Propofol Etomidate

The respiratoiy depressant effects of ketamine and morphine may be additive. The dose requirements of desflurane, etomidate, propofol and thiopental may be lower after opioid use. Opisthotonos or grand mal seizures have rarely been associated with the use of propofol with alfentanil and/or fentanyl. The effects of in-halational anaesthetics may be enhanced by opioid analgesics. 

The other method used is infusion of intravenous anaesthetics such as propofol, etomidate (for induction) and the barbiturates such as thiopental and pentobarbital. Investigations into the mechanism of anaesthesia have made use of all these compounds in order to identify a common mode of action linked to likely mechanisms within the CNS. 

Hypnotics. Common hypnotics are thiopental, propofol, midazolam, etomidate, ketamine and inhaled anesthetics. The incidence of hypersensitivity reactions with thiopental is rare. Recently, thiopental was involved in less than 1% of allergic reactions in France [9]. Ever since Cremophor EL, used as a solvent for some non-barbiturate hypnotics, has been avoided, many previously reported hypersensitivity reactions have disappeared. In the last French surveys, reactions to propofol accounted for less than 2.5% of allergic reactions, and reactions to midazolam, etomidate or ketamine appear to be really rare [9]. Finally, no immune-mediated immediate hypersensitivity reaction involving isoflurane, desflurane or sevoflurane has been reported despite their wide use. 

The GABA-gated chloride ion channel is modulated by several classes of drugs that bind to allosteric sites on the receptor complex the benzodiazepines, barbiturates and related intravenous general anesthetics such as etomidate and propofol, as well as anesthetic steroids and endogenous neurosteroids. It appears that some types of GABAa receptor are directly enhanced by ethanol and volatile general anesthetics (Fig. 16-2) [7,8,20]. 

TIVA has become feasible thanks to the introduction of agents with a suitably short duration of action, including the injectable anesthetics propofol and etomidate, the analgesics alfentanil und remifentanil, and the muscle relaxant mivacurium. These drugs are eliminated within minutes after being adminster-ed, irrespective of the duration of anesthesia. 

Answer This feature of bradycardia is typical of patients who take (3-blockers, which should be continued so they result ultimately in better anesthetic management. The drugs given could have been modified (i.e., etomidate instead of propofol, which does not raise or may cause a slower heart rate). The potent opioids in the fentanyl family all cause vagal transmitted bradycardia. The muscle relaxant vecuronium (norcuron) has no effect on heart rate and could have been replaced by pancuronium, which has a vagolytic effect and will counter bradycardia in the usual induction bolus doses. 

Imidazoie compounds etomidate Stericaiiy hindered aikyi phenois propofol Steroids eitanoione, Aithesin, minaxolone (none currentiy avaiiabie)... 

Barbiturates may precipitate episodes of acute intermittent porphyria (AIP) and their use is contraindicated in patients who are predisposed to this condition. Some animal models indicate that ketamine, etomidate, and the benzodiazepines may be porphyrinogenic and propofol is considered to be the intravenous anaesthetic of choice in AlP-prone patients. 

Figure 4.4 Structural formulae of propofol, etomidate, and ketamine.

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. 

Finally, newer intravenous anesthetics such as etomidate (Amidate) and propofol (Diprivan) are available. Etomidate is a hypnoticlike drug that causes a rapid onset of general anesthesia with a minimum of cardiopulmonary side effects. Flence, this drug may be useful in patients with compromised cardiovascular or respiratory function. Propofol is a short-acting hypnotic that is useful as a general anesthetic in some... 

Several drugs are used intravenously, alone or in combination with other drugs, to achieve an anesthetic state (as components of balanced anesthesia) or to sedate patients in intensive care units who must be mechanically ventilated. These drugs include the following (1) barbiturates (thiopental, methohexital) (2) benzodiazepines (midazolam, diazepam) (3) opioid analgesics (morphine, fentanyl, sufentanil, alfentanil, remifentanil) (4) propofol (5) ketamine and (6) miscellaneous drugs (droperidol, etomidate, dexmedetomidine). Figure 25-2 shows the structures of... 

Effects on respiration are similar to those of thiopental at usual anesthetic doses. However, propofol causes a marked decrease in systemic blood pressure during induction of anesthesia, primarily through decreased peripheral resistance. In addition, propofol has greater negative inotropic effects on the heart than etomidate and thiopental. Apnea and pain at the site of injection are common adverse effects of bolus administration. Muscle movements, hypotonus, and (rarely) tremors have also been reported following its use. Clinical infections due to bacterial contamination of the propofol emulsion have led to the addition of antimicrobial adjuvants (eg, ethylenediaminetetraacetic acid and metabisulfite). 

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). 

Olkkola KT, Tammisto T. Quantifying the interaction of rocuronium (Org 9426) with etomidate, fentanyl, midazolam, propofol, thiopental, and isoflurane using closed-loop... 

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