BLS

BLS refers to the core competency live-saving skill set of CPR, activation of the emergency response system, and expedient use of an automated external defibrillator (AED). BLS certification is offered to the public and is required for healthcare providers with variations in management suggestions based on level of training and comfort. Any person found unresponsive or with absent or gasping/agonal breath sounds should be suspected to be in cardiac arrest (IIa/C-LD). Pulse checks by a healthcare provider in this setting should last at most 10 seconds (II/C). If the person cannot be aroused, the AHA guidelines for CPR and emergency cardiac care stress immediate activation of the emergency response system for out-of-hospital arrests and initiation of chest compressions to provide Circulation prior to Airway management and Breathing, or C-A-B. This was changed from A-B-C in 2010 to emphasize the initial focus on restoring circulation based on survival studies. The C-A-B sequence emphasizes circulation first to minimize delays in chest compressions associated with establishing a patent airway. Beginning with chest compressions may also increase likelihood that bystanders will perform CPR on persons who have suffered from SCA as lay persons may find airway management challenging and hesitate to initiate CPR. In fact, the guidelines changed in 2017 to emphasize that untrained lay rescuers may provide compression only CPR (I/C-LD), and dispatchers should offer compression-only CPR instructions (I/C-LD). Lay persons trained in CPR should still add rescue breaths when trained or able. For lone rescuers, the public is taught the “phone first/phone fast” rule. For adults, children aged 8 years and older, and all children known to be at high risk for arrhythmias, the emergency medical system (911; EMS) should be activated (phone first) before attempts at resuscitation by a lone rescuer. An initial resuscitation attempt followed by the activation of EMS (“phone fast”) is indicated for children less than 8 years old and for all ages in cases of submersion or near drowning, arrest secondary to trauma, and drug overdose. Owing to the increased rate of unresponsiveness secondary to opioid overdose, family members are recommended to have naloxone available to administer in coordination with alerting EMS.

1. Circulation (chest compressions). It is estimated that chest compressions can provide up to one-third of the normal cardiac output. To ensure sufficient circulation, especially coronary and cerebral flow, compressions should occupy a minimum 60% of the arrest event time (IIb/C-LD) with a target of 80% and minimal pauses between shocks (I/C-LD). The patient should be on a firm surface, preferably a backboard when possible, and flat with their head at the level of the thorax. This is especially true in an OR where the soft surgical table padding/gel absorbs energy from compressions, which can decrease their effectiveness. For a prone, intubated patient in the OR who cannot be quickly turned supine for CPR, one member can place a clenched fist between the subxiphoid area and the OR table with compressions over the corresponding region of the back (IIb/C). Proper positioning involves placing the heel of your hand in the center of the patient’s chest at the intermammary line with the heel of the other hand on top of the first so that the hands are overlapped and parallel (IIa/B). Shoulders can be positioned directly over the patient and elbows locked. The chest should depress to a minimum 2 inches in adults (I/C-LD) and at least one-third of the anterior-posterior chest diameter for pediatric patients (roughly 2 inches in children, 1.5 inches in infants) (IIa/C-LD). For children, single responders can use the heel of one or both hands (IIb/C). In infants, single responders should use a two-finger technique, whereas the two-thumb encircling hands technique is used with multiple responders (IIb/C). The chest compression rate should be at least 100/min, and allow for complete chest recoil by targeting equal compression and relaxation times (IIb/C). While rate and depth tend to err on the lower side, compressions quality can also suffer from being too deep or too fast, thus upper bounds of 2.4 inches for depth and 120 for rate were introduced. Given this notably small range of 2 to 2.4 inches (5-6 cm), compression feedback devices that optimize performance should be used when available (IIb/B-R). The target compression-ventilation ratio is 30:2 for single responders with two breaths being delivered over less than 10 seconds (IIa/C-LD). With two or more people, the 30:2 ratio is preserved, and providers should switch every 2 minutes (five cycles) in less than 5 seconds (IIa/B). In children, the compression-ventilation ratio is 15:2 when there are two rescuers to reflect the more respiratory driven arrest incidence. If an advanced airway such as an endotracheal tube (ETT) or laryngeal mask airway (LMA) is in place during two-rescuer CPR, ventilations should be given at a rate of 10 breaths/min simultaneously with compressions without pauses. Another described maneuver is the precordial “thump” whereby the rescuer slams the underside of their fist to the mid-sternum to depolarize the heart. This maneuver can be considered for monitored patients with unstable or pulseless VT if a defibrillator is not immediately available (IIb/C), although this method of triggering depolarization with swift mechanical impulses should not be used to “pace” the heart.
2. Airway and breathing. Although recent guideline changes have focused on circulation (all the way to compression-only CPR), maintaining a patent airway with adequate ventilation and oxygenation remains critical (I/C). It becomes more vital as arrest time increases owing to exhaustion of alveolar oxygen reserve and accumulation of carbon dioxide. Spontaneous ventilation is evaluated by observation and auscultation and aided by repositioning, most commonly through a head tilt-chin lift technique (IIa/B). If a cervical spine injury is suspected based on the scene or nature of injury, a jaw thrust without head extension should be attempted (IIb/C), although if unsuccessful at establishing airway patency, a head tilt should still be used (I/C). If ventilation remains impossible after these maneuvers and an advanced airway is not available, efforts to clear the airway of a suspected foreign body should be attempted. In primary foreign body obstruction, abdominal thrusts (Heimlich maneuver) should be attempted ( IIb/B) and chest thrusts considered when unsuccessful (IIb/B). This differs for infants for whom back blows are delivered in succession with chest compressions for foreign body obstruction. When an adult has spontaneous circulation by palpable pulses but ineffective breathing alone, rescue breaths should be provided 10 to 12 times per minute or every 5 to 6 seconds (IIb/C). Breaths should be delivered over 1 second with enough volume for visible chest rise, roughly 500 to 600 mL in adults (IIa/C). Rescue breaths during cardiac arrest should be similarly provided over 1 second with visible chest rise. In the absence of an advanced airway, compressions are briefly paused for breaths at the 30:2 ratio whether there are one or more providers. With an advanced airway in place, breaths should be given every 6 seconds (10/min) concurrent with compressions as mentioned above. Hyperventilation (III/B) in any setting from excess respiratory rate or tidal volume should be avoided as it can cause gastric insufflation provoking aspiration and, more importantly, it can increase intrathoracic pressure, impair venous return, and lower cardiac output, which ultimately worsens outcomes.
3. Defibrillation in BLS refers to the use of AEDs, which should be retrieved as part of the initial activation of the emergency response system. Timely defibrillation and CPR are major determinants of a successful resuscitation. Defibrillation is the definitive management for pulseless VT and VF (I/A). When an arrest is witnessed and an AED is within reach, the defibrillator should be used as soon as possible (IIa/C-LD). For unwitnessed arrests, CPR should be initiated while the AED is being retrieved (IIa/B-R). Public access defibrillation programs have enabled public safety professionals (eg, fire personnel, police, security guards, and airline attendants) to employ readily accessible AEDs. The devices themselves are small and lightweight and use adhesive electrode pads for both sensing and delivering shocks. Visual and voice prompts are provided to assist the operators with the goal of making it usable by an untrained bystander. After analysis of the frequency, amplitude, and slope of the ECG signal, the AED advises either “shock indicated” or “no shock indicated.” The AED is manually triggered and does not automatically defibrillate the patient as an automatic shock could injure someone touching the patient. AEDs are now also equipped with pediatric pad-cable systems that attenuate the adult dose to a smaller dose appropriate for children. The dose attenuators should be used in children less than 8 years of age and less than 25 kg in weight. For infants, manual defibrillation is recommended, but if unavailable, an AED with or without an attenuator can be used. There are efforts to make AED analysis more sophisticated such as incorporating artifact filtering so that compressions can be continued during rhythm analysis. At this point, these technologies are not reliable enough to promote (IIb/C-EO).
4. Reassessment. Although it is tempting to see if the defibrillation worked by checking for a pulse immediately after a shock, the heart still needs time to establish sufficient forward flow and compressions should be resumed immediately after shock delivery (IIb/C-LD) with a rhythm check after five cycles of CPR (2 minutes). For healthcare providers, if there is evidence of a perfusing rhythm, the pulse can be checked to determine if there is ROSC. If a nonshockable rhythm or no pulse is detected, CPR should be resumed with rhythm checks after every five cycles as before.