Tag Archives: anesthesia

Effect of Isoflurane Anesthesia on the Heart Rate and Blood Pressure Response to Autonomic Nervous System Stimulation and Inhibition in Rats

DOI: 10.2478/amma-2020-0016

Objective: Many experimental studies aim to assess the autonomic nervous system (ANS), but this is often hampered by interactions with anesthetic drugs. We aimed to evaluate whether isoflurane anesthesia is suitable for ANS evaluation in rats.
Methods: Six Wistar rats were anesthetized with isoflurane (4 L/min, 2.5%). Systolic blood pressure (SBP) and heart rate (HR) were measured at baseline and 20 min after sympathetic inhibition (propranolol, 5 mg/kg) and stimulation (isoproterenol, 2.5 mg/kg), and parasympathetic inhibition (atropine nitrate, 2 mg/kg) and stimulation (carbamylcholine, 0.4 mg/kg; acetylcholine, 0.1 mg/kg). Six additional rats were used to assess the effects of isoproterenol, carbamylcholine, and atropine nitrate in the absence of anesthesia.
Results: Propranolol significantly decreased the HR and the SBP, whereas isoproterenol significantly increased the HR (all p≤0.01) in the isoflurane-anesthetized rats. However, the HR response to sympathetic stimulation was significantly reduced in the anesthetized compared to the non-anesthetized rats (p=0.03). Carbamylcholine and acetylcholine significantly decreased both the HR and SBP (all p<0.05) in the anesthetized rats, but the response to carbamylcholine administration was significantly more pronounced in the non-anesthetized rats (p=0.03). Atropine nitrate significantly increased the HR (p<0.001) in the non-anesthetized rats, but it had no effect on either the HR or the SBP in the presence of isoflurane anesthesia (both p>0.05).
Conclusions: Isoflurane anesthesia appears to interfere with both components of the ANS and is therefore not an optimal approach for experimental ANS evaluation. Our data indicate autonomic receptors and/or post-receptor mechanisms as the most likely site for isoflurane-ANS interactions.

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Influence of General Anesthesia on Impulsivity and Learning Ability-Experimental Study

DOI: 10.1515/amma-2016-0045

Objective: To investigate the effect of anesthesia on rats’ ability of learning and over their impulsivity.
Material and Methods: We studied eight Wistar adult male rats, test and drug naive subjects. Animals were separated in two groups, group A and B with four members each. Group A included the anesthetized animals. The combination of ketamine, xylazine and piplophen in 2ml/kg body weight dosage was used and testing was done 24 hours after anesthesia. Group B was taken as control. The study was conducted using the ”Delay discounting” apparatus. Experiments assessing impulsive behavior were conducted using automated operant chambers, equipped with two nose-poke holes (holes where pellets of food were released). Rat’s answer was considered touching the nose-poke hole. One answer was rewarded with pellets of food of 45 mg each (small reward), while another hole released five pellets of 45 mg each (high reward). Both types of rewards were presented immediately after rat’s answer and were followed for a period of 25 seconds timeout. During the training phase, rats were placed in operant chambers 30 minutes per day, 5 consecutive days. The growing percent of preference for greater reward indicates learning.For the testing phase the procedure was similar, but a delay was introduced before the release of the big reward. During this phase, the preference for higher reward was indicative for non-impulsive behaviour.
Results: The results didn’t show significant statistically differences between the two groups.
Conclusions: Anesthesia had no effect on learning ability nor on impulsivity.

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How About Investing a Little Bit More in the Bloody Approach?

Last year Prof Gurman initiated the publication in our journal of a series of happenings in the field of anesthesia
and intensive care. They escalated to an unwanted outcome and the end of every story was decided in the courtroom. This is why the medical cases turned into legal cases.
There is no happy end to a legal case except for the patient to recover and the doctors to acknowledge their good faith and flawless professional behavior. Still, if some wisdom issues from a legal case, there is a positive reflection one can use later on.
The comments an anesthetist would immediately formulate after confrontation with such a case would be self
defendant, and in no case neutral. And the best defense is evidence-based.
When trying to find medical evidence for radial nerve palsy on the net, the first results the Google offered where
583000 entries. When adding anesthesia, the figure dropped to 237000 and further to 2940 if filtered with
an additional noun, positioning. Thus medical literature referring to the reported case is not exotic, and yet few of the titles red and of the articles studied consecutively were relevant to the subject of the research. [More]

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Modification of Renal Permeability for Proteins after General Anesthesia with Sevoflurane and Desfluran

Introduction: Sevoflurane degradation by carbon dioxide absorbents during low-flow anesthesia lead to the formation of a haloalkene called compound A, which causes nephrotoxicity.
Material and methods: We determined proteinuria by spectophotometry at 600 nm, preoperatively and postoperatively at 24 and 72 hours in 52 patients undergoing general anesthesia with sevoflurane and 25 patients undergoing general anesthesia with Desfluran. We selected patients without previous renal disease, with anesthetic risk ASA I–III who underwent major abdominal and thoracic surgery lasting more than 150 minutes and we used a 2 l/minute FGF-fresh gas flow, with a MAC-minimal alveolar concentration of 1.5 to 1.8 for Sevoflurane, and of 6–8 MAC for Desfluran.
Results: Renal permeability is impaired by general anesthesia with Sevoflurane (p ˂ 0.0001) and Desfluran (p > 0,001). The amount of filtered protein has a maximum at 24 hours after surgery with gradual decrease within 72 hours, but without reaching the normal preoperative values.
Conclusions: There is proteinuria after exposure to volatile agents like Sevoflurane and Desfluran recording a maximum in the first 24 hours and there is also a tendency to normalization within 72 hours. We noticed a marked impairment of renal permeability in association with specific groups of pathology as septic patients, diabetics, hypertensives, especially after Sevoflurane anesthesia. There was no-one case of acute renal failure in which to criminalize Sevoflurane or Desfluran.

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