[Changes in ocular circulation in halothane-nitrous oxide intubation anesthesia with special reference to the...

In part I of this study [Hessemer and associates, Klin. Mbl. Augenheilk. 199 (1991) 346-355] the phenomenology of the ocular circulatory changes, found during general anesthesia using halothane and nitrous oxide, has been described. These changes are analyzed with respect to their mechanisms.--

There was a significantly (P less than 0.05) linear relation between the anesthesia-induced reduction of the systolic ocular (retinal and ciliary) blood pressures and the decrease of the systolic brachial artery pressure (delta Ps,bra). The same relation was present between the reduction of the systolic ocular (retinal and ciliary) perfusion pressures and delta Ps,bra. The correlation coefficients for the designated relations ranged between 0.37 and 0.58. The relation between the anesthesia-induced intraocular pressure reduction and delta Ps,bra was--in tendency--linear (P = 0.07), at least for the time period 5-15 min after intubation; the correlation coefficient amounted to 0.37. The reduction of both the ocular pulsation volume (PVoc) and the pulsatile ocular blood flow (Fp,oc) did not depend on the systemic blood pressure, but on the arterial CO2 tension (PCO2): Decreasing PCO2--i.e., increasing hyperventilation--was paralleled by decreases of PVoc and Fp,oc. The relations PVoc vs. PCO2 and Fp,oc vs. PCO2 were significantly linear (P less than 0.01), the correlation coefficients ranged between 0.58 and 0.7.(ABSTRACT TRUNCATED AT 250 WORDS)