Acta anaesthesiologica Scandinavica
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Acta Anaesthesiol Scand · May 1993
Is there a cholinergic and an adrenergic phase of the oculocardiac reflex during strabismus surgery?
We investigated the counterregulatory effect of the oculocardiac reflex (OCR) in 25 infants and children during strabismus surgery under three experimental conditions. In group 1, a series of measurements were recorded when the OCR was elicited by traction. The beat-to-beat heart rate reduction ranged from -26 to -64 beats/min (median: -46 beats/min). ⋯ The bradycardia and the counterregulation may be referred to as cholinergic and adrenergic phrases of the OCR. Atropine eliminates the cholinergic phase. Our study indicates that there may be receptors and afferent fibres for both phases, which can be blocked by local anaesthetics.
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Colloid osmotic pressure (COP) of some of the most frequently used plasma replacement fluids was measured with a colloid osmometer. COP of 4% human albumin solutions was only half that of normal human serum (13.6 +/- 0.6 vs. 27.5 +/- 2.7 mmHg (1.8 +/- 0.1 vs. 3.7 +/- 0.4 kPa)) (mean +/- s.d.), whereas COP of 20% human albumin solutions was eight times higher (196.0 +/- 12.3 mmHg (26.1 +/- 1.6 kPa)). Enhancing the protein concentration from 4% to 20% in the human albumin solutions increased COP 14-fold, reflecting the exponential relationship between protein concentration and COP of a solution. ⋯ Dextran 70 (6%) had a COP more than twice, and Ringer-Dextran 60 (3%) about 75% of that of normal human serum. Dextran 40 (10%) and gelatin (3.5%, Haemaccel) leaked markedly through the membrane of the colloid osmometer, making acceptable measurements impossible. Seven different hydroxyethyl starch (HES) solutions were measured, and the COP varied between half and 3 times that of normal human serum, depending on molecular weight and concentration of the HES.
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Acta Anaesthesiol Scand · May 1993
Comparative StudyVolume-controlled inverse ratio ventilation: effect on dynamic hyperinflation and auto-PEEP.
The effects of inverse ratio ventilation (IRV) and PEEP on dynamic hyperinflation and auto-PEEP were studied in sedated, paralysed patients with adult respiratory distress syndrome (ARDS) (n = 9) and in 10 postoperative patients after coronary artery by-pass (CABG). During volume-controlled mechanical ventilation with constant tidal volume (V(T) 12 ml.kg-1) and respiratory rate (12.min-1), two consecutive experiments were carried out: (1) with constant I:E ratio PEEP was increased in steps of 2 cmH2O (0.2 kPa) from 0 to 12 cmH2O (0 to 1.2 kPa) and (2) with no PEEP I:E ratio was changed stepwise from 1:4 to 4:1. Flow, V(T), peak airway pressure (Pmax) and static end-expiratory pressure (PEEPtot) were registered. ⋯ The changes in the end-expiratory lung volume (EELV) were measured with respiratory inductive plethysmograph. We found that: (1) increasing PEEP and IRV caused a similar increase in EELV and PEEPtot in ARDS, but in CABG the increase in EELV was greater with PEEP; (2) at the same PEEPtot the increase in EELV was similar with PEEP and IRV in both groups; and (3) the reduction in Pmax was marginal during IRV. We conclude that the effect of reduced expiratory time on end-expiratory lung volume and pressure during volume controlled IRV is similar to the use of PEEP.
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Acta Anaesthesiol Scand · May 1993
Randomized Controlled Trial Comparative Study Clinical Trial Controlled Clinical TrialCaudal buprenorphine for postoperative analgesia in children: a comparison with intramuscular buprenorphine.
This study was conducted on 44 children aged 1-10 years, who had undergone lower extremity orthopaedic surgery under general anaesthesia. Patients were divided into two groups: Group 1 (n = 23) received buprenorphine caudally and Group 2 (n = 21) received buprenorphine intramuscularly, at the completion of the surgery. The dose of buprenorphine used in both the groups was 4 micrograms.kg-1 body weight. ⋯ The duration of analgesia was significantly greater with caudal buprenorphine (median 20.20 h) than with intramuscular buprenorphine (median 5.20 h). Of the patients in the caudal group, 43% did not require any supplemental analgesia during the first 24 h, whereas all the patients in the intramuscular group required supplements within 10 h postoperatively. Caudal buprenorphine (4 micrograms.kg-1 body weight) provided 10.8 h to more than 24 h of analgesia in children, with fewer side effects.
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Acta Anaesthesiol Scand · May 1993
Randomized Controlled Trial Comparative Study Clinical TrialComparison of epidural methadone with epidural diamorphine for analgesia following caesarean section.
Analgesia provided by either 5 mg diamorphine, or 5 mg methadone administered by the epidural route during elective caesarean section was compared in 40 women. The median time to further analgesia in the methadone group was 395 min, and 720 min in the diamorphine group, P = 0.0003. Linear analogue scores to assess pain were measured 2-hourly for 12 h, then again at 24 h postoperatively. ⋯ Continuous pulse oximetry data were available for 12 h post-operatively in 15 patients receiving methadone, and in 17 patients receiving diamorphine. One or more episodes of significant desaturation (< 90% for 30 s), occurred in three patients receiving methadone, and in nine patients receiving diamorphine. Desaturation to 90-92% occurred in a further three patients given epidural diamorphine, and in one further patient given epidural methadone.