteration of AHA cardiopulmonary guidelines from 2010 suggested higher hand placement during chest compressions in pregnant women in order to adjust for cephalad cardiac displacement caused by the gravid uterus.8 This suggestion was removed following preliminary evidence showing the absence of vertical displacement in magnetic resonance imaging (MRI).9 However, a recent MRI study in non-pregnant patients without evidence of cardiac disease showed that the structure underneath the sternum is the LV in only 52% of cases.10

Due to the unique physiological and anatomical changes of full-term pregnancy, we sought by means of transthoracic echocardiography (TTE) to evaluate the effect of the gravid uterus and left uterine displacement on the position of the maternal LV.

Section snippets

Methods

We conducted a prospective observational study after obtaining ethics approval from our institution’s ethics review board (HSD STUDY00003612). After obtaining informed written consent, we included 20 women, with a singleton pregnancy, who were admitted to our antepartum unit in their third trimester of pregnancy (≥28 weeks’ gestational age) during the period from December 2017 to December 2018. We collected demographic information (height, weight, age, gestational age, amniotic fluid index and

Results

The demographic characteristics of our cohort are included in Table 1. Images obtained in the lower half of the sternum provided little or no visualization of the LV (Fig. 1). The ideal imaging window was found to be located 5.8 (±2) cm cranial to the distal end of the xiphoid process cm (supine position) and 6.1 (±2) cm (lateral position), cranial to the distal end of the xiphoid process, using the left parasternal border as a reference for both locations. The middle portion of the LV and its

Discussion

We present the results of a pilot study using echocardiography to document the position of the LV in a cohort of pregnant women between 30 and 34 weeks’ gestation. The maternal LV was located approximately 6 cm cranial to the distal tip of the xiphoid process, with no variation between the supine and left uterine displacement positions. No evidence of lateral displacement was observed. Ideal echocardiographic visualization of the LV suggests that LV location during pregnancy may be

Declarations of interest

None.

Funding sources

None.

Acknowledgement

The authors would like to thank Dr Christopher Barnes for his assistance creating the drawing submitted as Fig. 3.

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