Anaesthesia premedication

It has use in prophylaxis of acid aspiration syndrome after induction of anaesthesia. In a dose of 150 mg HS as premedication affords reliable protection against the consequences of acid aspiration until 11 AM the next day and decreases the danger of aspiration by reducing the high volumes of gastric juice. 

Thiopentone is administered as a 2.5% solution, the usual intravenous induction dose being 3-5 mg kg-1 in adults and 5-6 mg kg-1 in children. The dose necessary to induce anaesthesia is reduced by premedication, during early pregnancy and in critically ill patients. Patients over 70 years of age require a 30-40% lower dose because of a decrease in the volume of distribution, lower plasma proteins, and a slower redistribution of the drug from vessel-rich tissues. However, the above doses are merely guidelines, and the calculated dose should be administered over 10-20 seconds and the drug titrated to clinical effect, i.e. loss of eyelash reflex. 

Complications cannot be attributed to endoscopy itself, but to the pre-existing conditions localized perforations, risks associated with aspiration, cardiac problems, lowered blood pressure, etc. Premedication may therefore be inappropriate in individual cases, and endotracheal intubation or endotracheal anaesthesia is then indicated. 

Aguiar A J A, Hussni C A, Luna S P L 1993 Propofol compared with propofol/guaiphenesin after detomidine premedication for equine surgery. Journal of Veterinary Anaesthesia 20 26-28... 

Table 3.11 Pharmacokinetic parameters showing the influence of xylazine premedication (0.2 mg/kg, i.m.) on the disposition of ketamine (5 mg/kg, i.v.) and the duration of anaesthesia in female ruminant calves. Results are expressed as mean + SEM n = 4.

Anxiety disorders, alcohol withdrawal, premedication in anaesthesia Sleep disorder... 

General anaesthesia usually involves administration of several drugs with different actions for premedication, induction and maintenance of anaesthesia. 

Premedication is intended to prevent the parasympathetic effects of anaesthesia (excessive salivation and bronchial secretion and a reduction in heart rate) and to reduce anxiety or pain. Premedication and adjuncts to general anaesthesia are discussed further on page 234. 

Premedication is used to prepare the patient for general anaesthesia. The objective is to reduce feelings of anxiety and lightly sedate the patient. In addition, drugs may be used to prevent parasympathetic effects of some general anaesthetics. 

Four main groups of drugs are used as premedication and as adjuncts to general anaesthesia sedatives antimuscarinic drugs muscle relaxants and analgesics. Table 12.2 shows actions and examples of drugs used to supplement general anaesthesia. 

Premedication is the use of drugs to reduce a patient s anxiety and to prevent parasympathetic effects of the anaesthetic. Muscle relaxants and analgesics are used as adjuncts to anaesthesia, respectively to cause muscle relaxation and aid surgery and to reduce patient discomfort post-operatively. 

It is employed basieally as an analgesie for the control of pain associated with all kinds of surgery. It may also be used an an adjunet to all drugs eommonly employed for regional and general anaesthesia. It is one of the eomponents in Fentanyl citrate and Droperidol Injection which is used as premedication for anaesthesia and also as an supplement for induction and maintenance of anaesthesia. 

Anaesthetic medication, including drugs used in premedication, induction, maintenance of anaesthesia, muscle relaxation, analgesia (intra- and... 

To produce surgical anaesthesia, it has been seen that a plasma thiopental concentration of 39-42 pg/mL is necessary [78]. The average dose required for induction is essentially independent of age in patients between 20 and 60 years [59]. A reduction in dose may be required for patients over the age of 60 with severely deteriorated hepatic function, with moderately affected kidney function [59], or those heavily premedicated with narcotics and other central depressants [61]. 

In patients premedicated with atropine 7.5 micrograms/kg, pethidine (meperidine) 1 mg/kg, and 500 mg of probenecid, the duration of anaesthesia with thiopental 7 mg/kg was prolonged by 65%,... 

Midazolam markedly potentiates the anaesthetic action of haloth-ane. Similarly, the effects of propofol or thiopental are greater than would be expected by simple addition when midazolam is given concurrently, although the extent varies between the endpoints measured (analgesic, motor, hypnotic). Quazepam reduces induction time for propofol anaesthesia and premedication with diazepam reduces the dose of ketamine required. 

Thiopental has been shown to act synergistically with midazolam at induction of anaesthesia in two studies. " In one of these studies, midazolam reduced the dose of thiopental required to produce anaesthesia by 50%." In a further double-blind, placebo-controlled study in 23 patients, premedication with intravenous midazolam 50 micrograms/kg, given 20 minutes before the induction of anaesthesia, reduced the thiopental dose requirements for multiple anaesthetic end-points, including hypnotic, motor, EEG and analgesia. Potentiation was greatest for the motor endpoint (about 40%) and smallest for analgesia (18%). ... 

Wilder-Smith OHG, Ravussin PA Decosterd LA, Despland PA, Bissonnette B. Midazolam premedication and thiopental induction of anaesthesia interactions at multiple end-points. Br... 

Opioid analgesics would be expected to potentiate the respiratory depressant effects of barbiturate anaesthetics. A study has found that the dose of thiopental required to induce anaesthesia was reduced by pretreatment with fentanyl. The manufacturer recommends reduced doses of thiopental in patients premedicated with opioids. ... 

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