Midwive's assessment of the upper sensory level after epidural blockade

Abstract

SummaryThe crhility of midwives to assess accurately the level of epidural blockade after a short period of instruction was examined. Midwives are permitted by their National Board rules to administer a prescribed bolus of local anacsthetic (the topup) through an epidural catheter, after the first injection by an anaesthetisl, to maintain analgesia during labour. The decision to top-up is made when the mother complains of returning pain. The only check on accidental intrathecal injection is obvious respiratory difficulty or hypotension when the top-up is administered. This is unsatisfactory and has led to occasional serious complications. The assessment of thc lcvcl of blockade is an important precaution.against continuation of an accidental intrathecal injection, so it is essential that the level before, and after, top-up should be asscsscd accurately. Seventy-two midwives estimated theThe present trial assesses the ability of the midwife to determine the upper sensory level of the block after a short period of simple instruction by an anaesthctist. The ultimate aim would be to develop a safe technique for centres in which midwifery staff carry out thc top-up procedure. MethodThe duty obstetric anaesthetist administered the top-up when clinically indicated, and positioned the mother appropriately during routine rnanagemcnt of epidural analgesia in labour. Thirty minutes later the midwife who attended the mother was instructed by the anacsthetist how to assess the upper level of the block. It was explained that at the upper limit of the epidural block the mother would perceive a diffcrence in sensation caused by movement of an ice-cube over the skin. The midwife was told to move the ice-cube lightly up the left side of the mother's body from groin to neck and to ask her to indicate when she was aware of the cold from the ice-cube. This level was indicated with a skin marker. The procedure was then repeated on the right side. The anaesthetist then followed the same mcthod and finally recorded the dermatome levels of both assessmcnts. The grade of both the midwife and anaesthetist were recorded, as were any comments from the participants (mother, anaesthetist and midwife). ResultsOnc hundrcd patients were assessed by both a midwife and an anacsthetist during the study. Seventy-two midwives and twenty-four anaesthetists, of different grades, took part on a varying number of occasions ( Table I).The midwives and anaesthetists were in complete agreement on the level of the block (71.5%), or were within one spinal segment (a further 17%) on the majority of occasions (Fig. I). The greatest variation was three segments and the number of times the assessment differed by two or three segments was small (9.5% and 2% respectivcly). Midwives overestitnated the level in 9.5% of measurements, and underestimated it on 19% of occasions.

Epidural Medication after the Initial Dose: Reflections on Current Methods of Administration during Labour

“…Additional recommendations have been suggested from time to time, such as aspirating and giving a test dose before each top-up dose and regular assessment of the upper level of block by the midwife. 35 The value of these additional tests has not been clearly established. Both false-positive and false-negative results can occur with the former, while in practice it is often difficult to determine an upper level of sensory block when using local anaesthetics in low dosages.…”

Regional anaesthesia—children are different

“…These include (i) loss of cold discrimination using a volatile spray (e.g. ethyl chloride) ( 5), ice cubes ( 6), wet alcohol sponge ( 7), metallic roller ( 8) or ice cold test tube ( 9) (ii) loss of pain sensation using a variety of needles, and (iii) loss of light touch sensation using cotton wool, a tickling finger, fine gas jet ( 10) or von Frey hair ( 11). Other methods which are seldom used in the clinical situation include skin conduction responses ( 12), cutaneous current perception threshold ( 9), laser Doppler flowmetry ( 13), infrared thermography ( 14) and somatosensory evoked potentials after dermatomal stimulation ( 15)…”

How would patients prefer to spend the waiting time before their operations?

“…Loss of cold discrimination may be assessed using a volatile spray [1] (e.g. ethyl chloride), ice cubes [2], a wet alcohol sponge [3] or an ice‐cold test‐tube [4]. Loss of pain sensation may be assessed using a variety of needles while loss of light touch sensation may be assessed using cotton wool, a finger or, possibly, a von Frey hair [5].…”