Does stress influence the performance of cardiopulmonary resuscitation? A narrative review of the literature

Cardiopulmonary resuscitation represents a major physical and psychological challenge for all involved health care workers because survival of the patients is closely related to the timely and accurate actions of rescuers. Consequently, rescuers may experience high levels of acute mental stress. Stress, in turn, may influence attentional resources and distractibility, which may affect the quality of resuscitation. This narrative review summarizes the current state of research concerning the influence of stress on resuscitation performance. Peer-reviewed studies retrieved in scientific databases were eligible. We found that rescuers experience high levels of stress and some associations of higher levels of stress with lower resuscitation performance. Finally, few interventional studies assessed whether interventions aiming at reducing levels of stress may have a beneficial effect on resuscitation performance, but results are variable. Although the mechanisms linking stress to performance of emergency teams are still not fully understood, factors such as individual experience and self-confidence of rescuers, gender composition and hierarchy within resuscitation teams may play an important role. This review provides a targeted overview of how stress can be defined and measured, how it may influence emergency situations such as a cardiopulmonary resuscitation, and which interventions have the potential to reduce overwhelming stress.     

Procedural experience with out-of-hospital endotracheal intubation

OBJECTIVE: Out-of-hospital rescuers likely need regular clinical experience to perform endotracheal intubation (ETI) in a safe and effective manner. We sought to determine the frequency of ETI performed by individual out-of-hospital rescuers. DESIGN: Analysis of an administrative database of all emergency medical services (EMS) patient care reports in Pennsylvania. SETTING: Commonwealth of Pennsylvania from January 1 to December 31, 2003. SUBJECTS: EMS advanced life support rescuers (paramedics, prehospital nurses, and EMS physicians) who reported at least one patient contact during the study period. INTERVENTIONS: None. MEASUREMENTS: We calculated individual rescuer ETI frequency and opportunity. We evaluated relationships between ETI frequency and the number of patient contacts. We also examined the relationship with practice setting (air medical vs. ground rescuers and urban vs. rural rescuers). MAIN RESULTS: In 1,544,791 patient care reports, 11,484 ETIs were reported by 5,245 out-of-hospital rescuers. The median ETI frequency was one (interquartile range, 0-3; range, 0-23). Of 5,245 rescuers, >67% (3,551) performed two or fewer ETIs, and >39% (2,054) rescuers did not perform any ETIs. The median number of ETI opportunities was three (interquartile range, 0-6; range, 0-76). ETI frequency was associated with patient volume (Spearman's rho = 0.67) and was higher for air medical (p = .006) and urban (p < .0001) rescuers. ETI frequency was not associated with response (Spearman's rho = -0.01) or transport (Spearman's rho = -0.06) times. CONCLUSIONS: Out-of-hospital ETI, an important and difficult resuscitation intervention, is an uncommon event for most rescuers.     

Evaluation of M-AID, a first aid application for mobile phones

BACKGROUND: When performed effectively, cardiopulmonary resuscitation (CPR) by bystanders reduces mortality due to sudden cardiac arrest. Telemedicine applications offer a means by which bystanders can get specific instructions for handling the emergency situation. M-AID, a first aid application for mobile phones, uses an intelligent algorithm of 'yes' or 'no' questions to judge the ongoing situation and give the user detailed instructions. The aim of this study was to evaluate the benefit of this mobile phone application in a scenario of sudden cardiac arrest. METHODS: One hundred and nineteen volunteers were assigned at random either to the test or the control group. All participants were confronted with the same scenario of acute coronary syndrome leading to cardiac arrest. The participants were either equipped with a mobile phone running the software (test group) or had to handle the situation without support (control group). The participants received a certain amount of credits for each action taken according to a pre-defined protocol and these credits were added to a score and compared between the groups. Participants were divided into subgroups according to their medical and technical experience. RESULTS: The test group generally achieved a slightly higher average score that was not statistically significant (21.11 versus 19.97; p=0.302). In contrast, the performance of the individuals in the control group was significantly faster (2.41 min versus 4.24 min; p<0.001). Use of the mobile phone software did not enhance the chance of survival. Subgroup analysis showed that experienced mobile phone users performed significantly better than non-experienced individuals, but not as well as participants with advanced first aid knowledge. CONCLUSIONS: Experience in the use of mobile phones is a prerequisite for the efficient use of the tested M-AID version. This application cannot replace skills acquisition by practical training. In a subgroup with experience in mobile phone use and basic knowledge in CPR, the device improved performance of CPR.     

TO SEE OR NOT TO SEE-Better dispatcher-assisted CPR with video-calls? A qualitative study based on simulated trials

BACKGROUND: Video communication through mobile telephone is now available in many parts of the world. We ask how mobile phone video-calls compares with traditional phone calls for dispatcher-assisted cardiopulmonary resuscitation (T-CPR). METHODS: Primary data was collected through individual interviews with six dispatchers after their participation in simulated cardiac arrest. They had 10 scenarios each, during which they guided rescuers on resuscitation. During half of the scenarios they used video-calls, and traditional phone calls for the rest. Concepts from modern systems theory were used to analyse the material. RESULTS: Video-calls influenced the information basis and understanding of the dispatchers. The dispatchers experienced that (1) video-calls are useful for obtaining information and provides adequate functionality to support CPR assistance; (2) their CPR assistance becomes easier; (3) the CPR might be of better quality; but (4) there is a risk of "noise". DISCUSSION: We emphasize visual observation as a way of constructing professional understanding when using video-calls, which may provide a new basis for dispatcher assistance. Video-calls may improve rescuer compliance. The role and content of telephone-directed protocols used by dispatchers may need adjustments when video-calls are used for medical emergencies. CONCLUSION: Video communication can improve the dispatchers' understanding of the rescuer's situation, and the assistance they provide.     

Emergency medical services for treatment of mass casualties

The French emergency medical system (EMS) is the Service d'Aide Médicale Urgente (SAMU). In case of mass casualties, involving 100 simultaneous victims, SAMU has developed a disaster plan, "The White Plan." This plan is closely correlated to the Red Plan of the Fire Department, to provide advanced life support (ALS) at the incident site, followed in a continuum by medical transport and hospitalization in the appropriate services. To obtain the best chance of survival and recovery, there must be optimal coordination among all rescuers. This objective was approached by adopting a formal protocol designed for each city. In France, the medical organization for the treatment of casualties is operated by anesthesiologists who are qualified to perform ALS, preanesthetic evaluation en route, anesthesia for the multitrauma patient, and postanesthetic resuscitation in a continuum from the accident scene to the ICU.     

PQRST – A unique aide-memoire for capnography interpretation during cardiac arrest

The use of capnography is recommended during resuscitation. By implementing the mnemonic “PQRST”, rescuers have a ready-made checklist to help them achieve the full potential of capnography. This approach can facilitate efforts to both reduce the hands-off time and individualize the treatment, which can lead to improved survival for our patients.     

Could the survival and outcome benefit of adrenaline also be dependent upon the presence of gasping upon arrival of emergency rescuers?

A recent systematic review and meta-analysis of randomized controlled trials of adrenaline use during resuscitation of out-of-hospital cardiac arrest found no benefit of adrenaline in survival to discharge or neurological outcomes. It did, however, find an advantage of standard dose adrenaline (SDA) over placebo and high dose adrenaline over SDA in overall survival to admission and return of spontaneous circulation (ROSC), which was also consistent with previous reviews. As a result, the question that remains is "Why is there no difference in the rate of survival to discharge when there are increased rates of ROSC and survival to admission in patients who receive adrenaline?" It was suggested that the lack of efficacy and effectiveness of adrenaline may be confounded by the quality of cardiopulmonary resuscitation (CPR) during cardiac arrest, which has been demonstrated in animal models. CPR quality was not measured or reported in the included randomized controlled trials. However, the survival and outcome benefit of adrenaline may also depend upon the presence of witnessed gasping and/or gasping upon arrival of emergency rescuers, which is a critical factor not accounted for in the analyses of the cited animal studies that allowed gasping but showed the survival and neurological outcome benefits of adrenaline use. Moreover, without the aid of gasping, very few rescuers can provide high-quality CPR. Also, age and the absence of gasping observed by bystanders and/or upon arrival of emergency- rescuers may be important factors in the determination of whether vasopressin instead of adrenaline should be used first.     

两种消毒方法对医务人员移动电话机表面的消毒效果

目的观察两种消毒方法对医务人员移动电话机的消毒效果。方法通过现场采样和细菌检测方法,对某医院医务人员移动电话机进行细菌污染调查和消毒效果评价。结果该医院医务人员移动电话机细菌污染率达到94%。采用75%乙醇消毒液擦拭消毒后,其消毒效果合格率为98%;用含乙醇的复方皮肤消毒液擦拭消毒后,消毒效果合格率达到100%。结论医护人员使用中的移动电话机污染严重,用75%乙醇及其复方皮肤消毒液擦拭消毒可取得满意消毒效果。     

The use of a cardiac output monitor to guide the initial fluid resuscitation in a patient with burns

A case of initial resuscitation of a patient with severe burns is described. Such patients can have hypotension and reduced organ perfusion for a number of reasons, and can remain in the emergency department for many hours while awaiting transfer to specialist centres. The case provides a comparison between resuscitation using traditional burns formulae and a relatively new and simple-to-use cardiac output (CO) monitor--the Vigileo monitor (Edwards Lifesciences, Irvine, California, USA). The case demonstrates that relying on fluid regimes alone can lead to insufficient resuscitation. We suggest that using technologies such as those mentioned in this article, which have the potential to be used in the emergency department, could improve the initial resuscitation of patients with burns.     

Methylene chloride: Report of five exposures and two deaths

Five patients presented to the emergency department (ED) following exposure in an enclosed space to methylene chloride (dichloromethane), used for removing paint. Two workers and three rescuers were involved. Two rescuers complained only of dizziness and mild nausea, and were subsequently discharged from the ED. One rescuer was asymptomatic. Worker no. 1 arrived in cardiac arrest and eventually died in the ED despite resuscitation efforts. Worker no. 2 also presented to the ED in cardiac arrest, and was successfully resuscitated to pulse and blood pressure. However, he never regained consciousness or spontaneous respirations, and died on the fourth day. Of interest is that worker no. 2's carboxyhemoglobin level increased from 2% to 8% over the 9 hours following admission, despite administration of 40% to 50% oxygen by endotracheal tube. Among the conclusions that can be drawn are (1) the cause of death in these patients was not carbon monoxide poisoning, but solvent-induced narcosis; (2) carboxyhemoglobin levels may continue to rise following cessation of exposure, despite administration of high flow oxygen; (3) rescuers can easily become victims if proper protective clothing and respirators are not worn.     

Partial pressure of end-tidal carbon dioxide predicts successful cardiopulmonary resuscitation in the field

Kolar and colleagues contribute an additional and important incentive for rescuers to utilize end-tidal carbon dioxide tensions as a routine monitor to guide management and decision-making during cardiopulmonary resuscitation. They conclude that below-threshold levels of 14 mmHg (1.5 kPa) measured after 20 minutes of cardiopulmonary resuscitation reliably predict that spontaneous circulation cannot be restored.In their report on 737 patients who sustained out-of-hospital cardiac arrest, collected over an interval of 9 years in a well-organized emergency medical system, Kolar and colleagues confirmed that the measurement of end-tidal carbon dioxide tension (PetCO₂) is predictive of the outcomes of cardiopulmonary resuscitation [1]. The authors provide impressive data supporting the conclusion that, in their population, failure to increase PetCO₂ to levels exceeding 14 mmHg (1.5 kPa) after 20 minutes of attempted resuscitation served as a reliable guide for terminating unsuccessful cardiopulmonary resuscitation. The population studied, however, differed in some respects from the majority of earlier demographic reports that the authors cited with hospital survival <3%. More than 53% survived. The majority of instances of cardiac arrest reported by them was witnessed, and as many as one-third of victims received bystander cardiopulmonary resuscitation – favoring improved outcomes. Fatal outcomes, as anticipated, were associated with a doubling of the response time of professional rescuers, presumably in the absence of bystander utilization of automated external defibrillators, especially since a majority of survivors had shockable ventricular fibrillation or ventricular tachycardia.As the authors pinpoint, PetCO₂ has evolved into a technically facile and singularly useful monitor to guide cardiopulmonary resuscitation. PetCO₂ provides an indirect measurement of the cardiac output generated by chest compression and thereby guides the effectiveness of the procedure, including chest compression, to achieve better outcomes. It also allows uninterrupted chest compression because it promptly signals the return of spontaneous circulation [2]. PetCO₂ is likely to promptly identify asphyxia, in contrast to primary cardiac causes of arrest as previously reported by one of the present authors [3]. PetCO₂ measurement during cardiopulmonary resuscitation may not require routine endotracheal intubation, which usually interrupts chest compression and under crisis conditions has a high failure rate and disproportionate airway injury. The alternatives of a laryngeal mask airway or even a facial mask incorporating a mainstream carbon dioxide sensor may be utilized. Because injection of bolus epinephrine produces a sharp although transient reduction in PetCO₂ when injected intravenously [4], clinicians would best be alerted to this potential error.These considerations notwithstanding, Kolar and colleagues contribute an additional and important incentive for rescuers to utilize PetCO₂ as a routine monitor to guide management and decision-making during cardiopulmonary resuscitation.     

A model for evaluation of gas exchange: mouth to mouth ventilation of infants by emergency medical technicians

We describe a model for evaluating techniques of infant ventilation during resuscitation. The utility of the model is illustrated by testing performance of emergency medical technicians in mouth to mouth ventilation of a model 4 kg infant. Ventilation was generally adequate with mean (+/- S.D.) frequency 22 +/- 9 breaths per minute and tidal volume 40 +/- 13 ml. Gas delivered to the model consisted of PICO2 7 +/- 6 mmHg and FIO2 0.20 +/- 0.007. Assuming normal metabolic rate and respiratory dead space, alveolar gas composition resulting from the simulated resuscitations would be PACO2 = 31 +/- 20 and PAO2 = 110 +/- 19 mmHg. Nine of ten rescuers would have achieved satisfactory PACO2 less than or equal to 50 and PAO2 greater than or equal to 100. However, the rescuers' exhaled oxygen concentration is not adequate to correct hypoxemia if associated with hypoventilation or a wide alveolar to arterial oxygen gradient.     

Recently published papers: take your predictions with a drop of saline... and breathe deeply before turning on your phone

Early recognition of sick patients with a poor prognosis, and the rapid institution of appropriate therapy are tenets of good medical management across all specialties. Here we highlight five recent papers that aid us in achieving such goals in and around the intensive care unit (ICU). Both score-generating clinical tools and clinical acumen are championed for identifying the sick, while appropriate, early intervention in acute deterioration is shown to be beneficial, before and after ICU admission. Saline or albumen for resuscitation? The answer became clearer in May, as did what to do about all those mobile phones...     

E MERGING C OMMUNICATION T ECHNOLOGIES IN E MERGENCY M EDICAL S ERVICES

Advances in communication technologies are changing the face of emergency medical services (EMS). Two communication technologies in particular—cellular-enhanced 9-1-1 service and automatic crash notification (ACN)—will have a considerable impact on EMS. Although enhanced 9-1-1 service from land-line phones is now available in nearly every EMS system across the country, enhanced 9-1-1 service from cell phones currently does not exist. With more and more emergency calls made from cell phones, the implementation of this service is a clear priority. Automatic crash notification, a quickly emerging technology, can potentially provide EMS systems with invaluable data within seconds of when a collision occurs. However, many issues with regard to ACN systems need to be addressed, including liability concerns, access to ACN data, ability of drivers to understand the ACN system, and ACN system architecture. The potential interfaces between ACN systems and EMS systems create significant opportunities to enhance EMS resource management and care of patients involved in motor vehicle crashes. With both cellular-enhanced 9-1-1 and ACN in their infancy, EMS physicians and administrators have a valuable opportunity to provide leadership in the development of these services.     

Willingness to perform mouth-to-mouth ventilation by health care providers: A survey

BackgroundDuring cardiopulmonary resuscitation (CPR), mouth-to-mouth ventilation (MTM) is only effective if rescuers are willing to perform it.MethodsTo assess the degree of willingness or reluctance in performing MTM, a survey including 17 hypothetical scenarios was created. In each scenario health hazards for the rescuer needed to be balanced against the patient's need for MTM. Respondents were recruited from health care workers attending courses at a medical simulation center. Respondents reported their willingness or reluctance to perform MTM for each scenario using a 4 point scale.ResultsThe questionnaire had responses by 560 health care workers. Reluctance to perform MTM varied with the scenario. Some health care workers refused to ventilate patients who could benefit from MTM. In all scenarios even when resuscitation was both futile and potentially hazardous, some health care workers were willing to perform MTM. Age and level of experience tend to reduce the propensity to engage in MTM. Parental propensity to ventilate one's own child was stronger than any other motivator.ConclusionsHIV infection is not the only condition for which rescuers hesitate to perform MTM. Bag-valve-mask devices for mechanical ventilation should be available in all locations where health care workers may be called upon to resuscitate apneic patients making the decision to perform MTM moot.     

Recommendations of the international guidelines 2000 conference on cardiopulmonary resuscitation and emergency cardiac care: an overview

The greatest potential for survival of sudden cardiac arrest can be achieved only by providing early intervention using evidence-based therapies that have been studied over time. Emergency cardiac care and the 2000 advanced cardiac life support guidelines encompass all therapies that have been shown to improve outcomes in patients who experience life-threatening events that involve the cardiovascular, cerebrovascular, and pulmonary systems. Early recognition of warning signs, activation of emergency medical systems within the community, basic cardiopulmonary resuscitation, early defibrillation, airway management, and intravenous medication administration are key factors in improving resuscitation outcomes.     

Psychological impact on dispatched local lay rescuers performing bystander cardiopulmonary resuscitation

AimWe studied the short-term psychological impact and post-traumatic stress disorder (PTSD)-related symptoms in lay rescuers performing cardiopulmonary resuscitation (CPR) after a text message (TM)-alert for out-of-hospital-cardiac arrest, and assessed which factors contribute to a higher level of PTSD-related symptoms.MethodsThe lay rescuers received a TM-alert and simultaneously an email with a link to an online questionnaire. We analyzed all questionnaires from February 2013 until October 2014 measuring the short-term psychological impact. We interviewed by telephone all first arriving lay rescuers performing bystander CPR and assessed PTSD-related symptoms with the Impact of Event Scale (IES) 4–6 weeks after the resuscitation. IES-scores 0–8 reflected no stress, 9–25 mild, 26–43 moderate, and 44–75 severe stress. A score ≥26 indicated PTSD symptomatology.ResultsOf all alerted lay rescuers, 6572 completed the online questionnaire. Of these, 1955 responded to the alert and 507 assisted in the resuscitation. We interviewed 203 first arriving rescuers of whom 189 completed the IES. Of these, 41% perceived no/mild short-term impact, 46% bearable impact and 13% severe impact. On the IES, 81% scored no stress and 19% scored mild stress. None scored moderate or severe stress. Using a multivariable logistic regression model we identified three factors with an independent impact on mild stress level: no automated external defibrillator connected by the lay rescuer, severe short-term impact, and no (very) positive experience.ConclusionLay rescuers alerted by text messages, do not show PTSD-related symptoms 4–6 weeks after performing bystander CPR, even if they perceive severe short-term psychological impact.     

The effect of seeing the rhythm display on performance of cardiopulmonary resuscitation

Semiautomated external defibrillators are widely used by prehospital emergency personnel. Some of the devices have a rhythm display and some show only text commands on the screen. To evaluate the effects on cardiopulmonary resuscitation (CPR) performance of seeing the rhythm during resuscitation, 60 fire-fighter students were randomly divided in two groups and trained to use either a defibrillator with a rhythm display or one without a display. The students in both groups formed teams of two rescuers, and their performance of CPR on a manikin was tested using a predefined rhythm sequence in a simulated cardiac arrest situation. The teams using a defibrillator with a rhythm display more often interrupted CPR for pulse checks than those who did not see the rhythm (P=0.003). The duration of CPR between rhythm analyses was shorter in the group who saw the rhythm on the screen (P=0.002). Our data suggest that seeing an organised rhythm on a monitor during CPR interferes with adherence to CPR algorithms which may have a negative influence on the performance of CPR.     

Using lithium ion batteries in the aeromedical environment: A calculated risk?

Lithium ion batteries are increasingly utilised within helicopter emergency medical services. Their favourable chemical profile confers many desirable properties: they are small, lightweight and provide a high specific capacity (energy to weight ratio) coupled with a slow self‐discharge rate, ensuring a longer functional availability for vital equipment. They are frequently used in routine medical equipment including ventilators, monitors and intravenous pumps, and in aviation specific items, such as satellite and mobile phones, VHF radios and navigation systems.     

Rescuer's position and energy consumption, spinal kinetics, and effectiveness of simulated cardiac compression

BACKGROUND: Cardiopulmonary resuscitation is often performed in compromised conditions and for long periods. OBJECTIVE: To compare energy expenditure, compression effectiveness, and kinetics of the spine during simulated chest compression with the rescuer in different positions. METHODS: A 3-group design with 36 nurses (26 females) and 20 male emergency medical technicians was used. Participants performed chest compressions on a mannequin while kneeling on the floor, standing, or kneeling on the bed at the edge of the mattress (bed mount). Oxygen consumption and effectiveness of chest compression were recorded. Muscle moment and power at the lumbosacral joint were determined by recording motions of the lower limbs and pelvis with an electromagnetic tracking device and measuring ground reaction forces with a force plate. RESULTS: A total of 80% of chest compressions delivered by male rescuers (vs 40% delivered by females) were effective, irrespective of position. Male rescuers consumed less oxygen when delivering chest compressions while standing than while kneeling (P = .03), but effective compression ratio also was lower. In female rescuers, effective compressions correlated positively with oxygen consumption in the standing (r = 0.42, P = .04) and bed-mount (r = 0.53, P = .008) positions. Administering chest compressions while standing involved a larger moment magnitude and required more power than doing so while kneeling. CONCLUSION: Administering chest compressions while standing demands more power but consumes less oxygen than doing so while kneeling, perhaps because fewer cardiac compressions delivered while standing are effective.