Predicting ROSC in out-of-hospital cardiac arrest using expiratory carbon dioxide concentration: Is trend-detection instead of absolute threshold values the key?

AIM

Guidelines recommend detecting return of spontaneous circulation (ROSC) by a rising concentration of carbon dioxide in the exhalation air. As CO₂ is influenced by numerous factors, no absolute cut-off values of CO₂ to detect ROSC are agreed on so far. As trends in CO₂ might be less affected by influencing factors, we investigated an approach which is based on detecting CO₂-trends in real-time.

METHODS

We conducted a retrospective case-control study on 169 CO₂ time series from out of hospital cardiac arrests resuscitated by Muenster City Ambulance-Service, Germany. A recently developed statistical method for real-time trend-detection (SCARM) was applied to each time series. For each series, the percentage of time points with detected positive and negative trends was determined.

RESULTS

ROSC time series had larger percentages of positive trends than No-ROSC time series (p=0.003). The median percentage of positive trends was 15% in the ROSC time series (IQR: 5% to 23%) and 7% in the No-ROSC time series (IQR: 3% to 14%). A receiver operating characteristic (ROC) analysis yielded an optimal threshold of 13% to differentiate between ROSC and No-ROSC cases with a specificity of 58.4% and sensitivity of 73.9%; the area under the curve was 63.5%.

CONCLUSION

Patients with ROSC differed from patients without ROSC as to the percentage of detected CO₂ trends, indicating the potential of our real-time trend-detection approach. Since the study was designed as a proof of principle and its calculated specificity and sensitivity are low, more research is required to implement CO₂-trend-detection into clinical use.

Senior citizens as rescuers: Is reduced knowledge the reason for omitted lay-resuscitation-attempts? Results from a representative survey with 2004 interviews

Objective

Resuscitation (CPR) provided by a bystander prior to the arrival of the emergency services is a beneficial factor for surviving a cardiac arrest (CA). Our registry-based data show, that older patients receive bystander-CPR less frequently. Little is known on possible reasons for this finding. We sought to investigate the hypothesis that awareness of CPR measures is lower in older laypersons being a possible reason for less CPR-attempts in senior citizens.

Methods

1206 datasets on bystander resuscitations actually carried out were analyzed for age-dependent differences. Subsequently, we investigated whether the knowledge required carrying out bystander-CPR and the self-confidence to do so differ between younger and older citizens using computer-assisted telephone interviewing. 2004 interviews were performed and statistically analyzed.

Results

A lower level of knowledge to carry out bystander-CPR was seen in older individuals. For example, 82.4% of interviewees under 65 years of age, knew the correct emergency number. In this group, 66.6% named CPR as the relevant procedure in CA. Among older individuals these responses were only given by 75.1% and 49.5% (V = 0.082; P < 0.001 and V = 0.0157; P < 0.001). Additionally, a difference concerning participants’ confidence in their own abilities was detectable. 58.0% of the persons younger than 65 years were confident that they would detect a CA in comparison to 44.6% of the participants older than 65 years (V = 0.120; P < 0.001). Similarly, 62.7% of the interviewees younger than 65 were certain to know what to do during CPR compared to 51.3% of the other group (V = 0.103; P < 0.001).

Conclusions

Lower levels of older bystanders' knowledge and self-confidence might provide an explanation for why older patients receive bystander-CPR less frequently. Further investigation is necessary to identify causal connections and optimum ways to empower bystander resuscitation.

Kids save lives: a six-year longitudinal study of schoolchildren learning cardiopulmonary resuscitation: Who should do the teaching and will the effects last?

AIMS

This prospective longitudinal study over 6 years compared schoolteachers and emergency physicians as resuscitation trainers for schoolchildren. It also investigated whether pupils who were trained annually for 3 years retain their resuscitation skills after the end of this study.

METHODS

A total of 261 pupils (fifth grade) at two German grammar schools received resuscitation training by trained teachers or by emergency physicians. The annual training events stopped after 3 years in one group and continued for 6 years in a second group. We measured knowledge about resuscitation (questionnaire), chest compression rate (min(-1)), chest compression depth (mm), ventilation rate (min(-1)), ventilation volume (mL), self-efficacy (questionnaire). Their performance was evaluated after 1, 3 and 6 years.

RESULTS

The training events increased the pupils' knowledge and practical skills. When trained by teachers, the pupils achieved better results for knowledge (92.86% ± 8.38 vs. 90.10% ± 8.63, P=0.04) and ventilation rate (4.84/min ± 4.05 vs. 3.76/min ± 2.37, P=0.04) than when they were trained by emergency physicians. There were no differences with regard to chest compression rate, depth, ventilation volume, or self-efficacy at the end of the study. Knowledge and skills after 6 years were equivalent in the group with 6 years training compared with 3 years training.

CONCLUSIONS

Trained teachers can provide adequate resuscitation training in schools. Health-care professionals are not mandatory for CPR training (easier for schools to implement resuscitation training). The final evaluation after 6 years showed that resuscitation skills are retained even when training is interrupted for 3 years.

Difficult intubation and outcome after out-of-hospital cardiac arrest: a registry-based analysis

Background

Airway management during resuscitation attempts is pivotal for treating hypoxia, and endotracheal intubation is the standard procedure. This German Resuscitation Registry analysis investigates the influence of airway management on primary outcomes after out-of-hospital cardiac arrest, in a physician-based emergency system.

Methods

A total of 8512 patients recorded in the German Resuscitation Registry (2007–2011) were analyzed. The Return of Spontaneous Circulation After Cardiac Arrest (RACA) score was used to compare observed return of spontaneous circulation (ROSC) rates with the ROSC predicted by the score and to analyze factors influencing the primary outcome. Patients were classified into three groups: difficult intubation, impossible intubation, and a control group with normal airways.

Results

The observed ROSC matched the predicted ROSC in the group with difficult airways. The impossible intubation group had lower ROSC rates (31.3 % vs. 40.5 %; P < 0.05). Impossible intubation was more frequent in men (OR 2.28; 95 % CI, 1.43–3.63; P = 0.001), young patients (OR 2.18; 95 % CI, 1.26–3.76; P = 0.005) and those with trauma (OR 2.22; 95 % CI, 1.01–4.85; P = 0.046). Fewer impossible intubations were reported when the emergency physicians were anesthesiologists (OR 0.65; 95 % CI, 0.44–0.96; P = 0.028). If a supraglottic airway device was not used in the impossible intubation group, the observed ROSC (18.0 %; 95 % CI, 7.4–28.6 %) was poorer than predicted (38.2 %) (P < 0.05).

Conclusions

Outcomes after resuscitation attempts are poorer when endotracheal intubation is not possible. Predictive factors for impossible intubation are male gender, younger age, and trauma. Supraglottic airway devices should be used at an early stage whenever these negative factors are present.

Electronic supplementary material

The online version of this article (doi:10.1186/s13049-015-0124-0) contains supplementary material, which is available to authorized users.

[Teaching resuscitation in schools: "The earlier, the better...."]

Sudden cardiac arrest is a major contributor to avoidable deaths in Europe. Immediate start of basic life support (BLS) by laypersons is among the most successful strategies in the treatment of cardiac arrest patients. Despite the fact that more than half of all cardiac arrests in Germany are witnessed by a bystander, only in one fifth of all arrests layperson resuscitation is initiated. One strategy to enhance bystander BLS is to establish cardiac resuscitation tuition in schools. BLS instructions for pupils have been proven to be successfully implemented independent from children's age or physical ability. Although an age-adjusted curriculum seems reasonable even usage of automatic external defibrillators (AED) can be taught effectually. The earlier in the life of a student BLS-instruction begins, the more successful the training is. However a national German curriculum for BLS-training in schools has yet to be established in Germany.

Teaching resuscitation in schools: annual tuition by trained teachers is effective starting at age 10. A four-year prospective cohort study

AIMS

Evaluation of school pupils' resuscitation performance after different types of training relative to the effects of training frequency (annually vs. biannually), starting age (10 vs. 13 years) and facilitator (emergency physician vs. teacher).

METHODS

Prospective longitudinal study investigating 433 pupils in training and control groups. Outcome criteria were chest compression depth, compression frequency, ventilation volume, ventilation frequency, self-image and theoretical knowledge. In the training groups, 251 pupils received training annually or biannually either from emergency physicians or CPR-trained teachers. The control group without any training consisted of 182 pupils.

RESULTS

Improvements in training vs. control groups were observed in chest compression depth (38 vs. 24 mm), compression frequency (74 vs. 42 min(-1)), ventilation volume (734 ml vs. 21 ml) and ventilation frequency (9/min vs. 0/min). Numbers of correct answers in a written test improved by 20%, vs. 5% in the control group. Pupils starting at age 10 showed practical skills equivalent to those starting at age 13. Theoretical knowledge was better in older pupils. Self-confidence grew in the training groups. Neither more frequent training nor training by emergency physicians led to better performance among the pupils.

CONCLUSIONS

Pupils starting at age 10 are able to learn cardiopulmonary resuscitation with one annual training course only. After a 60-min CPR-training update, teachers are able to provide courses successfully. Early training reduces anxieties about making mistakes and markedly increases participants' willingness to help. Courses almost doubled the confidence of pupils that what they had learned would enable them to save lives.

[Do sociodemographic factors influence emergency medical missions? : analysis in the City of Münster]

BACKGROUND

Demographic development and changes in healthcare utilization have led to a rising number of calls for emergency services. In Germany life-threatening situations are responded by physician-staffed ambulances in a 2-tier system whereas paramedic-staffed ambulances are dispatched in non-life-threatening emergencies. A nationwide protocol guides dispatchers in triage decisions. In the years 1999 to 2009 a continuous rise in the number of calls for a physician-staffed ambulance in Münster was recorded. The degree of healthcare utilization according to socioeconomic status and age structure was retrospectively examined.

METHODS

For the year 2006 all emergency calls in the City of Münster responded to by physician-staffed ambulances were analyzed. Each call was assigned to 1 of the 45 urban districts. The local incidence of emergency calls (calls/100 residents/year) was determined and compared to the socioeconomic status which was defined as the percentage of welfare and unemployment benefit recipients per district. Patient condition was assessed by the Munich National Advisory Committee for Aeronautics (M-NACA) score. This scoring system allows calls to be allocated to either life-threatening conditions or non-life-threatening conditions by objective vital parameters. The age structure of the emergency callers was also examined.

RESULTS

Urban districts with a low socioeconomic status showed a higher incidence of emergency calls requiring physician-staffed ambulance responses than districts with a high socioeconomic status. Measured by the M-NACA scoring system, the fraction of life-threatening emergencies among all calls proved to be equal to districts with a high socioeconomic status. A correlation between elderly patients and increasing numbers of life-threatening emergencies was found.

CONCLUSIONS

A low socioeconomic status of an urban district will result in more ambulance responses. However, the proportion of life-threatening emergencies is equal to districts with a high socioeconomic status. Thus, the greater need for physician-staffed ambulance responses matches clinical needs and legitimates current resource use in a 2-tier ambulance system. Indications for the abuse of physician-staffed ambulances were not found. Considering an aging population the number of emergency calls will rise in the future.