Acidosis and Neuromuscular Blockade

Abstract

The effect of different types of acidosis on sensitivity to neuromuscular blocking agents was studied in vivo on the tibialis muscle of cats and in vitro in the phrenic nerve diaphragm preparation of the rat. In vivo metabolic acidification was caused by diffusion of weak organic acids, which penetrate easily into the cell and imitate closely the state of metabolic acidosis in man. Respiratory acidosis was caused by inhalation of 10% carbon dioxide in oxygen. In the in vitro experiments, acidification was caused by titration with the same acids as well as hydrochloric acid. pH was lowered to levels just above 7.0. Blank in vivo studies showed that the metabolic acidosis by itself causes no significant depression of indirect muscle contraction, while respiratory acidosis causes only a slight depression. A minor depression was seen in the blank in vitro metabolic acidosis studies.Both succinylcholine and decamethonium blocks are strongly antagonised in vivo and in vitro by metabolic and respiratory acidosis. Pancuronium bromide block was potentiated by metabolic and respiratory acidosis both in the in vivo and in vitro experiments. It is most likely that changes in transmembrane potential are the cause for the changes in sensitivity seen in these experiments. R. B. (1956) Plasma, extracellular and muscle electrolyte responses to acute metabolic acidosis. Calculation of intracellular pH from the distribution of 5,5-dimethyl-2,4-oxazolidinedione (DMO) Application to skeletal muscle of the dog. TOBIN,

Effects of small peripheral temperature changes on the evoked baseline electromyographic response

“…Increases in isoflurane partial pressures are reported to potentiate steroidal muscle relaxation recorded by MMG (11) and EMG (12). Respiratory acidosis has been demonstrated to have a significant effect on twitch tension in cat without muscle relaxation (13,14). End-tidal isoflurane concentration was within ∫0.1% of the fixed value in our normoventilated patients.…”

The Influence of Acid-Base Balance on Anesthetic Muscle Relaxants: A Comprehensive Review on Clinical Applications and Mechanisms

“…The experiment showed that alkalosis potentiated the action of succinylocholine [60]. A study on the impact of acidosis on neuromuscular blockade showed that succinylocholine and decamethonium are antagonized by both metabolic and respiratory acidosis [61]. Succinylcholine remains the preferred drug for inducing paralysis, especially when there is a requirement for a swift onset and conclusion of its effects.…”

Apples and Oranges—All ‘Vitamin C’ May Not Be Created Equal

“…In contrast, sodium ascorbate is conceivably less acidifying in vivo due to the accompanying sodium cations. Indeed, it is well recognized in translational research that infusion of high-dose intravenous ascorbic acid induces metabolic acidosis and profound acidemia (3, 4). The LOVIT trial did not present data on acid–base changes immediately after the infusion of ascorbic acid.…”