Tracheal intubation

Pulmonary Normal breath sounds, undergoing tracheal intubation for mechanical ventilation CV ECG shows sinus tachycardia, otherwise normal Abd Within normal limits... 

Does the patient have an adequate airway and ventilation (hemoglobin saturation greater than 92%) If not, trained emergency personnel should consider performing tracheal intubation with initiation of mechanical ventilation. 

Consider tracheal intubation in cases of respiratory compromise. Treat patients who have bronchospasm with aerosolized bronchodilators. Use these and all catecholamines with caution because of the enhanced risk of cardiac dysrhythmias after exposure to some chemicals. When bronchodilators are needed, the lowest effective dose should be given and cardiac rhythm should be monitored. After decontamination, patients who are comatose,... 

Halothane is non-irritant and can be inhaled at high concentrations to produce rapid, smooth induction of anaesthesia. It obtunds the protec five pharyngeal and laryngeal reflexes. At deeper planes, tracheal intubation may be performed. Halothane has a pronounced bronchodilating action and this may be an advantage in patients with chronic obstructive airways disease. Both tachypnoea and slowing of respiration may be observed at deeper planes of anaesthesia. 

Local anaesthetics can be applied topically, deposited around peripheral nerves, or infiltrated into tissues. Central neural blockade can be produced by injection into the subarachnoid or epidural spaces. Less common uses are for intravenous regional anaesthesia and attenuation of cardiovascular responses to tracheal intubation. The membrane-stabilising effect of local anaesthetics has been utilised in the treatment of myocardial arrhythmias. 

Maximum block after suxamethonium develops in 60-90 seconds following a dose of 1 mg-kg-1 (about 3xED95) with a duration of action of 5-10 minutes. This dose provides near ideal intubating conditions in 60-90 seconds. It is because of a rapid onset and a short duration of action that suxamethonium is considered as the ideal agent for facilitating tracheal intubation during rapid sequence induction. 

Bronchospasm is not a direct action of these drugs but blockade of p-receptors increases the reactivity of the airway and increases the likelihood of bronchospasm during laryngoscopy and tracheal intubation. It is also possible that the severity, and possibly the incidence of acute anaphylaxis is increased in patients on large doses of 3 blockers and that resuscitation may be hampered in these circumstances. 

Bronchospasm occurs in more than half of the more severe hypersensitivity reactions, either on its own or as an accompaniment to other changes. It is more common, as one would expect, in asthmatic patients and in patients receiving muscle relaxants (where tracheal intubation may be a factor). It should, however, only be regarded as indicative of a reaction if other forms of airway obstruction and other causes of tracheal irritation have been excluded. 

Etomidate is a carboxylated imidazole that can be used for induction of anesthesia in patients with limited cardiovascular reserve. Its major advantage over other intravenous anesthetics is that it causes minimal cardiovascular and respiratory depression. Etomidate produces a rapid loss of consciousness, with minimal hypotension even in elderly patients with poor cardiovascular reserve. The heart rate is usually unchanged, and the incidence of apnea is low. The drug has no analgesic effects, and coadministration of opioid analgesics is required to decrease cardiac responses during tracheal intubation and to lessen spontaneous muscle movements. Following an induction dose, initial recovery from etomidate is less rapid (< 10 minutes) compared with recovery from propofol. 

Seizures induced by local anesthetics are usually treated with intravenous anesthetic drugs (eg, thiopental 1-2 mg/kg, propofol 0.5-1 mg/kg, midazolam 0.03-0.06 mg/kg). The muscular manifestations of a seizure can be blocked using a short-acting neuromuscular relaxant drug (eg, succinylcholine, 0.25-0.5 mg/kg IV). It should be emphasized that succinylcholine does not alter the CNS manifestations of local anesthetic-induced seizure activity. Rapid tracheal intubation can prevent pulmonary aspiration of gastric contents and facilitate hyperventilation. 

Myxedema coma is a medical emergency. The patient should be treated in the intensive care unit, since tracheal intubation... 

Adrenocortical function has been assessed in a randomized trial after intravenous etomidate in 30 patients who required rapid-sequence induction and tracheal intubation (402). The controls received midazolam. Etomidate caused adrenocortical dysfunction, which resolved after 12 hours. 

Rap id onset of action makes rocuronium useful for tracheal intubation in patients with gastric contents. 

Grover, V. K., Sharma, S., Mahajan, R. P, and Singh, H. (1987), Intranasal nitroglycerin attenuates pressor response to tracheal intubation in beta-blocker treated hypertensive patients, Anesthesia, 42, 884-887. 

In 113 patients undergoing general anesthesia, intravenous midazolam 15 mg slowed recovery of the twitch height after vecuronium and atracurium compared with diazepam. The recovery index was not altered (162). However, in another study in 20 patients, midazolam 0.3 mg/kg did not affect the duration of blockade, recovery time, intensity of fasciculations, or adequacy of relaxation for tracheal intubation produced by suxamethonium 1 mg/kg, nor the duration of blockade and adequacy of relaxation for tracheal intubation produced by pancuronium 0.025 mg/kg in incremental doses until 99% depression of muscle-twitch tension was obtained (161). Furthermore, in 60 patients undergoing maintenance anesthesia randomly assigned to one of six regimens (etomidate, fentanyl, midazolam, propofol, thiopental plus nitrous oxide, or isoflurane plus nitrous oxide), midazolam did not alter rocuronium dosage requirements (165). 

Intravenous anaesthetics should be given only by those fully trained in their use and who are experienced with a full range of techniques of managing the airway, including tracheal intubation. 

Precautions. Ketamine should be used under the supervision of a clinician experienced in tracheal intubation, should this become necessary. Pulse and blood pressure must be monitored closely. Supplementary opioid analgesia is often required in surgical procedures causing visceral pain. 

Rocuronium is another steroid derivative that has the advantage of a rapid onset of action. After a dose of 0.6 mg/kg tracheal intubation can be achieved after 60 seconds. It has negligible cardiovascular effects and has a similar duration of action to vecuronium. 

Paralysis is preceded by muscular fasciculation, and this may be the cause of the muscle pain experienced commonly after its use. The pain may last 1-3 days and can be minimised by preceding the suxamethonium with a small dose of a competitive blocking agent. Suxamethonium is the neuromuscular blocker with the most rapid onset and the shortest duration of action. Tracheal intubation is possible in less than 60 seconds and total paralysis lasts up to 4 min with 50% recovery in about 10 min (t / for effect). It is particularly indicated for rapid sequence induction of anaesthesia in patients who are at risk of aspiration — the ability to secure the airway rapidly with a tracheal tube is of the utmost importance. If intubation proves impossible, recovery from suxamethonium and resumption of spontaneous respiration is relatively rapid. Unfortunately, if it is impossible to ventilate the paralysed patient s lungs, recovery may not be rapid enough to prevent the onset of hypoxia. 

Only those who can undertake tracheal intubation and ventilation of the patient s lungs should use these drugs. 

Avoid imnecessary stimulation, which may induce rigidity and spasms. The primary treatment for spasms and rigidity is sedation with a benzodiazepine, such as midazolam or diazepam. Additional sedation may be provided with propofol or a phenothiazine, usually chlorpromazine. In severe disease prolonged spasms and respiratory dys-fimction will necessitate tracheal intubation and mechanical ventilation will be required. If the patient has been intubated and sedation alone is inadequate to control spasms, a neuromuscular blocking drug, e.g., intermittent doses of pancuronium or a continuous infusion of atracurium, will be required. 

Mirakhur RK, Lavery GG, Clarke RS, Gibson FM, McAteer E. Atracurium in chnical anaesthesia effect of dosage on onset, duration and conditions for tracheal intubation. Anaesthesia 1985 40(8) 801-5. 

The incidence of adverse events related to an endoscopy sedation regimen that included propofol (in addition to midazolam and fentanyl), delivered by specially trained general practitioners, has been examined in a prospective audit (8) 28 472 procedures were performed over 5 years. There were 185 sedation-related adverse events, 107 with airway or ventilation problems 123 interventions were necessary to maintain ventilation. No patients required tracheal intubation and there were no deaths. The authors concluded that appropriately trained general practitioners encountered a low incidence of adverse events and could safely use propofol for sedation during endoscopy. It should be noted that aU the general practitioners had some experience in anesthesia or intensive care and were individually trained by the Director of Anesthesia. 

A 71-year-old man complained of difficulty in breathing and was desaturated on pulse oximetry for 5 minutes after cervical plexus blockade (89). He required tracheal intubation, was ventilated for 110 minutes, and was then successfully extubated. It was thought that the most likely diagnosis was cardiorespiratory failure exacerbated by phrenic nerve blockade. 

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