SummaryPressure waveform analysis provides a reliable confirmatory adjunct to the loss-of-resistance technique to identify the epidural space during thoracic epidural anaesthesia, but its role remains controversial in lumbar epidural analgesia during labour. We performed an observational study in 100 labouring women of the sensitivity and specificity of waveform analysis to determine the correct location of the epidural needle. After obtaining loss-of-resistance, the anaesthetist injected 5 ml saline through the epidural needle (accounting for the volume already used in the loss-ofresistance). Sterile extension tubing, connected to a pressure transducer, was attached to the needle. An investigator determined the presence or absence of a pulsatile waveform, synchronised with the heart rate, on a monitor screen that was not in the view of the anaesthetist or the parturient. A bolus of 4 ml lidocaine 2% with adrenaline 5 lg.ml À1 was administered, and the epidural block was assessed after 15 min. Three women displayed no sensory block at 15 min. The results showed: epidural block present, epidural waveform present 93; epidural block absent, epidural waveform absent 2; epidural block present, epidural waveform absent 4; epidural block absent, epidural waveform present 1. Compared with the use of a local anaesthetic bolus to ascertain the epidural space, the sensitivity, specificity, positive and negative predictive values of waveform analysis were 95.9%, 66.7%, 98.9% and 33.3%, respectively. Epidural waveform analysis provides a simple adjunct to loss-of-resistance for confirming needle placement during performance of obstetric epidurals, however, further studies are required before its routine implementation in clinical practice.

Background:The primary objective of this study was to identify pre-anesthetic airway assessment parameters that would predict Cormack and Lehane grade III and IV laryngoscopy views in pediatric patients undergoing cardiac catheterization procedures. The secondary end points were to identify factors that would contribute to difficult laryngoscope views in this subset of patients.Settings and Design:Prospective observational study performed at a single tertiary cardiac care center.Materials and Methods:199 children below 5 years of age undergoing elective cardiac catheterization were included. Pre-anesthetic airway assessment was done by modified Mallampati grading, lower lip to chin distance [LCD], tragus to mouth angle [TMA], thyromental distance [TMD], neck circumference [NC], and the ratio of height to thyromental distance [RHTMD]. Demographic data including American Society of Anesthesiologists physical status [ASA PS] were recorded for each child. Receiver Operating Characteristic curves were plotted and Areas Under the Curve were measured to identify the best cut off values for each of the airway evaluation method that would predict poor laryngoscopy views as well as assess their accuracy in doing so.Results:LCD, TMD and low body mass index were found to have good sensitivity, specificity and accuracy in predicting Grade III and IV laryngoscope views. ASA PS grade III and above patients had a significantly higher incidence of poor laryngoscope visualization.Conclusions:LCD, TMA, TMD, NC, RHTMD and BMI could all be used combinedly as screening tools during pre-anesthetic airway evaluation for predicting difficult laryngoscope views in children. Among these, LCD, TMD along with low body mass index might have better accuracy.

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(Anaesthesia. 2017;72(7):840–844) Epidural failure is a significant problem in obstetric anaesthesia with one survey of parturients reporting a failure rate of 23%. There can be many causes of epidural failure, including technical failure due to misidentification of the epidural space. A false loss-of-resistance during epidural needle advancement is a common cause of misidentification. Pressure waveform analysis has been used to provide confirmation of correct epidural needle position when the loss-of-resistance technique was used to identify the epidural space during thoracic epidural procedures. Accurate needle placement is confirmed if a pulsatile waveform synchronized with arterial pulsations is seen. In one study, the failure rate decreased from 24% with loss-of-resistance only to 2% with the addition of pressure waveform analysis. However, the reliability of this technique for lumbar epidural analgesia for labor is unclear. This observational study was performed to determine the reliability of pressure waveform analysis in identifying accurate epidural needle placement during lumbar epidural insertion for labor analgesia.