Serum BDNF levels and the antidepressant effects of electroconvulsive therapy with ketamine anaesthesia: a preliminary study

Objective To firstly examine the relationship between serum brain-derived neurotrophic factor (BDNF) levels and antidepressant response to ketamine as an anaesthesia in electroconvulsive therapy (ECT) in Chinese patients with treatment-refractory depression (TRD). Methods Thirty patients with TRD were enrolled and underwent eight ECT sessions with ketamine anaesthesia (0.8 mg/kg) alone. Depression severity, response and remission were evaluated using the 17-item Hamilton Depression Rating Scale (HAMD-17). Enzyme-linked immunosorbent assay (ELISA) was applied to examine serum BDNF levels in patients with TRD at baseline and after the second, fourth and eighth ECT sessions. Baseline serum samples were also collected for 30 healthy controls. Results No significant differences were observed in serum BDNF levels between patients with TRD and healthy controls at baseline (p > 0.05). The remission rate was 76.7% (23/30) after the last ECT treatment, although all patients with TRD obtained antidepressant response criteria. Serum BDNF levels were not altered compared to baseline, even between remitters and nonremitters (all p > 0.05), despite the significant reduction in HAMD-17 and Brief Psychiatric Rating Scale (BPRS) scores after ECT with ketamine anaesthesia (all p < 0.05). The antidepressant effects of ECT with ketamine anaesthesia were not correlated with changes in serum BDNF levels (all p > 0.05). Conclusion This preliminary study indicated that serum BDNF levels do not appear to be a reliable biomarker to determine the antidepressant effects of ketamine as an anaesthesia in ECT for patients with TRD. Further studies with larger sample sizes are warranted to confirm these findings.

Does the posteromedial cortex play a primary role for the capacity for consciousness in rats?

It remains unclear how specific cortical regions contribute to the brain’s overall capacity for consciousness. Clarifying this could help distinguish between theories of consciousness. Here, we investigate the association between markers of regionally specific (de)activation and the brain’s overall capacity for consciousness.We recorded electroencephalographic (EEG) responses to cortical electrical stimulation in 6 rats, and computed Perturbational Complexity Index state-transition (PCIST), which has been extensively validated as an index of the capacity for consciousness in humans. We also estimated the balance between activation and inhibition of specific cortical areas with the ratio between high and low frequency power (HF/LF) from spontaneous EEG activity at each electrode. We repeated these measurements during wakefulness, and under the influence of ketamine anaesthesia at two doses: the minimal dose needed to induce behavioural unresponsiveness and twice this dose.We found that PCIST was only slightly reduced from wakefulness to light ketamine anaesthesia, but dropped significantly down with deeper anaesthesia. The high-dose effect was selectively associated with reduced HF/LF ratio in the posteromedial cortex, which strongly correlated with PCIST. Conversely, behavioural unresponsiveness induced by light ketamine anaesthesia, was associated with similar spectral changes in frontal, but not posterior cortical regions.These findings seem to support the claim that the posteromedial cortex may play a primary role for the capacity for consciousness. Such region-specific associations between cortical activation and the overall capacity for consciousness must be accounted for by theories of consciousness.

Comparison of Medetomidine-Diazepam-Ketamine and Medetomidine-Ketamine Anaesthesia in Dogs

This study was carried out to compare the anaesthetic and cardiopulmonary effects of medetomidine-diazepam-ketamine (MDK) with medetomidine-ketamine (DK) induced anaesthesia in dogs.Ten (10) apparently healthy local dogs comprising of 5 females and 5 males with Mean ± SD body weight of 20.40±2.93kg randomly allocated into two groups A (n=5), B (n=5) were used for this study. Dogs in group A were premedicated with an intravenous injection of 0.005mg/kg medetomidine, followed by an intravenous injection of 0.25mg/kg diazepam and 4mg/kg ketamine combination 3-5 minutes later. Meanwhile group B were given an intravenous injection of medetomidine (0.005 mg/kg) and ketamine (5mg/kg) combination. Anaesthetic indices and degree of analgesia(assessed by positive response of a dog to haemostatic pressure and defined as gross purposeful movement of head and/limb withdrawal which indicates perception of pain) were recorded while cardiopulmonary parameters were measured before anaesthesia and at five (5) minutes interval throughout anaesthesia. There was 100% negative pain perception in dogs in the group administered with MDK while 70% negative pain perception was recorded in dogs in the group administered with MK. The MDK group showed longest duration of anaesthesia (32.00 ± 1.1 minutes) and shortest time to standing (2.40 ± 1.5 minutes) compared with the MKgroup (6.80 ± 2.7 minutes). Although, both groups did not show significant decrease (P>0.05) in heart and respiratory rates. The MK group showed more cardiopulmonary effects. It was concluded that protocol of MDK provided better and longer anaesthesia/analgesia compared with MKin dogs, with minimal effects on vital body parameters, for extended surgical interventions.

The Difficult Airway

The difficult airway can be challenging to deal with in any setting. In resource-poor environments pathologies are often advanced, specialist equipment may be absent and trained assistance may be lacking, adding to the challenge. The chapter offers practical advice on assessment, planning, and management of difficult airways under these circumstances. Useful techniques considered include spontaneously breathing ketamine anaesthesia, airway topicalization for awake airway management techniques, blind nasal intubation, and awake tracheostomy. Common airway pathologies that may be encountered are described. Practical considerations regarding decision making for tracheostomy, care of tracheostomy on the ward, and management of tracheostomy emergencies are also discussed.

Anaemia and Hypoproteinaemia in Pregnant Sheep during Anaesthesia

The aim of this study was to document the packed cell volume (PCV), haemoglobin concentration and total protein concentration of maternal blood before, during and after anaesthesia. Six singleton Merino-cross pregnant ewes at 116-117 days of gestation were premedicated with intramuscular acepromazine (0.02 mg/kg) and buprenorphine (0.01 mg/kg), and anaesthesia was induced with intravenous midazolam and ketamine. Anaesthesia was maintained with isoflurane in 100% oxygen. Serial blood samples were collected the day before anaesthesia (baseline), immediately prior to induction of anaesthesia (pre-op), at the end of the procedure (intra-op) and the following day (post-op). There was a significant change in the PCV during the study (p = 0.003) with an initial decrease of 12.5% from the baseline (0.36 (0.36–0.4) to 0.315 (0.29–0.34), p = 0.044), a further intraoperative decrease of 41.7% from the baseline (0.21 (0.195–0.245), p = 0.002) and an increase the day afterwards (0.3 (0.285–0.35), p > 0.99 compared with baseline). The haemoglobin concentration also changed (p < 0.0001) (baseline: 114 (111.8–123); pre-op: 97 (77.25–104.5), 14.9% decrease, p = 0.022; intra-op: 70 (61.5–83.25), 38.5% decrease, p = 0.0009; post-op: 101.5 (96.25–114) g/L, p > 0.99). Likewise the change in total protein during the study was significant (p = 0.0003) and decreased from the baseline [70 (67.25–70.75) g/L] prior to anaesthesia (61 (58.25–64.5) g/L, 12.9% decrease, p = 0.0437) and further during anaesthesia (55.5 (53.75–63.25) g/L, 20.7% decrease, p = 0.0021) with an increase [63 (61.25–67) g/L, p > 0.99] on the first post-op day. In conclusion, intraoperative anaemia and hypoproteinaemia occurred in this study. These alterations are attributed to a combination of the side effects of acepromazine and haemodilution.