**3. Ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT): debrillation**

### **3.1 Early vs. late rhythm analysis**

Rhythm analysis is an important component of the CPR algorithm. It helps us to determine further course of action based upon the type of rhythm: shockable or non-shockable. No specific time frame is given to check the rhythm by the currently available literature. A randomized control trial was conducted to compare the impact of brief interval 30–60 s versus long interval of 120 s of chest compression before rhythm analysis in OHCA [22]. It was concluded that the duration for rhythm analysis is to be decided by the EMS team based on local circumstances. It is usually preferable to have an early rhythm analysis in cases where bystander CPR was given before EMS arrival. The authors also emphasized on delivering highquality chest compressions before defibrillation.

#### **3.2 Analysis during compressions with fast reconfirmation**

There is a need for rhythm analysis intermittently while performing CPR. Chest compressions can create artifacts that make it difficult to analyze the rhythm. [23]. Thus, interruptions of chest compressions (CCs) are mandatory during

CPR. Ineffective and interrupted chest compressions can lead to poor outcomes post-CPR [24, 25]. While using an AED, the duration of interruption includes time for rhythm analysis, charging, and a warning to stand clear of the patient before a shock is delivered.

The analysis during compressions with fast reconfirmation (ADC-FR) is a new technology that can significantly reduce the CC interruptions. It comprises of special accelerometers embedded in the defibrillator pads that can sense the CCs. During the CCs, high pass digital filters are applied to analyze the ECG. This filtered rhythm is then compared with the previously validated data to determine whether the rhythm is shockable or not. This rhythm is further cross-checked with the compression-free ECG picked up during the interruption of CCs. In case of shockable rhythm, the defibrillator gets charged just 4 s before 2 min CPR interval. This ensures minimal interruption during CPR.

In a retrospective study, the sensitivity and specificity were found to be >95% and 99%, respectively, for identifying shockable/non-shockable rhythm which exceeds the AHA recommendations for standard artifact-free ECG analysis. Recent studies have demonstrated higher CC fractions have a higher likelihood of ROSC and survival after OHCAs [25–32]. We can conclude that ADC-FR is a new alternative that can accurately differentiate shockable from non-shockable rhythm [33]. More clinical studies need to be conducted to provide supportive evidence for ADC-FR.

#### **3.3 Defibrillation strategy**

Defibrillation is one of the most important strategies that can improve postcardiac arrest patients' outcome. Over the last two decades, various studies have demonstrated the relevance of early defibrillation in shockable rhythms [34]. With every minute of delay in defibrillation, there is a decrease in survival by 7–10%. Combined crucial basic life support strategy of early CPR and early defibrillation can improve the overall survival of the patient [35]. The development of an automated external defibrillator (AEDs) was an important breakthrough. Efforts are being made to encourage targeted lay-person early defibrillation. These devices can record the rhythm, analyze it, and deliver a shock. A recent study has demonstrated better neurological outcomes with the application of public access AED to patients of OHCA regardless of the first documented rhythm [36].

There is an evidence of high first shock success rate with biphasic waveform with less incidence of post-shock myocardial dysfunction for both atrial and ventricular arrhythmias, as compared to monophasic waveform [37, 38]. It is recommended to start with the biphasic shock energy of 150 or 360 J in case of the monophasic waveform. There is a strong recommendation to follow defibrillators' manufacturer's instructions for initial and subsequent shocks [23]. Single shock is always preferred over stacked shocks to minimize interruptions in chest compressions [37, 38]. Secondly, it is seen that if a biphasic waveform is unable to defibrillate, then chest compressions are the next best step. It is recommended to escalate the defibrillation energy with subsequent biphasic shocks. This escalation may be useful in preventing the risk of fibrillation [39].

#### **3.4 Hands-on defibrillation**

"All clear" is a routine warning given before the delivery of defibrillation. Due to potential side effects, it is important not to be in touch with the patient while delivering a shock. There have been some case reports in the literature of rescuer

**5**

*Cardiopulmonary Resuscitation: Recent Advances DOI: http://dx.doi.org/10.5772/intechopen.91866*

**4. Airway, oxygenation, and ventilation**

remains uncertain.

oxygen.

**4.1 Oxygen dose during CPR**

**4.2 Airway management during CPR**

being thrown away [40, 41] to as severe as death [42]. In all these cases, the rescuers were barehanded. The main aim of defibrillation is to deliver the appropriate dose (100–360 J) of energy to defibrillate the patient without causing any harm to the rescuer [43]. The energy used is same for cardiac arrest with ventricular fibrillation and pulseless ventricular tachycardia. Lloyd et al. first demonstrated the safety of gloves while defibrillation [44]. This triggered the idea of "hands-on defibrillation" minimizing the CC interruptions during shock delivery. In previous studies, the relationship between the success rate of defibrillation and the time delay between chest compression and shock delivery has already demonstrated [45, 46]. Subsequently, studies have been conducted to determine the efficacy of different types of gloves. One study concluded nitrile glove, neoprene gloves, and fire-fighter gloves can prevent the detection of defibrillation in 99% of cadaver cases [47]. A polythene sheet as thin as 0.002 inches can reduce the current delivered [48]. With the use of these new safety measures, hands-on defibrillation can be made safer.

Oxygen supplementation during CPR has been an acceptable practice. But the concentration of oxygen delivery during CPR can benefit or harm the overall survival depending on the clinical situations. Similarly, various devices have been used in various clinical settings for securing the airway. Ventilation strategies during CPR have been also proposed by various guidelines but the optimal ventilation protocol

The optimum tissue and blood oxygenation during CPR are unknown and no study has been done to define the oxygenation goals during CPR. The common practice of giving 100% oxygen during CPR has been challenged in some clinical situations. Most of the current guidelines suggest the use of maximal possible oxygen concentration during CPR. There are numerous limitations to these recommendations. Lack of current clinical evidence to suggest optimal tissue/ blood oxygenation during CPR and unavailability of techniques measuring tissue oxygenation during CPR are important limitations in deciding optimum dosing of

Airway management during CPR includes basic airway management by the bag and mask ventilation with or without oropharyngeal airways and advanced airway management like supraglottic airway devices (SAD) and endotracheal intubation. The optimal management of airway during CPR is an unclear and traditional belief of superiority of advanced airway over basic airway management has been challenged by some of the recent observational studies. Most of the studies comparing various advanced airway devices like an endotracheal tube, combitube, supraglottic airway devices and bag and mask device during CPR were observational studies and were done in OHCA patients. The data were extrapolated for IHCA settings. Most of the newer guidelines in developing and low resource countries also recommend the use of any advanced airway or bag and mask to secure airway to achieve adequate ventilation. Type of airway device in use depends on the skills of rescuer [49]. Tracheal intubation mandates training of health care provider and may be

*Cardiopulmonary Resuscitation: Recent Advances DOI: http://dx.doi.org/10.5772/intechopen.91866*

*Sudden Cardiac Death*

shock is delivered.

for ADC-FR.

**3.3 Defibrillation strategy**

ing the risk of fibrillation [39].

**3.4 Hands-on defibrillation**

ensures minimal interruption during CPR.

CPR. Ineffective and interrupted chest compressions can lead to poor outcomes post-CPR [24, 25]. While using an AED, the duration of interruption includes time for rhythm analysis, charging, and a warning to stand clear of the patient before a

technology that can significantly reduce the CC interruptions. It comprises of special accelerometers embedded in the defibrillator pads that can sense the CCs. During the CCs, high pass digital filters are applied to analyze the ECG. This filtered rhythm is then compared with the previously validated data to determine whether the rhythm is shockable or not. This rhythm is further cross-checked with the compression-free ECG picked up during the interruption of CCs. In case of shockable rhythm, the defibrillator gets charged just 4 s before 2 min CPR interval. This

The analysis during compressions with fast reconfirmation (ADC-FR) is a new

In a retrospective study, the sensitivity and specificity were found to be >95% and 99%, respectively, for identifying shockable/non-shockable rhythm which exceeds the AHA recommendations for standard artifact-free ECG analysis. Recent studies have demonstrated higher CC fractions have a higher likelihood of ROSC and survival after OHCAs [25–32]. We can conclude that ADC-FR is a new alternative that can accurately differentiate shockable from non-shockable rhythm [33]. More clinical studies need to be conducted to provide supportive evidence

Defibrillation is one of the most important strategies that can improve postcardiac arrest patients' outcome. Over the last two decades, various studies have demonstrated the relevance of early defibrillation in shockable rhythms [34]. With every minute of delay in defibrillation, there is a decrease in survival by 7–10%. Combined crucial basic life support strategy of early CPR and early defibrillation can improve the overall survival of the patient [35]. The development of an automated external defibrillator (AEDs) was an important breakthrough. Efforts are being made to encourage targeted lay-person early defibrillation. These devices can record the rhythm, analyze it, and deliver a shock. A recent study has demonstrated better neurological outcomes with the application of public access AED to patients

There is an evidence of high first shock success rate with biphasic waveform with less incidence of post-shock myocardial dysfunction for both atrial and ventricular arrhythmias, as compared to monophasic waveform [37, 38]. It is recommended to start with the biphasic shock energy of 150 or 360 J in case of the monophasic waveform. There is a strong recommendation to follow defibrillators' manufacturer's instructions for initial and subsequent shocks [23]. Single shock is always preferred over stacked shocks to minimize interruptions in chest compressions [37, 38]. Secondly, it is seen that if a biphasic waveform is unable to defibrillate, then chest compressions are the next best step. It is recommended to escalate the defibrillation energy with subsequent biphasic shocks. This escalation may be useful in prevent-

"All clear" is a routine warning given before the delivery of defibrillation. Due to potential side effects, it is important not to be in touch with the patient while delivering a shock. There have been some case reports in the literature of rescuer

of OHCA regardless of the first documented rhythm [36].

**4**

being thrown away [40, 41] to as severe as death [42]. In all these cases, the rescuers were barehanded. The main aim of defibrillation is to deliver the appropriate dose (100–360 J) of energy to defibrillate the patient without causing any harm to the rescuer [43]. The energy used is same for cardiac arrest with ventricular fibrillation and pulseless ventricular tachycardia. Lloyd et al. first demonstrated the safety of gloves while defibrillation [44]. This triggered the idea of "hands-on defibrillation" minimizing the CC interruptions during shock delivery. In previous studies, the relationship between the success rate of defibrillation and the time delay between chest compression and shock delivery has already demonstrated [45, 46]. Subsequently, studies have been conducted to determine the efficacy of different types of gloves. One study concluded nitrile glove, neoprene gloves, and fire-fighter gloves can prevent the detection of defibrillation in 99% of cadaver cases [47]. A polythene sheet as thin as 0.002 inches can reduce the current delivered [48]. With the use of these new safety measures, hands-on defibrillation can be made safer.
