Effects of intravenous and topical laryngeal lidocaine on heart rate, mean arterial pressure and cough response to endotracheal intubation in dogs

A randomized clinical trial comparing the efficacy of lidocaine administered intravenously, intranasally or as infraorbital nerve block in dogs undergoing rostral rhinosocopy

OBJECTIVE

To compare the efficacy of lidocaine administered intravenously, intranasally or as an infraorbital nerve block in dogs undergoing rostral rhinoscopy.

STUDY DESIGN

Randomized clinical trial.

ANIMALS

A total of 43 client-owned dogs.

METHODS

After premedication with medetomidine 0.01 mg kg-1 and methadone 0.2 mg kg-1 intramuscularly, anaesthesia was induced with propofol and maintained with isoflurane in oxygen. Dogs were randomly allocated to receive 2 mg kg-1 of 2% lidocaine as a bilateral infraorbital nerve block (INB) via the caudal intraoral approach, via bilateral topical intranasal administration (TIA) or as an intravenous bolus (IVB). At 5 minutes following lidocaine administration, responses to rhinoscopy (RR) and biopsies (RB) were evaluated using a simple scoring system (0: no reaction; 1: reaction). Response to the rhinoscopy in the recovery period (RE) was recorded. Recovery quality was scored using a simple descriptive score. Heart rate, respiratory rate and noninvasive arterial blood pressure were recorded. Intravenous (IV) fentanyl 0.001 mg kg-1 was administered if an increase > 20% in any variable occurred. Gross movement was attenuated using propofol 0.5 mg kg-1 IV. Scores were analysed using the Chi-square test with Monte Carlo method. Cardiorespiratory changes among and overtime between groups were compared using one-way anova and one-way anova for repeated measures, respectively, or the correspondent non-parametric tests; p < 0.05.

RESULT

Of the 43 dogs, 42 completed the study. No statistically significant differences were detected in either physical reactions or changes in cardiorespiratory variables for RR, RB, RE or recovery quality, although RB tended to be higher in group TIA (7/10 versus 1/10 INB and 3/13 IVB).Various cardiorespiratory variables changed overtime within groups.

CONCLUSIONS AND CLINICAL RELEVANCE

In dogs, all three investigated techniques attenuated responses during rostral rhinoscopy in dogs, although INB and IVB were more efficacious when biopsies were taken.

Effect of intravenous fentanyl on cough reflex and quality of endotracheal intubation in cats

OBJECTIVE

To assess the effects of intravenous (IV) fentanyl on cough reflex and quality of endotracheal intubation (ETI) in cats.

STUDY DESIGN

Randomized, blinded, negative controlled clinical trial.

ANIMALS

A total of 30 client-owned cats undergoing general anaesthesia for diagnostic or surgical procedures.

METHODS

Cats were sedated with dexmedetomidine (2 μg kg^-1 IV), and 5 minutes later either fentanyl (3 μg kg^-1, group F) or saline (group C) was administered IV. After alfaxalone (1.5 mg kg^-1 IV) administration and 2% lidocaine application to the larynx, ETI was attempted. If unsuccessful, alfaxalone (1 mg kg^-1 IV) was administered and ETI re-attempted. This process was repeated until successful ETI. Sedation scores, total number of ETI attempts, cough reflex, laryngeal response and quality of ETI were scored. Postinduction apnoea was recorded. Heart rate (HR) was continuously recorded and oscillometric arterial blood pressure (ABP) was measured every minute. Changes (Δ) in HR and ABP between pre-intubation and intubation were calculated. Groups were compared using univariate analysis. Statistical significance was set as p < 0.05.

RESULTS

The median and 95% confidence interval of alfaxalone dose was 1.5 (1.5-1.5) and 2.5 (1.5-2.5) mg kg^-1 in groups F and C, respectively (p = 0.001). The cough reflex was 2.10 (1.10-4.41) times more likely to occur in group C. The overall quality of ETI was superior in group F (p = 0.001), with lower laryngeal response to ETI (p < 0.0001) and ETI attempts (p = 0.045). No differences in HR, ABP and postinduction apnoea were found.

CONCLUSIONS AND CLINICAL RELEVANCE

In cats sedated with dexmedetomidine, fentanyl could be considered to reduce the alfaxalone induction dose, cough reflex and laryngeal response to ETI and to improve the overall quality of ETI.

The effect of intravenous lidocaine on propofol dosage in painless bronchoscopy of patients with COPD

Background

We tested the hypothesis that intravenous (IV) lidocaine reduces propofol requirements in painless bronchoscopy in patients with chronic obstructive pulmonary disease (COPD).

Methods

A total of 93 patients who underwent bronchoscopy were included in this randomized placebo-controlled study. The patients were randomly divided into two groups. After the IV doses of nalbuphine, patients were given a bolus of propofol, which was titrated if necessary until loss of consciousness. Then patients were given IV lidocaine (2 mg/kg then 4 mg/kg/h) or the same volume of saline. The primary endpoint was the propofol requirements. Secondary endpoints were the incidence of hypoxemia, the incidence of cough during glottis examination, the systolic blood pressure (SBP) and heart rate (HR) during bronchoscopy procedures, the bronchoscopist's comforts, and the time for wakefulness before recovery.

Results

Lidocaine infusion resulted in a significant reduction in propofol requirements (p &lt; .0001), and the incidence of hypoxemia (p = .001) and cough (p = .003) during examination decreased significantly in the lidocaine group. During the examination, the fluctuation of SBP and HR was significantly lower than that in the control group, and the difference was statistically significant (p &lt; .05). Bronchoscopist's comforts were higher in the lidocaine group (p &lt; .001), and time for wakefulness (p &lt; .001) were significantly lower in the lidocaine group.

Conclusion

In painless bronchoscopy in patients with COPD, IV infusion of lidocaine resulted in a reduction in propofol dose requirements and reduce the incidence of adverse events.

Evaluation of the time to desensitization of the larynx of cats following topical lidocaine application

OBJECTIVES

The objective of this study was to evaluate the time to decreased reactivity of the arytenoid cartilages in cats after application of topical lidocaine.

METHODS

One hundred and ten mixed-breed cats were randomly assigned to one of five groups based on the time between application of lidocaine and stimulation of the larynx: 5 (T5), 15 (T15), 30 (T30), 45 (T45) or 60 (T60) s. Cats were premedicated with dexmedetomidine, ketamine and buprenorphine. Anesthesia was induced with propofol to effect. Lidocaine 2% (2 mg/kg) was applied topically to the vocal cords using a catheter attached to a syringe under direct laryngoscopy. After lidocaine application, the designated time elapsed and the vocal cords were stimulated with the patient end of an endotracheal tube. Severity of reaction was reported as none, mild, moderate or severe. All cats were intubated after the reactivity score was recorded. Anesthesia was maintained with isoflurane and 100% oxygen while cats were spayed or castrated. Cats were monitored in recovery for signs of respiratory complications and pain.

RESULTS

There was a significant difference in overall reactivity score between T5 and T45 (P = 0.0038). Also, there was a significant difference in the number of cats with no reaction compared with cats with any reaction between T5 and T30 (P = 0.03), as well as between T5 and T45 (P = 0.0028). No cat had a severe reactivity score at T45 or T60. All cats were successfully intubated. There were no complications during intubation, maintenance of anesthesia or recovery.

CONCLUSIONS AND RELEVANCE

As the lowest overall reactivity score occurred at T45, it is recommended to wait at least 45 s after application of topical lidocaine before attempting tracheal intubation.

Effects of 2% lidocaine hydrochloride solution as a coinduction agent with propofol on cardiopulmonary variables and administered propofol doses in healthy dogs premedicated with hydromorphone hydrochloride and acepromazine maleate

OBJECTIVE

To evaluate the effects of lidocaine as a coinduction agent with propofol on cardiopulmonary variables and administered propofol doses in healthy dogs premedicated with hydromorphone hydrochloride and acepromazine maleate and anesthetized with isoflurane.

ANIMALS

40 client-owned dogs (American Society of Anesthesiologists physical status classification I or II and age ≥ 6 months) scheduled to undergo anesthesia for elective procedures.

PROCEDURES

In a randomized, blinded, controlled clinical trial, dogs received 2% lidocaine hydrochloride solution (2.0 mg/kg [0.9 mg/lb], IV; n = 20) or buffered crystalloid solution (0.1 mL/kg [0.05 mL/lb], IV; 20; control treatment) after premedication with acepromazine (0.005 mg/kg [0.002 mg/lb], IM) and hydromorphone (0.1 mg/kg, IM). Anesthesia was induced with propofol (1 mg/kg [0.45 mg/lb], IV, with additional doses administered as needed) and maintained with isoflurane. Sedation was assessed, and anesthetic and cardiopulmonary variables were measured at various points; values were compared between treatment groups.

RESULTS

Propofol doses, total sedation scores, and anesthetic and most cardiopulmonary measurements did not differ significantly between treatment groups over the monitoring period; only oxygen saturation as measured by pulse oximetry differed significantly (lower in the lidocaine group). Mean ± SD propofol dose required for endotracheal intubation was 1.30 ± 0.68 mg/kg (0.59 ± 0.31 mg/lb) and 1.41 ± 0.40 mg/kg (0.64 ± 0.18 mg/lb) for the lidocaine and control groups, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

No propofol-sparing effect was observed with administration of lidocaine as a coinduction agent for the premedicated dogs of this study. Mean propofol doses required for endotracheal intubation were considerably lower than currently recommended doses for premedicated dogs. (J Am Vet Med Assoc 2020;256:93-101).

Comparison between intravenous lidocaine and fentanyl on cough reflex and sympathetic response during endotracheal intubation in dogs

OBJECTIVE

To compare the effects of intravenous (IV) lidocaine and fentanyl on the cough reflex and autonomic response during endotracheal intubation in dogs.

STUDY DESIGN

Randomized, blinded, superiority clinical trial.

ANIMALS

A total of 46 client-owned dogs undergoing magnetic resonance imaging.

METHODS

After intramuscular methadone (0.2 mg kg^-1), dogs were randomized to be administered either IV lidocaine (2 mg kg^-1; group L) or fentanyl (7 μg kg^-1; group F). After 5 minutes, alfaxalone was administered until endotracheal intubation was possible (1 mg kg^-1 IV over 40 seconds followed by 0.4 mg kg^-1 increments to effect). Total dose of alfaxalone was recorded and cough reflex at endotracheal intubation was scored. Heart rate (HR) was continuously recorded, Doppler systolic arterial blood pressure (SAP) was measured every 20 seconds. Vasovagal tonus index (VVTI) and changes (Δ) in HR, SAP and VVTI between pre-intubation and intubation were calculated. Groups were compared using univariate and multivariate analysis. Statistical significance was set as p < 0.05.

RESULTS

Group F included 22 dogs and group L 24 dogs. The mean (± standard deviation) alfaxalone dose was 1.1 (± 0.2) and 1.35 (± 0.3) mg kg^-1 in groups F and L, respectively (p = 0.0008). At intubation, cough was more likely in group L (odds ratio = 11.3; 95% confidence intervals, 2.1 - 94.2; p = 0.01) and HR increased in 87.5% and 54.5% of groups L and F, respectively (p = 0.02). The median (range) ΔHR between pre-intubation and intubation was higher (13.1%; - 4.3 to + 55.1) in group L (p = 0.0021). Between groups, SAP and VVTI were similar.

CONCLUSION AND CLINICAL RELEVANCE

At the stated doses, whilst reducing the alfaxalone dose, fentanyl is superior to lidocaine in suppressing the cough reflex and blunting the increase in HR at endotracheal intubation in dogs premedicated with methadone.

Application via mechanical dropper alleviates sufentanil-induced cough: a prospective, randomized, single-blinded trial

Background

It was reported that prolonging the injection time or diluting administration can reduce the incidence of opioid-induced cough. However, the incidence of sufentanil-induced cough (SIC) via a standardized infusion rate is unclear. A mechanical dropper is an infusion filtering device commonly used for intravenous degassing; it can also be used to administer special drugs due to its temporary storage and dilution effect. This study assesses the effectiveness of administration via mechanical dropper on SIC.

Methods

Two hundred patients undergoing general anesthesia were enrolled. Patients received sufentanil at a strength of 0.3 μg·kg^− 1 either via T-connector (group C) or by mechanical dropper (group M) at 1 ml·s^− 1. Cough severity was graded as none (0), mild (1–2), moderate (3–5), or severe (> 5), and the incidence of SIC was evaluated for 5 min after the start of sufentanil injection. Other adverse reactions such as hypotension, hypertension, bradycardia, tachycardia, hypoxemia, vomiting, and aspiration during the induction period of general anesthesia were also observed. The primary outcome was the incidence of SIC. The secondary outcomes were the severity of SIC and other adverse reactions.

Results

The incidence of SIC in group M was significantly lower than that in group C (2% versus 21%, P = 0.000), and the prevalence of moderately severe coughing was also statistically different (none in group M versus 11% in group C, P = 0.001). However, there were no statistical differences in the incidence of other adverse reactions between two groups (P > 0.05).

Conclusion

Sufentanil application via mechanical dropper can significantly alleviate the occurrence of SIC during the induction phase of total intravenous general anesthesia. This method is simple, safe, and reliable, and has wide prospective application for clinical use.

Trial registration

Chinese Clinical Trial Register, ChiCTR-IOR-17011561. Registered on 3 June 2017.

Anesthetic effects and body weight changes associated with ketamine-xylazine-lidocaine administered to CD-1 mice

Anesthesia for mice is commonly performed through the injection of parenteral agents via the intraperitoneal (IP) route. Variability in anesthetic sensitivities has been noted in mice resulting in inconsistencies in anesthetic depth and/or mortality. Anesthetic protocols that improve consistency and safety are needed. The objectives of this study were to assess the effects of intraperitoneal (IP) ketamine (95 mg/kg) and xylazine (7 mg/kg) alone or combined with lidocaine at 4, 8, or 16 mg/kg on time to loss (LRR) and return (RRR) of righting reflex, duration of immobilization and loss of pedal withdrawal response (PWR), body weight and histopathology in CD-1 mice. In a prospective, randomized trial, 36 male CD-1 mice, 4–6 weeks of age were randomly assigned to 5 groups: saline (SA, n = 4); ketamine-xylazine (KX, n = 8); ketamine-xylazine-lidocaine 4 mg/kg (KXL4, n = 8); ketamine-xylazine-lidocaine 8 mg/kg (KXL8, n = 8); ketamine-xylazine-lidocaine 16 mg/kg (KXL16, n = 8). Two mice in each group were euthanized at day 2 post-injection and the remaining mice were euthanized at day 11 post-injection. After IP injection, LRR and RRR, duration of immobilization and loss of PWR, body weight and histopathology were evaluated. LRR occurred sooner in mice receiving KXL16 compared with KX, with median (range) times of 78 (62–104) and 107 (91–298) seconds, respectively. Loss of PWR occurred in 1, 5, 4, 6 mice for groups KX, KXL4, KXL8, and KXL16 respectively. Median (range) duration of absent PWR was longer in mice receiving KXL16 at 13 (0–30) minutes, compared to KX at 0 (0–9) minutes. Duration of immobilization and RRR were not different between groups. Weight loss occurred 2 days following anesthesia but was not different between groups. Weight gain was significantly greater in all lidocaine groups 11 days post-injection compared to KX. No mortality or histopathologic abnormalities were observed in any group. Lidocaine administered with ketamine and xylazine shortens the onset of anesthesia in mice and improves anesthetic depth without prolonging recovery time.