Extubation series, Part 1: Weaning

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Danelle Howard
Registered Respiratory Therapist, cross-trained in the Pulmonary Lab, caring for critically ill patients one breath at a time. Professional interests: mechanical ventilation, capnography, and waveforms.

The Pre-brief

A common question I am asked while precepting is, “How do I know when to start the weaning process and when to extubate?” As an extubationist, I prefer to start SBT first thing in the morning before multi-disciplinary rounds. Weaning with the intent of extubation should be the ultimate goal as delays in extubation can cause complications associated with poor outcomes, such as longer length of hospital days, excessive sedation, VILI, and infection.

What are non-physician weaning protocols?

Weaning is the process of decreasing ventilator support with the end goal of extubation. A spontaneous breathing trial (SBT) assesses the patient’s ability to breathe while receiving minimal or no ventilatory support. Weaning protocols managed by non-physician clinicians have been proposed as best practice according to 2001 clinical practice guidelines. The respiratory therapists and bedside nurses can facilitate the weaning process without delay, such as waiting for multi-disciplinary rounds. The respiratory therapist, in collaboration with the bedside nurse, should begin the spontaneous awakening trial (SAT) with the SBT making it a combined protocol. The SAT provides clinicians with the most accurate assessment for the need of sedatives. A study by Girard et al. showed that when the SAT and SBT were paired, the mechanical ventilation days were reduced, ultimately reducing the hospital length of stay by four days when compared with not combining the SAT and SBT into the same protocol. 

It is important to note that conducting SBT while the patient is on minimal sedation has been associated with improved outcomes, including reduced mortality. Dexmedetomidine can safely be used in the agitated patient during the weaning process for comfortability until extubation. 

Best Practice 

  • Daily assessment which includes 
  1. Reversal of underlying cause
  2. Oxygen requirements are <.50 and PEEP <8 with adequate oxygenation
  3. Hemodynamically stable
  4. Intact respiratory drive with the ability to initiate spontaneous breaths
  5. +cuff leak test 
  6. Improved chest x-ray 
  • Perform an SAT, which includes, but is not limited to, improved mental status and neuromuscular improvement. For example, being able to follow commands and lift the head off the bed. 
  • Once the daily assessment and the SAT are met, SBT can begin for a minimum of 30 minutes but no more than 120 minutes. Excessive weaning can cause fatigue. 

Monitor 

  • Respiratory rate 
  • Respiratory distress 
  • Oxygenation
  • Mental status
  • Hypercapnia
  • Cardiac rhythm
  • Blood pressure 
  • Rapid Shallow Breathing Index (RSBI) <105

When to wean 

Weaning begins with assessing the ability of the patient for an SBT. A collective task force facilitated by the American College of Chest Physicians, the American Association of Respiratory Care, and the American College of Critical Care Medicine stated that “once the underlying process that necessitated mechanical ventilation is resolved, SBT and weaning should start.” This could be done by T-piece trial, CPAP, or PS.  

Failure to wean 

Not all patients will meet the criteria to wean. This does not necessarily mean that they cannot be successfully weaned. Approximately 20% to 30% percent of patients are difficult to wean. Special considerations, finding out the reason for the difficulty, and a patient-specific approach can be made. 

The Debrief

  • The use of a combined SBT and SAT weaning protocol results in better outcomes.  
  • The Cochrane systematic review showed that protocols led to shorter total mechanical ventilation days with fewer side effects, shorter duration of weaning, and ICU length of stay.  
  • Weaning predictors are parameters that are intended to help clinicians predict whether weaning attempts will be successful or not and are not absolute. 

Click here for The Vitals: When to Pull the Tube by Dr Ramaswamy

References

  1. Girard, T., Singh, J., & Hargett, K. Spontaneous Awakening and Breathing Trials / 19. HTTPS://www.scam.org/getattachment/86464100-4b13-4da5-b3d1-39a9a4cceb64/Spontaneous-Awakening-and-Breathing-Trials.

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