[Clonidine for remifentanil-induced hyperalgesia: a double-blind randomized, placebo-controlled study of clonidine under intra-operative use of remifentanil in elective surgery of the shoulder]. / Clonidin bei Remifentanil-induzierter Hyperalgesie: Doppelblinde randomisierte, placebokontrollierte Studie mit Clonidin unter intraoperativer Analgesie mit Remifentanil bei Schultereingriffen.

BACKGROUND: In the postoperative period, α2-adrenergic agonists have an opioid sparing effect. In a previous, experimental study, it was also shown that clonidine attenuates remifentanil-induced hyperalgesia. In this study, we examined under clinical conditions whether early administration of a single dose of clonidine can inhibit remifentanil-induced hyperalgesia in patients undergoing elective surgery of the shoulder and with continuous intraoperative use of remifentanil. PATIENTS AND METHODS: In this study 40 patients received double-blind and randomized either 150 µg clonidine or placebo intravenously before skin incision. Anaesthesia was maintained with propofol and remifentanil (0.23 ± 0.09 µg/kg body weight/min) and morphine (0.1 mg/kg body weight) was administered 20 min before incision closure. Postoperatively, the patients were given a patient-controlled analgesia pump (PCA) with morphine. RESULTS: Overall morphine consumption as well as overall assessment of pain with the visual analogue scale in the first 24 h postoperatively did not differ significantly between the groups. Isolated pain scores at 12 h and 24 h were significantly enhanced in the clonidine group (p<0.05). CONCLUSION: An early single dose of 150 µg of clonidine did not reduce the postoperative morphine consumption and pain scores in patients undergoing elective surgery of the shoulder with remifentanil/propofol-based anaesthesia. After the effect of clonidine has presumably subsided the pain can even increase, therefore further studies with repetitive doses of clonidine should be carried out.

Early cardiorespiratory patterns in severely burned patients with concomitant inhalation injury.

Hemodynamic and oxygenation parameters were determined during the first 24 h in 13 burned patients with concomitant inhalation injury (burn surface area 40-60 percent). In all patients right ventricular function was severely compromised evidenced as a significant increase in end-diastolic volumes, decrease in ejection fractions, low stroke work indices and increased pulmonary vascular resistances. Inotropic support with dobutamine and careful titration of volume infusion according to end-diastolic volume indices improved the hemodynamics as demonstrated by significant increases in right ventricular ejection fractions in all patients without any changes in mean arterial pressures, urine output and oxygenation. Assessment of ventricular performance by a specially designed pulmonary artery catheter is helpful in the management of severely burned patients with concomitant inhalation injury.

Pharmacodynamics of mivacurium in severely burned patients.

The pharmacodynamics of mivacurium, a new short-acting non-depolarizing muscle relaxant, were studied in nine severely burned patients with concomitant inhalation injury. Complete neuromuscular blockade was achieved within 1.3 min (controls 3.0 min) following the usually recommended intubating dose (0.15 mg/kg/BW 2 x ED95) of mivacurium. The clinical duration of neuromuscular blockade and the recovery times were slightly prolonged, due to significantly reduced serum cholinesterase activity (clinical duration 24.6 min vs. 15.3 min). This pharmacodynamic profile makes mivacurium preferable for intermittent on-demand neuromuscular blockade in the severely burned patient.