Basic life support (BLS) is the component of the immediate care provided for the victims of life-threatening conditions, leading to cardiac arrest and injuries till the patient can be shifted to a hospital. It can be given by doctors, nurses, paramedics, or even by the trained bystanders.
The brain is very sensitive to hypoperfusion. Therefore, the main objective of BLS is to restore cerebral perfusion at the earliest.
Survival after a cardiac arrest depends on the effective implementation of the following steps called chain of survival.
- Prompt recognition of cardiac arrest and immediate activation of emergency response system.
- Early initiation of cardiopulmonary resuscitation (CPR) with particular emphasis on chest compressions.
- Rapid defibrillation.
- Initiation of advanced life support.
- Effective postcardiac arrest care.
The American Heart Association (AHA) periodically revises the guidelines for BLS and advanced cardiac life support (ACLS). The 2015 AHA guidelines laid emphasis on the following:
- Sequence of BLS: Circulation–Airway–Breathing (C–A–B)
- High-quality CPR
- Use of naloxone intramuscular or intranasal in suspected opioid overdose
- Use of defibrillator for witnessed cardiac arrests as soon as possible.
BASIC LIFE SUPPORT/CARDIOPULMONARY RESUSCITATION FOR ADULTS
Basic life support consists of the following main parts:
- Chest compressions
Overview of Initial Basic Life Support Steps (Table 1.1)
- Assessment and scene safety.
- Remove victim from the hazardous environment to a place where care may be provided without putting the victim or BLS provider at a risk of harm.
- Look for response and breathing pattern. If there is no response and the victim is not breathing or gasping, shout for help.
- Check the victim's carotid pulse (take at least 5 seconds but no more than 10 seconds) (Fig. 1.1).
- Activate the emergency response system and get an automatic external defibrillator (AED) if available and return to the patient.
- Start CPR. Perform five cycles of chest compressions and breaths (30:2), starting with compressions (C–A–B sequence).
High-quality CPR improves a victim's chance of survival. The BLS provider should follow these critical characteristics of chest compressions while providing high-quality CPR (Fig. 1.2):
- Start compressions within 10 seconds of recognition of cardiac arrest.
- Allow complete chest recoil after each compression.
- Minimize interruptions in compressions (try to limit interruptions to <10 seconds).
- In case of lay rescuer or sole rescuer present, compression only CPR is sufficient.
- Give effective breaths that make the chest rise.
In an unresponsive patient, the airway may be occluded due to the decreased tone of the tongue and pharyngeal muscles. There are two methods of opening the airway to provide rescue breaths (Table 1.2 and Figs. 1.3A and B).
- Avoid pressing deeply into the soft tissue under the chin as this may block the airway
- Avoid using the thumb to lift the chin
- Do not close the victim's mouth completely.
Respiratory arrest is a condition where the patient's respiratory efforts are either inadequate to maintain oxygenation or completely absent.
Management of a respiratory arrest includes the following components:
- Administering oxygen
- Keeping the airway open using basic airway adjuncts
- Suctioning if necessary to clear secretions
- Providing basic ventilation using bag mask equipment
- Securing an advanced airway
- Identifying the cause.
Basic Airway Adjuncts
In unresponsive patients, the tongue can fall back and obstruct the airway due to loss of tone of the throat muscles. This can be prevented by the basic airway opening techniques (head tilt–chin lift or jaw thrust). In addition to this, two basic airway adjuncts (oropharyngeal airway or nasopharyngeal airway) can be used to facilitate ventilation during resuscitation (Fig. 1.4).
These are indicated only in unconscious patients and come in various sizes. The correct size should be chosen for each patient for maximum benefit and to minimize complications like oral trauma.
- Choose the correct size: It should be the distance between the first incisor and the angle of the mandible.
- If it is too large, it may close the glottis and close the airway.
- In adults: insert the tube with the concavity upwards and then rotate it to 180° when it touches the back of the throat.
- In children and infants: insert the tube with the concavity downwards while using a tongue depressor to hold the tongue forward.
- It is contraindicated in conscious patients as it can induce a gag resulting in vomiting.
- Choose the correct size: It should be the distance between the tip of the nose and the earlobe.
- It is inserted through one of the nostrils after lubricating it with an anesthetic jelly. Push it till the flared end is at the nostril.
- It can be inserted in semiconscious patients.
- It is contraindicated in patients with base of skull fractures and nasal bleeds.
- Ventilation may be provided mouth-to-mouth or mouth-to-nose
- A mask or an improvised device (such as a rolled up board) may be used
- Give two rescue breaths after every 30 compressions
- Give sharp rescue breaths, each over not more than 1 second
- Provide enough tidal volume to see the chest rise, avoid excessive ventilation
- In an in-hospital setting, get a bag-mask for ventilation, if available.
Bag-mask ventilation is a very efficient method of temporarily providing positive pressure ventilation.
This device consists of:
- Self-inflating reservoir bag along with a mask;
- A one-way valve which prevents rebreathing the exhaled air
- Oxygen port for supplying supplemental oxygen.
Use the E–C clamp technique to bag-mask a patient (Table 1.3). If done properly, it is as effective as a secured airway. Bag-mask ventilation can be done by one or two people (Fig. 1.5).
The following are the steps involved in bag-mask ventilation:
- Place mask on the victim's face. Use an airway adjunct if available.
- The nasal end of the mask should cover the bridge of the nose, not extending over the eyes; the body of the mask should cover the nose and mouth, and the other end not extending beyond the chin.
- Hold the mask using a single hand E–C technique or with both the hands (preferred) if an additional rescuer is present.
- Apply firm pressure, forming a good mask seal.
- Ventilate using a volume just sufficient to cause chest rise (not more than 8–10 mL/kg).
- Squeeze the bag steadily over a second. Avoid explosive squeezing.
- Connect bag mask device to reservoir bag with O2 supply if available.
- Give two ventilations after every 30 compressions for patients without an advanced airway.
- Give asynchronous ventilation every 8–10 seconds (6–8 per minute) to patients with an advanced airway in place.
Basic life support for adults is explained in Flowchart 1.1.
BASIC LIFE SUPPORT/CARDIOPULMONARY RESUSCITATION FOR CHILDREN (CHILDREN FROM 1 YEAR OF AGE TO PUBERTY)
The child BLS sequence is similar to the sequence in adults. Following are the key differences:
- Compression-ventilation ratio for two rescuer CPR is 15:2 and for lone rescuer is 30:2
- Compression depth: Compress at least one-third of the depth of the chest, approximately 5 cm (2 inches).
- Compression technique: Can use one- or two-handed chest compressions for very small children.
- Defibrillation dose: 2 J/kg.
- To activate the emergency response system, following points are to be considered:
- In case of unwitnessed arrest and if the rescuer is alone, provide 2 minutes of CPR before leaving the child to activate the emergency response system and get the defibrillator.
BASIC LIFE SUPPORT/CARDIOPULMONARY RESUSCITATION FOR INFANTS
The key points for infant BLS are:
- Pulse check: Feel the brachial artery in infants to check pulse.
- Technique of chest compressions: Two fingers for single rescuer and two thumb encircling hand technique for two rescuers (Fig. 1.6).
- Compression depth: At least one-third the chest depth, approximately 4 cm (1½ inches).
- Compression–ventilation ratio for two rescuer CPR is 15:2 and for lone rescuer, 30:2.
- Defibrillation dose: 2 J/kg.
- To activate the emergency response system, follow the same steps as followed for children.
Basic life support for infants is explained in Flowchart 1.2.
Defibrillation and Cardioversion
- Defibrillation is the nonsynchronized delivery of a shock that depolarizes the entire cardiac tissue into a refractory period, making it unable to sustain or propagate an aberrant circuit. It is performed during a cardiac arrest in a pulseless patient.
- Cardioversion is the delivery of energy that is synchronized to the QRS complex, thus only depolarizing the active circuit causing arrhythmia. It is used to revert arrhythmias in awake patients (Table 1.4).
Monophasic versus Biphasic Defibrillators
- Defibrillators are machines that deliver electrical energy to the heart by monophasic or biphasic waveform technology through paddles applied on the chest wall.
- Monophasic defibrillators deliver the charge in only one direction, from one electrode to the other. They use higher energy, typically 360 J and have many disadvantages. They are no longer used in most EDs.
- Currently, almost all the AEDs, manual and implantable defibrillators use the biphasic waveform technology.
Using an Automatic External Defibrillator
- Read the instructions on the AED
- Stick the pads on the chest wall.
Place the right pad (white) below the right clavicle and the left pad (red) on the left inferior-lateral chest, lateral to the apex.
- If the patient has an open thorax injury, respective pads may be placed on the left and right axilla.
- Turn on the AED and follow the voice prompts.
- The AED will analyze the cardiac rhythm and will deliver defibrillation if a shockable rhythm is present.
Using a Manual Defibrillator
- Turn on the defibrillator to the biphasic mode.
- Select the desired dose of energy (200 J in adults, 2 J/kg in children).
- Remove paddles, apply gel on the paddles.
- Charge paddles using the charge button on the paddles or on the device.
- Place paddles over the chest wall. (Sternal paddle below the right clavicle and apex paddle on left lateral chest wall.
- Resuscitation team should stay clear of contact, oxygen circuit should be disconnected.
- Deliver shock by using the discharge button on the paddles or on the device.
- Resume CPR immediately; do not pause to check pulse/electrical rhythm soon after the shock.
Cardioversion Using a Manual Defibrillator
- Turn on the defibrillator to the biphasic mode.
- Select the desired dose of energy (50–200 J).
- Remove paddles, apply gel on the paddles. Pads may also be used, if available.
- Place paddles/pads over the chest wall. (Sternal paddle below the right clavicle and apex paddle on left lateral chest wall).
- Turn on the synchronized mode.
- Resuscitation team should stay clear of contact and oxygen circuit should be disconnected.
- Keep paddles on contact while holding discharge till shock is delivered.
- Check pulse and electrical activity immediately after the shock.
- If arrhythmia persists, repeat the cardioversion with higher doses.