29.2.1. Medical Considerations
188.8.131.52. Is the Patient at Acute Risk of Suffering Harm?
Hemodynamics and gas exchange must be included in the assessment of the acute need for emergency treatment. While an SpO2 of 87% is certainly abnormally low, it might not impose an acute danger to the patient on the short term. Two factors are important: whether the patient has organs at risk of hypoperfusion (and thus cellular hypoxia) and if sufficient oxygen carrying capacity exists to compensate for lower oxygen saturation.
Oxygen-carrying capacity (or oxygen delivery) depends on cardiac output, hemoglobin concentration, and hemoglobin oxygen saturation. The patient was slightly anemic (Hgb 110 g/dL), although with an increase in heart rate from 81 to 105 beats per minute following development of the cuff leak, some compensation had occurred by increasing cardiac output to maintain oxygen delivery.
The patient was not known to have coronary artery or cerebrovascular disease; he had no specific risk factors and was thus unlikely to have hypoperfusion of vital organs. As such, a borderline SpO2 could be tolerated for a short period of time.
It was concluded that this patient needed urgent troubleshooting, but not necessarily an emergency ETT exchange, allowing a carefully planned procedure to prevent further harm.
184.108.40.206. Which Are the Management Options for Treatment?
In a prospective multicenter study involving 426 patients, Boulain1 reported that self-extubation occurred in 46 patients (11%), and 18 of these patients did not require reintubation. Therefore, it is necessary to assess the patient's ability to breathe unassisted and determine the need for further ventilatory assistance. While it is possible that a subgroup of self-extubated patients not yet capable of completely breathing on their own may be amenable to noninvasive ventilaton (NIV), this patient's halo frame precluded NIV due to technical constraints.
Indicators for the ability to ventilate include respiratory rate, the patient's work of breathing, and gas exchange. In this patient, an increase in heart and respiratory rate and the decrease in SpO2, combined with clearly visible usage of accessory muscles of respiration indicate the need for further ventilatory support. His respiratory failure was likely multifactorial, including the aspiration pneumonia as well as compromised intercostal and diaphragmatic muscular function due to his high spinal cord injury. As the patient needed further ventilatory assistance, an ETT exchange was indicated.
29.2.2. Airway Considerations
220.127.116.11. What Should Be the Initial Management?
First, the patient should be placed on FiO2 of 1.0 to improve oxygenation. This increased the SpO2 to 91%, which helped to buy some time to adequately prepare for the procedure. Also, even though the leak prevailed, some degree of minute ventilation remained, as not all of the delivered tidal volume escaped and the patient continued spontaneous breathing efforts.
An attempt can be made to reestablish ventilation by fixing the pilot line. However, in this case, the line had multiple tears and could not be fixed.
Alternative approaches in the case of life-threatening hypoxemia should aim to temporarily restore oxygenation until a definitive airway can be placed. The existing tube, if ineffective, can be removed and the patient's respiratory efforts assisted with bag-mask-ventilation. Ventilation can be improved by use of an oropharyngeal airway. However, in most cases, even with a leaky cuff, some ventilation can be maintained by hyperventilating with high flows and respiratory rate (>30 breaths per minute), mimicking high-frequency ventilation.
The high-frequency oscillation (HFO) mode of ventilation can provide sufficient oxygenation even with a cuff leak. Indeed, during routine use of HFO, a cuff leak is sometimes purposefully used to improve ventilation. It is an ideal rescue maneuver in a situation where a patient desaturates and cannot be ventilated by other means. This option could be considered before a leaky tube was removed. HFO would be the preferred technique in this situation if a patient had profound gas exchange impairment, such as ARDS, to be used until arrangements for safe ETT exchange were made.
There should always be alternatives at hand in case the first attempt to reintubate the patient fails following removal of the faulty ETT. These can follow the ASA algorithm for the difficult airway and might include, but are not confined to, smaller ETTs, alternatives to DL, an appropriately sized EGD, and cricothyrotomy equipment. More help should be obtained as a difficult situation such as this can always be better managed with additional medical and nursing staff. Calling for additional expertise is not a sign of incompetence, but of professionalism!
18.104.22.168. How Might the Presence of a Halo Jacket Impact Airway Management?
The presence of a halo jacket can impact all facets of airway management. In this case, the trachea of the patient was first intubated by awake bronchoscopic intubation, and a direct laryngoscopic view had not been assessed thereafter. The halo jacket fixes the head in a neutral position, and prevents any flexion or extension of the neck (Figure 29-1). With direct laryngoscopy (DL), it is likely that at best a Cormack/Lehane (C/L) Grade 3 view will be achieved. Tracheal intubation is more likely to succeed with alternatives to DL, such as flexible or rigid fiber- or video-optic devices (see Chapters 9 and 10). Should intubation fail and the patient require oxygenation by positive pressure ventilation between attempts, BMV could also prove challenging due to decreased head extension, and for the same reason, EGD insertion may be difficult. Finally, cricothyrotomy is usually performed with the head extended, so this can also be expected to be somewhat more difficult in the patient with a halo jacket.
In this agitated and uncooperative patient, it is unlikely that an awake look DL assessment under topical airway anesthesia and light sedation will be an option. Alternative approaches must be considered.
22.214.171.124. What Other Risks Are Inherent in This Situation?
Enteral nutrition imposes an additional risk for aspiration while the airway is unprotected. Enteral feeds should be stopped immediately and the feeding tube suctioned to clear as much gastric content as possible.
An already agitated patient may well get more delirious if ventilatory support suddenly stops and hypoxemia develops. Sedation will also be needed to allow the patient tolerate the tube exchange procedure. On the other hand, should reintubation fail during tube exchange, preservation of spontaneous ventilation will add a margin of safety. When practical, nonpharmacological ways of calming the patient (talk-down and reassurance with the help of additional staff) cannot be overestimated. If needed, short-acting drugs such as propofol are preferred.
The reasons for the patient's continuing need for mechanical ventilation are weakness and pneumonia. Weakness alone as a cause of respiratory failure could be treated by noninvasive ventilation (NIV). However, in this case, severe agitation is a contraindication to NIV and as previously suggested the halo jacket will cause difficulty with its application. Pneumonia on the other hand causes edema, atelectasis, and ventilation-perfusion mismatch, resulting in hypoxemic respiratory failure. To aggravate the situation, the loss of PEEP due to the cuff leak will lead to even more atelectasis formation in unstable regions. Furthermore, functional residual capacity (FRC) will be reduced, increasing the patient's susceptibility to hypoxemia. As the combination of these factors increases the risk of hypoxemia within minutes, tube exchange should not be deferred for long.
Although a leak is clearly audible, other significant alterations of the airway should be anticipated. Mucosal swelling from inflammation and general edema, as well as displacement of tissue from the previous trauma may cause physical impediment to the placement of a new ETT or total obscuring of laryngeal inlet anatomy after the defective tube is removed.