PEDOT: PSS), ITO/poly(N-vinylcarbazole) (PVK) and
PEDOT: PSS/PVK were measured using ultraviolet photoelectron spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS). By decoupling the vacuum shift and energy-bending, the energy-bending at these interfaces can be simulated using an electrostatic model that takes into account the energetic disorder of the polymers. The model is further extended to include blended mixtures of semiconductors at differing concentrations and it was found that a very good agreement exists between the experiment and theory for all interfaces. This suggests that the electrostatic model can be used to describe energy-bending at the interface between any organic semiconductors. Further investigation into the effect of the Gaussian density of states width on energy-bending is warranted.
Methods: This was a retrospective analysis conducted in a tertiary centre. Records of all patients who underwent surgery and received CSA between December 2008 and July 2017 were reviewed. Their demographic profiles, type and duration of surgery were analysed. The outcomes measured were the success of CSA, technical evaluation and difficulties encountered, intraoperative haemodynamics, usage of vasopressors and any reported complications. Statistical analysis was done using Chi-square test.
Results: Three hundred and eighteen patients (94%) successfully underwent surgery using CSA. Twenty cases (6%) had failed CSA, of which five of them had CSA insertion failure, while the rest failed to complete the operation under CSA, thus requiring conversion to general anaesthesia. Patients who have had an initial intrathecal local anaesthetic (LA) volume ≥1.5 ml had higher odds (odds ratio (OR) 2.78; 95% confidence interval [CI], 1.70-4.57) of developing hypotension compared to those who had <1.5 ml (P < 0.001). There were no reported post-dural puncture headache, neurological sequelae or infection.
Conclusion: CSA is a useful anaesthetic technique with low failure rate. The key to achieving haemodynamic stability is by giving a small initial bolus, then titrating the block up to required height using aliquots of 0.5 ml of intrathecal LA through the catheter.