Effect of Sevoflurane on Diaphragmatic Contractility in Dogs

Abstract

The effect of sevoflurane on diaphragmatic contractility was investigated in 12 anesthetized, mechanically ventilated dogs with the thorax opened. Animals were divided into two groups of six each: the sevoflurane and time control groups. We assessed contractility by the transdiaphragmatic pressure (Pdi) during supramaximal stimulation of the phrenic nerve at frequencies of 0.5, 10, 20, 50, and 100 Hz under quasiisometric conditions. The integrated electrical activity (Edi) of the crural and costal parts of the diaphragm (Edi cru, Edi cost) was also measured. In the sevoflurane group, diaphragmatic contractility was determined during three levels of anesthesia, specifically 0, 1.0, and 1.5 minimum alveolar anesthetic concentration (MAC). Measurements were made at the start of the stimulation (initial) and at the end of the 2-s period (2-s). Increasing the depth of sevoflurane anesthesia did not cause any significant differences in Pdi and Edi at 0.5-, 10-, and 20-Hz stimulation. By contrast, at 50- and 100-Hz stimulation, initial Pdi during 1.0 and 1.5 MAC sevoflurane exposure decreased significantly compared with the 0 MAC value (P less than 0.05). In addition, there was a statistical difference in 2-s Pdi between 1.0 and 1.5 MAC at 100-Hz stimulation (P less than 0.05). The Edi cru showed similar changes in Pdi at both measurements, whereas there was no remarkable change in Edi cost. There was no significant change either in Pdi or in Edi with respect to time in the time control group. We conclude from these results that sevoflurane impairs diaphragmatic contractility through its inhibitory effect on neuromuscular transmission, predominantly of the crural part.

The Effect of Four Anaesthetic Protocols for Maintenance of Anaesthesia on Trans-Diaphragmatic Pressure in Dogs

“…It is reported that the P di value during a normal sniff is more than 58.84 mmHg in men and more than 51.49 mmHg in women [37]. In veterinary medicine, the effect of different drugs on diaphragmatic contractility has also been studied by measuring P di in a fatigued diaphragm [7], [8], [11], [13], [14].…”

“…While enflurane depresses diaphragmatic function in a dose-dependent manner, halothane and isoflurane show little effect on it [7], [8], [11], [12] and sevoflurane has an intermediate effect [13], [14]. It has also been shown that halothane depresses P di and the electrical activity of the diaphragm in spontaneously breathing dogs [5].…”

The effect of propofol on airway pressures generated by magnetic stimulation of the phrenic nerves

“…A study in dogs during propofol anaesthesia [17] detected a fall in TwPdi of 10% to 20%. Volatile anaesthetic agents have also been found to reduce diaphragm contractility in some animal studies [18,19,20], but not all [21].…”

The Recovery Profile of Reduced Diaphragmatic Contractility Induced by Propofol in Dogs

“…The favorable recovery profile associated with propofol offers advantages over traditional anesthetic and sedative medications in clinical situations (1). Like volatile anesthetics (halothane, enflurane, isoflurane, and sevoflurane) (2)(3)(4)(5), propofol decreases contractility in nonfatigued and fatigued diaphragm (6,7). No studies have been reported evaluating the recovery from reduced diaphragmatic contractility caused by propofol.…”