Cardiac Arrest Airway Management

Introduction

  • Cardiac arrest involves loss of systemic circulation and functional cardiac activity.
  • It's managed in prehospital and emergency department settings.
  • Up to 450,000 patients annually experience out-of-hospital cardiac arrest (OHCA) in the United States.
  • Less than 9% of patients with OHCA survive to discharge.
  • Less than 7% survive to discharge with favorable neurologic status.
  • Management includes:
    • Cardiopulmonary resuscitation (CPR) with high-quality chest compressions.
    • Early defibrillation in shockable rhythms.
    • Ventilation and oxygenation.

Discussion

Initial Airway Management Strategy

  • Classic "Airway-Breathing-Circulation” (A-B-C) approach has shifted; resuscitation now focuses on circulation (“C-A-B”).
  • Prioritize CPR and defibrillation of shockable rhythms.
  • In the first minute after non-asphyxial cardiac arrest, prioritize compressions and defibrillation over ventilation.
  • Studies show similar outcomes (survival to discharge, 30-day survival) with compression-only CPR compared to standard CPR.
  • Airway management and ventilation become more important as resuscitation continues.
    • Hypoxemia, hypercapnia, and acidemia can have deleterious effects.
  • In patients with antecedent hypoxia or respiratory cause of cardiac arrest, airway management with ventilation is crucial.
  • A step-wise approach to airway management is necessary.
  • Focus on evaluating airway patency and removing any airway obstruction while ensuring adequate oxygenation and ventilation.
  • Specific airway strategy varies based on personnel and resources.
  • In non-asphyxial cardiac arrest, perform the minimum airway intervention that allows oxygenation and ventilation until return of spontaneous circulation (ROSC).
  • May start with compression-only CPR or bag-valve-mask (BVM) ventilation.
  • Cardiac arrest results in muscle tone loss, which may lead to airway obstruction.
    • Ensure a patent airway using head tilt, chin lift, or jaw thrust.
    • Nasopharyngeal and oral airways may also improve airway patency.
  • BVM ventilation is the most readily accessible modality for delivering breaths during resuscitation in those without a definitive airway.
  • During CPR, an advanced airway may be placed for ventilation based on setting and provider skills.
  • Prioritize high-quality compressions throughout the resuscitation.

Breath Delivery During CPR

  • Rescue breathing serves to ventilate an unconscious patient.
    • Can be performed mouth-to-mouth or with BVM.
  • Patients without an advanced airway: 30 compressions followed by 2 respirations (30:2 ratio).
    • Compressions should be paused for ventilations and then restarted immediately.
  • Patients with an advanced airway (supraglottic airway [SGA] or endotracheal tube [ETT]): one asynchronous ventilation every 8–10 s.
    • These do not need to be coordinated with compressions.
  • Each ventilation (with or without advanced airway) should be short (less than 1 s), with enough tidal volume for chest rise.
    • Approximately 500–600 mL in adults.
  • Avoid excessive ventilation.
    • High ventilatory rates or tidal volumes increase intrathoracic pressure.
    • Reduces venous return, cardiac output, and cerebral and coronary perfusion pressures.
    • Overventilation is associated with lower defibrillation success and overall survival.
  • Resuscitation team leader must closely monitor the provider performing ventilations to ensure appropriate technique, rate, and amount.

Bag-Valve-Mask (BVM) Ventilation Considerations

  • BVM is the most readily available modality to provide ventilation in cardiac arrest.
  • BVM ventilation is associated with improved outcomes compared to advanced airway in OHCA patients.
  • BVM is not a secure airway; may increase risk of gastric insufflation and aspiration.
  • Two-person BVM strategy is recommended for improved mask seal.
  • A patent airway is necessary for BVM ventilation.
    • May necessitate use of a nasopharyngeal airway (NPA) or oropharyngeal airway (OPA).
  • A positive end-expiratory valve should be added to the BVM circuit.
  • Important components that improve BVM efficacy include:
    • Mask seal
    • Patient positioning
  • One-person BVM is possible using the C-E finger position.
    • Thumb and second finger form a “C” over the mask, other three fingers pull the mandible to the mask.
    • Provides a mask seal, jaw thrust, and chin tilt.
  • Two-person BVM strategy provides greater seal and is associated with improved outcomes.
    • One rescuer uses either a double-handed C-E approach, or all four fingers on both hands to perform a jaw thrust/chin tilt while their thumbs and thenar eminence are placed over the mask, which forms a V-E seal.
    • The latter approach results in less hand and finger fatigue for the provider.

Advanced (Invasive) Airway

  • An advanced airway may include an SGA or ETI.
  • Advantages:
    • Improved oxygenation and ventilation.
    • Reducing the risk of aspiration of gastric contents.
    • Allows for continuous compressions during ventilation.
    • Requires fewer providers to ensure proper airway seal and patency.
  • Placement can result in interruptions in chest compressions and other resuscitative efforts.
    • Clinician inserting an advanced airway must ensure placement does not result in significant interruption in chest compressions.
  • Recommended in:
    • Asphyxial cause of arrest
    • Prolonged arrest or transport
    • Cases managed with limited experienced personnel
  • Variety of SGA devices available:
    • Laryngeal mask airway (LMA)
    • iGel
    • King LT
    • Combitube
    • Esophageal tracheal airway
  • First generation SGAs, such as the LMA Classic, contain a single breathing port.
  • Second-generation SGAs have features that improve the airway seal or have a second channel for gastric aspiration, which reduce the risk of aspiration.
  • Advantages of SGAs:
    • Reduced need for training compared with ETI.
    • Less required equipment compared to ETI.
    • Ability to be placed blindly without vocal cord visualization while high-quality compressions are ongoing.
  • SGAs may reduce the risk of aspiration compared with BVM ventilation but can be associated with greater risk of air leak and aspiration compared to ETI, even with second-generation devices.
  • If air leak is present with an SGA, a 30:2 compression to ventilation ratio should be considered.
  • If ETI is performed during cardiac arrest, the most experienced provider should perform the intubation and must ensure they do not interrupt chest compressions.
  • ETI is recommended for those with a respiratory cause of arrest or if ventilation is inadequate with BVM or SGA.
  • 2019 International Liaison Committee on Resuscitation (ILCOR) guidelines suggest using an SGA if an advanced airway is utilized for patients with OHCA in settings with a low ETI success rate.
    • High success rate defined as greater than 95 % success rate after two ETI attempts.
  • However, in settings with high ETI success rate, either SGA or ETI may be utilized.
  • 2020 Advanced Cardiac Life Support guidelines emphasize that providers should master one advanced airway technique for the primary approach and a second technique as backup.
  • Placement of an advanced airway should not interrupt chest compressions, and if ETI is performed, ETT confirmation is required.

Video Laryngoscopy (VL) vs Direct Laryngoscopy (DL)

  • Video laryngoscopy (VL) has become increasingly utilized for ETI over the last two decades.
  • VL devices project an image of the airway to the provider using a lighted camera at the end of the laryngoscope blade.
  • VL devices may include traditional geometry devices, hyperangulated devices, and channeled devices.
  • In OHCA, VL was highly successful in obtaining first pass success (97.3%) and was associated with fewer interruptions in chest compressions.
  • Based on the available data, VL is associated with improved glottic view and higher overall and first pass success rates when compared to DL, as well as fewer adverse events and interruptions in compressions.
  • Individual clinician should utilize the device in which they are most comfortable and experienced.

Cricoid Pressure During Intubation

  • Traditionally, cricoid pressure during ETI was considered as a means to reduce gastric insufflation and the risk of aspiration.
  • However, there is currently no evidence that cricoid pressure assists with ventilation or intubation or decreases the risk of aspiration in patients with cardiac arrest.
  • Cricoid pressure can prevent adequate ventilation and reduce the likelihood of success placement of SGA or ETT, and airway trauma may also occur.
  • Guidelines do not recommend the routine use of cricoid pressure for airway management in CPR.

ETI Confirmation

  • A variety of techniques can be used for ETT confirmation, including:
    • Chest rise
    • Auscultation of breath sounds
    • Condensation of the ETT
    • Direct visualization
    • Capnography
    • Point-of-care ultrasound (POCUS)
  • Qualitative or quantitative capnography is commonly used; sensitivity decreases in those with cardiac arrest due to decreased systemic perfusion (62–70 %). Quantitative waveform capnography demonstrates four phases with a value with an appropriately placed ETT, while digital capnometry provides a number but not a waveform.
  • POCUS is a reliable and rapid modality to confirm ETI.
  • Assessing for chest rise, auscultation of breath sounds, condensation of the ETT, and direct visualization should not be used in isolation to confirm ETI.
  • Quantitative waveform capnography demonstrates high sensitivity and specificity when ROSC is present but has lower sensitivity during cardiac arrest.
  • POCUS demonstrates high sensitivity and specificity regardless of the presence of ROSC.
  • POCUS and capnography should be utilized in cardiac arrest, though capnography should be interpreted with caution given limitations in the absence of ROSC.

Mechanical Ventilation

  • Following placement of an advanced airway, a maximum of 10 breaths per minute should be provided with simultaneous CPR for patients in cardiac arrest.
  • In an average-sized adult, a tidal volume of 500–600 mL can provide adequate minute ventilation and avoid gastric insufflation.
  • Overventilation during cardiac arrest increases tidal volume, which raises the intrathoracic pressure.
  • A mechanical ventilator may be utilized for ventilation during cardiac arrest rather than manual ventilation.
  • Following ROSC, guidelines recommend use of a lung protective ventilation strategy (4–8 mL/kg ideal body weight with lower plateau pressures and appropriate PEEP).
  • A PaCO2PaCO_2 level between 35 and 55 mmHg is recommended.
  • Avoid hypocapnia.
  • During cardiac arrest, 100 % FiO2FiO_2 should be administered if available based on current guidelines.
  • In post-ROSC patients, literature suggests hypoxia is associated with reduced survival to hospital discharge; hyperoxia may be associated with increased mortality.
  • Base on the current evidence and guidelines, a lung protective strategy of ventilation is recommended while titrating ventilator settings to maintain a PaCO<em>2PaCO<em>2 between 35 and 55 mmHg and the FiO</em>2FiO</em>2 to maintain an oxygen saturation of 92–98 %.
  • Hypoxia and hyperoxia should be avoided.

Conclusion

  • CPR includes high-quality chest compressions and ventilation.
  • Resuscitation must prioritize circulation with high-quality compressions, but airway management is often necessary to provide ventilation as the resuscitation continues.
  • BVM is effective for ventilation during CPR efforts with a compression to ventilation ratio of 30:2.
  • Breaths should be provided over less than 1 s, with a tidal volume that causes chest rise, while avoiding overventilation.
  • Either an SGA or ETT may be placed, but this must not interrupt compressions.
  • In settings with high ETI success rate, ETI can be performed, but SGA is otherwise recommended if an advanced airway is needed.
  • VL is associated with an improved glottic view and higher first pass success.
  • Cricoid pressure is not recommended by guidelines.
  • ETI should be confirmed with capnography or POCUS.
  • A lung protective strategy of ventilation is recommended with avoidance of hypoxia in patients who are mechanically ventilated.