Effects of isoflurane and sevoflurane alone and in combination with butorphanol or medetomidine on the bispectral index in chickens

Background The bispectral index (BIS) is an anaesthesia monitoring technique able to assess the level of central nervous system depression in humans and various animal species. In birds, it has been validated in chickens undergoing isoflurane anaesthesia. The aim of this study was to evaluate in an avian species the influence of isoflurane and sevoflurane on BIS, each at different minimum anaesthetic concentrations (MAC) multiples, alone or combined with butorphanol or medetomidine. Ten chickens (5 males and 5 females) underwent general anaesthesia with isoflurane or sevoflurane alone, and combined with either intramuscular administration of butorphanol (1 mg/kg) or medetomidine (0.1 mg/kg), in a prospective and cross-over study (i.e., 6 treatments per animal). BIS measurements were compared to heart rate (HR), non-invasive blood pressure (NIBP) and to a visual analogue scale (VAS) of anaesthesia depth. Results HR was significantly increased, and both NIBP and VAS were significantly reduced, with higher gas concentrations. NIBP (but not HR or VAS) was additionally affected by the type of gas, being lower at higher concentrations of sevoflurane. Butorphanol had no additional effect, but medetomidine led to differences in HR, NIBP, and in particular a reduction in VAS. With respect to deeper level of hypnosis at higher concentrations and the absence of difference between gases, BIS measurements correlated with all other measures (except with HR, where no significant relationship was found) The difference in BIS before (BISpre) and after stimulation (BISpost) did not remain constant, but increased with increasing MAC multiples, indicating that the BISpost is not suppressed proportionately to the suppression of the BISpre values due to gas concentration. Furthermore, neither butorphanol nor medetomidine affected the BIS. Conclusions The difference of degree of central nervous system depression monitored by BIS compared with neuromuscular reflexes monitored by VAS, indicate that BIS records a level of anaesthetic depth different from the one deducted from VAS monitoring alone. BIS provided complementary information such as that medetomidine suppressed spinal reflexes without deepening the hypnotic state. As a consequence, it is concluded that BIS improves the assessment of the level of hypnosis in chickens, improving anaesthesia monitoring and anaesthesia quality in this species.

Comparison of three ECG machines for electrocardiography in green iguanas (Iguana iguana)

The aim of the study was to compare the heart rate, QRS interval, and R wave amplitude across three electrocardiogram models, and assess the ability of each of them to provide electrocardiograms (ECG) for clinical interpretation. The three electrocardiogram models included ECG Seiva Praktik Veterinary, CardioStore ECG and AliveCor Veterinary Heart Monitor. The data were collected from twelve healthy adult captive green iguanas (Iguana iguana) monitored under a manual restraint at a room temperature of 22.6–28.0 °C. The ECGs using the Seiva Praktik and CardioStore ECG veterinary electrocardiography were performed with standard 4 lead ECG recordings. The AliveCor Veterinary Heart Monitor was placed (with the use of gel) directly on the lateral body wall. The mean heart rate was 42 ± 8 beats/min (CardioStore), 50 ± 11 beats/min (Seiva Praktik Veterinary), and 51 ± 9 beats/min (AliveCor Veterinary Heart Monitor). No significant difference in the heart rate was observed. A significant difference (P < 0.05) in the QRS duration was observed between the CardioStore and AliveCor Veterinary Heart Monitor. Significant differences (P < 0.01) in the R wave amplitude were detected between the CardioStore and AliveCor Veterinary Heart Monitor and between the Seiva Praktik Veterinary and AliveCor Veterinary Heart Monitor. The ECGs produced by the Seiva Praktik VVeeterinary and CardioStore machines were interpretable at 100%, while those produced by the AliveCor Veterinary Heart Monitor were interpretable at 66%. Seiva Praktik Veterinary is most appropriately used as an anaesthesia monitoring tool. AliveCor Veterinary Heart Monitor could be used as an additional diagnostic tool, but the results should be ideally confirmed with a standard ECG machine. Seiva Praktik Veterinary is the most appropriate tool for monitoring the ECG within the anaesthesia, while CardioStore might be most appropriately used as an advanced diagnostic tool by virtue of its software assistance. The ECGs obtained with AliveCor Veterinary Heart Monitor should be confirmed using a standard ECG machine.

Anaesthesia considerations and techniques for Pressurised IntraPeritoneal Aerosol Chemotherapy (PIPAC)

Pressurised IntraPeritoneal Aerosol Chemotherapy (PIPAC) is a novel surgical technique to administer aerosolized chemotherapy into the abdominal cavity as treatment for peritoneal metastasis from various cancers. As the surgery is unique and there are concerns about occupational hazards, specific anaesthetic setup and techniques are required. Notably, our institution’s experience with PIPAC has enlightened us that anaesthesia requirements during PIPAC are generally uncomplicated and that the majority of the patients undergoing PIPAC do not require invasive monitoring, advanced intra or postoperative analgesia like epidurals or PCA. The need for postoperative intensive unit care is also not required in routine PIPAC cases. We describe the anaesthetic considerations involved and the detailed preparation of staff, space, anaesthetic equipment and drugs to facilitate the appropriate modifications for anaesthesia monitoring and maintenance for an elective set up as well as our standard operating procedure for an emergency situation should it arise.