Removal of an endotracheal tube (tracheal extubation) should be carried out in an environment with adequate supervision and highly qualified personnel with a sufficient share of experience who have the necessary equipment.
- Significant depression of consciousness and the absence of protective reflexes (swallowing and coughing);
- The risk of aspiration of gastric contents in a patient unconscious;
- General anesthesia;
- The impossibility of providing airway patency with other methods;
- The need for mechanical ventilation, cardiopulmonary resuscitation.
Impossibility of appropriate laying of the patient (injuries of the face and neck, limitation of mobility of the cervical spine, etc.). In such cases, tracheal intubation using a fiber bronchoscope is sometimes necessary, conicotomy may be an emergency intervention, and tracheotomy may be an operation of choice (insertion of a tube directly into the trachea through the neck tissue).
Predicting the outcome of extubation is extremely important since both premature and unsuccessful extubation can end fatally. Nevertheless, there is practically no literature on the subject, with the exception of several sources citing the methods of this kind of forecasting. Unsuccessful extubation is not a sign of poor preparation of the doctor since repeated intubation may be necessary both immediately after extubation and after some time and be the result of many reasons, including the deterioration of the initial condition or the development of concomitant pathology. Nevertheless, observation before extubation must be carried out, especially in terminal patients, when the probability of reintubation is high. Clinical protocols, in this case, include close monitoring of the patient after extubation, rapid identification of respiratory disorders and the same rapid reintubation or tracheostomy. Thus, unsuccessful extubations can be regarded as indicators of monitoring the quality of care and patient monitoring.
Determination of preparedness for extubation
The endotracheal tube should be removed as soon as the patient no longer needs artificial support for airway patency. Clinically, the signs of the primary cause of respiratory failure should soften, the patient should be able to perform normal spontaneous ventilation and gas exchange.
Extubation of patients with respiratory failure is carried out using the following criteria:
- the ability to maintain normal blood saturation of O2 and the ratio of PaO2 and FiO2 more than 150 – 200 when the O2 content in the inhaled mixture is not more than 40 – 50% and the level of PEEP is not more than 5 – 8 mbar;
- the ability to retain the pH of arterial blood and the content of carbon dioxide on the exhale in the range of normal values;
- successful passage of a test for spontaneous breathing at 30 – 120 min, conducted at a PEEP level of 5 mbar, with a low support pressure of 5 – 7 mbar, with a normal level of gas exchange and hemodynamic stability;
- in adults, the frequency of spontaneous respiration during extubation should not exceed 35 per minute;
- adequate respiratory muscle strength should be determined;
- the largest negative inspiratory pressure is more than –30 mbar (today it is recognized more than –20 mbar);
- VC more than 10 ml / kg (in newborns more than 150 ml / kg);
- spontaneous minute ventilation (MV) in adults on expiration is 10 ml / kg;
- CROP-index (compliance, resistance, oxygenation, and ventilating pressure) above the threshold of 0.2 – 0.15 15 mL x mm Hg / respiration / min / kg;
chest compliance of more than 25 ml / cm H2O;
- respiratory work less than 0.8 J / l;
- the oxygen price of breathing is less than 15%, it is especially important for chronic respiratory failure requiring prolonged mechanical ventilation;
- the dead space / tidal volume (VD / VT) ratio is less than 0.6, and in children – less than 0.5 – indicates a pre-estimated probability of successful extubation at 96%;
- the occlusal pressure in the airways in the first 0.1 s is lower than 6 cm H2O, which, when normalized to the highest inspiratory pressure, indicates the likelihood of successful extubation in 88% and 98%, respectively;
- in premature infants, the introduction of testing compared to a standard clinical examination led to a reduction in the time to extubation;
- peak flow on expiration after 3 cough attempts of more than 60 l / min;
- in newborns, the total respiratory compliance (obtained from the VT / PIP-PEEP ratio) of less than 0.9 mL / cm H2O was associated with unsuccessful extubation, when a value of more than 1.3 mL / cm H2O was associated with a favorable prognosis;
- integrated indicators of the measured vital capacity of the lungs (VC, boundary value = 635 mL), the ratio of respiratory rate to tidal volume (f / VT, boundary value = 88 breaths / min / L) and the highest expiratory pressure (MEP, boundary value = 28 cm H2O).
In addition to treating respiratory failure, artificial airways sometimes serve as airway protection. The need for such protection can be assessed by the following criteria:
- adequate level of consciousness;
- adequate protective reflexes from the respiratory tract (reduced cough strength, 0–2 points), evaluated using the “white card test”, indicates a high
- probability of unsuccessful extubation;
- uncomplicated secretion removal.
In addition to resolving processes that require respiratory protection, the following should be considered:
- finding a patient in the ICU;
- age over 70 years or under 24 months;
- severe general condition;
- hemoglobin less than 100 g / l;
- use of extended iv sedation;
- the need for frequent sanitation of the respiratory tract;
- loss of protective reflexes from the respiratory tract;
- congenital conditions associated with instability of the spine (for example, trisomy 21);
- limited physical access to the respiratory tract;
- history of multiple unsuccessful attempts at intubation;
- age up to 6 months;
- medical history of preterm birth;
- congenital heart disease with formed pulmonary hypertension;
- the presence of airway obstruction or laryngeal edema, determined by the reduction of leakage past ETT during ventilation with positive pressure.
The percentage of leakage or the difference between the expiratory tidal volume with a swollen and deflated cuff is more than 15.5%. The test did not prove its predictive value in cardiac surgery patients.
Air leakage may be an age-dependent prognostic indicator of post-extubation stridor in children older than 7 years but is not prognostically significant in children younger than this age.
Air leakage can be used as a prognostic criterion for post-extubation stridor in children with anatomical respiratory tract disorders: traumatological, with croup, after tracheal surgery.
- The presence of stable hemodynamics;
- The presence of stable non-respiratory functions;
- Normal values of plasma electrolytes;
- Evidence of malnutrition causing respiratory muscle weakness;
- Anesthetic literature indicates that the patient should not take anything by mouth before extubation.
The issue of continuing transpyloric tube feeding during the procedure is controversial.
Prophylactic medication before extubation to reduce the likelihood of reintubation:
- consider the need for lidocaine to prevent coughing and laryngospasm after extubation;
- the use of corticosteroids, pursuing preventive purposes, is justified in newborns but not in older children;
- prophylactic use of steroids can reduce the incidence of post-extubation stridor in children but not in newborns, and especially not in adults;
- prophylactic administration of corticosteroids with croup correlates with a lower frequency of reintubation;
- caffeine reduces the risk of apnea in young children, but does not reduce the frequency of unsuccessful extubation;
- methylxanthines stimulate respiratory rate and reduce the likelihood of developing apnea in newborns with reduced respiratory drive, especially in those born with low body weight.
After extraction of the endotracheal tube, the patient should adequately breathe through the natural airways, saturation should be within the normal range and there should be no need for tracheal reintubation.
The clinical outcome of extubation can be assessed by physical examination, auscultation, invasive and non-invasive assessment of gas exchange or chest x-ray. The quality of the procedure is assessed through extended monitoring and systematic verification of indications for reintubation. The quality of the procedure as a whole can be estimated by the frequency of unsuccessful extubations and by the frequency of reintubation.
When the patient was extubated on his or her own and there is no need for re-intubation, this suggests that planned extubation should be performed earlier. After extubation, some patients may need non-invasive respiratory support.
Non-invasive respiratory support
Infants who received non-invasive nasal respiratory support with positive inspiratory pressure after extubation showed a significantly lower incidence of unsuccessful extubation compared to those who received nasal constant positive airway pressure (CPAP).
In newborns and premature babies, CPAP through binasal catheters are more effective than through mono-catheters. Routine use of post-extubation non-invasive ventilation in adults is discouraged. In patients with COPD, a post-extubation CPAP of 5 mbar with support for inspiratory pressure of 15 mbar improved gas exchange and decreased pulmonary shunt, reduced respiratory function.
Post-extubation drug therapy
A left-epinephrine aerosol is as effective as epinephrine racemate in treating post-extubation laryngeal edema in children. There are no randomized trials confirming the effect of epinephrine racemate in post-extubation stridor in newborns.
Heliox can relieve symptoms of partial airway obstruction, improve patient comfort, reduce breathing, and prevent the need for reintubation.
Patients with developed post-extubation complications are prescribed bronchoscopy, which is used to establish the level of obstruction and also perform local therapeutic interventions (remove the secret, introduce drugs, remove the foreign body).
Tracheal extubation components
Extubation of a patient implies the readiness of personnel for immediate re-intubation and the availability of all necessary equipment for this.
The following instruments and preparations should always be available in the ICU for tracheal extubation.
- a constant source of oxygen (stationary supply, cylinders or oxygen concentrator);
- devices for inhalation O2;
- vacuum aspirator and sterile catheters of various sizes;
- Ambu bag or respiratory fur from anesthesia apparatus;
- facies masks of all sizes;
- air ducts of various shapes (all that are possible from stock in ICU);
- endotracheal tubes with cuffs and without them of all sizes;
- a complete set for tracheal intubation (laryngoscope, blades, spare batteries, conductors, lubricant, syringe for inflating the cuff);
- laryngeal masks of different sizes;
- a set for emergency tracheostomy (scalpel, local anesthetics, epinephrine, tubes);
- nasogastric tubes;
- pulse oximeter;
- cardio monitor;
- sets for arterial puncture with the purpose of analysis of the SAC;
- sedative, intravenous anesthetics, muscle relaxants, drugs to lower ICD;
- it is desirable to have a simple anesthesia apparatus with a seasoned vaporizer (fluorotan).
Requirements for ICU staff:
- personnel should be specially trained and have all the necessary skills for extubation and emergency reintubation and tracheostomy;
- personnel must know the technique of all the manipulations described above;
- personnel must be technically trained to work with the equipment.
Monitoring in the post-extubation period is designed to ensure the timely response of staff to any emergency situations. Personnel should be constantly prepared to assist with impaired breathing or circulation.
A frequent assessment of respiratory function is essential and includes physical signs, an assessment of neurological status, airway patency, hemodynamic status, and auscultation.
- pulse oximeter;
- heart monitor;
- apparatus for measuring blood pressure;
The causes of hypoxemia after extubation can include:
- inability to deliver sufficient tidal volume via natural airways;
- acute airway obstruction due to laryngospasm;
- post-extubation edema of the respiratory tract;
Typical (basis) causes of hypercapnia after extubation:
- airway obstruction due to edema of the trachea, vocal cords or larynx;
- the weakness of the respiratory muscles;
- increased work of breathing;