Veterinary anaesthesia and analgesia最新文献

Objective

To compare respiratory system compliance (C_RS), expressed per kilogram of bodyweight (C_RSBW), calculated without end-inspiratory pause (EIP) and after three EIP times (0.2, 0.5 and 1 seconds) with that after 3 second EIP (considered the reference EIP for static C_RS) and to determine the EIP times that provided C_RSBW values in acceptable agreement with static C_RSBW during controlled mechanical ventilation (CMV) in anaesthetized dogs.

Study design

Prospective, randomized, nonblinded, crossover clinical study.

Animals

A group of 24 client-owned dogs with healthy lungs undergoing surgery in lateral recumbency.

Methods

During CMV in dogs undergoing general anaesthesia, five EIPs [0 (no EIP), 0.2, 0.5, 1 and 3 seconds] were consecutively applied in random order. Tidal volume (Vt) was set at 10 mL kg^–1 and positive end-expiratory pressure (PEEP) was not applied. Respiratory rate and inspiratory time were established according to each EIP time, setting EIP between 0 and 50% of the inspiratory time. The C_RSBW was calculated as [expired Vt/(plateau pressure – PEEP)]/bodyweight and recorded every 15 seconds for 2 minutes after a 5 minute equilibration period with each EIP. One-way anova for repeated measures and the Bland–Altman analysis were used to compare C_RSBW and evaluate agreement between EIP times, respectively.

Results

The C_RSBW was significantly greater as the EIP time increased up to 1 second (p < 0.05). In the Bland–Altman analysis, none of the tested EIPs (0, 0.2, 0.5 and 1 seconds) provided 95% confidence intervals for limits of agreement within the maximum allowed difference considered for acceptable agreement with 3 second EIP.

Conclusions

and clinical relevance An EIP ≤ to 1 second does not provide a C_RSBW value in acceptable agreement with static C_RSBW in healthy dogs. Besides, the application of an EIP ≤ to 0.5 seconds underestimates the static C_RSBW to an increasing extent as the EIP time decreases.

Objective

To compare the analgesic effect of a bilateral ultrasound-guided erector spinae plane block (ESPB) in dogs undergoing hemilaminectomy using either a low-volume high-concentration (LV-HC) or a high-volume low-concentration (HV-LC) local anaesthetic solution.

Study design

Retrospective observational equivalence trial.

Animals

A total of 391 client-owned dogs undergoing hemilaminectomy.

Methods

Dogs were assigned to group LV-HC or HV-LC depending on whether 0.2–0.25% levobupivacaine (0.4–0.5 mL kg^–1) or 0.125–0.15% levobupivacaine (0.8–1 mL kg^–1) was used to perform the ESPB, respectively. The number of dogs in which intraoperative rescue fentanyl boluses were administered, the total dose of fentanyl administered, the overall methadone consumption during the first 24 hours postoperatively and anaesthetic complications were recorded. Univariate and multivariate statistical analyses were performed considering p < 0.05 significant.

Results

A total of 248 and 143 dogs were assigned to groups LV-HC and HV-LC, respectively. In group HV-LC, the number of dogs requiring fentanyl intraoperatively (64.3%) was higher (p = 0.0001) than that in group LV-HC (43.5%). The overall intraoperative fentanyl consumption was higher in group HV-LC between the first skin incision and the end of the lamina drilling (p = 0.028). According to the regression analysis, the group allocation was the best variable to predict the intraoperative fentanyl consumption (p < 0.001).

Antimuscarinic drugs were administered more frequently in group LV-HC (p < 0.02). However, the prevalence of hypotension and other pharmacological cardiovascular interventions did not differ between groups. No differences in methadone consumption during the first 24 hours postoperatively were found between the groups.

Conclusionsand clinical relevance

When performing a bilateral ESPB in dogs undergoing hemilaminectomy, compared with HV-LC, the use of LV-HC local anaesthetic solution reduces the intraoperative fentanyl consumption without affecting the postoperative methadone requirement.

Objective

To evaluate cardiovascular effects of oral tasipimidine on propofol-isoflurane anaesthesia with or without methadone and dexmedetomidine at equianaesthetic levels.

Study design

Prospective, placebo-controlled, blinded, experimental trial.

Animals

A group of seven adult Beagle dogs weighing (mean ± standard deviation) 12.4 ± 2.6 kg and a mean age of 20.6 ± 1 months.

Methods

The dogs underwent four treatments 60 minutes before induction of anaesthesia with propofol. PP: placebo orally and placebo (NaCl 0.9%) intravenously (IV); TP: tasipimidine 30 μg kg^–1 orally and placebo IV; TMP: tasipimidine 30 μg kg^–1 orally and methadone 0.2 mg kg^–1 IV; and TMPD: tasipimidine 30 μg kg^–1 orally with methadone 0.2 mg kg^–1 and dexmedetomidine 1 μg kg^–1 IV followed by 1 μg kg^–1 hour^–1.

Isoflurane in oxygen was maintained for 120 minutes at 1.2 individual minimum alveolar concentration preventing motor movement. Cardiac output (CO), tissue blood flow (tbf), tissue oxygen saturation (stO₂) and relative haemoglobin content were determined. Arterial and mixed venous blood gases, arterial and pulmonary artery pressures and heart rate (HR) were measured at baseline; 60 minutes after oral premedication; 5 minutes after IV premedication; 15, 30, 60, 90 and 120 minutes after propofol injection; and 30 minutes after switching the vaporiser off. Data were analysed by two-way anova for repeated measures; p < 0.05.

Results

Tasipimidine induced a significant 20–30% reduction in HR and CO with decreases in MAP (10–15%), tbf (40%) and stO₂ (43%). Blood pressure and oxygenation variables were mainly influenced by propofol-isoflurane-oxygen anaesthesia, preceded by short-lived alterations related to IV methadone and dexmedetomidine.

Conclusions and clinical relevance

Tasipimidine induced mild to moderate cardiovascular depression. It can be incorporated into a common anaesthetic protocol without detrimental effects in healthy dogs, when anaesthetics are administered to effect and cardiorespiratory function is monitored.

Objective

To develop and evaluate a low-cost three-dimensional (3D)-printed video laryngoscope (VL_VET) for use with a commercial borescope.

Study design

Instrument development and pilot study.

Animals

A total of six adult male Beagle dogs.

Methods

The VL_VET consisted of a laryngoscope handle and a Miller-type blade, and a detachable camera holder that attached to various locations along the blade. The laryngoscope and camera holder were 3D-printed using black polylactic acid filament. Dogs were premedicated with intravenous (IV) medetomidine (15 μg kg⁻¹) and anesthesia induced with IV alfaxalone (1.5 mg kg⁻¹). The VL_VET, combined with a borescope, was used for laryngeal visualization and intubation. Performance was evaluated by comparing direct and video-assisted views in sternal recumbency. The borescope camera was sequentially positioned at 2, 4, 6, 8 and 10 cm from the blade tip (distance_LARYNX-CAM), which was placed on the epiglottis during intubation or laryngoscopy. At the 10 cm distance_LARYNX-CAM, laryngeal visualization was sequentially scored at inter-incisor gaps of 10, 8, 6, 4 and 2 cm. Laryngeal visualization scores (0–3 range, with 0 = obstructed and 3 = unobstructed views) were statistically analyzed using the Friedman’s test.

Results

Under direct visualization, the 2 cm distance_LARYNX-CAM had a significantly lower score compared with all other distance_LARYNX-CAM (all p = 0.014) because the view was obstructed by the camera holder and borescope camera. With both direct and camera-assisted views, visualization scores were higher at inter-incisor gaps ≥ 4 cm compared with 2 cm (all p < 0.05).

Conclusions and clinical relevance

During laryngoscopy and intubation, the VL_VET and borescope facilitated both direct and video laryngoscopy at distance_LARYNX-CAM in Beagle dogs when inter-incisor gaps were ≥ 4 cm.

Objective

To evaluate the effect of increased respiratory system resistance (R_RS) on dynamic compliance (C_dyn) assessed by the NM3 monitor (C_dyn(NM3)) and the E-CAiOV module (C_dyn(ECAiOV)).

Study design

Prospective laboratory study.

Methods

A training test lung (TTL) simulated the mechanical ventilation of a mammal with 50 and 300 mL tidal volumes in three conditions of R_RS [normal (R_BL), moderately increased (R₁) and severely increased (R₂)] and a wide range of clinically relevant C_dyn. Simulations at increased R_RS were paired with simulations at R_BL with the same static compliance for comparisons. Pearson’s correlation coefficient and concordance correlation coefficient between the measurements at R_BL with the ones with increased R_RS were calculated. Bland–Altman plots were also used to evaluate the agreement of C_dyn(ECAiOV) and C_dyn(NM3) at R_BL (control values) with their paired values at R₁ and R₂. Relative bias and limits of agreement (LOAs) were calculated and LOAs larger than 30% were considered unacceptable. Trending ability of C_dyn(NM3) and C_dyn(ECAiOV) were evaluated by polar plots. Values of p < 0.05 were considered significant.

Results

The effect of increased R_RS was more pronounced for C_dyn(ECAiOV) than for C_dyn(NM3). Unacceptable agreement was only observed in C_dyn(NM3) at R₂ in the 300 mL simulation (bias = –18.3% and lower LOA = –45%). For C_dyn(ECAiOV), agreement was unacceptable for all tested R_RS in both simulations, being the worst at R₂ in the 300 mL simulation (bias = –54.7% and lower LOA = –100.2%). Both levels of increased R_RS caused poor trending ability for C_dyn(ECAiOV), whereas the same effect was only observed for C_dyn(NM3) at R₂.

Conclusions and clinical relevance

In the presence of increased R_RS, C_dyn estimated by the NM3 monitor presented better capability to distinguish between changes in R_RS from changes in respiratory system compliance.

Objective

To compare the success rate and extent of sciatic nerve staining with a bupivacaine–dye solution using two injection techniques: ‘blind’ or ultrasound-guided approach.

Study design

Prospective, experimental, randomized, cadaveric study.

Animals

Adult female Wistar rat cadavers [n = 24, mass 352 g (323–374)].

Methods

Each sciatic nerve was randomly allocated to one of two groups: ‘blind’ (group B) or ultrasound-guided approach (group US) to injection. Following injection of bupivacaine–dye solution (0.1 mL), gross anatomical dissection was performed to visualize nerve staining, categorizing it as either positive or negative. The length of nerve staining was then measured and visual inspection conducted to identify potential nerve damage. Fisher's exact test was used to compare positive or negative nerve staining, and the Wilcoxon signed rank test used to compare the length of nerve staining between groups.

Results

In group B, the bupivacaine–dye solution stained 16/24 sciatic nerves (67% success). In group US, staining was successfully observed in all 24 nerves (100% success, p < 0.004). The length of nerve staining [median (interquartile range)] was 2 (2–3) mm in group B and 5 (4–6) mm in group US (p < 0.001). One sciatic nerve in group B had injectate distributed over 16 mm, suggestive of an intraneural injection. No signs of laceration or nerve damage were visible under 6× magnification in either group.

Conclusions and clinical relevance

The ultrasound-guided approach for sciatic nerve injection demonstrated a higher success rate with superior injectate distribution when compared with the ‘blind’ approach. Ultrasound guidance is recommended over a ‘blind’ approach for sciatic nerve block in rats when possible.