The electrocardiographic and haemodynamic responses to the induction of anaesthesia, followed by laryngoscopy and endotracheal intubation have been studied in a group of 16 untreated hypertensive patients, and a group of 20 patients receiving antihypertensive therapy up to and including the day of operation. The influence of five different induction agents, thiopentone, methohexitone, propanidid, diazepam, and neuroleptanalgesia induced by a combination of phenoperidine and droperidol were compared. Neuroleptanalgesia caused less arterial hypotension than any of the other agents, but afforded only marginally more protection than other agents against hypertension, tachycardia and dysrhythmia associated with laryngoscopy and tracheal intubation. Both propanidid and diazepam caused dramatic but transient hypotension in a small number of patients and were not investigated further. Unlike its effects in normotensive subjects, methohexitone caused greater hypotension than thiopentone in hypertensive patients. The rationale is presented for the prophylactic blockade of beta-adrenergic receptors to prevent hypertensive crises during laryngoscopy and intubation in both treated and untreated hypertensive patients.

Studies of anaesthesia in relation to hypertension ii: haemodynamic consequences of induction and endotracheal intubation

SUMMARY The effects of the new, highly selective alpha2-adrenergic agonist, dexmedetomidine, were studied in a randomized, placebo-controlled, double-blind trial in 24 ASA I patients. Dexmedetomidine 0.6 μg kg−1 or saline was given i.v. 10 min before induction of anaesthesia. The required dose of thiopentone was significantly (P

Dexmedetomidine attenuates sympathoadrenal responses to tracheal intubation and reduces the need for thiopentone and peroperative fentanyl

Reflex cardiovascular effects of laryngoscopy and tracheal intubation in anaesthetized patients have been described previously and include a pressor response, and tachycardia despite the increase in systemic arterial pressure (King et al., 1951). Increased cervical sympathetic activity in the anaesthetized cat following mechanical stimulation of the nasopharynx and epipharyngeal region was recorded by Tomori and Widdicombe (1969); hypertension and tachycardia are common responses in normotensive patients (Dingle, 1966; Forbes and Dally, 1970; Prys-Robertsetal., 1971; Takki et al., 1972; Fox et al., 1977; Lehtinen, Hororka and Widholm, 1984). Although the direct recording of sympathetic nervous activity is difficult in man, measurements of the plasma concentrations of catecholamines have consistently demonstrated increases in noradrenaline following laryngoscopy (Russell et al., 1981; Derbyshire et al., 1983; Marty, Couture and De Champlain, 1983; Cummings et al., 1984) and so confirmed sympathetic mediation in this response. Complications of the pressor response following laryngoscopy include myocardial ischaemia (Prys-Roberts et al., 1971; Roy, Edelist and Gilbert, 1979), cardiac failure and intracranial haemorrhage (Fox et al., 1977), and increases in intracranial pressure (Burney and Winn, 1975). These complications are serious enough in normotensive patients, but

Studies of Anaesthesia in Relation to Hypertension

The cardiovascular response to laryngoscopy and intubation was investigated in lightly anaesthetised patients admitted to hospital for elective intracranial surgery. One group of patients was given fentanyl 5 microgram/kg body weight before induction with thiopentone and suxamethonium. The other group served as controls. Fentanyl treatment caused a significant attenuation of the blood pressure and pulse response to laryngoscopy and intubation. Different techniques for induction of anaesthesia are discussed in relation to the demands of neuroanaesthesia.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2044.1981.tb08676.x

Treatment of stress response to laryngoscopy and intubation with fentanyl

Background: The authors compare three techniques for insertion of the ProSeal ™ laryngeal mask airway.

Methods: Two hundred forty healthy patients aged 18-80 yr were randomly allocated for ProSeal ™ laryngeal mask airway insertion using the digital, introducer tool (IT), or gum elastic bougie (GEB)-guided techniques. The digital and IT techniques were performed according to the manufacturer's instructions. The GEB-guided technique involved priming the drain tube with the GEB, placing the GEB in the esophagus under direct vision, and inserting the ProSeal ™ laryngeal mask airway using the digital technique with the GEB as a guide. Failed insertion was defined by any of the following criteria: (1) failed pharyngeal placement; (2) malposition (air leaks, negative tap test results, or failed gastric tube insertion if pharyngeal placement was successful); and (3) ineffective ventilation (maximum expired tidal volume 45 mmHg if correctly positioned). Any visible or occult blood was noted. Sore throat, dysphonia, and dysphagia were assessed 18-24 h postoperatively.

Results: Insertion was more frequently successful with the GEB-guided technique at the first attempt (GEB, 100%; digital, 88%; IT, 84%; both P < 0.001), but success after three attempts was similar (GEB, 100%; digital, 99%; IT, 98%). The time taken to successful placement was similar among groups at the first attempt but was shorter for the GEB-technique after three attempts (GEB, 25 ± 14 s; digital, 33 ± 19 s; IT, 37 ± 25 s; both:P < 0.003). There were no differences in the frequency of visible blood, but occult blood occurred less frequently with the GEB-guided technique (GEB, 12%; digital, 29%; IT, 31%; both:P < 0.02) but was similar among techniques if insertion was successful at the first attempt. There were no differences in postoperative airway morbidity.

Conclusion: The GEB-guided insertion technique is more frequently successful than the digital or IT techniques. The authors suggest that the GEB-guided technique may be a useful backup technique for when the digital and IT techniques fail.

Gum elastic bougie-guided insertion of the ProSeal laryngeal mask airway is superior to the digital and introducer tool techniques.

SUMMARY In twenty-two normotensive patients anaesthesia was induced with thiopentone, nitrous oxide and oxygen, suxamethonium, and endotracheal intubation. Laryngoscopy and insertion of an endotracheal tube were immediately followed by an average rise in mean arterial pressure of 25 mm Hg (SE 2.2, range 2–45). There was no significant difference in this response between groups premedicated with morphine and with amylobarbitone. There was no evidence that this effect caused lasting damage in normotensive patients. The possible cardiac or cerebral complications which might result in hypertensive patients are discussed.

A. Millar Forbes

Papers

Acute hypertension during induction of anaesthesia and endotracheal intubation in normotensive man