Anaesthesia, 1990, Volume 45, pages 920-923
Posture and epidural catheter insertion The relationship between skill, experience and maternal posture on the outcome of epidural catheter insertion
P. A. STONE, A. W. A. KILPATRICK AND J . THORBURN
Summary This study was undertaken to investigate the outcome of epidural catheter insertion in the sitting or lateral position in mothers during labour. An initial prospective randomised study period (144 patients) suggested that the sitting position offered some superiority over the lateral in terms of technical ease of insertion. It was concluded, b y minimising the subjective aspects in a follow-up, prospective nonrandomised study period (152 patients), that the determining factor lies in the skill and experience of the anaesthetist. There was no signiJicant difference in complication rates or maternal discomfort between the two positions in either study period.
Key words Anaesthetic techniques, regional; epidural. Complications.
The insertion of epidural catheters for analgesia in labour may be carried out with the patient in the sitting or lateral position. The position used is primarily related to the preference of the anaesthetist and is based on the technique taught during the anaesthetist’s initial training period. No previous studies have been undertaken to evaluate the effect of position with respect to successful identification of the epidural space. The aim of this study was to investigate the effect of maternal posture on the ease of insertion of epidural catheters for analgesia in labour, the associated complication rates and patient discomfort. Methods To minimise the subjective aspects of the study it was divided into two sections. In the first study period the position of the patient was randomly allocated, and in the second the anaesthetist used the position that he (she) considered appropriate. Randomised study period. One hundred and fifty patients who had requested epidural analgesia during labour consented to take part in the study. They were randomly allocated to have the epidural sited in the sitting or lateral position. All epidurals were performed by anaesthetists who had at least completed their training period in obstet-
ric anaesthesia and were happy to perform the technique in either position. Nonrandomised study period. Anaesthetists were asked to perform epidurals with the patient in the position which they considered to be most appropriate, to record details of the position used, whether it was chosen as the anaesthetist’s preference, patient’s preference or for any other reason. The anaesthetist’s usual preference, if any, was stated and any reason for deviation from this. One hundred and fifty two patients were studied in this manner. The methods were as outlined below during the two study periods. At least 16 anaesthetists, from registrar to consultant grade, participated in the study. A standardised epidural technique was employed, using loss-of-resistance via a midline approach. On identification of the epidural space, 5 ml of ‘solution’ (normal saline or local anaesthetic) were injected via the needle before an attempt was made to pass the epidural catheter 5 cm into the epidural space. The needle was then removed and the catheter withdrawn to the desired position. Tuohy needles 16- or 18- gauge were used (Portex Minipack systems); size was chosen according to the anaesthetist’s preference. The anaesthetist who performed the epidural insertion recorded details as follows: patient position; patient’s height and weight; gauge of Tuohy needle; time taken from
P.A. Stone,* FRCSEd, FCAnaes, A.W.A. Kilpatrick, FCAnaes, Registrars, J. Thorburn, FCAnaes, Consultant, Department of Anaesthesia, Queen Mother’s Hospital, Yorkhill, Glasgow. Correspondence should be addressed to Dr Thorburn please. *Currently Senior Registrar in Anaesthesia, Royal Gwent Hospital, Newport, Gwent. Accepted 4 April 1990. 0003-2409/90/110920 + 04 %03.00/0
@ 1990 The Association of Anaesthetists of Gt Britain and Ireland
920
Posture and epidural catheter insertion cleaning patient’s back until injection of test dose via the epidural catheter, the insertion time; ease of identification of the epidural space, by a 10-cm visual analogue scale; number of skin punctures with Tuohy needle; reasons for more than one skin puncture; whether the catheter passed freely 5 cm into the epidural space; any problems encountered; complications in relation to siting of the epidural catheter; was the patient moved to the alternative position, and, if so, why? The patient was asked, once analgesia was established, to indicate the overall discomfort associated with the procedure by marking a 10-cm visual analogue scale. In addition, she was asked to indicate which position she would prefer, if any, if she were ever to have a further epidural. Analysis of results was by Chi-squared, Mann-Whitney U tests and Spearman’s correlation as appropriate. A probability value of less than 0.05 was considered to indicate statistical significance.
Results
92 1
The difficulty scores, use of more than one skin puncture, individual complication rates and maternal pain scores were similar for each maternal position. There was evidence of blood vessel puncture in 18% of patients who were in the sitting position compared with 12% who were in the lateral; this difference is not statistically significant. There were two inadvertent dural punctures with the needle in the lateral group, and one with the catheter in each group. There was a positive correlation between body mass index and epidural insertion time in the lateral group, with a Spearman correlation coefficient of +0.41 (p < 0.01). No significant correlation was found between body mass index and epidural insertion time in the sitting group. The mean time f w epidural insertion in patients with a body mass index value that exceeded 30, that is the relatively obese patients, was significantly longer in the lateral group (n = 12), in whom the mean (SD) insertion time was 17.01 (15.91) minutes compared with 6.54 (3.39) minutes in the sitting group ( n = 18); p < 0.01; Mann-Whitney U test).
Randomised study period (Table I)
Nonrandomised study period (Table 2)
After enrolment of 150 patients into the study sufficient data were available for analysis in 144 patients. The patients were comparable with respect to their body mass indices (i.e. weight/height2). Sixteen-gauge needles were more commonly used in both the sitting and lateral groups; comparable percentages of each group were carried out with this size. The mean insertion time was significantly longer in the lateral group. Failure to pass the catheter freely which led to more than one skin puncture was also more common in this position. More patients in the lateral group expressed a preference for the other position if they were to have another epidural. The need to move patients to the other position was more frequent in those allocated to the lateral position.
The patients were comparable with respect to their body mass indices. Sixteen-gauge Tuohy needles were again used more often; there was no difference in the incidence of use between those in the sitting and lateral positions. The time for insertion, difficulty scores, failure to pass the catheter freely and need for more than one skin puncture were similar for each maternal position. There were no inadvertent dural punctures in either group, and evidence of blood vessel puncture was more common in the sitting group (8%) than the lateral group (4%) although this difference is not statistically significant. Maternal pain scores and position preference were similar for each group, as was the need to move patients to the other position. There was positive correlation in the sitting position between body mass index and time taken
Table 1. Randomised study results Sitting (n=71) Body mass index (SD) 16-G needle size, when answered, (others 18-G) Ease of insertion Mean time for insertion; minutes (SD) Mean difficulty score (SD) (visual analogue scale) Failure to pass catheter freely Failure to pass catheter freely, leading to more than one skin puncture More than one skin puncture
Complications Evidence of blood vessel puncture Dural tap, needle Dural tap, catheter Maternal comfhrt Mean maternal pain score (SD) Pain score >5.5 < 3.5 Maternal position preference, for other position Need to move patient to other position ns, not significant.
Lateral (n = 73)
27.8 (4.3) 45/68 = 66%
26.4 (3.8) 44/71 =62%
6.56 (4.57) 1.79 (2.1 1 )
10.9 (9.91) 2.44 (3.01)
p
Posture and epidural catheter insertion The relationship between skill, experience and maternal posture on the outcome of epidural catheter insertion
P. A. STONE, A. W. A. KILPATRICK AND J . THORBURN
Summary This study was undertaken to investigate the outcome of epidural catheter insertion in the sitting or lateral position in mothers during labour. An initial prospective randomised study period (144 patients) suggested that the sitting position offered some superiority over the lateral in terms of technical ease of insertion. It was concluded, b y minimising the subjective aspects in a follow-up, prospective nonrandomised study period (152 patients), that the determining factor lies in the skill and experience of the anaesthetist. There was no signiJicant difference in complication rates or maternal discomfort between the two positions in either study period.
Key words Anaesthetic techniques, regional; epidural. Complications.
The insertion of epidural catheters for analgesia in labour may be carried out with the patient in the sitting or lateral position. The position used is primarily related to the preference of the anaesthetist and is based on the technique taught during the anaesthetist’s initial training period. No previous studies have been undertaken to evaluate the effect of position with respect to successful identification of the epidural space. The aim of this study was to investigate the effect of maternal posture on the ease of insertion of epidural catheters for analgesia in labour, the associated complication rates and patient discomfort. Methods To minimise the subjective aspects of the study it was divided into two sections. In the first study period the position of the patient was randomly allocated, and in the second the anaesthetist used the position that he (she) considered appropriate. Randomised study period. One hundred and fifty patients who had requested epidural analgesia during labour consented to take part in the study. They were randomly allocated to have the epidural sited in the sitting or lateral position. All epidurals were performed by anaesthetists who had at least completed their training period in obstet-
ric anaesthesia and were happy to perform the technique in either position. Nonrandomised study period. Anaesthetists were asked to perform epidurals with the patient in the position which they considered to be most appropriate, to record details of the position used, whether it was chosen as the anaesthetist’s preference, patient’s preference or for any other reason. The anaesthetist’s usual preference, if any, was stated and any reason for deviation from this. One hundred and fifty two patients were studied in this manner. The methods were as outlined below during the two study periods. At least 16 anaesthetists, from registrar to consultant grade, participated in the study. A standardised epidural technique was employed, using loss-of-resistance via a midline approach. On identification of the epidural space, 5 ml of ‘solution’ (normal saline or local anaesthetic) were injected via the needle before an attempt was made to pass the epidural catheter 5 cm into the epidural space. The needle was then removed and the catheter withdrawn to the desired position. Tuohy needles 16- or 18- gauge were used (Portex Minipack systems); size was chosen according to the anaesthetist’s preference. The anaesthetist who performed the epidural insertion recorded details as follows: patient position; patient’s height and weight; gauge of Tuohy needle; time taken from
P.A. Stone,* FRCSEd, FCAnaes, A.W.A. Kilpatrick, FCAnaes, Registrars, J. Thorburn, FCAnaes, Consultant, Department of Anaesthesia, Queen Mother’s Hospital, Yorkhill, Glasgow. Correspondence should be addressed to Dr Thorburn please. *Currently Senior Registrar in Anaesthesia, Royal Gwent Hospital, Newport, Gwent. Accepted 4 April 1990. 0003-2409/90/110920 + 04 %03.00/0
@ 1990 The Association of Anaesthetists of Gt Britain and Ireland
920
Posture and epidural catheter insertion cleaning patient’s back until injection of test dose via the epidural catheter, the insertion time; ease of identification of the epidural space, by a 10-cm visual analogue scale; number of skin punctures with Tuohy needle; reasons for more than one skin puncture; whether the catheter passed freely 5 cm into the epidural space; any problems encountered; complications in relation to siting of the epidural catheter; was the patient moved to the alternative position, and, if so, why? The patient was asked, once analgesia was established, to indicate the overall discomfort associated with the procedure by marking a 10-cm visual analogue scale. In addition, she was asked to indicate which position she would prefer, if any, if she were ever to have a further epidural. Analysis of results was by Chi-squared, Mann-Whitney U tests and Spearman’s correlation as appropriate. A probability value of less than 0.05 was considered to indicate statistical significance.
Results
92 1
The difficulty scores, use of more than one skin puncture, individual complication rates and maternal pain scores were similar for each maternal position. There was evidence of blood vessel puncture in 18% of patients who were in the sitting position compared with 12% who were in the lateral; this difference is not statistically significant. There were two inadvertent dural punctures with the needle in the lateral group, and one with the catheter in each group. There was a positive correlation between body mass index and epidural insertion time in the lateral group, with a Spearman correlation coefficient of +0.41 (p < 0.01). No significant correlation was found between body mass index and epidural insertion time in the sitting group. The mean time f w epidural insertion in patients with a body mass index value that exceeded 30, that is the relatively obese patients, was significantly longer in the lateral group (n = 12), in whom the mean (SD) insertion time was 17.01 (15.91) minutes compared with 6.54 (3.39) minutes in the sitting group ( n = 18); p < 0.01; Mann-Whitney U test).
Randomised study period (Table I)
Nonrandomised study period (Table 2)
After enrolment of 150 patients into the study sufficient data were available for analysis in 144 patients. The patients were comparable with respect to their body mass indices (i.e. weight/height2). Sixteen-gauge needles were more commonly used in both the sitting and lateral groups; comparable percentages of each group were carried out with this size. The mean insertion time was significantly longer in the lateral group. Failure to pass the catheter freely which led to more than one skin puncture was also more common in this position. More patients in the lateral group expressed a preference for the other position if they were to have another epidural. The need to move patients to the other position was more frequent in those allocated to the lateral position.
The patients were comparable with respect to their body mass indices. Sixteen-gauge Tuohy needles were again used more often; there was no difference in the incidence of use between those in the sitting and lateral positions. The time for insertion, difficulty scores, failure to pass the catheter freely and need for more than one skin puncture were similar for each maternal position. There were no inadvertent dural punctures in either group, and evidence of blood vessel puncture was more common in the sitting group (8%) than the lateral group (4%) although this difference is not statistically significant. Maternal pain scores and position preference were similar for each group, as was the need to move patients to the other position. There was positive correlation in the sitting position between body mass index and time taken
Table 1. Randomised study results Sitting (n=71) Body mass index (SD) 16-G needle size, when answered, (others 18-G) Ease of insertion Mean time for insertion; minutes (SD) Mean difficulty score (SD) (visual analogue scale) Failure to pass catheter freely Failure to pass catheter freely, leading to more than one skin puncture More than one skin puncture
Complications Evidence of blood vessel puncture Dural tap, needle Dural tap, catheter Maternal comfhrt Mean maternal pain score (SD) Pain score >5.5 < 3.5 Maternal position preference, for other position Need to move patient to other position ns, not significant.
Lateral (n = 73)
27.8 (4.3) 45/68 = 66%
26.4 (3.8) 44/71 =62%
6.56 (4.57) 1.79 (2.1 1 )
10.9 (9.91) 2.44 (3.01)
p
