Anesthetics, apnea with

Used as a pretreatment for anesthetic induction with etomidate, fentanyl 500 pg produced apnea in all patients, with a 67% incidence of nausea and a 47% incidence of postoperative vomiting (80). 

Two former preterm infants (postconceptual age 38 weeks) both received spinal anesthetics for inguinal herniorrhaphy (block level T4—6) (197). No other medications were given. Both infants had frequent episodes of perioperative apnea and associated bradycardia. One had a 20-second bout of apnea, with an oxygen saturation of 70% and a heart rate of 80/minute, the other a 30-second bout of apnea, with a saturation of 70% and a heart rate of 60/minute. These episodes persisted for 8 hours into the postoperative period in one of the infants. 

General anesthesia - Remifentanil is not recommended as the sole agent in general anesthesia because loss of consciousness cannot be assured and because of a high incidence of apnea, muscle rigidity, and tachycardia. Remifentanil is synergistic with other anesthetics and doses of thiopental, propofol, isoflurane, and midazolam have been... 

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. 

The efficacy and safety of new inhalation anesthetics has to be evaluated in pharmacological experiments. Robbins (1946) defined the anesthetic AD50 as the concentration of anesthetic at which 50 % of mice failed to right themselves for 15 s when placed in a rotating bottle with a known concentration of anesthetic. The concentration of the anesthetic that caused apnea in 50 % of the mice in 10 min was defined as the LD50 and the ratio LD50IAD50 as and an index of safety. 

A former preterm infant had two awake caudal anesthetics for herniotomy within 3 weeks (84). The first was uneventful with bupivacaine 0.25% at 35 weeks of age. At 38 weeks, the baby had intraoperative and postoperative bouts of apnea after inadvertent administration of bupivacaine 0.125% plus clonidine. 

One of the drugs that is metabolized in the blood is succi-nylcholine, a muscle relaxant that is hydrolyzed by the pseudocholinesterase of liver and plasma to succinyhnono-choline. The short duration of action of succinyhnonocho-line (5 min) is due to its rapid hydrolysis in plasma. Patients with atypical cholinesterase who cannot metabohze succi-nylchohne suffer pronounced apnea. Procaine, a local anesthetic, is also hydrolyzed by pseudocholinesterase. 

Respiratory Barbiturates are respiratory depressants. Induction doses of thiopental decrease minute ventilation and tidal volume with a smaller and inconsistent decrease in respiratory rate reflex responses to hypercarbia and hypoxia are diminished by anesthetic barbiturates at higher doses or in the presence of other respiratory depressants such as opiates, apnea can result. With the exception of uncommon anaphylactoid reactions, these drugs have little effect on bronchomotor tone and can be used safely in asthmatics. 

This dmg, also known as Diprivan, is chemically unlike any of the previously described iv agents and was developed following the discovery of the anesthetic activity of the 2,6-diethyl analogue (111). Propofol itself is insoluble in water and is usually formulated in a soya bean oil emulsion. Propofol induction, with or without an opioid, is smooth and similar to that of other agents, although pain at the injection site and apnea have been reported (112,113). Recovery after induction and maintenance is faster, with fewer side effects, than with thiopentone (114), although sexual disinhibition has been anecdotally reported (115). Propofol is rapidly distributed, metabolized, and eliininated (116). 

Figure 1 A beagle dog was anesthetized with propofol and etomidate and intubated. One 250-mL breath of ammonia vapor above an 8-M ammonia solution was administered to the dog. The end-tidal COj shows an apnea followed by rapid, shallow breathing. The arterial pressure tracing demonstrates the short-lived decrease in heart rate and attendant hypotension. The transpulmonary pressure illustrates that the apnea and tachypnea was due to the absence of ventilatory drive, rather than airway occlusion.

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