We read with interest your recent article (‘Heads Up’ on Advances in CPR, February 2024) on the importance of “head-up” CPR in combination with active compression-decompression and an impedance threshold device in improving out-of-hospital cardiac arrest (OHCA) outcomes (ASA Monitor 2024;88:1-4). As you point out, this change in patient position is advantageous only if the correct system is utilized to maintain cerebral perfusion in an “uphill” position. Proper position is also critical for chest compression. Compression of the left ventricular outflow track (LVOT) is a common and underappreciated error, which can also adversely affect cerebral (and coronary) perfusion. Recent data have shown that transesophageal echocardiography (TEE) imaging is often helpful in guiding where to compress the chest (J Echocardiogr 2021;19:28-36; Resuscitation 2018;137:140-47; J Am Coll Cardiol 2020;76:745-54). Compression location is particularly important as clinicians rely more and more on automated chest compression devices, which can migrate across the chest over time.

There are multiple elegant demonstrations of TEE use to improve quality of CPR, both by changing the area of maximum compression and/or changing the depth of sternal movement. Changing the focus of chest compression so it is located sufficiently caudad to effect efficient ventricular emptying and filling rather than over the LVOT and aortic root has been possible with TEE guidance. Likewise, ME 4C views can help “eyeball” depth of sternal compression and recoil to suggest when more (or better-directed) force is needed. Not unexpectedly, suboptimal CPR performance as judged by TEE is associated with poor resuscitation outcomes (Resuscitation 2020;154:31-7). This guidance solely relates to the role of TEE in improving CPR quality and does not include other ways TEE may be helpful in OHCA management (Resuscitation 2018;137:140-7; J Am Coll Cardiol 2020;76:745-54; Resuscitation 2020;154:31-7).

The goal of CPR is to restart the heart and preserve the brain, and position matters when treating intraoperative arrest. While uncommon, intraoperative arrest is associated with a >50% mortality (Eur J Anaesthesiol 2023;40:724-36). Both a change in patient position and TEE-guided chest compressions potentially can increase cerebral perfusion and reduce mortality. But there is “no free lunch.” Both incorrect use of “head up CPR” and TEE can also reduce cerebral perfusion when there are lengthy interruptions during device placement, TEE probe insertion, or when trying to obtain a clearer TEE image with ongoing compressions.

Uninterrupted, well-performed CPR is best practice. Pauses of >10 seconds during CPR for “head up CPR,” TEE insertion or imaging, endotracheal intubation, or even for pulse check can reduce cerebral and coronary perfusion and therefore are dangerous (Ann Emerg Med 2019;73:610-16). These challenges can all be anticipated and overcome when core physiological principles underlying CPR are understood and followed and all OR personnel know their respective roles in a code. New positioning tools and methodologies that complement manual compressions – including those used to optimize the position of the head and thorax during CPR, to enhance circulation, and to guide optimal chest compression location – can help in the heat of battle to optimize patient care and the likelihood of a positive outcome (Crit Care Med 2024;52:170-81).

Barry Swerdlow, MD, FASA