Juan Pablo Zhenlio, MD
Background
Identifying patients ready for extubation can prevent unnecessarily prolonged intubations and its associated complications:
-ventilator associated pneumonia, lung injury
-wasting of respiratory muscles
-increased sedation requirement
-direct airway trauma related to endotracheal tube/airway suctioning
-venous thrombosis
-pressure wounds
Resource consumption can also be reduced significantly as the mean incremental cost of mechanical ventilation in intensive care unit patients was 1,522 dollars per day in a large database review. https://www.ncbi.nlm.nih.gov/pubmed/15942342
It should be part of a patient’s daily assessment to identify candidates for extubation. Acceptable rate of failure of extubation in the ICU is about 10%. Lower rates of failure likely mean unnecessary prolonged intubations.
Why is the patient intubated? How difficult was the intubation?
Was the patient intubated for airway protection/decreased mental status and has the risk of airway compromise resolved?
We have a lot of TBI patients and intubate in the emergency room for GCS of 8 or less. But we also intubate patients with GCS of 9-14 if it will expedite the workup or we feel they cannot protect their airway. Extubating TBI patients or those with altered mental status is quite subjective and requires a careful review of whether they will protect their airway. An attending should be consulted about these decisions.
Has the underlying disease process improved that led to acute respiratory failure? (i.e. sepsis, pneumonia/pneumonitis, pancreatitis, traumatic injury, neuromuscular disorder)
If the process has improved extubation should be considered. It is important to be aware that the patient may have been weakened by the process though and have lost significant chest wall and diaphragm strength.
How difficult was the intubation? Mallampati score, airway/cervical edema, maxillofacial trauma, multiple provider attempts at intubation, need for special equipment for intubation?
Here the intubation procedure note or the anesthesia record needs to be reviewed as you never want to extubate a patient before knowing how difficult it was to place the tube. Extra caution should be made with patients with cervical collars, halos or recent cervical spine operations.
Extubation criteria
Assess mental status off sedation, calculate GCS score
-awake and arousable
-follows commands
-ability to raise head off pillow
-will patient be able to cough respiratory secretions and protect the airway from aspiration after extubation
Assess for stable hemodynamics and acid/base status
-minimal pressor requirements
-arterial pH > 7.25
Assess respiratory status and ventilatory settings. Evaluate patient for adequate oxygenation and ventilation on FiO2 0.4 and PS 5-10 cm, PEEP 5-8 cm
-SpO2 >90%
-evaluate PaO2 to FiO2 ratio
-rapid shallow breathing index(RSBI)
Briefly on RSBI-This index captures multiple elements that are required for a patient to maintain after extubation. It is a ratio of RR/tidal volume. Very quickly it allows a crude assessment of chest wall strength and respiratory system compliance. RSBI ≥105 breaths/min/L is better at identifying patients who will fail weaning than an RSBI <105 breaths/min/L is at identifying patients who can be successfully weaned. See the UpToDate entry on RSBI which also includes the original references: https://www.uptodate.com/contents/weaning-from-mechanical-ventilation-the-rapid-shallow-breathing-index
Extubating to BiPAP in COPD and the obese
Extubating to BiPAP in COPD patients is a well researched and accepted concept to reduce extubation failure. BiPAP may also be useful in morbidly obese patients but there is not significant literature yet to support it.
Extubation failure
-Monitor closely for signs of poor oxygenation or a decline in mental status
-Patients who are >65 years old, chronic cardiac or respiratory disease have elevated risk of extubation failure. Other risk factors include pneumonia and a positive fluid balance during the 24 hrs preceding extubation.
-Follow the respiratory rate-a steadily rising RR is one of the most common signs of extubation failure.