Effects of remifentanil and fentanyl on intraocular pressure during the maintenance and recovery of anaesthesia in patients undergoing non-ophthalmic surgery.

BACKGROUND AND OBJECTIVE: To compare the effects of remifentanil and fentanyl on intraocular pressure during the maintenance and recovery of anaesthesia in patients undergoing elective non-ophthalmic surgery. METHODS: Thirty-two patients (ASA I-II) were randomized into two groups to receive either a continuous infusion of remifentanil (0.25-0.5 microg kg(-1) min(-1), n =16, Group R) or an intermittent bolus of fentanyl (2-5 microg kg(-1), n = 16, Group F) during the maintenance of anaesthesia. For the induction of anaesthesia, Group R received remifentanil 1 microg kg(-1) and Group F received fentanyl 2 microg kg(-1); both groups then received propofol 2 mg kg(-1) with vecuronium 0.1 mg kg(-1). Anaesthesia in both groups was maintained with a continuous infusion of propofol 4-8 mg kg(-1) h(-1). Ventilation of the lungs was controlled to a constant end-tidal PCO2 of 4.7-5.4 kPa. Blood pressure, electrocardiography, heart rate and oxygen saturation were monitored throughout anaesthesia. Intraocular pressure was determined before surgery, during the maintenance of anaesthesia, 2 min after emergence and in the recovery room using a Perkins hand-held applanation tonometer by an ophthalmologist blinded to the anaesthetic technique. RESULTS: After induction of anaesthesia, a significant decrease in intraocular pressure in the remifentanil group from 13.6 +/- 2.6 to 7.1 +/- 3.1 mmHg (P < 0.001) and in the fentanyl group from 13.7 +/- 2.2 to 9.7 +/- 3.4 mmHg (P < 0.001) was observed and maintained during anaesthesia. Thirty minutes after the end of anaesthesia, intraocular pressure returned to baseline values in both groups (remifentanil: 13.9 +/- 2.8 mmHg, P = 0.28; fentanyl: 13.6 +/- 2.3 mmHg, P = 0.59). The intraocular pressure and haemodynamic variables did not differ significantly between the two groups (intraocular pressure, P = 0.7327; blood pressure, P = 0.1295; heart rate, P = 0.8601). CONCLUSIONS: Remifentanil maintains intraocular pressure at an equally reduced level compared with fentanyl.

Effect of different doses of cisatracurium on intraocular pressure in sedated patients.

BACKGROUND AND OBJECTIVE: The aim was to examine the course of intraocular pressure after relaxation with different doses of cisatracurium. METHODS: The investigation was carried out as a prospective, randomized double-blind study in a crossover design in 30 postoperative patients with stable haemodynamic and respiratory function (ASA I and II). To exclude any disrupting factors, patients remained intubated and continuously sedated. Twenty patients received an intubation dose (2 x ED95) of cisatracurium (0.1 mg kg(-1)) compared with atracurium (0.5 mg kg(-1)). In a second series, 10 patients were given an effective dose, ED95 (0.05 mg kg(-1)), and a repeat dose (0.02 mg kg(-1)) of cisatracurium. The intraocular pressure was determined before (T0) as well as 1 (T1), 5 (T5), 10 (T10), 15 (T15), 20 (T20) and 45 (T45) min after bolus administration. RESULTS: Intraocular pressure decreased after an intubation dose of either cisatracurium or atracurium, and reached a minimum after 10 min (6.7 +/- 2.2 and 7.9 +/- 2.1 mmHg, respectively). There was no significant difference between either muscle relaxant (P = 0.27). When lower doses of cisatracurium (0.05 and 0.02 mg kg(-1)) were applied, the intraocular pressure also decreased, albeit to a lesser extent and with a delayed onset (8.4 +/- 1.9 mmHg after 10 min, 9.9 +/- 3.4 mmHg after 15 min). There was no significant difference between dosages (p = 0.44). CONCLUSIONS: Cisatracurium is a useful drug in patients when a decrease of intraocular pressure is wanted and where muscle relaxation is necessary and acceptable.

Sevoflurane and propofol decrease intraocular pressure equally during non-ophthalmic surgery and recovery.

BACKGROUND: To provide good control of intraocular pressure (IOP) during anaesthesia and surgery, we conducted a study comparing the effects on IOP during maintenance and recovery of sevoflurane vs propofol anaesthesia in 33 patients (ASA I-II) undergoing elective non- ophthalmic surgery. METHODS: Anaesthesia was induced with propofol 2 mg kg(-1), fentanyl 2 micro g kg(-1) and vecuronium 0.1 mg kg(-1). Patients were allocated randomly to receive either propofol 4-8 mg kg(-1) h(-1) (group P; n=16) or 1.5-2.5 vol% sevoflurane (group S; n=17) for maintenance of anaesthesia. Fentanyl 2-4 micro g kg(-1) was added if necessary. The lungs were ventilated with 50% air in oxygen. Blood pressure, heart rate, oxygen saturation and end-tidal carbon dioxide were measured before and throughout anaesthesia and in the recovery room. IOP was determined with applanation tonometry (Perkins) by one ophthalmologist blinded to the anaesthetic technique. RESULTS: There was a significant decrease in IOP after induction and during maintenance of anaesthesia in both groups. No significant differences in IOP between the two groups was found. CONCLUSION: Sevoflurane maintains the IOP at an equally reduced level compared with propofol.

The long-term antinociceptive effect of intrathecal S(+)-ketamine in a patient with established morphine tolerance.

IMPLICATIONS: Our report describes for the first time the continuous long-term intrathecal application of S(+)-ketamine in a patient with chronic pain and morphine tolerance. Intrathecally applied S(+)-ketamine led to a significant pain reduction and consecutively reduced the doses of intrathecal morphine required for pain relief even several weeks after the cessation of the 24-day period of intrathecal S(+)-ketamine administration.

Waste anaesthetic gases induce sister chromatid exchanges in lymphocytes of operating room personnel.

Genotoxicity related to waste anaesthetic gas exposure is controversial. We have investigated the frequency of sister chromatid exchanges in peripheral lymphocytes of operating room personnel exposed to trace concentrations of isoflurane and nitrous oxide. Occupational exposure was recorded using a direct reading instrument. Frequencies of sister chromatid exchanges were measured in lymphocyte cultures of 27 non-smokers working in the operating room and 27 non-smoking controls. Personnel were exposed to an 8-h time-weighted average of nitrous oxide 11.8 ppm and isoflurane 0.5 ppm. After exposure, sister chromatid exchange frequency was increased significantly (mean 9.0 (SD 1.3) vs 8.0 (1.4) in exposed and control personnel, respectively) (P < 0.05). We conclude that exposure to even trace concentrations of waste anaesthetic gases may cause genetic damage comparable with smoking 11-20 cigarettes per day.