Cardiac arrest is defined as cessation of cardiac mechanical activity. It is a clinical diagnosis,confirmed by unresponsiveness, absence of detectable pulse and apnea or agonal respirations.CPR is an attempt to restore spontaneous circulation through any of the broad range of manoeuvers and techniques. It is essential to act immediately as irreversible damage can occur in a short time. Within 15 seconds of cardiac arrest, the patient loses consciousness, electro-encephalogram (EEG) becomes flat after 30 second, pupils dilate fully after 60 seconds and cerebral damage takes place within 90-300 seconds.
The heart rhythm associated with cardiac arrest can be either ventricular fibrillation/ventricular tachycardia (VF/VT) or other rhythms including Pulseless Electrical Activity (PEA) or asystole.Survivability and other outcomes are much better if the associated rhythm is VT or VF. It is extremely important to recognize VT or VF as the underlying rhythm, because these rhythms need defibrillation as quickly as possible for optimal outcomes.
Basic Life Support
The action taken during the first few minutes of an emergency are critical to victim’s survival.BLS covers 3 links in the chain of survival. This refers to maintaining airway, supporting breathing and circulation at the site of arrest till further help becomes available. If the victim is unresponsive, his head should be positioned and airway should be opened by performing the Triple Airway Manoeuver (Head tilt-Chin lift-Jaw thrust).
Supporting Breathing
Breathing is assessed by looking at the chest for any respiratory movements, listening or feeling for breathes sounds. If there are no breathing efforts, initially 2 rescue breaths are provided. In absence of any equipment, mouth to mouth or nose resuscitation remains the best method. The aim is to deliver small volume (400-600 ml) over 1-2 seconds with cricoid pressure if possible.The earlier practice of delivering large volume of air (800-1200 ml) is no longer recommended.Ventilation, Chest Compressions Even when the first three defibrillation attempts fail, the best chance of resuscitation still lies in successful defibrillation. Airway is secured by endotracheal intubation if skills are available or,otherwise, by a laryngeal mask airway or a combitube. Ventilation is commenced with 100 per cent oxygen. Fifteen compressions and 2 ventilations are given for a minute and defibrillation is tried again. Once airway is secure by intubation or a laryngeal mask airway, uninterrupted chest compressions should be carried out, without pausing for ventilations. The rate of compression should be 100/minute and ventilation should be carried out at 12 breaths/minute.Supporting Circulation No longer than 10 seconds should be spent in assessing circulation. Pulse check for lay rescuer has now been de-emphasized since it takes time and accuracy is only 65 per cent. External chest compressions can produce peak systolic pressure of 60-80 mm of Hg. In adults, a ratio of 15:2 (15 chest compressions followed by 2 artificial breaths) has been adopted for a single rescuer as well as two rescuers performed external chest compressions can produce in children the rate of compression should be maintained close to 100/minute or roughly 2 per second.
Defibrillation
This step is the key to survival. The survival rate is 90 per cent if the patient is defibrillated within 1 minute and only 10 per cent if it is delayed till 10 minutes after arrest. In an adult, one should start with 200 J and increase the energy to 360 J after two shocks. In case of biphasic defibrillators, continuing energy of 200 J is considered optimal. In children, the energy requirement is calculated at the rate of 2-4 J/kg. The optimal paddle sizes are 13 cm (adults), 8-10cm (children) and 4.5-5 cm (infants). The standard paddle position is where one electrode is placed over the right side of upper part of sternum just below clavicle and the other one is placed over the apex.
Advanced Cardiac Life Support
ACLS is best done in a hospital or at the scene by expert paramedical personnel if significant delay is anticipated in transfer of the victim to the hospital. The tasks performed during this phase, include continuation of BLS, use of equipment for ventilation and circulation, 12 lead electrocardiography (ECG) and arrhythmia recognition, establishment of intravascular access and drug therapy and lastlyprehospital fibrinolytic therapy for acute coronary syndromes (ACS) and stroke in certain advanced healthcare setups. Venous access in CPR drugs are used with an aim to improve organ perfusion and to protect brain and heart from hypoxia, to facilitate defibrillation and to prevent recurrence of arrhythmias and to normalize metabolic derangements.
Vein Access
A Vein access is important during CPR. Even though a central venous line is ideal, its placement takes time, expertise and it has the potential to interrupt the process of CPR. Therefore, the next best option is a peripheral line. It has been shown that circulation time can be significantly reduced if 20 ml of saline is pushed after a drug bolus in a peripheral line. The other routes of drug delivery are tracheal, intra-osseous and even intra-cardiac/nasal/ Femoral. The tracheal route deserves special mention. The drug (2-3 times the intravenous dose) is diluted in 10 ml of saline and instilled in the tube, followed by 5 ventilations. Intraosseous route may be tried in children in the same dosages as those for the tracheal route. Intra-cardiac, nasal or femoral routes are no longer recommended and instilled in the tube, followed by 5 ventilations. Intraosseous route may be tried in children in the same dosages as those for the tracheal route. Intra-cardiac, nasal or femoral routes are no longer recommended.
Pharmacotherapy
Vasopressors
Adrenaline or epinephrine enhances cerebral and myocardial blood flow by preventing arterial collapse and by augmenting aortic diastolic pressure through alpha 1 and 2 receptors. The optimal dose is 1 mg every 3-5minutes. In children, it can be given in the dosages of 10 μg/kg or 0.1ml/kg of 1 in 10000 solution. Dose dependent improvement in regional myocardial and cerebral blood flow has been recorded in various studies but no improvement in hospital discharge and survival has been seen vasopressin.As a single bolus of 40 U, vasopressin has been recommended as an alternative to epinephrine in VF/pulseless VT refractory to defibrillation. Further studies are required to evaluate the efficacy of this drug. Vasopressin acts on non-adrenergic V1 receptors and has been recommended in case of fibrillatory arrest (40IU, single dose). The studies have recorded several advantages over adrenaline such as lack of beta effect, no impact of acidosis on its efficacy and even lower incidence of post resuscitation myocardial dysfunction.
Antiarrhythmic Agents
Contribution of lignocaine during arrest, to aid resuscitation from refractory VF remains uncertain. Lignocaine is an alternative in this situation if amiodarone is not available. Other problems associated with it are increase in defibrillation threshold, higher incidence of asystole after its use and a very delicate toxic to therapeutic ratio. Second choice behind amiodarone and procainamide. Amiodarone is useful in treatment of both atrial and ventricular arrhythmias. It is now recommended during ACLS after defibrillation and adrenaline. The dose is 150 mg diluted in 20 ml of 5 per cent dextrose given over 10 min, followed by infusion @1 mg/min for 6 hours and then @ 0.5 mg/min.
Sodium-bicarbonate (NaHCO 3 )
There is no definite recommendation regarding its use in cardiac arrest. Whenever possible,bicarbonate therapy should be guided by the bicarbonate concentration or calculated base deficit obtained from blood gas analysis. Sodium-bicarbonate is definitely indicated if there is hyperkalemia and tricyclic antidepressant toxicity and pre-existing metabolic acidosis. Calcium (Ca++) usually has no role unless patient presents with calcium channel blocker toxicity or if there is evidence of hypocalcemia or hyperkalemia. The dose of calcium gluconate is 0.5 ml/kg (maximum – 20 ml) of 10 per cent solution whereas 10 per cent solution of calcium chloride can be given in a dose of 0.2 ml/kg upto a maximum of 10 ml.
Magnesium
(Mg++) mirrors the action of extra cellular potassium in stabilizing myocardial cell membrane and it is indicated only if hypokalemia or hypomagnesaemia is known to be present or the patient is diagnosed to be having a rhythm called “Torsade de Pointers”. The dose (as magnesium sulphate) is 1-2 gm diluted in 100 ml of 5 per cent dextrose given over 30-60 min followed by an infusion of 0.5-1.0 gm/hour.
Atropine
Enhances automaticity and conduction of both sinoatrial and atrio-ventricular node and is most effective in haemodynamically significant bradycardia because of vagal stimulation. It also has a role in slow pulse less electrical activity (PEA). The recommended dose in PEA and asystole is 1.0 mg IV and repeated 3-5 minutes if required. For bradycardia, the dose is 10 μg/kg repeated every 3-5 minutes up to a total dose of 40 μg/kg.
Assessment of CPR and When to Stop?
Termination of CPR efforts can be a difficult decision to make. It is apparent from the literature that prolonged resuscitative efforts are unlikely to be successful if there is no return of spontaneous circulation within 30 minutes of commencement of CPR.
The heart rhythm associated with cardiac arrest can be either ventricular fibrillation/ventricular tachycardia (VF/VT) or other rhythms including Pulseless Electrical Activity (PEA) or asystole.Survivability and other outcomes are much better if the associated rhythm is VT or VF. It is extremely important to recognize VT or VF as the underlying rhythm, because these rhythms need defibrillation as quickly as possible for optimal outcomes.
Basic Life Support
The action taken during the first few minutes of an emergency are critical to victim’s survival.BLS covers 3 links in the chain of survival. This refers to maintaining airway, supporting breathing and circulation at the site of arrest till further help becomes available. If the victim is unresponsive, his head should be positioned and airway should be opened by performing the Triple Airway Manoeuver (Head tilt-Chin lift-Jaw thrust).
Supporting Breathing
Breathing is assessed by looking at the chest for any respiratory movements, listening or feeling for breathes sounds. If there are no breathing efforts, initially 2 rescue breaths are provided. In absence of any equipment, mouth to mouth or nose resuscitation remains the best method. The aim is to deliver small volume (400-600 ml) over 1-2 seconds with cricoid pressure if possible.The earlier practice of delivering large volume of air (800-1200 ml) is no longer recommended.Ventilation, Chest Compressions Even when the first three defibrillation attempts fail, the best chance of resuscitation still lies in successful defibrillation. Airway is secured by endotracheal intubation if skills are available or,otherwise, by a laryngeal mask airway or a combitube. Ventilation is commenced with 100 per cent oxygen. Fifteen compressions and 2 ventilations are given for a minute and defibrillation is tried again. Once airway is secure by intubation or a laryngeal mask airway, uninterrupted chest compressions should be carried out, without pausing for ventilations. The rate of compression should be 100/minute and ventilation should be carried out at 12 breaths/minute.Supporting Circulation No longer than 10 seconds should be spent in assessing circulation. Pulse check for lay rescuer has now been de-emphasized since it takes time and accuracy is only 65 per cent. External chest compressions can produce peak systolic pressure of 60-80 mm of Hg. In adults, a ratio of 15:2 (15 chest compressions followed by 2 artificial breaths) has been adopted for a single rescuer as well as two rescuers performed external chest compressions can produce in children the rate of compression should be maintained close to 100/minute or roughly 2 per second.
Defibrillation
This step is the key to survival. The survival rate is 90 per cent if the patient is defibrillated within 1 minute and only 10 per cent if it is delayed till 10 minutes after arrest. In an adult, one should start with 200 J and increase the energy to 360 J after two shocks. In case of biphasic defibrillators, continuing energy of 200 J is considered optimal. In children, the energy requirement is calculated at the rate of 2-4 J/kg. The optimal paddle sizes are 13 cm (adults), 8-10cm (children) and 4.5-5 cm (infants). The standard paddle position is where one electrode is placed over the right side of upper part of sternum just below clavicle and the other one is placed over the apex.
Advanced Cardiac Life Support
ACLS is best done in a hospital or at the scene by expert paramedical personnel if significant delay is anticipated in transfer of the victim to the hospital. The tasks performed during this phase, include continuation of BLS, use of equipment for ventilation and circulation, 12 lead electrocardiography (ECG) and arrhythmia recognition, establishment of intravascular access and drug therapy and lastlyprehospital fibrinolytic therapy for acute coronary syndromes (ACS) and stroke in certain advanced healthcare setups. Venous access in CPR drugs are used with an aim to improve organ perfusion and to protect brain and heart from hypoxia, to facilitate defibrillation and to prevent recurrence of arrhythmias and to normalize metabolic derangements.
Vein Access
A Vein access is important during CPR. Even though a central venous line is ideal, its placement takes time, expertise and it has the potential to interrupt the process of CPR. Therefore, the next best option is a peripheral line. It has been shown that circulation time can be significantly reduced if 20 ml of saline is pushed after a drug bolus in a peripheral line. The other routes of drug delivery are tracheal, intra-osseous and even intra-cardiac/nasal/ Femoral. The tracheal route deserves special mention. The drug (2-3 times the intravenous dose) is diluted in 10 ml of saline and instilled in the tube, followed by 5 ventilations. Intraosseous route may be tried in children in the same dosages as those for the tracheal route. Intra-cardiac, nasal or femoral routes are no longer recommended and instilled in the tube, followed by 5 ventilations. Intraosseous route may be tried in children in the same dosages as those for the tracheal route. Intra-cardiac, nasal or femoral routes are no longer recommended.
Pharmacotherapy
Vasopressors
Adrenaline or epinephrine enhances cerebral and myocardial blood flow by preventing arterial collapse and by augmenting aortic diastolic pressure through alpha 1 and 2 receptors. The optimal dose is 1 mg every 3-5minutes. In children, it can be given in the dosages of 10 μg/kg or 0.1ml/kg of 1 in 10000 solution. Dose dependent improvement in regional myocardial and cerebral blood flow has been recorded in various studies but no improvement in hospital discharge and survival has been seen vasopressin.As a single bolus of 40 U, vasopressin has been recommended as an alternative to epinephrine in VF/pulseless VT refractory to defibrillation. Further studies are required to evaluate the efficacy of this drug. Vasopressin acts on non-adrenergic V1 receptors and has been recommended in case of fibrillatory arrest (40IU, single dose). The studies have recorded several advantages over adrenaline such as lack of beta effect, no impact of acidosis on its efficacy and even lower incidence of post resuscitation myocardial dysfunction.
Antiarrhythmic Agents
Contribution of lignocaine during arrest, to aid resuscitation from refractory VF remains uncertain. Lignocaine is an alternative in this situation if amiodarone is not available. Other problems associated with it are increase in defibrillation threshold, higher incidence of asystole after its use and a very delicate toxic to therapeutic ratio. Second choice behind amiodarone and procainamide. Amiodarone is useful in treatment of both atrial and ventricular arrhythmias. It is now recommended during ACLS after defibrillation and adrenaline. The dose is 150 mg diluted in 20 ml of 5 per cent dextrose given over 10 min, followed by infusion @1 mg/min for 6 hours and then @ 0.5 mg/min.
Sodium-bicarbonate (NaHCO 3 )
There is no definite recommendation regarding its use in cardiac arrest. Whenever possible,bicarbonate therapy should be guided by the bicarbonate concentration or calculated base deficit obtained from blood gas analysis. Sodium-bicarbonate is definitely indicated if there is hyperkalemia and tricyclic antidepressant toxicity and pre-existing metabolic acidosis. Calcium (Ca++) usually has no role unless patient presents with calcium channel blocker toxicity or if there is evidence of hypocalcemia or hyperkalemia. The dose of calcium gluconate is 0.5 ml/kg (maximum – 20 ml) of 10 per cent solution whereas 10 per cent solution of calcium chloride can be given in a dose of 0.2 ml/kg upto a maximum of 10 ml.
Magnesium
(Mg++) mirrors the action of extra cellular potassium in stabilizing myocardial cell membrane and it is indicated only if hypokalemia or hypomagnesaemia is known to be present or the patient is diagnosed to be having a rhythm called “Torsade de Pointers”. The dose (as magnesium sulphate) is 1-2 gm diluted in 100 ml of 5 per cent dextrose given over 30-60 min followed by an infusion of 0.5-1.0 gm/hour.
Atropine
Enhances automaticity and conduction of both sinoatrial and atrio-ventricular node and is most effective in haemodynamically significant bradycardia because of vagal stimulation. It also has a role in slow pulse less electrical activity (PEA). The recommended dose in PEA and asystole is 1.0 mg IV and repeated 3-5 minutes if required. For bradycardia, the dose is 10 μg/kg repeated every 3-5 minutes up to a total dose of 40 μg/kg.
Assessment of CPR and When to Stop?
Termination of CPR efforts can be a difficult decision to make. It is apparent from the literature that prolonged resuscitative efforts are unlikely to be successful if there is no return of spontaneous circulation within 30 minutes of commencement of CPR.
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