A new variant position of head-up CPR may be associated with improvement in the measurements of cranial near-infrared spectroscopy suggestive of an increase in cerebral blood flow in non-traumatic out-of-hospital cardiac arrest patients: A prospective interventional pilot study

Abstract

Aim of the study

This study aimed to investigate the effect of the head-up position implemented during cardiopulmonary resuscitation (CPR) on cerebral blood flow (CBF) using near-infrared spectroscopy in out-of-hospital cardiac arrest patients.

Methods

Baseline characteristics (age, sex, cerebral performance category before cardiac arrest, witnessed cardiac arrest, bystander CPR, first monitored rhythm, no-flow time, prehospital low-flow time, CPR duration in the emergency department (ED), and reason for stopping CPR in the ED) were recorded. The changes of CBF were derived from the optical oscillation waveform measured by near-infrared spectroscopy in adult patients with out-of-hospital cardiac arrest by alternating head-up and supine positions at 4-minute intervals while performing CPR. The CBF velocity according to the head position was also evaluated using the time derivative of the oscillation waveform.

Results

During the study period, 28 patients were enrolled. The median increase in CBF in the prefrontal area in the head-up position was 14.6% (Interquartile range, 8.8–65.0), more than that in the supine position. An increase in CBF was observed in the head-up position compared with the supine position in 83.3% of the patients included in the analysis.

Conclusion

CBF increased when the head-up position was used during CPR in non-traumatic out-of-hospital cardiac arrest patients.

Introduction

Out-of-hospital cardiac arrest (OHCA) is a major public health challenge worldwide, with an average global incidence of 55 OHCA per 100,000 person-years in adults.¹ According to a study by Yan et al.², 29.7% of patients with cardiac arrest worldwide had a return of spontaneous circulation (ROSC), and 22% were admitted to the hospital. Cardiac arrest patients, even those that survive, rarely have a good neurological outcome.

The neurological outcome in cardiac arrest patients is affected by the severity of hypoxic-ischaemic brain injury caused by a decrease in cerebral blood flow (CBF). Therefore, recovery of CBF is crucial for good neurological outcomes in patients3., 4., 5. Consequently, there have been several studies on ways to elevate CBF in patients from the time of cardiopulmonary resuscitation (CPR) using devices such as active chest compression-decompression (ACD) or impedance threshold device (ITD)6., 7..

Head-up CPR was recently proposed as a method to increase CBF. In a study using a porcine model, intracranial pressure (ICP) was low, and CBF and cerebral perfusion pressure (CePP) increased when performing head-up during CPR,⁸ and the same results were shown in a study using a human cadaver.⁹ However, existing studies are limited in that they are animal or cadaver experiments, as it is difficult to measure CBF in real-time while performing CPR in OHCA patients.

The direct measurement of intracranial pressure and cerebral perfusion pressure requires an invasive procedure, however, it is technically and ethically difficult to perform this procedure during CPR. Near-infrared spectroscopy (NIRS) is a device that measures oxy/deoxy-haemoglobin in a specific part of the brain, and several studies have shown that this measurement value is closely related to CBF.10., 11. Moreover, a previous study reported that by using NIRS, the quality of chest compression and the change in CBF produced by chest compression could be estimated during CPR.¹² Therefore, we sought to investigate the head-up position (HUP) effect on CBF during CPR using NIRS.