Proficiency-based progression training: implementing a novel approach to training for epidural analgesia in labour.

BACKGROUND: Epidural insertion is a challenging anaesthetic procedural skill to learn and may require up to 75 attempts to achieve competency. Proficiency-based progression (PbP) training based on unambiguously defined metrics was associated with a 53% reduction in epidural failure rate. The aim of this observational study was to examine the feasibility of implementation of innovative PbP training for labour epidural insertion performed by novices in a busy tertiary hospital. METHODS: All trainees who were scheduled to commence their obstetric anaesthesia training were invited to participate. Novices undertook intensive PbP training with one-to-one supervision by an anaesthetist trained in PbP. Trainees proceeded to the clinical phase only after attaining the pre-defined proficiency benchmark. All subsequent attempts at labour epidural catheter placement were evaluated. RESULTS: All 12 novice trainees who were scheduled for their initial exposure to obstetric anaesthesia completed PbP training in epidural catheter insertion successfully. The average duration of the training courses was 70 (SD 11) min. Trainee characteristics were broadly similar. They performed a total of 180 labour epidural catheter placements with an overall epidural failure rate of 12.2% (22/180). The proportion of supervisor takeover was 6% (11/179). The incidence of complications was 4% (8/180) and difficulty in epidural catheter insertion due to patient factors was 16% (29/180). Patient satisfaction rates were 80% (satisfied or very satisfied), with 20% unsatisfied with their experience of epidural insertion. CONCLUSION: In our experience, PbP training in epidural placement is feasible within existing departmental resources in a busy tertiary teaching hospital setting.

Using psychometric ability to improve education in ultrasound-guided regional anaesthesia: a multicentre randomised controlled trial.

The learning curve for novices developing regional anaesthesia skills, such as real-time ultrasound-guided needle manipulation, may be affected by innate visuospatial ability, as this influences spatial cognition and motor co-ordination. We conducted a multinational randomised controlled trial to test if novices with low visuospatial ability would perform better at an ultrasound-guided needling task with deliberate practice training than with discovery learning. Visuospatial ability was evaluated using the mental rotations test-A. We recruited 140 medical students and randomly allocated them into low-ability control (discovery learning), low-ability intervention (received deliberate practice), high-ability control, and high-ability intervention groups. Primary outcome was the time taken to complete the needling task, and there was no significant difference between groups: median (IQR [range]) low-ability control 125 s (69-237 [43-600 s]); low-ability intervention 163 s (116-276 [44-600 s]); high-ability control 130 s (80-210 [41-384 s]); and high-ability intervention 177 s (113-285 [43-547 s]), p = 0.06. No difference was found using the global rating scale: mean (95%CI) low-ability control 53% (95%CI 46-60%); low-ability intervention 61% (95%CI 53-68%); high-ability control 63% (95%CI 56-70%); and high-ability intervention 66% (95%CI 60-72%), p = 0.05. For overall procedure pass/fail, the low-ability control group pass rate of 42% (14/33) was significantly less than the other three groups: low-ability intervention 69% (25/36); high-ability control 68% (25/37); and high-ability intervention 85% (29/34) p = 0.003. Further research is required to determine the role of visuospatial ability screening in training for ultrasound-guided needle skills.

Fascial layers influence the spread of injectate during ultrasound-guided infraclavicular brachial plexus block: a cadaver study.

BACKGROUND: Fascial layers of the neurovascular sheath containing the brachial plexus influence distribution of local anaesthetic, hence increasing the risk of block failure when performing infraclavicular brachial plexus block (ICB). METHODS: Ultrasound-guided infraclavicular brachial plexus block was performed on cadavers using a single injection technique with dye (20-30 ml). After injection, we carried out consecutive dissection of the neurovascular bundle to study dye injectate spread and identify the presence of fascial layers. Ultrasound video images (scout scan and injection) and recordings of dissections were evaluated by independent experts (regional anaesthetists and anatomists). RESULTS: Well defined fascial layers were identified at dissection in seven out of 12 infraclavicular spaces studied. These fascial layers impeded the spread of dye injectate substantially in six cases and partially in one case. No fascial layers were identified at dissection in five cases, in each of which the spread of injectate was complete throughout the neurovascular bundle. The sensitivity and specificity of ultrasonography and haptic sensation for detection of fascial layers were poor. CONCLUSIONS: When fascial layers are present in the neurovascular sheath, they impede the spread of injectate during infraclavicular brachial plexus block. Ultrasound detection of these fascial layers is unreliable in cadavers. These findings support the use of greater volumes of injectate or a multiple injection technique when performing this block.

Kynurenine pathway metabolism and the neurobiology of treatment-resistant depression: Comparison of multiple ketamine infusions and electroconvulsive therapy.

Current first-line antidepressants can take weeks or months to decrease depressive symptoms. Low dose ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, shows potential for a more rapid antidepressant effect, with efficacy also evident in previously treatment-resistant populations. However, a greater understanding of the physiological mechanisms underlying such effects is required. We assessed the potential impact of ketamine infusion on neurobiological drivers of kynurenine pathway metabolism in major depression (HPA axis hyperactivity, inflammation) in patients with treatment-resistant depression compared to gender-matched healthy controls. Furthermore, we assessed these biomarkers before and after electroconvulsive therapy (ECT), which is currently the gold standard for management of treatment-resistant depression. As previously demonstrated, treatment with ketamine and ECT was associated with improved depressive symptoms in patients. At baseline, waking cortisol output was greater in the ECT cohort, kynurenine was greater in the ketamine cohort, and kynurenic acid was lower in patients compared to healthy controls, although inflammatory markers (IL-6, IL-8, IL-10 or IFN-γ) were similar in patients and controls. Furthermore, in patients who responded to ECT, the cortisol awakening response was decreased following treatment. Despite a trend towards reduced kynurenine concentrations in those who responded to ketamine, ketamine was not associated with significant alterations in any of the biomarkers assessed.

The effect of metrics-based feedback on acquisition of sonographic skills relevant to performance of ultrasound-guided axillary brachial plexus block.

The objective of this study was to examine the effect of metrics-based vs. non-metrics-based feedback on novices learning predefined competencies for acquisition and interpretation of sonographic images relevant to performance of ultrasound-guided axillary brachial plexus block. Twelve anaesthetic trainees were randomly assigned to either metrics-based-feedback or non-metrics-based feedback groups. After a common learning phase, all participants attempted to perform a predefined task that involved scanning the left axilla of a single volunteer. Following completion of the task, all participants in each group received feedback from a different expert in regional blocks (consultant anaesthetist) and were allowed to practise the predefined task for up to 1 h. Those in the metrics-based feedback group received feedback based on previously validated metrics, and they practised each metric item until it was performed satisfactorily, as assessed by the supervising consultant. Subsequently, each participant attempted to perform ultrasonography of the left axilla on the same volunteer. Two trained consultant anaesthetists independently scored the video recording pre- and post-feedback scans using the validated metrics list. Both groups showed improvement from pre-feedback to post-feedback scores. Compared with participants in the non-metrics-based feedback group, those in the metrics-based feedback group completed more steps: median (IQR [range]) 18.8 (1.5 [17-20]) vs. 14.3 (4.5 [11-18.5]), p = 0.009, and made fewer errors 0.5 (1 [0-1.5]) vs. 1.5 (2 [1-6]), p = 0.041 postfeedback. In this study, novices' sonographic skills showed greater improvement when feedback was combined with validated metrics.

Construct validity of a novel assessment tool for ultrasound-guided axillary brachial plexus block.

The purpose of this study was to examine the construct validity and reliability of a novel metrics-based assessment tool, previously developed for ultrasound-guided axillary brachial plexus block. Five expert and eight novice anaesthetists performed a total of 18 ultrasound-guided axillary brachial plexus blocks on the same number of patients. A trained investigator video-taped procedures according to a pre-defined protocol. Two trained consultant anaesthetists independently scored the videos using the assessment tool. Compared with novices, experts completed more steps (mean 41.0 vs. 33.1, p = 0.001), had fewer procedural errors (2.8 vs. 7.9, p < 0.0001), had fewer critical errors (0.8 vs. 1.3, p = 0.030), and fewer total errors (3.5 vs. 9.1, p < 0.0001). The mean inter-rater reliability for scoring of experts' performance was 0.91, for novices' performance was 0.84, and for all performance combined (n = 18) was 0.88. This assessment tool is valid, and discriminates reliably between expert and novice performance for placement of ultrasound-guided axillary brachial plexus blocks.

MicroRNAs as biomarkers for major depression: a role for let-7b and let-7c.

There is a growing emphasis in the field of psychiatry on the need to identify candidate biomarkers to aid in diagnosis and clinical management of depression, particularly with respect to predicting response to specific therapeutic strategies. MicroRNAs are small nucleotide sequences with the ability to regulate gene expression at the transcriptomic level and emerging evidence from a range of studies has highlighted their biomarker potential. Here we compared healthy controls (n=20) with patients diagnosed with major depression (n=40) and who were treatment-resistant to identify peripheral microRNA biomarkers, which could be used for diagnosis and to predict response to electroconvulsive therapy (ECT) and ketamine (KET) infusions, treatments that have previously shown to be effective in treatment-resistant depression (TRD). At baseline and after treatment, blood samples were taken and symptom severity scores rated using the Hamilton Depression Rating Scale (HDRS). Samples were analyzed for microRNA expression using microarray and validated using quantitative PCR. As expected, both treatments reduced HDRS scores. Compared with controls, the baseline expression of the microRNA let-7b was less by ~40% in TRD patients compared with controls. The baseline expression of let-7c was also lower by ~50% in TRD patients who received ECT. Bioinformatic analysis revealed that let-7b and let-7c regulates the expression of 27 genes in the PI3k-Akt-mTOR signaling pathway, which has previously been reported to be dysfunctional in depression. The expression of miR-16, miR-182, miR-451 and miR-223 were similar to that in controls. Baseline microRNA expression could not predict treatment response and microRNAs were unaffected by treatment. Taken together, we have identified let-7b and let-7c as candidate biomarkers of major depression.

Serum BDNF as a peripheral biomarker of treatment-resistant depression and the rapid antidepressant response: A comparison of ketamine and ECT.

BACKGROUND: Ketamine is associated with rapid antidepressant efficacy but the biological mechanisms underpinning this effect are unclear. Serum brain-derived neurotrophic factor (sBDNF) is a potential circulating biomarker of treatment-resistant depression (TRD) and ketamine response but it is unclear if this is a common target of both ketamine and electroconvulsive therapy (ECT), the current gold standard for TRD. Moreover, the impact of multiple ketamine infusions on sBDNF has not yet been established. METHODS: Thirty five TRD patients with a current DSM-IV diagnosis of recurrent depressive disorder received up to 12 ECT sessions (N=17) or up to three intravenous infusions of low-dose (0.5mg/kg) ketamine (N=18). Blood samples were taken over the course of the study for assessment of sBDNF. Symptom severity and response were monitored using the 17-item Hamilton Depression Rating Scale (HDRS). sBDNF was assessed in 20 healthy controls to allow comparison with TRD patients. RESULTS: As expected, sBDNF was lower in TRD patients at baseline compared to healthy controls. Ketamine and ECT treatment were both associated with significant reductions in depressive symptoms. However, sBDNF was significantly elevated only at one week following the first ketamine infusion in those classified as responders one week later. sBDNF was not elevated following subsequent infusions. ECT reduced depressive symptoms, as expected, but was not associated with an enhancement in BDNF. LIMITATIONS: Patients continued with their psychotropic medications throughout this trial. CONCLUSIONS: SBDNF normalisation does not appear to be a prerequisite for symptomatic improvement in TRD following ketamine or ECT treatment.

Clinical evaluation of a novel technology for non-invasive and continuous measurement of plasma haemoglobin concentration.

We undertook the first clinical evaluation of a novel, non-invasive device for the continuous measurement of plasma haemoglobin concentration in 25 patients undergoing elective cardiac surgery. At four pre-determined intervals, samples of blood were taken for plasma haemoglobin estimation on a blood gas analyser and a laboratory device and were compared with the plasma haemoglobin estimation on the novel device using the Bland-Altman method. The 95% limits of agreement for estimation of plasma haemoglobin concentration for the device vs. laboratory, the device vs. the blood gas analyser and the blood gas analyser vs. the laboratory were 101.3 g.l(-1) , 103.1 g.l(-1) and 14.5 g.l(-1) , respectively. The bias (mean difference) in each case was 27.4 g.l(-1) , 25.1 g.l(-1) and 2.4 g.l(-1) , respectively. We conclude that the novel device in its current form is not a suitable replacement for more invasive methods of determining plasma haemoglobin concentration in patients in the setting of cardiac surgery; however, lessons learnt from the study will help to improve the device's future performance.

Use of dynamic time warping for accurate ECG signal timing characterization.

Dynamic time warping techniques have been used to characterize the timing variation of the constituent components of the human electrocardiogram (ECG). Lead II ECG recordings were obtained in 21 subjects, 10 male and 11 female aged between 13-65 years. The fiducial points in each cardiac cycle were identified in the recordings across the range of heart rate from 46-184 beats/min. A set of second order equations in the square root of the cardiac cycle time was obtained to describe the duration each of the constituent components in the ECG signal. The accuracy of the dynamic time warping technique was verified against professionally annotated clinical recordings in the on-line PhysioNet™ database. The equations obtained allow a Lead II ECG signal to be synthesized in which the variation with heart rate of the profile of each in the signal mirrors the true in-vivo behaviour.

Effect of feedback content on novices' learning ultrasound guided interventional procedures.

BACKGROUND: Feedback, of various forms, is effective at improving performance of medical procedures in simulated and clinical settings. Our objectives were to compare the effects of two forms of feedback on i) novice learning of in-plane technique for ultrasound-guided interventional procedures and ii) to evaluate novice retention of skill 24 hours after a standard learning session. METHODS: Performance data were collected from 30 novices. All participants received training in the form of a standard training video. Participants were randomly allocated to one of three groups: Group C (Control) received no feedback; Group KR (Knowledge of Result) received feedback at the end of each series of tasks in the form of predefined performance intervals; and Group KP (Knowledge of Procedure) received feedback in the form of augmented error feedback. Each participant completed the series of tasks five times, using a standardized phantom model. Participants attempted to perform the same tasks 24 hours later using the same phantom. This performance was videotaped and assessed by two blinded assessors for predefined time and errors. RESULTS: All groups demonstrated significant learning effect in terms of imaging, needling and performance time. Error reduction was significant over time intervals measured and also in-between groups with significant difference between Control : KP (P<0.001) and KR: KP (P=0.001) but not between Control and KR groups. Marked and similar levels of skill attrition were identified in all three groups 24 hours after the learning phase CONCLUSION: When feedback was based on KP, novices acquired pre-defined skills more quickly and made fewer errors during the learning phase (compared with controls). When feedback content was based on KR novices acquired pre-defined skills more quickly but made similar numbers of errors during the learning phase (compared with controls). In conclusion, these findings should inform development of training and assessment programs for peripheral nerve blockade.

Effect of epidural analgesia on change in Mallampati class during labour.

Mallampati class has been shown to increase during labour. Epidural analgesia might influence this change. The aim of our study was to compare the change in Mallampati class during labour in parturients who did and did not receive epidural analgesia and study the association of these changes with pre-defined clinical characteristics. We performed a prospective observational study of 190 parturients. Using standard methodology, photographs of the upper airway were taken with a digital camera during early labour and within 90 min of delivery. Two to three consultant anaesthetists, blinded to the origin of the photographs, evaluated the images obtained and assigned a Mallampati class to each. Overall, Mallampati class increased in 61 (32.1%), decreased in 18 (9.5%) and did not change in 111 (58.4%) parturients (p<0.001). The proportions of parturients in the epidural and non-epidural groups who demonstrated an increase, decrease and no change in Mallampati class were similar. Of the relationships between change in Mallampati class and the other factors studied, only the total dose of epidural levobupivacaine during labour demonstrated a weak positive correlation 0.17 (p=0.039) with Mallampati class. This study confirms that labour is associated with an increase in the Mallampati class in approximately one third of parturients. Our findings indicate that having an epidural does not influence the likelihood of a change in Mallampati class during labour.

A clinical assessment tool for ultrasound-guided axillary brachial plexus block.

BACKGROUND: Competency in anesthesia traditionally has been determined subjectively in practice. Optimal training in procedural skills requires valid and reliable forms of assessment. The objective was to examine a procedure-specific clinical assessment tool for ultrasound-guided axillary brachial plexus block for inter-rater reliability and construct validity in a clinical setting. METHOD: This was a prospective observational study. Using prior work at our institution, the clinical assessment tool was developed consisting of a 63-point task-specific checklist and a global rating scale. The anesthesiologists were assigned to three groups based on prior experience of performing an axillary block: group 1 ('novices') < 10 procedures, group 2 ('intermediates') 50-80 procedures and group 3 ('experts') > 100 procedures. Each participant performed two consecutive blocks that were videotaped. Two blinded independent experts trained in the marking of the tool evaluated the videotapes. RESULTS: There were five participants per group. The inter-rater reliability between assessors was 0.842 and 0.795 for the checklist and global rating scale, respectively. There was a consistent difference between (each pair of) the three groups in terms of both the checklist and global rating scale (P < 0.05). For the checklist, expert vs. intermediate group P = 0.023, expert vs. novice group P < 0.001 and intermediate vs. novice group P = 0.019. For the global rating scale, expert vs. intermediate group P < 0.001, expert vs. novice group gave P < 0.001 and intermediate vs. novice group P = 0.023. CONCLUSION: The objective of task-specific checklist and global rating scale are reliable and valid measures of axillary block performance between different levels of expertise.