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PR47: Critical Care Anesthesia Planning

Applicable To

Introduction

Provision of anesthesia is one of the cornerstones of critical care practice.  The ideal induction agent has a rapid onset of action, minimal side effects, and is cleared quickly so that recovery is rapid.  No induction agent is ideal for all patients and all medications have side effects.  This anesthesia guideline is design around the three phases for intubation: induction, maintenance, and emergence.  These phases can be further divided into the four A’s of anesthesia planning: anesthesia, analgesia, autonomic stability, and areflexia.  The sequencing of medications and the procedure performed is based on the individual patient’s needs and risk factors.

Indications

• Any patient requiring anesthesia for the purpose of intubation, maintenance, or emergence
  • Rapid sequence intubation is indicated for any patient who is at risk of aspiration with induction
• Sedation facilitated intubation
• Clinical scenarios where a difficult airway is suspected
• Delayed sequence intubation
• Patients who will not tolerate an RSI procedure due to an inability to preoxygenate, or tolerate peri-intubation procedures including hemodynamic consequences
• Awake intubation
• Predicted difficult airway
• Unstable cervical spine

Contraindications

• Allergy or sensitivity to the medication
• Lack of equipment necessary to intervene, monitor, and maintain the airway, respirations, hemodynamics, and for any potential interventions
• Lack of trained personnel to perform the procedure safely

Cautions:

Cautions should be based around a risk stratification.  The complexity of risk stratification revolves around whether airway control is emergent, urgent, or elective.  Elements to consider when evaluating an individual patient's risks include: 

• Older age
• Significant comorbidities
• Signs of a difficult airway and whether the patient recently ate should be considered before sedation (these are not contraindications but considerations)
• Any patient that is difficult or likely difficult to ventilate
• Any patient that is hemodynamically unstable or likely to become unstable
• Obesity
• Pregnancy

Procedure

Amnesia

Induction and maintenance of amnesia is incredibly important to the long-term psychological outcomes of patients who undergo ETI.  It can be achieved with the use of:

• Etomidate
• KetAMINE
• ProPOFol
• MIDAZOlam
• Dexmedetomidine

Analgesia

Effective analgesia not only makes the patient more comfortable, but also decreases the amount of post-intubation sedation required to maintain the desired clinical state through pharmacological synergy.  Agents used in maintaining analgesia include: 

• KetAMINE
• FentaNYL
• MORPHine
• HYDROMORphone

Autonomic Stability

Most patients will require some form of hemodynamic resuscitation in the peri-intubation phase.  Hypotension is associated with an increased morbidity and mortality, which is especially true in patients with traumatic brain injuries or right heart syndromes.  Use of tools such as the shock index, in conjunction with clinical judgement, can identify patients at risk of hypotension in the context of endotracheal intubation.  Autonomic stability can be achieved through the use of: 

• Fluid bolus
• PhenyLEPHRine
• EPINEPHrine
• NORepinephrine

Areflexia

Areflexia produces the best laryngoscopic views possible, however it is also fraught with complications and potentially dire consequences.  It also lowers the required dose of sedation.  Deep sedation does not result in areflexia, but rather suppresses any response to stimulus.  Consider the use of:

• Succinylcholine (Depolarizing)
• Rocuronium (Non-Depolarizing)

Adult doses are shown in the table below.  See individual drug monographs for pediatric and expanded dosing strategies.

Goal	Options	Induction (Phase I)	Maintenance (Phase II)	Emergence (Phase III)
Analgesia	MORPHine FentaNYL KetAMINE Hydromorphone	Morphine (2-10mg)   Fentanyl (25-100mcg)   Ketamine (0.25-0.5 mg/kg)   Hydromorphone (0.2-1mg)	Morphine (1-10mg/hr)   Fentanyl (25-200mcg/hr)   Ketamine (0.05-1 mg/kg/hr)   Hydromorphone (0.5-3mg/hr)	See procedural analgesia if required
Amnesia	MIDAZOlam KetAMINE Propofol Etomidate Dexmedetomidine	Midazolam (0.1-0.3 mg/kg) Ketamine (0.5-2 mg/kg) Propofol (1-3 mg/kg) Etomidate (0.3 mg/kg) Dexmedetomidine	Midazolam (0.01-0.1mg/kg/hr) Ketamine (0.2-0.5 mg/kg/hr) Propofol (50-200mcg/kg/min) Dexmedetomidine (0.1-0.8 mcg/kg/hour)	See procedural sedation if required
Autonomic Stability	IV Fluids PhenyLEPHRine EPINEPHrine NORepinephrine DOPamine	IV Fluids (10-20ml/kg) Phenylephrine (50-100 mcg)   Epinephrine (50-100 mcg)   NORepinephrine (5-10 mcg)	IV Fluids (2-4ml/kg/hr) Phenylephrine (0.5-6mcg/kg/min)   Epinephrine (0.01-0.5 mcg/kg/min)   NORepinephrine (5-60 mcg/min)   Dopamine (2-20mcg/min)	IV Fluids (2-4ml/kg/hr)
Areflexia	Rocuronium Succinylcholine Cisatracurium	Rocuronium (0.6-1.2 mg/kg)   Succinylcholine (0.6-1.1 mg/kg)   Cisatracurium (0.15-0.2 mg/kg)	Rocuronium (0.6-1 mg/kg)   Cisatracurium (1-2 mcg/kg/min)	-------------

 

Notes

Resources

References

1. King A. Induction of general anesthesia: Overview. (2020). [Link]
2. King A. General anesthesia: Intravenous induction agents. (2020). [Link]
3. Berkow L. Rapid sequence induction and intubation (RSII) for anesthesia. (2020). [Link]
4. Brown CA. Approach to the anatomically difficult airway in adults outside the operating room.  (2021). [Link] 
5. Sterns RH. Maintenance and replacement fluid therapy in adults. (2019). [Link]