I declare that I am the sole author of this thesis entitled "Comparison of anesthetic power and cardiopulmonary effects of Halothane and Isoflurane anesthesia in small ruminants". Bibek Chandra Sutradhar, Professor, Department of Medicine and Surgery, CVASU for his meticulous guidance, continuous support, encouragement and expert planning right from selection of my work to successful completion of the manuscript. Bhajan Chandra Das, Professor, Department of Medicine and Surgery, CVASU for his immense inspiration, suggestions and cooperation.
I am also grateful to the staff of the Department of Medicine and Surgery, CVASU, for their assistance during my work. This study compared the anesthetic potency and cardiopulmonary effects between halothane and isoflurane in 20 goats during routine surgery. This study found that isoflurane anesthesia in small ruminants provides shorter and safer recovery with maximum preservation of cardiovascular and pulmonary functions.
In ruminants, halothane sensitizes the myocardium to cathecolamines, which is reversible by alpha-blockers such as acepromazine (Rezahani et al., 1977; Tranquilli et al., 1985). Thirty-four percent (34%) depression on minute ventilation and 59 percent increased airway resistance with 0.75 MAC halothane were reported in lambs during spontaneous breathing (Robinson et al., 1985). Isoflurane has been found to have low blood solubility and low biodegradability and to produce less myocardial depressant properties than halothane (Merin et al., 1991; Eger, 1981 and Wade et al., 1981).
Along with a rapid and smooth induction, propofol provides easy intubation in small ruminants (Reid et al., 1993;. In complex and longer procedures, such as orthopedic surgery, prepubic tendon rupture, diaphragmatic hernia or ventral hernia, anesthesia must be maintained with inhalational anesthetics (Riazuddin et al., 2004) Compared to injectable anesthesia, inhalant anesthesia causes faster changes in depth of anesthesia, earlier shift of central nervous system (CNS) depression, rapid elimination through the lungs, faster recovery from anesthesia and less risk of overdose (Bodh et al ., 2014).
- General anesthesia
- Basic requirements for anaesthesia in small ruminants
- Preoperative preparation
- Diazepam
- Induction
- Propofol
- Endotracheal intubation
- Inhalant anesthetics
- Mechanism of action of Inhalation anesthetics
- Pharmacokinetics of inhalant anesthetics
- Anesthetic Uptake and Distribution
- Elimination of Inhaled Anesthetics
- General Pharmacological Actions of Inhalant Anesthetics
- Central Nervous System
- Cardiovascular System
- Respiratory System
- Genitourinary system
- Halothane
- Isoflurane
- Monitoring the anaesthetized small ruminants
- Recovery
Because hypoxemia is common in goats undergoing general anesthesia, a physical examination should be performed prior to the anesthesia procedure (Hall et al., 2001). To maintain fluid levels, a balanced electrolyte solution can be administered via an intravenous catheter (Fulton et al., 1994). Solubility or partition coefficient is the affinity of the gas for a medium such as blood or fatty tissue (West et al., 2014).
In summary, ventilation, cardiac output and solubility of anesthetics contribute to the elimination of anesthetics (West et al., 2014). It is caused by interference with ventilation and pulmonary vasoconstriction by most inhalational anesthetics (West et al., 2014). Epinephrine-induced arrhythmias are absent with isoflurane anesthesia, as it does not sensitize the myocardium (Hall et al., 2014).
- Study area
- Study period
- Study design
- Anesthetic procedures
- Premedication
- Induction
- Intubation
- Maintenance
- Fluid and Temperature
- Parameters measured
- Statistical analyses
After induction, when the eyes had rotated ventrally and medially and the palpebral reflex was abolished, goats were placed in the sternum for intubation. A loop of gauze around the upper jaw and another loop around the lower jaw and tongue were placed to open the goats' mouths. The head was raised and the head and neck were kept in a straight line for better visualization of the epiglottis and larynx.
To visualize the larynx, a laryngoscope was used to apply pressure to the base of the tongue and the epiglottis. Confirmation of correct tube placement was done by looking at fogging in the tube and placing a few strands of gauze on the connector end of the ET tube, which is blown away on exhalation when the tube is correctly positioned. The setting of the vaporizer was adjusted according to the depth of anesthesia after monitoring the animal's response to various reflexes and the lack of painful response to surgery.
The endotracheal tube with its cuff inflated was left undisturbed until the swallowing reflex returned (ie, when the animal began to chew, moved its tongue and retracted it when pulled outwards, showed signs of return of good laryngeal control), after which the tube was disconnected from the anesthesia machine, and goats were allowed to breathe room air. Throughout the anesthesia period, goats received intravenous normal saline solution (Normal saline®; ACME laboratories Ltd) @ 10 ml/kg/hr in both groups. At the end of the operation, the vaporizer was closed and 100% O2 was given in the system until the animals woke up.
The time to extubation of the animals, the time to the first head movement, the time to enter the cistern position and the time to stand up were observed and recorded after cessation of anesthesia. Criteria used to assess the quality of induction; anesthesia and recovery in goats are summarized in Table 2. Criteria used to assess the quality of induction, anesthesia and recovery in goats induced with propofol and maintained with halothane (n = 10) or isoflurane (n=10).
Analysis of variance (ANOVA) was used to compare the means at different time intervals among the two groups.
- Findings of the heart rate (HR)
- Findings of the respiratory rate (RR)
- Findings of the oxygen saturation (SpO 2 )
- Findings of the blood pressure
- Findings of Temperature
- Recovery findings
No significant differences were found between two groups or between baseline values and other values. Systolic arterial pressure decreased significantly (p<0.05) in the HAL group from ten minutes to twenty-five minutes (Figure 13), with no significant differences in the ISO group from baseline. In the case of DAP, a significant difference (p<0.05) was found at twenty-five minutes from baseline in the HAL group (Figure 14).
Similarly, in the case of MAP, significant differences (p<0.05) were found only in the HAL group at twenty-five and thirty-five minutes (Figure 15) compared to baseline. MAP also differs significantly between the HAL and ISO groups, from five to fifty minutes, except at forty-five minutes (Figure 15). A significant decrease from baseline in rectal temperature during maintenance of anesthesia was found in both the HAL and ISO groups (Figure 16).
Values of systolic arterial pressure (SAP) in small ruminants during halothane and isoflurane maintenance anesthesia. Values of diastolic arterial pressure (DAP) in small ruminants during halothane and isoflurane maintenance anesthesia. Time to extubation, time to regain chest position and time to rise were significantly (p<0.05) less in the ISO group compared to the HAL group (Figure 17).
Mild regurgitation was found in two goats in the HAL group and one goat in the ISO group (Table 3). In the HAL group, mild salivation was observed in three goats and moderate salivation was found in two goats (Table 3). On the other hand, mild saliva secretion was found in two goats and no saliva was found in eight goats in the ISO group (Table 3).
Evanescent shivering and incoordination of the limb were found in three goats during recovery from halothane maintenance anesthesia.
40 During halothane anesthesia, reduced respiratory rate and depth have been observed in bulls (Greene et al., 1998) and cattle (Takase, 1976). In the case of ruminants, lateral recumbency and continuous ruminal fermentation that bloat during anesthesia cause impaired ventilation (Fujimoto and Lenehan, 1985; Lin et al., 2012). Although halothane causes a dose-dependent decrease in arterial blood pressure and cardiac output, it has very little effect on total peripheral resistance in dogs (Steffey and Howland, 1978) and goats (Hikasa et al., 1998).
In HAL group severe heat loss or hypothermia can be caused by vasodilation (Jones and McLaren, 1965). In a study in humans, a greater decrease in body temperature was found in the halothane group than the isoflurane group, which is similar to our study (Ramachandra et al., 1989). The decrease in rectal temperature in both groups may be due to decreased skeletal muscle tone, decreased metabolic rate and muscle relaxation along with depressed thermoregulatory center (Matsukawa et al., 1995).
Early recovery from isoflurane anesthesia has been attributed to a reduced stress response, better cardiovascular function, fewer changes in hepatic circulation, and faster elimination of anesthetics (Riazuddin et al., 2004). Whereas slower recovery under halothane maintenance anesthesia may be due to increased stress leading to catabolic pathways and depleting energy sources (Wagner et al., 1991). 42 increase in intraruminal pressure consistent with poor esophageal or esopharyngeal sphincter tone (Bodh et al., 2014).
The risk of regurgitation increases in case of inadequate fasting and improper positioning of patients where the rumen content sinks into the esophageal opening and prevents gas eructation from the rumen leading to rumen expansion and regurgitation of ruminal contents (Bodh et al., 2014 ). This may be caused by a reduction in the swallowing reflex (Kokkonen and Eriksson, 1987) or by jaws remaining partially open due to endotracheal tube placement (Bodh et al., 2014). In the HAL group, the postanesthetic shivering observed in three patients may be due to the residual excitatory effect of central nerve stimulation (Auer et al., 1978) or to the hypothermia found in the HAL group during recovery.
Core temperature at the end of the operation is the most important clue to determine the factor in the occurrence of post-operative shivering (Lienhar et al., 1992).
Sedative and cardiopulmonary effects of acepromazine, midazolam, butorphanol, acepromazine-butorphanol, and midazolam-butorphanol on propofol anesthesia in goats. Effects of sevoflurane, halothane, enflurane, and isoflurane on hepatic blood flow and oxygenation in chronically instrumented greyhound dogs. Comparison of cardiopulmonary effects of isoflurane and halothane after atropine-guaifenesin-thiamyl anesthesia for rumenotomy in steers.
Cardiopulmonary, hematologic, biochemical, and serum behavioral effects of sevoflurane compared with isoflurane or halothane in spontaneously ventilated goats. Clinical, cardiopulmonary, hematologic, and serial biochemical effects of sevoflurane and isoflurane anesthesia in spontaneously breathing oxygen in sheep. Cardiopulmonary effects of administration of a combined solution of xylazine, guaifenesin, and inhaled ketamine or isoflurane to mechanically ventilated calves.
Comparison of the cardiopulmonary effects of anesthesia maintained by continuous infusion of ketamine and propofol with anesthesia maintained by inhalation of sevoflurane in goats undergoing magnetic resonance imaging, America Journal of Veterinary Research. Comparison of the effects of isoflurane and desflurane on cardiovascular dynamics and regional blood flow in the chronically instrumented dog. Effects of 1 MAC desflurane on cerebral metabolism, blood flow and carbon dioxide reactivity in humans.
Effects of a minimal concentration of alveolar anesthetic sevoflurane on cerebral metabolism, blood flow and CO2 reactivity in cardiac patients. Comparison of the effects of halothane, isoflurane, and sevoflurane on atrioventricular conduction time in pentobarbital-anesthetized dogs. Comparative evaluation of general anesthesia with halothane and isoflurane on arterial pressure in dogs.
Clinical-physiological and hemodynamic effects of fentanyl with xylazine, medetomidine, and dexmedetomidine in isoflurane-anesthetized water buffalo (Bubalusbubalis).
