Cardiovascular Effects of Low Dose Calcium Chloride Infusions During Halothane Anaesthesia in Dorsally Recumbent Ventilated Ponies

Abstract

Summary The effects of calcium chloride administered at low infusion rates on the cardiovascular depression and the blood calcium balance were studied during a constant halothane anaesthesia in dorsally recumbent ventilated ponies. A pronounced cardiopulmonary depression characterized by decreases of all cardiac parameters and lowering of the mean arterial blood pressure was observed after the initial anaesthetic stabilization period of 30 minutes in the ponies. A significant decrease in the total calcium plasma concentration together with a constant ionized and complexed calcium fraction was present after the stabilization period.

Comparison between lithium dilution and pulse contour analysis techniques for cardiac output measurement in isoflurane anaesthetized ponies: influence of different inotropic drugs

“…Significant differences in SVR were expected between treatments, because enoximone induced vasodilation in humans (Vernon et al. 1991), dobutamine tended to reduce SVR in ponies (Gasthuys et al. 1991b; Lee et al.…”

Effects of xylazine/ketamine on cardiac function and serum ionised calcium in horses

“…Inhalant anaesthetics are proposed to cause myocardial depression through altered cellular calcium homeostasis at several sites (Rusy and Komai 1987). They also cause decreased circulating concentrations of ionised calcium (Steffey et al 1979;Gasthuys et al 1991;Grubb et al 1995), thus calcium availability to the cell may be reduced. Although results of this study cannot be used to predict cellular calcium utilisation, our results demonstrate that xylazineketamine does not cause a reduction in circulating concentrations of ionised calcium.…”

“…Myocardial depression induced .by inhalant anaesthetics and barbiturates is mediated by altered calcium homeostasis at the cellular level (Rusy and Komai 1987). Circulating concentrations of ionised calcium are decreased following induction of inhalant anaesthesia in horses (Steffey et al 1979;Gasthuys et al 1991;Grubb et al 1995). Ionised calcium concentrations have not been compared to indices of haemodynamic function in xylazine/ketamine anaesthetised horses.…”

Electrolyte disorders in horses with colic. Part 2: calcium, sodium, chloride and phosphate

“…Calcium is involved in excitation and contraction of cardiac muscle and the maintenance of vascular tone. It is a positive inotrope, causing an increase in smooth muscle contractility (Gasthuys et al 1991;Grubb et al 1996;Garcia-Lopez et al 2001). It also has important effects on the action potential, which is shortened with hypercalcaemia and prolonged with hypocalcaemia (Atkins 1999).…”

“…Volatile anaesthetics are also associated with a fall in plasma calcium concentrations (Dart et al 1992;Grubb et al 1999). Agents such as halothane and isoflurane inhibit the flow of calcium through ion channels in the myocardium and alter calcium balance in the sarcoplasmic reticulum (Gasthuys et al 1991;Grubb et al 1999). Endotoxaemia, sepsis and diarrhoea also result in low serum calcium concentrations (Dart et al 1992;Grubb et al 1996).…”