The association of arterial blood pressure waveform-derived area duty cycle with intra-arrest hemodynamics and cardiac arrest outcomes

Abstract

Aim: Develop a novel, physiology-based measurement of duty cycle (Arterial Blood Pressure-Area Duty Cycle [ABP-ADC]) and evaluate the association of ABP-ADC with intra-arrest hemodynamics and patient outcomes.

Methods: This was a secondary retrospective study of prospectively collected data from the ICU-RESUS trial (NCT02837497). Invasive arterial waveform data were used to derive ABP-ADC. The primary exposure was ABP-ADC group (<30%; 30-35%; >35%). The primary outcome was systolic blood pressure (sBP). Secondary outcomes included intra-arrest physiologic goals, CPR quality targets, and patient outcomes. In an exploratory analysis, adjusted splines and receiver operating characteristic (ROC) curves were used to determine an optimal ABP-ADC associated with improved hemodynamics and outcomes using a multivariable model.

Results: Of 1129 CPR events, 273 had evaluable arterial waveform data. Mean age is 2.9 years + 4.9 months. Mean ABP-ADC was 32.5% + 5.0%. In univariable analysis, higher ABP-ADC was associated with lower sBP (p < 0.01) and failing to achieve sBP targets (p < 0.01). Other intra-arrest physiologic parameters, quality metrics, and patient outcomes were similar across ABP-ADC groups. Using spline/ROC analysis and clinical judgement, the optimal ABP-ADC cut point was set at 33%. On multivariable analysis, sBP was significantly higher (point estimate 13.18 mmHg, CI95 5.30-21.07, p < 0.01) among patients with ABP-ADC < 33%. Other intra-arrest physiologic and patient outcomes were similar.

Conclusions: In this multicenter cohort, a lower ABP-ADC was associated with higher sBPs during CPR. Although ABP-ADC was not associated with outcomes, further studies are needed to define the interactions between CPR mechanics and intra arrest patient physiology.

Keywords: Cardiac Arrest; Cardiopulmonary Resuscitation; Pediatrics.

Figure 1:. ABP-ADC Beat-to-beat Calculation.

For each chest compression cycle, $i$, the peak arterial blood pressure value, $p_i$, which takes place at the peak time $t_{p,i}$, corresponds to the systolic blood pressure. The start time for the compression cycle was similarly determined. The start time $t_{s,i}$ for compression $i$ was 60% between the peak time $t_{p,i}$ of compression cycle $i$ and the peak time of compression cycle $i-1,t_{p,i-1}$, as shown in Equation 1: Equation 1: $$t_{s,i}=t_{p,i-1}+0.6\mathrm{*}\left(t_{p,i}-t_{p,i-1}\right)$$ The arterial waveform for one compression cycle was bounded by the compression’s start point $t_{s,i}$ and peak $p_i$ and with the start time of the next compression $t_{s,i+1}$. The cycle height was $p_i-s_i$ and the width was $t_{s,i+1}-t_{s,i}$. With the rectangle generated by these coordinates, ABP-ADC was calculated by summing the area under the ABP waveform and dividing by the total rectangular area: $$AD{C}_i=\frac{\sum _{t_{s,i}}^{t_{s,i+1}} \mathrm{m}\mathrm{a}\mathrm{x}\left(\left(ABP\left(t\right)-s_i\right),0\right)\mathrm{\Delta }t}{\left(p_i-s_i\right)\mathrm{*}\left(t_{s,i+1}-t_{s,i}\right)}$$

Figure 2:

Distribution of Arterial Blood Pressure – Area Duty Cycle (ABP-ADC) for each CPR event