Some anesthetic agents or adjunct medications administered during general anesthesia can cause an accelerated idioventricular rhythm (AIVR), which is associated with higher vagal tone and lower ...sympathetic activity. We encountered AIVR induced by vagal response to injection-related pain following local anesthetic infiltration into the oral mucosa during general anesthesia. A 48-year-old woman underwent extraction of a residual tooth root from the left maxillary sinus under general anesthesia. Routine preoperative electrocardiogram (ECG) was otherwise normal. Eight milliliters of 1% lidocaine (80 mg) with 1:100,000 epinephrine (80 μg) was infiltrated around the left maxillary molars over 20 seconds using a 23-gauge needle and firm pressure. Widened QRS complexes consistent with AIVR were observed for ∼60 seconds, followed by an atrioventricular junctional rhythm and the return of normal sinus rhythm. A cardiology consultation and 12-lead ECG in the operating room produced no additional concerns, so the operation continued with no complications. AIVR was presumably caused by activation of the trigeminocardiac reflex triggered by intense pain following rapid local anesthetic infiltration with a large gauge needle and firm pressure. Administration of local anesthetic should be performed cautiously when using a large gauge needle and avoid excessive pressure.
To test the postexposure analgesic efficacy of low doses of eugenol in zebrafish.
Prospective experimental study.
A total of 76 large adult zebrafish (Danio rerio).
Fish swimming behavior (median ...velocity, freeze time, high-speed swimming and distance moved in the vertical direction) was recorded in a 1.6 L video arena before and after exposure to eugenol (0, 1, 2, 5, 10 and 20 mg L
). In a second experiment, fish were anesthetized with 2-phenoxy-ethanol and treated with an injection of 5% acetic acid (noxious stimulus), and then exposed to 0, 1, 2 and 5 mg L
eugenol. The fish swimming behavior was also recorded.
The higher doses (10 and 20 mg L
) reduced the median velocity, high-speed swimming and distance moved in the vertical direction, and increased the freeze time. Zebrafish behavior was not altered by eugenol (1, 2 and 5 mg L
) after noxious stimulation.
The change in the behavior of zebrafish associated with a noxious stimulus can be monitored and is a good model for studying analgesia in fish. Eugenol (10 and 20 mg L
) induced zebrafish sedation. The response after a noxious stimulus was not affected by postexposure to lower doses, and thus we cannot recommend its use as an analgesic.
Introduction
A major goal in neonatal medicine is to reduce stress as much as possible in routine care. Bathing is one of the important routine cares for neonates, but it makes a big environmental ...change for them. We aimed to examine whether water temperature, room temperature, and position changes in tub bathing serve as noxious stimuli to neonates.
Methods
This prospective trial was performed in full-term and non-low-birth-weight neonates admitted to the hospital between July 2020 and March 2021. Those with underlying diseases, fetal distress, infection, and other medical conditions were excluded. Measurements were taken during the neonates’ first tub bath since birth, which was performed by a trained nurse. Changes in regional oxygen saturation (rSO
2
), determined using near-infrared spectroscopy, and water and room temperature, were examined at five different time points: upon entering the bath, head washing, position change, exiting the bath, and during the 3 min after bathing.
Results
In total, 17 neonates were analyzed. No changes in rSO
2
due to head washing or position change were observed; however, rSO
2
significantly decreased upon entering (78.5 ± 4.1% vs. 75.7 ± 4.1%,
p
< 0.001) and exiting the bath (75.8 ± 5.7% vs. 74.4 ± 5.4%,
p
< 0.04). The rate change in rSO
2
upon entering the bath showed a significant inverse correlation with water temperature (
r
= − 0.53,
p
< 0.03), and there were no significant correlations between rSO
2
and water or room temperature upon exiting the bath. There was no change in body skin temperature before and after bathing, but rSO
2
gradually decreased during the 3 min after bathing.
Conclusions
Neonates may perceive certain temperatures during bathing as noxious stimuli. Therefore, methods to minimize stress associated with bathing should be implemented to reduce the difference between water temperature and room temperature during bathing.
Trial registration
This trial has been registered at UMIN repository with the trial number UMIN000041045 (
https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000046500
). The date of the final dataset was April 01, 2021.
To determine the minimum infusion rate (MIR) of alfaxalone required to prevent purposeful movement of the extremities in response to noxious stimulation.
Prospective, experimental.
Eight healthy ...goats; four does and four wethers.
Anaesthesia was induced with alfaxalone 3 mg kg−1 intravenously (IV). A continuous IV infusion of alfaxalone, initially at 0.2 mg kg−1 minute−1, was initiated. Following endotracheal intubation the goats breathed spontaneously via a circle breathing circuit delivering supplementary oxygen. The initial infusion rate was maintained for 30 minutes before testing for responses. The stimulus was clamping on the proximal (soft) part of one digit of the hoof with Vulsellum forceps for 60 seconds. In the absence or presence of purposeful movement of the extremities, the infusion rate was reduced or increased by 0.02 mg kg−1 minute−1 and held constant for 30 minutes before claw-clamping again. Alfaxalone MIR was calculated as the mean of the infusion rates that allowed and abolished movement. Cardio-respiratory parameters were measured. Recovery from general anaesthesia was timed and quality scored. Results are presented as median (range).
The MIR of alfaxalone was 0.16 (0.14–0.18) mg kg−1 minute−1 or 9.6 (8.4–10.8) mg kg−1 hour−1. Induction of and recovery from anaesthesia were excitement-free. Cardio-respiratory changes were minimal, although compared to baseline HR increased, and at 2 minutes post-induction, (prior to oxygen supplementation), PaO2 decreased significantly from 84 (80–88) to 70 (51–72) mmHg 11.2 (10.7–11.7) to 9.3 (6.8–9.6) kPa. Sporadic muscle twitches, unrelated to depth of anaesthesia, were observed during the period of general anaesthesia. Time (minutes) to sternal recumbency and standing were 4.0 (3.0–10.0) and 41.5 (25.0–57.0) respectively.
Alfaxalone can be used for total intravenous anaesthesia (TIVA) in goats and is associated with minimal adverse effects. Oxygen supplementation is advised, especially when working at higher altitudes.
To determine the minimum infusion rate (MIR) of propofol required to prevent purposeful movement in response to a standardized stimulus in goats.
Prospective, experimental study.
Eight healthy goats ...(four does, four wethers).
Anaesthesia was induced with 4 mg kg−1 propofol intravenously (IV). A continuous IV infusion of propofol at 0.6 mg kg−1 minute−1 was initiated immediately to maintain anaesthesia. Following endotracheal intubation, goats breathed spontaneously via a circle breathing system delivering supplementary oxygen. The initial propofol infusion rate was maintained for 30 minutes before responses to noxious stimulation provided by clamping the proximal part of the claw with a Vulsellum forceps for 60 seconds were tested. In the presence or absence of purposeful movements of the extremities, the infusion rate was increased or reduced by 0.1 mg kg−1 minute−1 and held constant for 30 minutes before claw clamping was repeated. The propofol MIR for each goat was calculated as the mean of the infusion rates that allowed and abolished movement. Basic cardiopulmonary parameters were monitored, recorded and tested for statistical significance using Wilcoxon's signed rank test with Bonferroni adjustment for multiple testing. The quality of recovery from anaesthesia was assessed and scored.
The median MIR of propofol was 0.45 mg kg−1 minute−1 (range: 0.45–0.55 mg kg−1 minute−1). Induction and recovery were free of adverse behaviour. No statistically significant cardiopulmonary changes in comparison with baseline were observed, but clinically relevant hypoxaemia at 2 minutes after induction of anaesthesia was consistently observed. Chewing during anaesthesia was observed in three goats. Median times to extubation and standing were 3 minutes (range: 2–6 minutes) and 10 minutes (range: 7–21 minutes), respectively.
Propofol induction and maintenance of general anaesthesia minimally compromise cardiopulmonary function when oxygen is supplemented in goats.
This prospective blinded randomized study aimed to determine whether the timing of morphine and phenylbutazone administration affects the breathing response to skin incision, recovery quality, ...behavior, and cardiorespiratory variables in horses undergoing fetlock arthroscopy. Ten Standardbred horses were premedicated with acepromazine (0.04 mg kg(-1) IM) and romifidine (0.04 mg kg(-1) IV). Anesthesia was induced with diazepam (0.05 mg kg(-1)) and ketamine (2.2 mg kg(-1)) IV at T0. Horses in group PRE (n = 5) received morphine (0.1 mg kg(-1)) and phenylbutazone (2.2 mg kg(-1)) IV after induction and an equivalent amount of saline after surgery. Horses in group POST (n = 5) received the inversed treatment. Anesthesia was maintained with isoflurane 2% in 100% oxygen. Hypotension (mean arterial pressure <60 mmHg) was treated with dobutamine. All horses breathed spontaneously. Dobutamine requirements, respiratory rate (f R), heart rate (HR), mean arterial blood pressure, end-tidal CO2, inspired (i) and expired (e) tidal and minute volume (V T and Formula: see text), inspiratory time (IT), and the inspiratory gas flow (V Ti/IT) were measured every 5 min. Data were averaged during four 15 min periods before (P1 and P2) and after the incision (P3 and P4). Serial blood-gas analyses were also performed. Recoveries were unassisted, video recorded, and scored by three anesthetists blinded to the treatment. The postoperative behavior of the horses (25 demeanors), HR, and f R were recorded at three time points before induction (T0-24 h, T0-12 h, and T0-2 h) and six time points after recovery (TR) (TR + 2, 4, 6, 12, 24, 48 h). Data were compared between groups using a Wilcoxon test and within groups using a Friedman test or a Kruskal-Wallis signed-rank test when applicable. Tidal volumes (V Te and V Ti) were higher in PRE than in POST during all the considered periods but the difference between groups was only significant during P2 (V Te in mL kg(-1) in PRE: 13 9, 15, in POST: 9 8, 9, p = 0.01). None of the other variables were significantly different between and within groups. Under our experimental conditions, skin incision did not affect respiratory variables. Administration of pre- versus postoperative phenylbutazone and morphine did not influence recovery quality, HR, f R, or animal behavior.
Defining Depth of Anesthesia Shafer, S. L.; Stanski, D. R.
Handbook of experimental pharmacology,
2008
182
Book Chapter, Journal Article
Recenzirano
In this chapter, drawn largely from the synthesis of material that we first presented in the sixth edition of Miller’s Anesthesia, Chap 31 (Stanski and Shafer 2005; used by permission of the ...publisher), we have defined anesthetic depth as the probability of non-response to stimulation, calibrated against the strength of the stimulus, the difficulty of suppressing the response, and the drug-induced probability of non-responsiveness at defined effect site concentrations. This definition requires measurement of multiple different stimuli and responses at well-defined drug concentrations. There is no one stimulus and response measurement that will capture depth of anesthesia in a clinically or scientifically meaningful manner. The “clinical art” of anesthesia requires calibration of these observations of stimuli and responses (verbal responses, movement, tachycardia) against the dose and concentration of anesthetic drugs used to reduce the probability of response, constantly adjusting the administered dose to achieve the desired anesthetic depth. In our definition of “depth of anesthesia” we define the need for two components to create the anesthetic state: hypnosis created with drugs such as propofol or the inhalational anesthetics and analgesia created with the opioids or nitrous oxide. We demonstrate the scientific evidence that profound degrees of hypnosis in the absence of analgesia will not prevent the hemodynamic responses to profoundly noxious stimuli. Also, profound degrees of analgesia do not guarantee unconsciousness. However, the combination of hypnosis and analgesia suppresses hemodynamic response to noxious stimuli and guarantees unconsciousness.
An acute pain animal model for fMRI study would provide useful spatial and temporal information for studying the supraspinal nociceptive neuronal responses. The aim of the present study was to ...investigate whether the nociceptive responses in different brain areas can be differentiated by using functional magnetic resonance imaging (fMRI) in anesthetized rats. Functional changes in brain regions activated by noxious or non-noxious stimuli of the sciatic nerve were investigated using fMRI in a 4.7 T MR system in α-chloralose anaesthetized rats. To determine the electrical intensity for noxious and non-noxious stimuli, compound action potential recording was employed to reveal the type of fibers activated by graded electrical stimulation of sciatic nerve. It showed that innocuous A-β fibers were excited by two times the muscle twitch threshold and nociceptive A-δ and C fibers were recruited and excited by 10 and 20 times threshold, respectively. A series of four-slice gradient echo images were acquired during innocuous (two times threshold) and noxious (10 and 20 times threshold) stimuli in a 4.7 T MR system. Contralateral somatosensory cortex was the most prominent brain area activated by innocuous stimuli. Both signal intensity and activated areas were significantly increased in the somatosensory cortex, cingulate cortex, medial thalamus and hypothalamus during noxious stimuli. These four brain areas activated by noxious stimuli were significantly suppressed by prior intravenous injection of morphine (5 mg/kg). The present findings demonstrated that the difference of the innocuous and nociceptive responses in the brain could be detected and localized by an in vivo spatial map using fMRI. Results suggest that fMRI may be an invaluable tool for studying pain in anesthetized animals.
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