[The Effect of Non-Depolarising Muscle Relaxants on Ocular Pulse Amplitude and Intraocular Pressure]. / Beeinflussung der okulären Pulsamplitude und des Intraokulardrucks durch nicht depolarisierende Muskelrelaxanzien.

AIM: In general anaesthesia (GA) for ocular surgery the chosen non-depolarising muscle relaxant has a high influence on the fluctuations of intraocular pressure (IOP) and ocular pulse amplitude (OPA). PATIENTS AND METHODS: In 229 patients, who needed GA for their ophthalmic surgery, OPA and IOP were measured with the dynamic contour tonometer (DCT) before and 5 minutes after intubation. For GA, three groups of non-depolarising muscle relaxants, namely, mivacurium (n = 71), atracurium (n = 91) and rocuronium (n = 67) were used. RESULTS: The IOP decreased by about 4.0 ± 2.3 mmHg using mivacurium in GA, by about 6.1 ± 2.2 mmHg using atracurium and by about 7.4 ± 1.7 mmHg using rocuronium (p < 0.001). The relative decrease of the IOP was 20% for mivacurium, 31% for atracurium and 37% for rocuronium. For mivacurium the OPA decreased from 3.4 ± 1.5 mmHg to 2.2 ± 1.1 mmHg (p < 0.001) in contrast to atracurium (decrease from 3.6 ± 1.5 mmHg to 1.8 ± 0.8 mmHg; p < 0.001) and rocuronium (decrease from 3.1 ± 1.6 mmHg to 1.7 ± 0.9 mmHg; p < 0.001). Mean OPA reduction was lowest with mivacurium (1.3 mmHg) and the highest with atracurium (1.7 mmHg). The mean relative decrease of the OPA was 34% with mivacurium, 46% with atracurium and 43% with rocuronium (p < 0.001). There was no linear correlation between the relative OPA decrease and the relative IOP decrease. CONCLUSION: Risks for ophthalmic surgery may be minimised by avoiding mivacurium in general anaesthesia. Due to its negative effects on IOP and OPA mivacurium does not seem to be suitable for operations with a large opening in the eye such as penetrating keratoplasty and block excision. Rocuronium can be used because it induces a favourised intraoperative decrease of the IOP.

[Reduction of intraocular pressure and ocular pulse amplitude during general anesthesia]. / Sinken des Augeninnendrucks und der okularen Pulsamplitude während der Intubationsnarkose.

AIM: Measurement of the intraocular pressure (IOP) is an important tool for glaucoma diagnostics in children or patients with impaired cooperation. General anesthesia (GA) may significantly influence the IOP. This study aimed to evaluate the reduction of IOP during GA. PATIENTS AND METHODS: The IOP was measured in 229 patients in a recumbent position in the non-operated eye prior to and 5 min after the beginning of GA with a dynamic contour tonometer (DCT). RESULTS: The average IOP decreased from 19.9 ± 3.7 mmHg prior to GA to 14.1 ± 3.5 mmHg 5 min after beginning GA (p < 0.0001, IOP decrease 30 %). The GA caused a decrease of up to 2 mmHg in 6.1 %, 2-4 mmHg in 18.8 %, 4-6 mmHg in 21.0 %, 6-8 mmHg in 36.6 %, 8-10 mmHg in 13.6 %, 10-12 mmHg in 2.2 % and more than 12 mmHg in 1.7 % of the eyes. The ocular pulse amplitude (OPA) decreased from a mean of 3.4 ± 1.5 mmHg to 1.9 ± 1.0 mmHg (p < 0.0001, OPA decrease 41 %) under GA. CONCLUSION: A significant decrease of IOP (mean 6 mmHg) occurs during GA and under extreme conditions up to 13.8 mmHg. A decrease of OPA of 1.5 mmHg should be taken into consideration for patients under general anesthesia and under extreme conditions up to 7 mmHg.