Pharmacodynamics of pipecuronium neuromuscular blockade under peripheral hypothermia in child and cat: a combined clinical and pharmacological study

20 ASA class I or II children subjected to elective surgery were studied. Their mean + SD age was 3.4 + 1.4 year [range: 10 months-7 years], body weight: 15.6 + 4.8 kg [range: 10-25 kg]. Male/female ratio: 13/7. Anaesthesia was induced with thiopental 33.5 mg kg-1. Intubation was facilitated by topical Xylocaine 4% without a muscle relaxant. Peripheral hypothermia [30C] was induced in the right arm using ice bags. Body core and left arm temperature was given a ED95 [50 mu kg-1]. Neuromuscular function analyzer NS252 was used to deliver TOF stimulation at 12 second intervals. Onset of action of pipecuronium, duration of blockade and reversal time were recorded in minutes. Experimental study was conducted on intact anesthitized cat gastrocnemius sciatic nerve prepartion using an electronic square pulse stimulator and a platinum electrode. ED95 of pipecuronium was first estimate. Onset of action duration and reversal time of pipecuronium induced and the same parameters were recorded. It was found that peripheral hypothermal has significantly delayed the onset of action of pipecuronium from 2.4 + 1 to 5.5 + 1.3 min. In child and from 5 2 to 8 2.5 min. in cat [p < 0.001 and p < 0.05 respectively]. The duration of blockade was significantly increased form 35 + 6.5 to 46 + 8 min. in child and from 35 + 8 to 55 10 min. in cat [p < 0.01 and p < 0,05 respectively]. Reversal time was also significantly increased from 3.3 + 1 to 5.2 + 1.2 min. In child and form 5 + 3 to 13 + 4.4 min. In cat [p < 0.001]. Hypothermia has also reduced the cat gastrocnemius evoked twitch tension to 50% of its normothermic value. In conclusion peripheral hypothermia [30C] has markedly delayed the onset of action of pipecuronium in both child and cat. It augmented the duration of blockade. Reversal with neostigmine was hindered. These findings can be valuable if this drug is used in children during hypothermic cardiopulmonary bypass or in those subjected to inadvertent hypothermia

Rapid-sequence endotracheal in tubation using high-dose vecuronium in children

Rapid-sequence endotracheal intubation is used to secure the airway in emergency surgical procedures. Succinylcholine is the standard muscle relaxant used for this purpose. However, its use is associated with numerous side effects. Vecuronium bromide was used in high doses, several times the ED95, to induce rapid-sequence intubation in children aiming at reaching a dose that has a short onset time of neuromuscular blockade and at the same time does not, unduly, prolong the duration of action or hinder reversibility by neostigmine. 40 ASA class 1 or 2 children were divided in 4 groups [n = 10] the first three groups received vecuronium in either 0.1, 0.15 or 0.2 mg/kg, while the forth received succinylcholine 1.5 mg/kg. Innervator NS252 was used to stimulate ulnar nerve while myograph 2000 was used to record thumb adduction. TOF at 10 sec. intervals was used to count onset time of neuromuscular blockade which was found to decrease from 103 +/- 35 to 58 +/- 15 seconds as vecuronium dose was increased. The last mean value +/- SD was shorter than onset time of succinylcholine 1.5 mg/kg [60 +/- 18 seconds] with absent significant difference between them [P >0.05]. DBS at 12 second intervals was used during recovery to determine duration of action, recovery index and reversal time. Duration of action was increased from 31 +/- 10 to 40 +/- 13 to 53.7 +/- 17 minutes as vecuronium dose was increased. The longest duration of action was with Vec0.2 mg/kg which was still within the scope of many surgical operations

Epidural anesthesia alters stress response to surgery in children

The endocrinal response to surgical stress in lower abdomen and lower limb operations in 30 children, has been studied. Children were randomly allocated in one of two groups, each contained 15 children [N = 15]. Group 1 "control" received general anesthesia, while group 2 "epidural" received lumbar epidural blockade, in addition to light general anesthesia. Plasma cortisol and blood glucose levels have been estimated after induction of general anesthesia [control sample C], one, two and three hours later [1Hr, Hrs. and 3Hrs.]. It was found that plasma cortisol and blood glucose levels have significantly increased in group 1 "control" after one, two and three hours from start of surgery. On the other hand, in group 2 "epidural", the blockade of neurogenic impulses from site of surgery succeeded in attenuating these responses as evidenced by significantly lower plasma cortisol levels after two and three hours from the start of surgery compared to control value. Epidural anesthesia also succeeded in attenuating the hyperglycemic response to surgical stress as evidenced by a blood glucose level significantly lower in epidural group than control group at all intervals except for control sample. Therefore, epidural anesthesia can be considered a valuable technique to minimize the catabolic consequences of surgical stress in children. This can be of special value in high-risk children with poor nutritional status