Veterinary anaesthesia and analgesia最新文献

Objective: Complications from general anesthesia, including pneumonia and decreased wound healing, are influenced by changes in immune cell function secondary to sedatives and anesthetics. It was hypothesized that immune cell function would be depressed in the early postanesthetic period. The objective was to investigate airway immune cell function before and after a general anesthetic episode in an equine in vivo model using ex vivo cell stimulations with lipopolysaccharide (LPS) for assessment of immune function.

Study design: Prospective experimental study.

Animals: Six healthy, adult, institution-owned horses.

Methods: Each horse underwent a bronchoalveolar lavage (BAL) 3 days before and immediately after a 2 hour general anesthetic. The BAL fluid was examined for cytology, total nucleated cell count and isolation of immune cells. Airway immune cells were treated with LPS or media (control) for 6 hours and supernatant was analyzed via a commercially available immunoassay for cytokines [tumor necrosis factor alpha (TNFα), interleukin (IL)-1β, IL-6, interferon gamma (IFNγ) and CXC motif chemokine ligand 8 (CXCL8)]. Data were compared using t-tests and Mann-Whitney tests.

Results: Before anesthesia (baseline), LPS stimulation induced a significant increase in all cytokines of interest, except CXCL8, versus control samples. Unstimulated cells, after an anesthetic episode, had a significant 1.8-fold increase in IL-1β (p = 0.029), and a significant decrease in IL-6 and TNFα (p = 0.028 and 0.033, respectively) versus baseline. Following anesthesia, stimulated cells had a significant decrease in IL-6 and TNFα (p = 0.037 and 0.042, respectively) versus baseline.

Conclusions and clinical relevance: This study supports the use of an equine in vivo model to assess airway immune cell function in relation to general anesthetic use.

Objective: To evaluate induced hypothermia and rewarming times in Hispaniolan Amazon parrots (HAP; Amazona ventralis) anesthetized using isoflurane, sevoflurane or desflurane, and to describe selected cardiovascular and respiratory effects.

Study design: Randomized, balanced, crossover experimental study.

Animals: A group of 12 adult HAP.

Methods: Parrots were premedicated with intramuscular butorphanol (0.5 mg kg^-1) and anesthetized with the three inhalants with a 7 day washout period between events. Anesthesia was induced using isoflurane at 4 vol%, sevoflurane at 6 vol% or desflurane 12 vol% carried in oxygen, delivered via face mask. After orotracheal intubation, anesthesia maintenance was with end-tidal concentrations of 1.4-2% (Fe'Iso), 2.4-3% (Fe'Sevo) and 8.5-9.2% (Fe'Des). Hypothermia was defined as an esophageal temperature (BT) below 37.8 °C. External heat support was provided when BT dropped to 37.5 °C. Time for temperature decrease from 38.9 °C to 37.5 °C (T1), time to first increase in BT above 37.5 °C (T2) and time from external heat support to achieving 38.9 °C (T3) were recorded and compared via Friedman tests with post hoc Dunn's test. Heart rate, respiratory rate and end-tidal carbon dioxide, amongst other variables, were evaluated.

Results: All inhalants caused hypothermia (T1): isoflurane, 12 (2-37) minutes [median (range)]; sevoflurane, 12 (4-18) minutes; desflurane, 11.5 (6-24) minutes, with no significant differences between treatments (p > 0.05). T2 was significantly (p = 0.042) longer for sevoflurane than for desflurane but not isoflurane. Transient apnea was observed with all inhalants, including 25% of birds anesthetized with sevoflurane. Second-degree atrioventricular block and ventricular escape beats occurred with all inhalants with hypothermia potentially exacerbating cardiac arrhythmias.

Conclusions and clinical relevance: Hypothermia rapidly developed in butorphanol-sedated HAP anesthetized using isoflurane, sevoflurane or desflurane. Sevoflurane prolonged warming time. Hypothermia may be associated with an increased likelihood of bradyarrhythmia in parrots anesthetized with inhalants.

Objective: Phase 1: to determine the feasibility of desensitizing ventral branches of spinal nerves within the rectus sheath using an ultrasound-guided rectus sheath block (USRSB). Phase 2: to determine the effect of preoperative USRSB on intraoperative responses to surgical stimulation and postoperative pain.

Study design: Cadaveric study and prospective, randomized, blinded, parallel-arm clinical trial.

Animals: A group of five cat cadavers and 37 shelter-owned cats undergoing ovariohysterectomy.

Methods: Phase 1: anatomical dissection was performed on one uninjected cadaver. Abdominal walls were dissected in four cadavers (eight hemiabdomens) following bilateral USRSB using 1:1 new methylene blue and 0.5% bupivacaine (0.8 mL kg^-1 total). Phase 2: preoperative bilateral USRSB was performed with 0.8 mL kg^-1 of 0.25% bupivacaine (RSB) or equivalent volume of 0.9% saline (CONTROL). Intraoperative systolic arterial blood pressure (SAP), heart rate (HR), respiratory rate (f_R) and vaporizer setting (vap%) were recorded before skin incision, during celiotomy and abdominal wall closure. In recovery, cats were administered robenacoxib (2 mg kg^-1; CONTROL) or 0.9% saline (0.1 mL kg^-1; RSB) subcutaneously. Postoperative pain was evaluated for 6 hours using the Glasgow Composite Measure Pain Scale.

Results: Phase 1: spinal nerves T9-L3 were identified within the rectus sheath, and stained in 0%, 40%, 63%, 75%, 100%, 88%, 50% and 13% of hemiabdomens, respectively. Phase 2: 37 cats were included (RSB, n = 17; CONTROL, n = 20). Intraoperatively, SAP, HR and f_R were not significantly different between groups. Vap% was significantly lower in RSB during celiotomy (p = 0.036) and closure (p = 0.044). Postoperatively, RSB cats were 5.3 times (95% CI 1.8-8.3) more likely to require rescue analgesia than CONTROL cats.

Conclusions and clinical relevance: During surgery, USRSB with bupivacaine offered minor benefits and provided markedly less postoperative analgesia than robenacoxib, indicating that relying on USRSB provides insufficient postoperative analgesia for ovariohysterectomy in cats.

Objective: To compare the portion of tidal volume (V_T) ventilating dead space volumes in nonbrachycephalic cats and dogs with small body mass receiving volume-controlled ventilation (VCV) with a fixed V_T.

Study design: Prospective, experimental study.

Animals: A group of eight healthy adult cats and dogs [ideal body weight (IBW): 3.0 ± 0.5 and 3.8 ± 1.1 kg, respectively].

Methods: Anesthetized cats and dogs received VCV with a 12 mL kg^-1 V_T (inspiratory pause ≥ 0.5 seconds). Respiratory rate (f_R) was adjusted to maintain normocapnia. Airway dead space (V_Daw) and alveolar tidal volume (V_Talv) were measured by volumetric capnography. Physiological dead space (V_Dphys) and V_Dphys/V_T ratio were calculated using the Bohr-Enghoff method. Data recorded before surgery were compared by an unpaired t-test or Mann-Whitney U test (p < 0.05 considered significant).

Results: The IBW (p = 0.07), PaCO₂ (p = 0.40) and expired V_T [V_T(exp)] (p = 0.77) did not differ significantly between species. The V_Daw (mL kg^-1) was lower in cats (3.7 ± 0.4) than in dogs (7.7 ± 0.9) (p < 0.0001). The V_Talv (mL kg^-1) was larger in cats (8.3 ± 0.7) than in dogs (4.3 ± 0.7) (p < 0.0001). Cats presented a smaller V_Dphys/V_T ratio (0.33 ± 0.03) and V_Dphys (4.0 ± 0.3 mL kg^-1) than dogs (V_Dphys/V_T: 0.60 ± 0.09; V_Dphys: 7.2 ± 1.4 mL kg^-1) (p < 0.0001). The f_R and minute ventilation (V_T(exp) × f_R) were lower in cats than in dogs (p = 0.048 and p = 0.038, respectively).

Conclusions and clinical relevance: A fixed V_T results in more effective ventilation in cats than in dogs with small body mass because of species-specific differences in and V_Daw and V_Dphys. Because of the smaller V_Daw and V_Dphys in cats than in dogs, a lower f_R is required to maintain normocapnia in cats.