Canadian Anaesthetists' Society journal
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Large-volume low-pressure cuffs have been introduced in an endeavour to reduce the incidence of tracheal mucosal damage. These cuffs when inflated to clinical seal develop folds, which together with low clinical seal pressure may not protect against aspiration. ⋯ The incidence of dye tracking past the large-volume cuffs studies was 100 per cent whereas no aspiration of dye was seen past the red rubber tubes. Increasing cuff pressure in the large-volume cuffs beyond clinical seal to 50 cm H2O did not obliterate the dye-filled cuff folds, despite wide variation in the thickness of the cuff material.
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Randomized Controlled Trial Clinical Trial
Cardiovascular effects of non-depolarizing neuromuscular blockers in patients with coronary artery disease.
To compare haemodynamic responses associated with equipotent doses of muscle relaxants and high dose fentanyl (50 micrograms X kg-1), 40 non-hypertensive patients who were receiving beta adrenergic and calcium channel blocker therapy and undergoing coronary bypass surgery were randomized to four study groups receiving the following: (1) atracurium: 0.4 mg X kg-1, (2) pancuronium: 0.12 mg X kg-1, (3) vecuronium: 0.12 mg X kg-1, or (4) pancuronium-metocurine mixture: (0.4 mg + 1.6 mg X ml-1):1 ml/10 kg. Neuromuscular blockers were injected with fetanyl at induction. Haemodynamics were recorded with the patients awake (baseline), at two minutes post-induction, and at two and five minutes after intubation. ⋯ The pancuronium-metocurine mixture caused tachycardia which was less than, though not significantly different than with pancuronium; however, HR returned to baseline by five minutes with the mixture, but remained elevated with pancuronium (3 vs. 18 per cent, p less than 0.05). SVR fell more on induction with atracurium when compared to vecuronium (-18 vs. 1 per cent, p less than 0.05). These changes in HR or SVR were not accompanied by ECG signs of ischaemia.(ABSTRACT TRUNCATED AT 250 WORDS)
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In general, the cardiovascular system is more resistant to the toxic actions of local anaesthetics than is the central nervous system. However, if sufficient doses and blood levels of local anaesthetics are achieved, signs of profound cardiovascular depression may be observed. Differences exist between local anaesthetics in terms of their relative potential for cardiotoxicity. ⋯ However, large dosages of chloroprocaine solutions administered intrathecally have been associated with prolonged sensory-motor deficits in a few patients due probably to the low pH and presence of sodium bisulfite in the chloroprocaine solutions. In general, the incidence of toxic reactions to local anaesthetic agents is extremely low. However, as with any class of pharmacological agents, local anaesthetics may cause severe toxic reactions, due usually to the improper use of these drugs.