CPR Techniques and Process

Heart Rate to Initiate Chest Compressions

Last Full Review: ILCOR 2023

Profound bradycardia in newborns is typically due to hypoxia rather than a cardiac issue or compromise (Solevåg et al. 2016, F272). Thus, effective ventilation is paramount in newborns with bradycardia. Neonatal resuscitation algorithms include starting chest compressions when the heart rate remains less than 60 beats per minute, despite providing effective ventilation (via endotracheal tube, if possible) (Perlman et al. 2015, S204). What evidence supports the cut-off heart rate of less than 60 beats per minute, and is there evidence that compressions should be initiated at a different heart rate?

 

Evidence Summary

A scoping review by the International Liaison Committee on Resuscitation (ILCOR) (Ramachandran et al. 2023a, 442; Ramachandran et al. 2023b) sought evidence for neonates being resuscitated with ventilation and who have a slow heart to determine if chest compressions should be initiated at a heart rate other than less than 60 beats per minute. The evidence for the cut off number of under 60 beats per minute has not previously been evaluated by ILCOR. Outcomes of interest included survival rates, neurologic outcomes and time to return of spontaneous circulation. No studies were identified comparing different heart rate thresholds for initiation of chest compressions in newborns in the delivery room. Data from a fetal lamb study (Agrawal et al. 2019, 119) showed significantly lower peak systolic carotid flows for heart rates of less than 60 beats per minute compared to baseline. The scoping review concludes that there is insufficient information to alter current recommendations for starting compressions when the heart rate is less than 60 beats per minute after successful inflation of the lungs (Ramachandran et al. 2023a, 442; Ramachandran et al. 2023b).

Insights and Implications

The heart rate cut-off of less than 60 beats per minute was originally based on expert opinion. If bradycardia is present in a newborn, this is likely due to hypoxia, and efforts should be focused on improving ventilation and lung aeration. Indicators of effective ventilation in newborns include chest rise, audible air entry and a rising heart rate. In addition, the allowable length of time for providing effective ventilations before compressions is not well studied. A 2015 ILCOR Consensus on Science with Treatment Recommendations (Perlman et al. 2015, S204) notes that after birth, only about 60 seconds is allotted to determine heart rate and institute effective ventilation.

 

Neonatal Chest Compression Technique

Last Full Review: ILCOR 2023

The current Red Cross guidelines recommend the use of the two-thumb/encircling hands technique for providing chest compressions to infants. This recommendation was based on animal and manikin studies included in a systematic review (Millin et al. 2020, 161). Since then, additional studies evaluating this technique have been published, and new techniques for providing chest compressions to infants have been described.

 

Evidence Summary

A 2023 scoping review (Ramachandran et al. 2023b; Berg et al. 2023) by the International Liaison Committee on Resuscitation (ILCOR) sought evidence comparing the use of alternative techniques for providing cardiac compressions in neonates compared with the two-thumb/encircling hands technique. The scoping review identified 29 randomized crossover manikin studies, one observational and one randomized study, that compared various hand and finger positions. The data reported greater chest compression depth, less fatigue and a higher proportion of correct hand placement compared to the two-fingers technique (Ramachandran et al. 2023a, 442; Ramachandran et al. 2023b; Berg et al. 2023). A single randomized study in newborns compared two fingers versus two-thumb/encircling hands technique during cardiopulmonary resuscitation (CPR) in neonates of various gestational ages, reporting a significantly higher proportion of correct finger placement with the two-thumb/encircling hands technique (Saini et al. 2012, 690).

Alternative finger and/or hand position techniques—such as vertical two-thumb, knocking finger and flexed two-finger techniques—were identified in the scoping review. Data from these studies of newer techniques show similar performance compared with the two-thumb technique. The observational study in humans compared compressions with the two-thumb/encircling hands technique versus the one-hand technique, reporting a greater prevalence of inappropriately fast chest compression rate with the use of the one-hand technique (Ramachandran et al. 2023b). The scoping review concluded that there is insufficient information from the studies identified to consider altering existing recommendations or to prompt a systematic review. The current ILCOR treatment recommendation from 2015 (Perlman et al. 2015, S204) suggests that chest compressions in the newborn infant should be performed by the two-thumb/encircling hands technique as the preferred option. Data from the studies identified by the 2023 scoping review is considered insufficient to alter the existing recommendation for use of the two-thumb/encircling hands technique.

Insights and Implications

The Red Cross guidelines are informed by the 2015 ILCOR Consensus on Science with Treatment Recommendations (Perlman et al. 2015, S204; Wyllie et al. 2015, e169) of neonatal infant compression techniques. Several knowledge gaps were identified by this scoping review (Ramachandran et al. 2023b). Most importantly, almost all studies to date have been performed in manikins and provide information about CPR performance; there are no studies comparing compression techniques in newborns and reporting clinical outcomes. Because newer chest compression techniques were shown in the scoping review to result in similar performance measures when compared with the two-thumb/encircling hands technique, the recommended technique for neonatal chest compressions remains the two thumb/encircling hands method.

 

Compression-to-Ventilation Ratio for Neonatal CPR

Last Full Review: ILCOR 2023

A 3:1 compression-to-ventilation (CV) ratio has been recommended by the International Liaison Committee on Resuscitation (ILCOR) (Perlman et al. 2015, S204; Wyllie et al. 2015, e169) during neonatal chest compressions. This recommendation was based on animal and manikin studies and was last reaffirmed in 2020 (Wyckoff et al. 2020, S185). New studies have prompted a scoping review on this topic.

 

Evidence Summary

A 2023 scoping review (Ramachandran et al. 2023a, 442; Ramachandran et al. 2023b; Berg et al. 2023) by ILCOR sought evidence for use of any other CV ratio (5:1, 9:3, 15:2, synchronous) compared with the standard 3:1 CV ratio in neonates receiving cardiac chest compressions. The scoping review identified seven manikin studies, 15 animal studies and one clinical study evaluating different CV ratios, continuous compressions with asynchronous ventilation or continuous compressions with sustained inflations.

Mixed results were reported; however, studies of other CV ratios, such as 2:1, 4:1 or 9:3, did not report improved time to return of spontaneous circulation (ROSC) or survival (Ramachandran et al. 2023a, 442; Ramachandran et al. 2023b; Berg et al. 2023). The one human study, a pilot randomized trial with nine preterm infants born at less than 33 weeks’ gestation, reported faster time-to-ROSC with chest compressions plus repeated sustained inflations of 20 seconds per sustained inflation, compared with 3:1 CV cardiopulmonary resuscitation (CPR). A CV ratio of 3:1 was rated as more difficult than alternative CV ratios in one manikin study (Srikantan et al. 2005, 293).

Several manikin studies reported increased fatigue during continuous chest compressions with asynchronous ventilations compared with 3:1 CV ratio CPR. One animal study reported improved carotid blood blow and cerebral oxygen delivery with continuous chest compressions with asynchronous ventilation compared to 3:1 CV ratio CPR (Vali et al. 2021, 752). Another animal study showed significant improvement in time-to-ROSC and survival with continuous chest compressions with asynchronous ventilation compared to 3:1 CV ratio CPR (Aggelina et al. 2021, 60). However, several other animal studies did not find a difference in time-to-ROSC and survival.

Three animal studies with newborn piglet models reported that providing cardiac compressions with repeated 20 second sustained inflations led to faster time-to-ROSC, although results for survival were not consistent. In addition, a study using a transitional lamb model did not show faster time-to- ROSC (Ramachandran et al. 2023a, 442; Ramachandran et al. 2023b; Berg et al. 2023).

The scoping review concludes that evidence from the identified studies is insufficient to alter existing recommendations from 2015 (Perlman et al. 2015, S204; Wyllie et al. 2015, e169), which suggest the use of a coordinated 3:1 CV ratio for neonatal CPR.

Insights and Implications

The Red Cross guidelines are informed by the 2015 ILCOR Consensus on Science with Treatment Recommendations (Perlman et al. 2015, S204; Wyllie et al. 2015, e169). As with other aspects of chest compression in neonates, evidence from human studies is lacking and clinical trials are needed.

 

Feedback Devices During CPR of Newborn Infants

Last Full Review: ILCOR 2023

A 2015 International Liaison Committee on Resuscitation (ILCOR) Consensus on Science with Treatment Recommendations (Perlman et al. 2015, S204; Wyllie et al. 2015, e169) suggested against the routine reliance on any single feedback device, such as end-tidal carbon dioxide (ETCO₂) monitors or pulse oximeters, in asystolic or bradycardic neonates for the detection of the return of spontaneous circulation (ROSC) until more evidence becomes available. A scoping review (Solevåg et al. 2022, F272; Ramachandran et al. 2023a, 442; Berg et al. 2023) was recently completed by ILCOR to determine if there is sufficient new evidence to warrant a systematic review.

 

Evidence Summary

A 2023 scoping review (Ramachandran et al. 2023a, 442; Ramachandran et al. 2023b; Berg et al. 2023) by ILCOR sought evidence for the use of feedback devices in neonates receiving cardiac compressions compared with clinical assessments of compression efficacy. Outcomes of interest included decreased hands-off time or time-to-ROSC, improved perfusion and increased survival rates.

A total of 18 studies of chest compression feedback devices were identified (Ramachandran et al. 2023, 442; Ramachandran et al. 2023b; Berg et al. 2023). Twelve were manikin studies, four were animal studies and two were clinical (infant) studies. Categories of devices studied included auditory and visual feedback devices (i.e., visual versus metronome auditory device, custom designed real-time feedback software), visual feedback devices, auditory support devices, haptic devices (i.e., Smartwatch metronome with vibration), real-time physiologic feedback (ETCO₂) and blood pressure monitoring.

The use of an auditory-visual feedback device was reported in most manikin studies to improve chest compression depth, chest compression rate, duty cycle (fraction of chest compression time in an entire chest compression cycle) and percentage of correctly performed cycles. Use of a metronome in manikin studies was reported to result in more consistent chest compression rates, but without a difference in the average chest compression rate or applied force and pressure. Improvements in the proportion of optimal cardiac compression duration, rate and depth over time was reported with use of a smartwatch with haptic feedback. Popular music with a beat of 120 per minute significantly improved the number of chest compressions and ventilations delivered (Ramachandran et al. 2023a, 442; Ramachandran et al. 2023b; Berg et al. 2023).

Animal studies reported ETCO₂ to be highly sensitive and specific for determining ROSC, but in randomized studies there was no difference in time-to-ROSC or survival with cardiopulmonary resuscitation (CPR) with or without ETCO₂ guidance (Ramachandran et al. 2023a, 442; Ramachandran et al. 2023b).

In a human study (Maher et al. 2009, 662) of compression depth in six infants between 2 week’s and 7 months of age in cardiac arrest after cardiac surgery, physiological feedback from blood pressure was used to guide chest compression depth, with an increase in chest compression depth to one-half of the anterior-posterior chest diameter if a systolic blood pressure of 60 mmHg to 90 mmHg was not met. The use of blood pressure-guided CPR was found to increase systolic, mean arterial and pulse pressures compared with continuing with the use of one-third of the anterior-posterior diameter for compressions.

A retrospective review (Stine et al. 2019, e01871) in 49 newborns evaluated feedback using capnography values during CPR, with the finding that ETCO₂ between 17 mmHg and 18 mmHg correlated with the highest sensitivity and specificity for heart rate to have recovered to greater than 60 beats per minute.

The ILCOR scoping review concludes that with the paucity of clinical data, a systematic review is not warranted, and the treatment recommendation remains unchanged. While there are many new studies of feedback devices and techniques, most are manikin studies and the development of new recommendations for clinical practice are not yet justified (Ramachandran et al. 2023a, 442; Ramachandran et al. 2023b; Berg et al. 2023).

Insights and Implications

There is an urgent need for well-designed clinical studies addressing multiple aspects of the delivery of chest compressions in infants, including the use of feedback devices such as ETCO₂ monitors.