Klinische Monatsblätter für Augenheilkunde
-
Klin Monbl Augenheilkd · Nov 1991
Randomized Controlled Trial Clinical Trial[Ocular circulatory changes in halothane-nitrous oxide intubation anesthesia with special reference to arterial CO2 partial pressure. I. Phenomenology of changes].
In 20 patients (5 with cataract, 15 with strabismus), general anesthesia was performed using halothane (inspiratory concentration: 0.5 vol.%) and nitrous oxide (65 vol.%); thiopental was employed for induction of anesthesia, vecuronium and succinylcholine were used for neuromuscular blockade prior to intubation. In series 1, the patients were slightly hyperventilated (PCO2 33 mmHg, on average). In series 2, the arterial PCO2 was changed in a range between 20 and 45 mmHg. By means of oculo-oscillo-dynamography, we determined the systolic retinal and ciliary perfusion pressures (PPs,ret and PPs,cil) as well as the respective ocular blood pressures (Ps,ret and Ps,cil), the ocular pulsation volume (PVoc) and the pulsatile ocular blood flow (Fp,oc = PVoc x heart rate). The intraocular pressure (Pio) was measured with the Draeger hand-applanation tonometer. Results of series 1: Measured 5 and 15 min after intubation, PPs,ret was reduced by averages of 12.5 and 20.2 mmHg, respectively, corresponding to decreases of 13.1 and 21.2% compared to the initial values. Ps,ret was decreased by 15.4 mmHg (14.2%) 5 min after intubation and by 27.1 mmHg (25.0%) 15 min after intubation. The ciliary pressures (PPs,cil and Ps,cil) were changed by similar amounts. PVoc was reduced by 0.3 microliters (50.8%) during both time periods after intubation. Fp,oc was lowered by 19.5 microliters/min (41.0%) and by 26.4 microliters/min (55.5%), measured 5 and 15 min after intubation, respectively. Pio was decreased by 1.6 mmHg (11.3%) and by 7.6 mmHg (53.5%), respectively. The systolic brachial artery pressure was reduced by 12.6 mmHg (9.5%) 5 min after intubation and by 29.1 mmHg (21.9%) 15 min after intubation. The diastolic branchial artery pressure showed a slight initial increase, followed by a small decrease. All changes were highly significant (P less than 0.001; 1-factor analysis of variance plus Scheffé test). Results of series 2: In a PCO2 range between 40 and 45 mmHg (normo-until slight hypoventilation; determined 5 min after intubation), PVoc and Fp,oc averaged 0.43 microliter and 42.9 microliters/min, respectively. In a PCO2 range between 30 and 35 mmHg (slight hyperventilation), PVoc and Fp,oc averaged 0.38 microliters and 36.1 microliters/min, respectively; and in a PCO2 range between 20 and 25 mmHg (forced hyperventilation), they averaged 0.21 microliter and 22.8 microliters/min, respectively. All other variables were not dependent on the PCO2 level. ⋯ The lowering of PVoc and Fp,oc, observed during halothane-nitrous oxide anesthesia--especially with forced hyperventilation-, may be interpreted as reduced pulsatile choroidal blood flow.(ABSTRACT TRUNCATED AT 400 WORDS)
-
Klin Monbl Augenheilkd · Dec 1990
Randomized Controlled Trial Clinical Trial[Ocular circulatory changes caused by retrobulbar anesthesia with and without added adrenaline].
In 80 patients, retrobulbar anesthesia (RBA; 5 ml of a lidocaine-bupivacaine mixture with hyaluronidase) with or without addition of adrenaline (after-mixing concentration 1:500,000) was performed preoperatively. In 2 examination series, the acute and medium-term effects of RBA on the following ocular circulatory variables were investigated: ocular pulsation volume (PVoc), systolic ciliary and retinal perfusion pressures or blood pressures, respectively (method: oculo-oscillo-dynamography). ⋯ The lowering of PVoc--which variable is determined mainly by the pulsatile choroidal blood flow--in concert with the lowered ciliary perfusion and blood pressures is indicative of a reduced ciliary blood flow during RBA. Because of the decreased retinal perfusion and blood pressures, there is also a higher risk of reduced blood supply to the retina. Only to some degree, the observed inhibitory RBA effects on ocular circulation can be explained by adrenaline, and to an even smaller degree by the only transient Pio elevation.
-
Klin Monbl Augenheilkd · Feb 1989
Randomized Controlled Trial Comparative Study Clinical Trial[Preoperative use of suction cup oculopression in comparison with Vörösmarthy oculopression].
In contrast to Vörösmarthy oculopression (VOP), suction-cup oculopression (SOP) is "pure" oculopression without compression of orbital tissue. Prior to 44 cataract operations with posterior chamber lens implantation, the authors performed SOP (negative pressure - 110 mm Hg) or VOP (level of oculopression 30 mm Hg) of the same duration (average 26 min). Before oculopression, a retrobulbar injection (RBI) was performed for local anesthesia. ⋯ After RBI + SOP, a post-injection of anesthetic was necessary in three cases; no additional injection was required after RBI + VOP. In conclusion, identical preoperative reductions in IOP can be achieved with SOP and VOP. Regarding the form of the iris-vitreous diaphragm and the frequency of post-injection, the differences between the two methods may be related to the lack of orbital compression during SOP.