Fig. 42.1
Ten-year-old girl with neurofibromatosis status post spinal cord tumor resection, extubated with a vital capacity of 180 ml and no ventilator-free breathing ability, using a 15-mm angled mouthpiece (Malincrodt-Puritan-Bennett, Pleasanton, CA, USA) for ventilatory support
Table 42.1
Extubation criteria for continuously ventilator-dependent patients
Diagnosis of neuromuscular weakness (including critical care ventilatory failure) with inability to pass spontaneous breathing trials or autonomously breathe Afebrile Normal white blood cell count Absence of fixed airway obstruction due to upper motor neuron disease |
Oxyhemoglobin saturation ≥95 % for 12 h or more in ambient air All oxyhemoglobin desaturations <95 % reversed by mechanical insufflation-exsufflation via translaryngeal tube |
Fully alert and cooperative, receiving no sedative medications |
Chest radiograph abnormalities cleared or clearing Sufficient air leakage via upper airway for verbalization upon tube cuff deflation Normal PaCO2 at peak inspiratory pressures <35 cm H2O with the cuff deflated |
Successful extubation of continuously ventilator-dependent patients with no ventilator-free breathing ability was achieved using the following protocol. Normal alveolar ventilation was maintained and MIE used (pressures 40 to 70 cm H2O to −40 to −70 cm H2O with exsufflation-timed abdominal thrust) via the translaryngeal tube as needed until O2 sat remained ≥95 % in ambient air for 12 h or more. Once spontaneous breathing trials were failed but extubation criteria were met, the nasogastric tube was removed if present to facilitate immediate postextubation NVS. The VC was measured. The patient was then extubated directly to NVS on pressure control 18–20 cm H2O or assist/control mode 800–1500 ml delivered volumes and backup rate of 10–12/min. The NVS was provided via mouthpiece [19], nasal, or oronasal interface. The patients using mouthpiece NVS kept 15 or 22 mm angled mouthpieces accessible to their mouths (Fig. 42.1). Patients weaned themselves, when possible, by taking fewer and fewer mouthpiece IPPVs as tolerated. Diurnal nasal IPPV was used for children and for those who could not grab or retain a mouthpiece because of oral muscle weakness, inadequate jaw opening, or insufficient neck movement. Being open systems, the patients took as much of the delivered volumes as needed for comfortable alveolar ventilation. No supplemental oxygen was used. For episodes of SpO2 < 95 %, the following were evaluated: ventilator positive inspiratory pressure (PIP), interface air leak, CO2, and ventilator settings.
The success in extubating patients with little or no measurable CPF was the result of a variety of factors, but the experience of our respiratory therapists and the patients’ families with NVS and MIE was the most important factor. We relied on family members to provide MIE every 20–30 min as needed post extubation until the O2 sat no longer dipped below 95 %. Such a regimen simulates normal coughing frequency during episodes of bronchitis and pneumonia. The aggressive use of MIE via the endotracheal tube was the main intervention that resulted in normalization of SpO2 in ambient air, the most important criterion for extubation, and increasing VC [18].
Generally, pressures of 40 to 60 cm H2O to −40 to −60 cm H2O were also used with an exsufflation-timed abdominal thrust post extubation. Thus, the hospital staff and patients’ care providers used oximetry as feedback to maintain O2 sat ≥95 % by MIE and NVS. Extubation was only considered successful if the patient was discharged home without requiring reintubation.
Ventilator-dependent patients with NMD can only achieve successful extubation by using full NVS and MIE. Because of our extubation success rates for unweanable NMD patients, we no longer consider tracheotomy for ventilator-dependent patients with NMD who can be made to satisfy Table 42.1 criteria and now offer extubation and decannulation even to those with CPF < 160 l/m.
42.4 Decannulation of Unweanable Patients
Any patient with an indwelling tracheostomy tube who has understandable speech when the tube cuff is deflated is evaluated for decannulation. Patients without severe speech and swallowing impairment are usually good candidates. The ability to effect glottic closure and maintain airway patency during a cough is critical for successful decannulation. Unweanable patients for whom CPF can approach 160 l/m by manually assisted coughing (air stacking then a cough-timed abdominal thrust) [20] or by using MIE via the upper airway with the tracheostomy tube capped and those with experience in using NVS are strong candidates for decannulation, even if inspiratory and expiratory muscles are completely paralyzed.
If CPF via the upper airways with a capped fenestrated tracheostomy tube present is much lower than 160 l/m, the tube is removed, at least temporarily, and the ostomy covered. This decreases obstruction to upper airway airflows, permits greater assisted CPF, and facilitates the use of NVS as well as autonomous breathing. If, despite air stacking and coordinated abdominal thrusts, CPF levels still fail to approach 160 l/m, vocal cord paralysis, hypopharyngeal collapse, tracheal stenosis, or other reasons for airway obstruction are considered and the patient is referred for fiberoptic evaluation of the upper airway to eliminate possible reversible causes of upper airway obstruction.
Any nasogastric tube that is present is removed before decannulation. The patient is decannulated directly to full NVS and a pressure dressing is placed over the ostomy until the skin is closed (Fig. 42.2) (Tegaderm, 3M Company, St. Paul, MN, USA) [21–25]. Upon decannulation, most patients with VCs greater than 250 ml wean to nocturnal-only NVS [9, 21]. All patients transferred from continuous TMV to NVS prefer NVS overall and for safety, convenience, swallowing, speech, appearance, and comfort [15]. Noninvasive management also minimizes cost and facilitates return to the community rather than long-term institutionalization [26]. Whereas tracheostomized ventilator users will always be afraid of asphyxia from ventilator failure and accidental disconnection, two-thirds of NVS users with no inspiratory or expiratory muscle function and little or no measurable VC can be taught glossopharyngeal breathing for security in the event of ventilator malfunction or loss of access to the NVS interface [22, 23, 27]. The need to decannulate TMV users to NVS can be avoided, however, if unweanable patients are extubated without resort to tracheotomy. We have decannulated more than 200 continuously ventilator-dependent patients without a single failure [3, 16, 20, 22, 23]. In some cases, our decannulated and extubated continuously ventilator-supported cases have depended on NVS for more than 60 years for prolonged survival [28]. Unfortunately, few centers decannulate continuously ventilator-dependent patients [23–25].
Fig. 42.2
Twenty-six-year old man with Duchenne muscular dystrophy transferred for extubation after failing three extubations over a 26-day period. He used a 15-mm angled mouthpiece, as in Fig. 42.1, for daytime ventilatory support and a lip seal phalange with nasal prongs (Hybrid, Teleflex Medical, Research Triangle Park, NC, USA) for nocturnal ventilatory support
Finally, after years of debate and consensus conferences of “experts” whose knowledge of noninvasive ventilation is limited to CPAP and the use of low-span bi-level PAP for patients with “sleep-disordered breathing,” a Centers for Disease Control panel of respiratory experts and other consensus groups have recommended that NVS be used long term for up to 24 h per day ventilator dependence [29, 30]. Despite the fact that our center has managed more than 100 CNVS dependent DMD patients and has not needed to resort to tracheotomy to prevent respiratory mortality for DMD patients in more than 30 years, it has taken this long for recognition of the fact that, even in the absence of inspiratory or expiratory function, these patients can be managed noninvasively. No informed NMD patient, trained in NVS and MIE, prefers to undergo tracheotomy [15]. However, family and caregiver involvement in providing NVS and MIE is important for long-term success. The only appropriate indications for tracheotomy are failure of NVS and MIE to maintain normal O2 sat because of continuous saliva aspiration and irreversible upper airway obstruction resulting from upper motor neuron lesions. In our experience, this only occurs in patients with advanced bulbar ALS or severe central nervous system disease.
Related posts:
Predictive Models of Prolonged Mechanical Ventilation and Difficult Weaning
Postoperative Continuous Positive Airway Pressure (CPAP)
Noninvasive Mechanical Ventilation in Postoperative Spinal Surgery
BiPAP for Preoxygenation During Reintubation in Acute Postoperative Respiratory Failure
Discharge Planning of Neuromuscular Patients with Noninvasive Mechanical Ventilation After Difficult Weaning from Invasive Mechanical Ventilation: From ICU to Home Care
Organization of a Weaning Unit
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