[Weather influences on intraocular pressure in patients with chronic glaucoma or ocular hypertension]

From January 1979 to August 1984 intraocular pressure (IOP) was measured on the first Friday of each month under comparable conditions (same instruments, nearly always the same examiner) in a total of 109 patients in whom a primary chronic open-angle glaucoma or ocular hypertension had been diagnosed: The IOP was correlated to the local weather parameters (atmospheric pressure, cloud cover, relative air humidity, mean, maximum and minimum temperature, precipitation, duration of sunshine, mean and maximum wind velocity). In the large number of measurements a significant correlation was found only between IOP and atmospheric pressure: IOP was lower when air pressure was high. There was only a suggestion of a significant correlation between IOP and relative air humidity. However, further statistical analysis revealed that in fact both atmospheric pressure and relative air humidity account for only a negligible part of the variation in IOP values. From a practical point of view, therefore, the IOP of patients with primary chronic open-angle glaucoma or ocular hypertension is not influenced by weather conditions.

Central retinal artery occlusion in Sneddon's disease associated with antiphospholipid antibodies

A 33-year-old woman with retinal artery occlusion also had Sneddon's disease (livedo reticularis, neurologic abnormalities, and labile hypertension). While retinal artery occlusive disease obviously must be added to the symptomatic spectrum of this rare disorder, the detection of antiphospholipid antibodies in this patient has pathogenetic implications.

Cold ischemic arrest: comparison of calcium-free and calcium-containing solutions

Isolated pumping rat hearts, perfused with reconstituted blood, were studied to compare the effects of 30 minutes of ischemic arrest following calcium-free or normal, calcium-containing cold cardioplegia on recovery of mechanical function, lactate production, myocardial adenosine triphosphate concentration, and release of creatine kinase (CK). As in clinical situations, the volume of the infusate was only three to four times the intracavitary blood volume. Hearts arrested with calcium-free solution showed incomplete recovery of mechanical function, whereas hearts arrested with calcium-containing solution recovered completely. After calcium-free arrest, stroke volume recovered to 76 +/- 29% (standard deviation [SD]) of its prearrest value. Enzyme release (CK) was significantly higher after calcium-free cardioplegia (7.7 +/- 4.6 units [SD]) than after cardioplegia with normal calcium (2.1 +/- 1.6 units [SD]). Since the addition of only 0.025 mmol calcium ions to a liter of calcium-free solution completely prevented its negative effect, it was concluded that calcium-free cardioplegia may cause limited but pronounced damage to myocardial cells, presumably because it removes calcium from the cellular membranes--the so-called calcium paradox. Probably due to residual calcium in blood and extracellular fluid, the damage is not so extensive after calcium-free cardioplegia as to be noticeable in clinical surgical situations. Residual calcium in the heart does not exclude the possibility, however, that a calcium paradox occurs in small scattered areas of the heart.

Cardioplegic arrest in isolated blood-perfused working rat hearts

An isolated working rat heart model designed for function studies after elective cardiac arrest is described. Before and after a cold ischemic period (induced with St. Thomas' cardioplegic solution) of 30 min, hemodynamic and metabolic variables were assessed in a group of 13 hearts perfused with a modified Krebs-Henseleit solution and in a group of 13 hearts perfused with reconstituted blood. Functional recovery was about 90% in the nonblood-perfusate group and 98% in the blood-perfused group. Functional deterioration in time due to edema formation and limited oxygenation in electrolyte-perfused hearts was found to be of the same magnitude as the function loss ascribed to deleterious effects of cardioplegic arrest. The blood-perfused hearts showed hemodynamic stability during a 75 min continuous working period, and complete recovery of function after 30 min arrest.