Conflict of Interest Declaration
The ILCOR Continuous Evidence Evaluation process is guided by a rigorous ILCOR Conflict of Interest policy. The following Task Force members and other authors were recused from the discussion as they declared a conflict of interest: none applicable.
The following Task Force members and other authors declared an intellectual conflict of interest and this was acknowledged and managed by the Task Force Chairs and Conflict of Interest committees: none applicable.
Task Force Synthesis Citation
Considine J, Couper K, Greif R, Ong GYK, Smyth MA, Ng KC, Kidd T, Olasveengen TM, Bray J on behalf of the International Liaison Committee on Resuscitation (ILCOR) Basic Life Support (BLS), Advanced Life Support (ALS), the Paediatric Life Support, and the Education, Implementation and Team (EIT) Task Forces. Cardiopulmonary Resuscitation in Obese Patients Task Force Synthesis of a Scoping Review [Internet] Brussels, Belgium: International Liaison Committee on Resuscitation (ILCOR) Advanced Life Support Task Force, 2024 October 2. Available from: http://ilcor.org
Methodological Preamble and Link to Published Scoping Review
The continuous evidence evaluation process started with a scoping review of cardiopulmonary resuscitation in obese patients conducted by the ILCOR Basic Life Support (BLS), Advanced Life Support (ALS), the Paediatric Life Support, and the Education, Implementation and Team (EIT) Task Forces. Evidence for adult and pediatric literature was sought and considered by the Task Forces.
Scoping Review
Considine J, Couper K. Greif R, Ong GY-K, Smyth MA, Ng KC, Kidd T, Olasveengen TM, Bray J on behalf of the International Liaison Committee on Resuscitation (ILCOR) Basic Life Support (BLS), Advanced Life Support (ALS), Paediatric Life Support, and Education, Implementation and Team (EIT) Task Forces. Cardiopulmonary resuscitation in obese patients: a scoping review. [insert publication details once published]
PICOST
The PICOST (Population, Intervention, Comparator, Outcome, Study Designs and Timeframe)
Population: Adults and children in any setting (in-hospital or out-of-hospital) with cardiac arrest in any setting
Intervention: Cardiopulmonary resuscitation (including mechanical and e-CPR) in obese patients (as defined in specific papers).
Comparators: May have no comparator, comparator of non-obese patients, or compare modified CPR for obese patients with standard CPR.
Outcomes: Survival to hospital discharge with good neurological outcome and survival to hospital discharge were ranked as critical outcomes. Return of spontaneous circulation (ROSC), CPR quality measures (chest compression rate, chest compression depth, ventilation rate, tidal volume, end-tidal CO2), CPR timing (rime to commencement of rescue breaths, first compression, first defibrillation if shockable rhythm), CPR techniques (chest compressions, defibrillation, ventilation and airway management, vascular access & medications), health related quality of life and provider outcomes (safety, manual handling) were ranked as important outcomes.
Study Designs: Randomized controlled trials (RCTs) and non-randomized studies (non-randomized controlled trials, interrupted time series, controlled before-and-after studies, cohort studies) were eligible for inclusion. Case reports, animal and manikin studies were excluded, as were opinion pieces, conference abstracts, trial protocols and grey literature. All years and languages were included if there was an English abstract.
Timeframe: All years.
Literature search updated to 1 October 2024.
Search Strategies
Articles for review are obtained by searching PubMed, EMBASE, and Cochrane for all entries from database inception to 1 October 2024 (last searched on 1 October 2024). The search strategy was designed around the concepts of i) “Obesity” and ii) “Cardiac arrest” and “Cardiopulmonary Resuscitation” including their MESH terms, and Embase exploded terms.
Inclusion and Exclusion criteria
Included studies: i) studies of adults or children in cardiac arrest in any setting who were obese*; with or without a comparator of normal weight patients; and that reported one or more patient outcomes, CPR quality measures (chest compression rate, chest compression depth, ventilation rate, tidal volume, time to interventions) or CPR techniques (chest compressions, defibrillation, ventilation and airway management, vascular access). Randomized controlled trials (RCTs) and non-randomized studies (non-randomized controlled trials, interrupted time series, controlled before-and-after studies, cohort studies).
Excluded studies: case reports, animal studies, manikin studies, as pieces, conference abstracts, trial protocols and grey literature.
* At the time of this review, there was no universal definition of obesity so for the purposes of this scoping review, ‘obese’ was defined according to each individual study.
Data tables: BLS 2720 CPR in obese patients Data table
Task Force Insights
1. Why this topic was reviewed.
- This topic was chosen for review by the BLS; ALS; PLS; and Education, Implementation and Teams Task Forces because of the increasing prevalence of obesity worldwide and the specific challenges in providing cardiopulmonary resuscitation to this patient cohort.
- This topic has not previously been reviewed by ILCOR.
2. Narrative summary of evidence identified
In total, 7,739 citations were screened following removal of duplicates, 96 full text publications were screened for eligibility and 36 studies were included.1-25,27-37 Fourteen studies reported on OHCA,1,2,5,6,8,11,12,15,18-21,23,36 13 studies reported on IHCA,3,10,13,14,16,24,25,28-30,32-34 eight studies reported on both OHCA and IHCA,3,7,9,17,22,27,31,37 and in two studies, the cardiac arrest location was not reported.4,35 There were two studies of children23,29 and one study in which patient age was not reported.19 The most common outcomes reported were survival (n=29),2-20,22,24,26-31,33,36 neurological outcome (n=17)1,2,5,8,13,17-21,23,26,27,29,31,33,37 and ROSC (n=7).15,16,24,29,30,34,36
Neurological outcome
Both paediatric studies23,29reported worse neurological outcomes in obese children (compared with normal weight children) at hospital discharge29 and 12-months.23 Of the 15 adult studies reporting neurological outcomes, one showed no difference between obese and normal weight patients at 6-months,31 two studies reported obese patients were less likely to have favourable neurological outcome at 1-month,1,2 one study reported obese patients were more likely to have favourable neurological outcome at 1-month21 than normal weight patients. Of the adult studies of neurological outcome at hospital discharge, five studies reported no difference between obese and normal weight patients 5,8,13,17,20 and five studies reported obese patients had lower likelihood of favourable neurological outcomes than normal weight patients.18,19,27,33,37
Survival
There were five adult studies of short term survival: 7,11,15,24,36 one study11 reported obese patients had higher survival to ICU admission than normal weight patients, one study7 reported no difference in survival to ICU discharge and one study11reported obese patients had higher survival to ICU discharge than normal weight patients. One study36 reported no difference in survival to hospital admission, and one study15 reported obese patients had lower survival to hospital admission than normal weight patients. One study of survival to 24 hours reported no difference between obese and normal weight patients.24
Survival to hospital discharge was reported in 22 adult3-10,13-16,18-20,22,24,27,28,30,33,36 and one paediatric study.29 In children, survival to hospital discharge was less likely in obese children were than normal weight children.29 In adults, nine studies5-9,13,20,24,36 reported no difference in survival to hospital discharge between obese and normal weight adults, nine studies4,15,16,18,19,22,27,28,33 reported lower survival to hospital discharge in obese patients, and three studies3,10,14 reported higher survival to hospital discharge in obese patients. One study30 reported that obese patients had significantly higher survival to hospital discharge overall but subanalysis showed that survival to hospital discharge was lower in specific subgroups (age 60-69, Charlson comorbidity index 2-3 or greater than 8, and CPR on hospital days 0-3 or day 6).30
Of adult studies reporting survival from one to five years, two studies12,19 reported no difference in 4-year19 or 1-year12 survival between obese and normal weight patients, and one study5 reported obese patients were less likely than normal weight patients to be alive at 5 years. Two studies17,31) reported no difference in survival at 6-months between obese and normal weight patients, two studies2,12 reported obese patients had lower 30-day survival than normal weight patients and one study10 that treated BMI as a continuous variable reported that increasing BMI improved survival at 1 and 3 months.
ROSC
Seven studies reported ROSC.15,16,24,29,30,34,36 The sole paediatric study that reported on ROSC showed that obese children had significantly lower ROSC than normal weight children (IHCA).29 In adults, two studies24,36 reported no difference between obese and normal weight patients, two studies15,16 reported obese patients had significantly lower ROSC than normal weight patients, one study30 reported significantly higher ROSC in obese patients, and one study34 reported mixed results.
CPR quality or techniques
There was no difference in between obese and normal weight patients in ECMO complications,18 shock success,36 percentage of shocks delivered in less than 2 minutes,16,24 or VF/VT termination24 between obese and normal weight patients. One study of 21,237 IHCA at 328 hospitals,16 reported longer CPR duration in obese patients with VF/VT when ROSC was not achieved. When ROSC was achieved there was no difference in CPR duration between obese and normal weight patients.16 For PEA or asystolic arrests, CPR duration was longer in obese patients, irrespective of ROSC. 16 One study reported no significant relationship between BMI category and injuries sustained during CPR.35
3. Narrative Reporting of the task force discussions
The patient outcomes reported had conflicting results and differences in measurement. In adults there were variable results in neurological outcome, survival to hospital discharge, longer term survival (months to years), and ROSC. In children, there were two studies suggesting that obese children had worse neurological outcomes, lower survival and lower ROSC than normal weight children. The variability in results does not suggest an urgent need to deviate from standard CPR protocols, however there was some evidence that CPR duration may be longer in obese adults, which may have staffing and resource implications.
Knowledge Gaps
- There are few studies of CPR in obese infants, children and adolescents.
- A standardised definition of obese, or population specific definition of obese, for the purpose of resuscitation research is lacking.
- More robust adjustment for the many influences on CPR outcomes is needed if conclusions about the impact of obesity on CPR outcomes are to be used to shape clinical practice.
- Further research is needed on the effect of obesity on CPR techniques (such as chest compressions, airway management ventilation, defibillation), CPR quality, and time to, and delivery of, resuscitation interventions (such as vascular access and medications, use of mechanical CPR devices or ECMO) in both adults and children.
- Further research is needed to determine whether the degree of obesity influences CPR performance, outcomes following CPR including health-related quality of life, or inclusion in CPR research.
- Finally, studies of CPR in obese patients with a focus on provider outcomes (physical exertion, manual handling, fatigue) are urgently needed given the global prevalence of obesity.
- Standard CPR protocols should be used in obese patients.
Good Practice Statement:
Standard CPR protocols should be used in obese patients.
References
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