Effectiveness of Pre-Hospital Cardiopulmonary Resuscitation

Introduction

Holzer et al. (2005) states that the prevalence of cardiac arrest outside hospital settings range between 0.04 percent and 0.13 percent of the entire population in most advanced nations (p. 414). Recent trials have demonstrated that induced hypothermia plays a key role in pre-hospital cardiopulmonary resuscitation (Bernard, Gray & Buist, 2002). Kouwenhoven et al. (1960) invented closed-chest cardiac massage as a procedure for enhancing cardiopulmonary resuscitation (CPR). Kouwenhoven was able to record a 70 percent success rate when he employed CPR procedure among 20 patients. However, this remarkable achievement could be attributed to bias in the selection procedure given that some of his subjects had experienced cardiac arrest in either post-operative rooms or operating rooms. However, the success rate of successive trials during this period ranged between 3 percent and 26 percent (Greenfield, 1964).

It is important to note that, during this period, CPR was mainly administered amongst patients experiencing myocardial infarction. As the procedure of administering CPR enhanced, many healthcare facilities adopted the procedure amongst patients suffering from cardiac arrest. Although a number of clinical trials (McGrath, 1987) have approximated the overall success rate of cardiopulmonary resuscitation to be about 20 percent, recent researches have shown that the CPR success rate is much lower (Murphy et al., 1989). Consequently, concerns have emerged regarding the arbitrary use of cardiopulmonary resuscitation among older patients suffering from cardiac arrest. Therefore, this section will review relevant literature related to the effectiveness of CPR among patients suffering from cardiac arrest.

Impact of public access defibrillators

Pell et al. (2002) investigated the correlation between public access defibrillators and the out-of-hospital cardiac arrest survival rate. The cohort encompassed all cardiac arrest incidences that took place in a span of seven years. The Scottish Ambulance Service attended to 21,481 cardiac arrest incidences and 15, 189 occurrences satisfied the criteria of the Utstein convention. 79% (1200) incidences of cardiac arrest took place in areas incompatible for the location of public access defibrillators (i.e. residential places) whereas 3% (453) happened in appropriate areas (i.e. car parks). The information and results on defibrillation were accessible for 98.3% (14,947) cardiopulmonary arrests (Pell et al., 2002, p. 2. The ambulance crew administered defibrillation services on 59.5% (8895) of cardiac arrest cases. Nonetheless, the percentage of individuals who got defibrillation differed considerably between appropriate, possibly appropriate and inappropriate sites (Pell et al., 2002, p. 2).

Approximately 56.2% of the people with cardiopulmonary arrest received public defibrillation in inappropriate sites. On the other hand, 72.9% and 67.9% of patients with cardiac arrest received defibrillation in appropriate sites and possibly appropriate sites respectively. In addition the survival rate for cardiac arrest patients who did not receive defibrillation (irrespective of the site) was less than 1%. It is worth mentioning that the survival rate for cardiopulmonary arrest patients who received defibrillation (regardless of the type of site) was considerably high. Furthermore, the highest survival rate for cardiac arrest was among patients found in areas with appropriate access to public defibrillators. Generally, 70% of cardiac arrest patients received defibrillation in less than 3 minutes, in comparison to 58.3% of patients who experienced extended delays (Pell et al., 2002, p. 2).

Decreasing time to defibrillation

Weaver et al. (1988) reported that approximately all out-of-hospital cardiac arrest survivors were in ventricular fibrillation prior to the arrival of ambulance. This finding is based on the fact that pulse-less and asystole electrical motion typically denotes an extended period from the inception of preliminary ventricular fibrillation (Weaver et al., 1988). There is an inverse correlation between the percentage of cardiopulmonary arrest patients in ventricular fibrillation and the cardiac arrest period, with no concrete proof of a threshold effect (Wilcox-Gok, 1991; Nichol et al., 1998). Consequently, any medical procedure that decreases defibrillation time should augment the percentage of cardiac arrest patients who qualify for defibrillation and enhance survival rate. Nichol et al. (1998), propose four ways of decreasing defibrillation time. Conventional first-responders (i.e. fire-fighters and law enforcement personnel) should be trained on how to use external defibrillators so that they can attend to cardiac arrest patients. This strategy could effectively improve the pre-hospital cardiac arrest resuscitation (Pell et al., 2001).

Page et al. (2000) and Valenzuela et al. (2000) suggest that nonconventional emergency services personnel (i.e. community volunteers, security personnel and flight attendants) should be trained on how to use external defibrillators. For example, O’Rourke et al. (1997) reported that an Australian airline mounted an automatic defibrillator in the airports it landed on as well as in its entire airplane fleet. The researcher reported that, in a span of 64 months, the airline recorded 46 cardiopulmonary arrest incidences. The flight attendants were able to defibrillated 21 patients successfully while another six cardiac arrest patient survived. Page et al. (2000) also reported comparable results in a US airline. O’Rourke et al. (1997) also carried out a study in 32 casinos to explore the use of external defibrillators by security personnel. The researcher reported that 148 victims suffered from cardiopulmonary arrest within the casinos. The security personnel used the device on 105 victims who suffered cardiac arrest. In general, 56 victims were successfully resuscitated.

Jill et al. (2002) suggests that victims vulnerable to cardiac arrest attacks should be given external defibrillators. In addition, close friends and relatives of cardiac arrest victims should be trained on how to use the resuscitating machine. Jill et al. (2002) points out that approximately 60% of cardiopulmonary attacks take place within residential places of the victims. Lastly, external defibrillators should be installed in recreational centres and public places to facilitate easy access by the public. The resuscitation devices should be installed in public places in a manner that they can be easily accessed and used productively by the public. In addition, the public access defibrillators should be enhanced by interactive instructions.

Cost efficiency

When external defibrillators are widely distributed for public use, they can significantly augment pre-hospital cardiopulmonary resuscitation efforts. However, installing such resuscitating device in public places would significantly increase maintenance costs and expose them to vandalism. Nichol et al. (1998) developed an incremental cost efficiency model that could be used to improve access to out-of-hospital defibrillators in the US. The model eliminated 25% of cardiopulmonary arrests that took place in the rural settings. According to their findings, the survival rate of cardiopulmonary arrest was 7.9%. When untrained responders used the defibrillator in cardiac arrest resuscitation, the percentage improved to 8.7%. The percentage increased further to 11.8% when the police used the resuscitating device on cardiac arrest victims. In addition, the researchers estimated the incremental outlays/patients treated at £4590 ($7100) and $ 9000 correspondingly. In addition, the outlay/QALY (quality adjusted life year) was approximately $44000 and $2700 respectively. The conclusions made by the researchers seem to imply that these outlays were analogous to those found in the conventional health interventions (Nichol et al., 1998).

Jill et al. (2002) found that the overall survival rate from cardiac arrest attacks improved from 5% to 6.3% when automatic defibrillators were installed in recreational centres and public places such as shopping malls and airports which are visited regularly by many people vulnerable to cardiopulmonary attacks. It is worthy to note that these places are the most appropriate for installing automatic defibrillators given that they can be easily accesses by the public with respect to training, maintenance, cost efficiency and efficacy. In addition, it is important to train individuals who work in these places on how to use defibrillators as opposed to expecting lay people to use them in resuscitating efforts. Furthermore, it would not make economic sense if defibrillators are widely distributed in public places if the public is not educated on how to use them. In other words, automatic defibrillators should only be installed in public areas where first responders (i.e. fire-fighters and security personnel) are appropriately trained on how to use them to resuscitate people who succumb to cardiac arrest attack. This will not only improve the cost efficiency of the resuscitating device but also will improve the survival rate of victims experiencing cardiac arrest attack.

Hypothermia for Neuroprotection after Cardiopulmonary Arrest

Holzer et al. (2005) carried out a study to investigate how hypothermia enhanced recovery among cardiopulmonary arrest victims. The main areas of concern were short-term and long-term improvement in neurological survival. The researchers reported that when mild curative hypothermia was induced among cardiac arrest patients, their neurologic survival rate improved within the short-term period. The researchers found that this positive outcome appeared to be autonomous of the procedure employed to induce hypothermia (Holzer et al., 2005, p. 416).

In addition, the study found that this occurrence transformed into enhanced constructive long-term neurological survival rate that reached 6 months following cardiac arrest. However, this outcome is based on one trial only. Other clinical trials were somewhat diverse with respect to clinical details. For instance, two clinical experiments were manifold-center trials and incorporated victims who experienced ventricular fibrillation. According to Holzer et al. (2005), there is correlation between ventricular fibrillations and positive outcome. Three diverse methods were employed in the application of hypothermia. In addition, the researchers established that the influence of hypothermia was not affected by factors such as the inclusion of comatose patients and the form of hypothermia used (Holzer et al., 2005, p. 416).

Safety of Hypothermia

In addition, the researcher used data of individual patients to investigate the interaction between hypothermia and other clinical variables. Their data analysis revealed that the influence of hypothermia intervention was neither affected by the duration of the cardiopulmonary arrest nor the patient’s age. With respect to the safety of hypothermia, the researchers were unable to establish whether hypothermia intervention were detrimental to the wellbeing of cardiac arrest patients. Nonetheless, their data analysis appeared to suggest that hypothermia interventions had detrimental effects to cardiopulmonary victims. Some of the harmful effects the researchers identified were prevalence of severe infections and increased incidences of hemorrhagic complications. Nonetheless, the general positive outcomes associated with hypothermic interventions surpassed the expected complications (Holzer et al., 2005, p. 417).

Clinical Relevance of Hypothermia

Although the decrease in relative risk is somewhat modest, the researchers found that a reduction in absolute risk was definitely of clinical significance given that the underlying risk of adverse outcome was considerably higher. Consequently, the researchers were 95% convinced that they could permit an extra cardiac arrest patient to leave the sickbay with positive neurologic recuperation by administering treatment to between 4 and 13 cardiac arrest patients. This finding is comparable with several pharmacological treatments among patients suffering from chronic cardiovascular ailments. The use of mild curative hypothermia in this clinical trial was a simple treatment that did not essentially imply significance increase in resources. Holzer et al. (2002) reported that it suitable equipment could be used to regulate temperature. In addition, Bernard et al. (2002) reported that intravenous liquids could be stored in refrigerator and an ice-cube maker to maintain the desired temperature. Nonetheless, using these methods to regulate and sustain the desired temperature may be problematic. Potential adjustments in cooling methods should be undertaken in a cautious manner in order to guarantee the positive effect of hypothermia.

Holzer et al. (2005) suggests that future clinical studies must investigate the influence of hypothermia intervention on the long-term quality of life and cardiac arrest diagnosis. In addition, they suggest that a determination should be made regarding the best possible duration of hypothermia intervention. Finally, the researchers suggest that future clinical trials should investigate the efficiency of hypothermia treatment on an organizational perspective (Holzer et al., 2005, p. 417).

Quality of Pre-Hospital Cardiopulmonary Resuscitation

Wik et al. (2005) carried out a study to investigate the quality of pre-hospital CPR done by ambulance staff and compared the performance to the cardiopulmonary resuscitation guidelines (p. 299). The principle measure of performance in this study was the observance of CPR guidelines. In this research, the ambulance staff spent 50% of the available time to resuscitate 176 patients with cardiopulmonary arrest (Wik et al., 2005). In a related study, Van Alem et al (2003) found that fire-fighters and law enforcement personnel used only 45 % of the CPR duration before the ambulance staff arrived at the resuscitating scene. In that research, 66% of the period without cardiopulmonary resuscitation was due to the interference attributed to the defibrillators. On the contrary, in the study done Wik et al. (2005), approximately 18% of the period lost in cardiopulmonary resuscitation was explained by the mandatory pulse test and interference from defibrillator. These interruptions were expected to take place during the preliminary period of advanced cardiac life support. In addition, negligible disparities were observed in the outcomes for the initial 5 minutes and rest of the period (Wik et al., 2005).

Wik et al. (1994) and Van Hoeyweghen et al. (1993) reported that CPR of exceptional qualities enhanced survival prospects of cardiopulmonary patients. It seems that the most crucial aspect in human studies is the chest compression since a 4-second delay in chest compression reduces pressure of coronary perfusion. According to Wik et al. (2005), over 50% of the chest compressions administered were extremely trivial, a phenomenon that demonstrated reduced circulatory influence of the cardiopulmonary resuscitation administered. Besides compression intensity, the researcher found that blood flow was influence by the ratio between compression and decompression. The study also found that the average compression rate was elevated and could potentially reduce cardiac output as a result inadequate time for venous to go back to the heart during the decompression phase (Wik et al., 2005). In addition, the researchers did not report unusually elevated rates of ventilation among participants. On the contrary, Aufderheide et al (2004) found recently the mean rates of ventilation of 30/minute with maximum rates observed within a period of 16 seconds.

CPR training programs have been adopted internationally in the last 40 years in pursuance to the European Resuscitation Council and American Heart Association. The CPR programs outline the guidelines for administering cardiopulmonary resuscitation correctly. Nevertheless, the impact of these educative programs on clinical cardiopulmonary resuscitation or the influence of particular guidelines on the survival rates of cardiac arrest patients has been clinically investigated. The study undertaken by Wik et al. (2005) was not inspired to assess the influences of value of cardiopulmonary in an appropriate multivariate evaluation with other aspects (i.e. preliminary rhythm) that affect survival. A rudimentary evaluation between cardiac arrest survivors and cardiopulmonary non-survivors with ventricular fibrillation as preliminary rhythm revealed an inclination toward somewhat reduced period without chest compression amongst cardiac arrest patients. In addition, the researcher did not find disparities with respect to ventilation rate or compression depth (Wik et al., 2005).

In Wik et al. (2005) study, all anaesthetic nurses and paramedics possessed prior ACLC training. In addition, they attended an energizer training course before the study commenced. A number of variations from the 2000 global guidelines were attributed to insufficient retention of the information. For example, Aufderheide et al. (2004) found that the Cardiopulmonary resuscitation performance of some anaesthetic nurses and paramedics worsened within a few months after they had attended a refresher course. The inability to carry out chest compressions within 50% of the available period has also not been documented in similar clinical trials. Wik et al. (2005) suggests that the extremely intricate mental and physical procedure of administering cardiopulmonary resuscitation to patients with cardiac arrest is differs significantly from the training environment that is purely theoretical and abstract in nature. As a result, the cardiopulmonary performance is significantly different and probably less productive. Irrespective of the justifications, the CPR measured by Wik et al. (2005) differed significantly from the recommendation of advanced cardiac life support (ACLS) directives. In addition the researchers questioned the relevance of information such as monophasic versus biphasic and the ratios of compression/decompression in their attempts to modify proof-based cardiopulmonary resuscitation directives. Nonetheless, it remains to be seen if some of these defects deserve consideration during cardiopulmonary resuscitation training.

It is important to note that cardiopulmonary resuscitation training can be enhanced if more emphasis is given to understanding the errors made by anaesthetic nurses and paramedics in real life cardiopulmonary arrest settings. These training should thus lend more weight on real-life events rather than abstract concepts. Another tactic relates to the development of online instruments that can provoke the rescuer to enhance his/her cardiac arrest resuscitation skills and performance. Some studies have reported that using audio and video recordings to demonstrate how to administer chest compression rate have enhanced compression rate during cardiopulmonary arrest resuscitation amongst patients (Cummins et al., 1991). In addition a number of dummy studies have been carried out using audio feedback supported by constant online automated CPR assessment. These studies have demonstrated that rescuers who use this learning mechanism showed considerable improvement in their cardiopulmonary arrest resuscitation skills within the first 5 minutes (Wik et al., p. 303).

Conclusion

This paper has evaluated effectiveness of pre-hospital cardiopulmonary arrest resuscitation. The findings of several studies have been review to this end. For instance this paper reviewed the findings made by Pell et al. (2002) who investigated the correlation between public access defibrillators and the out-of-hospital cardiac arrest survival rate. The results of this study showed that approximately 56.2% of the people with cardiopulmonary arrest received public defibrillation in inappropriate sites. On the other hand, 72.9% and 67.9% of patients with cardiac arrest received defibrillation in appropriate sites and possibly appropriate sites respectively. In addition the survival rate for cardiac arrest patients who did not receive defibrillation (irrespective of the site) was less than 1%. This paper also reviewed the findings of a study by Wik et al. (2005) which investigated the quality of pre-hospital CPR done by ambulance staff and compared the performance to the cardiopulmonary resuscitation guidelines. It was observed that the ambulance staff spent 50% of the available time to resuscitate 176 patients with cardiopulmonary arrest (Wik et al., 2005). In a related study, Van Alem et al (2003) found that fire-fighters and law enforcement personnel used only 45 % of the CPR duration before the ambulance staff arrived at the resuscitating scene. It was observed that the reduction in the CPR duration was attributed to several factors including interruptions in the use of the defibrillator.

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