Propensity scores - A brief introduction for resuscitation researchers

Mechanical chest compression and extracorporeal life support for out-of-hospital cardiac arrest. A 30-month observational study in the metropolitan area of Milan, Italy

BACKGROUND

Return of spontaneous circulation (ROSC) is achieved in 25% of out-of-hospital cardiac arrest (OHCA) patients. Mechanical chest compression (mechCPR) may maintain better perfusion during transport, allowing hospital treatments like extracorporeal circulation life support (ECLS). We aim to assess the effectiveness of a pre-hospital protocol introduction.

METHODS

Observational, retrospective study assessing all OHCA patients aged 12-75, with no-flow time <20 min in a metropolitan area (Milan, Italy, 2013-2016).

PRIMARY OUTCOMES

ROSC and Cerebral Performance Category score (CPC) ≤2 at hospital discharge. Logistic regressions with multiple comparison adjustments balanced with propensity scores calculated with inverse probability of treatment weighting were performed.

RESULTS

1366 OHCA were analysed; 305 received mechCPR, 1061 manual chest compressions (manCPR), and 108 ECLS. ROSC and CPC ≤2 were associated with low-flow minutes (odds ratio [95% confidence interval] 0.90 [0.88-0.91] and 0.90 [0.87-0.93]), shockable rhythm (2.52 [1.71-3.72] and 10.68 [5.63-20.28]), defibrillations number (1.15 [1.07-1.23] and 1.15 [1.04-1.26]), and mechCPR (1.86 [1.17-2.96] and 2.06 [1.11-3.81]). With resuscitation times >13 min, mechCPR achieved more frequently ROSC compared to manCPR. Among ECLS patients, 70% had time exceeding protocol: 8 (7.5%) had CPC ≤2 (half of them with low-flow times between 45 and 90 min), 2 (1.9%) survived with severe neurological disabilities, and 13 brain-dead (12.0%) became organ donors.

CONCLUSIONS

MechCPR patients achieved ROSC more frequently than manual CPR patients; mechCPR was a crucial factor in an ECLS protocol for refractory OHCA. ECLS offered a chance of survival to patients who would otherwise die.

Long-Term Outcomes of Percutaneous Coronary Intervention for Patients With In-Stent Chronic Total Occlusion Versus De Novo Chronic Total Occlusion

Limited data are available on long-term outcomes and health status in the treatment of in-stent coronary chronic total occlusion (IS-CTO) and de novo coronary chronic total occlusion (de novo CTO). This study compared the long-term clinical outcomes and health status of percutaneous coronary intervention (PCI) for patients with IS-CTO versus patients with de novo CTO in the drug-eluting stent era. We screened 483 consecutive patients with 1 CTO lesion, including 81 patients with IS-CTO and 402 patients with de novo CTO. Propensity score matching was used to balance baseline characteristics between the 2 groups. The clinical end point was major adverse cardiac events (MACE). The success rates of CTO lesion revascularization were similar in both groups. In the propensity score-matched patients, after a median follow-up of 36 months, MACE was observed in 32.8% of patients with IS-CTO versus 13.5% of the patients with de novo CTO (P < .001), mainly driven by target-vessel revascularization (21.9% vs 6.7%; P < .01). Moreover, patients with IS-CTO had significantly worse Seattle Angina Questionnaire anginal stability scores than the patients with de novo CTO. In conclusion, patients with IS-CTO after PCI had a worse clinical outcome, mainly MACE, and a poorer anginal stability in the long term than patients with de novo CTO.

Lidocaine versus amiodarone for pediatric in-hospital cardiac arrest: An observational study

BACKGROUND

Lidocaine and amiodarone are both included in the pediatric cardiac arrest guidelines as treatments of shock-refractory ventricular fibrillation or pulseless ventricular tachycardia, although there is limited evidence to support this recommendation.

METHODS

In this cohort study from the Get With The Guidelines - Resuscitation registry, we included pediatric patients (≤18 years) with an in-hospital cardiac arrest between 2000 and 2018, who presented with an initial or subsequent shockable rhythm (ventricular fibrillation and pulseless ventricular tachycardia). Patients receiving amiodarone were matched to patients receiving lidocaine based on a propensity score, calculated from multiple patient, event, and hospital characteristics.

RESULTS

A total of 365 patients were available for the analysis, of which 180 (49%) patients were matched on the propensity score. The median age in the raw cohort was 6 (quartiles, 0.5-14) years, 164 (45%) patients were female, and 238 (65%) patients received an antiarrhythmic for an initial shockable rhythm. In the matched cohort, there were no statistically significant differences between patients receiving lidocaine compared to amiodarone in return of spontaneous circulation (RR, 0.99 [95%CI, 0.82-1.19]; p = 0.88), survival to 24 h (RR, 1.02 [95%CI, 0.76-1.38]; p = 0.88), survival to hospital discharge (RR, 1.01 [95%CI, 0.63-1.63]; p = 0.96), and favorable neurological outcome (RR, 0.65 [95%CI, 0.35-1.21]; p = 0.17). The results remained consistent in multiple sensitivity analyses.

CONCLUSIONS

In children with cardiac arrest receiving antiarrhythmics for a shockable rhythm, there was no significant difference in clinical outcomes between those receiving lidocaine compared to amiodarone.

The role of adrenaline in cardiopulmonary resuscitation

Adrenaline has been used in the treatment of cardiac arrest for many years. It increases the likelihood of return of spontaneous circulation (ROSC), but some studies have shown that it impairs cerebral microcirculatory flow. It is possible that better short-term survival comes at the cost of worse long-term outcomes. This narrative review summarises the rationale for using adrenaline, significant studies to date, and ongoing research.