|Year : 2013 | Volume
| Issue : 1 | Page : 70-74
Comparison of the lateral, Oxford and sitting positions for combined spinal and epidural anesthesia for elective caesarean section
PKS Laithangbam, N Ratan Singh, Rebecca L Fanai, S Sarat Singh, DS Shashank, Hem Anand Nayagam
Department of Anesthesiology, Regional Institute of Medical Sciences, Imphal, Manipur, India
|Date of Web Publication||17-Aug-2013|
N Ratan Singh
Department of Anesthesiology, Regional Institute of Medical Sciences, Imphal, Manipur
Background: Combined spinal-epidural anesthesia (CSEA) is being increasingly used for elective caesarean section. We evaluated its effectiveness in three positions: The left lateral, the Oxford position, and the sitting position. Materials and Methods: One hundred and fifty parturients (aged 18-40 years and ASA I and II) undergoing elective caesarean section were enrolled in this prospective randomized study after obtaining written informed consent and institutional ethical clearance. CSEA was performed in the left lateral position (Group A, n = 50), the Oxford position (Group B, n = 50), and the sitting position (Group C, n = 50) using the single space needle through needle technique with Espocan epidural set (B ' Braun). Intrathecal injection of 2.2 ml of bupivacaine heavy 0.5% was given with 27 G spinal needle present in the set, and the parturient was positioned supine after the subarachnoid block. Epidural anesthesia was supplemented with 3 ml of 0.5% bupivacaine plain after a test dose with 2 ml of 2% xylocaine with adrenaline 1:200,000 only, if intrathecal block level did not reach T 4 dermatome level within 15 min. Injection mephenteramine 3 mg incremental doses were given intravenously to bring back the systolic blood pressure (SBP) > 100 mm Hg, and total mephenteramine consumption in each group was noted. Intraoperative hemodynamic parameters, the degree of motor blockade (modified Bromage score) and time to reach T 4 dermatome as well as post-operative complications were monitored. Results: Time to reach T 4 dermatome was minimum in the left lateral position (8.60 ± 3.11 min versus 12.70 ± 4.35 min in the Oxford position and 10.64 ± 3.63 min in the sitting position; P < 0.001). The incidence of hypotension was maximum in the left lateral position (Group A 42%; Group B 30% and Group C 26%; χ2 = 6.0 and P = 0.199). Similarly, mephenteramine consumption was also maximum in the left lateral position (2.52 ± 3.05 mg vs. 1.50 ± 2.32 mg in Group B and 1.20 ± 2.01 mg in Group C; P = 0.03). However, Group A patients had the least requirement for epidural supplementation (Group A, 2 parturients; Group B, 9 parturients; and Group C, 4 parturient; χ2 between A and B = 5.06; P = 0.03). Conclusion: The lateral position had the least requirement for epidural supplementation but required more vigilance because of faster and higher block and tendency for more episodes of hypotension.
Keywords: Anesthesia, Combined spinal-epidural, Left lateral, Oxford and Sitting, Positions
|How to cite this article:|
Laithangbam P, Singh N R, Fanai RL, Singh S S, Shashank D S, Nayagam HA. Comparison of the lateral, Oxford and sitting positions for combined spinal and epidural anesthesia for elective caesarean section. J Med Soc 2013;27:70-4
|How to cite this URL:|
Laithangbam P, Singh N R, Fanai RL, Singh S S, Shashank D S, Nayagam HA. Comparison of the lateral, Oxford and sitting positions for combined spinal and epidural anesthesia for elective caesarean section. J Med Soc [serial online] 2013 [cited 2014 Mar 8];27:70-4. Available from: http://www.jmedsoc.org/text.asp?2013/27/1/70/116651
| Introduction|| |
The combined spinal epidural anesthesia (CSEA) was first described by Soresi  in 1937 in the United States and was first performed by Curelaru  in 1979. Its use in obstetrics is relatively new and has been used as both double  or single  inter-space technique.
Regional anesthesia for caesarean section is increasing in popularity.  Most of the caesarean sections are done under spinal anesthesia. However, its failure rate is around 4.2%.  CSEA has gained popularity because the main advantages of spinal and epidural anesthesia are retained and combined. ,
However, different investigators have given conflicting views about the incidence of hypotension and the need for vasopressors in different positions during performance of CSEA. While some ,, expressed more hypotension and need for vasopressors in the lateral position, others  opined higher incidence of the same in the sitting position. Yet, others , found similar incidence in both sitting and lateral positions.
Hence, the present study was designed to compare the intraoperative hemodynamic changes, the need for vasopressors and the degree of motor blockade when CSEA is induced in the lateral, Oxford and sitting positions.
| Materials and Methods|| |
After obtaining institutional ethics committee approval and written informed consent, 150 parturients (18-40 years, American society of anesthesiologist-ASA I and II) undergoing elective caesarean section were randomized into three groups before performance of CSEA. Group A (n = 50) patients were placed in the left lateral position, group B (n = 50) patients in the Oxford position, and group C (n = 50) patients in the sitting position before returning to the supine position for the caesarean section. Patients with significant cardiovascular, respiratory, spinal problems, and local infection were excluded from the study. Patients were pre-medicated with tablet ranitidine 150 mg the previous night before surgery. Intravenous (IV) line was started with 18 G IV cannula in the pre-operative room, and preloading was done with 20 ml/kg of Ringers lactate solution 30 min before intrathecal injection. After reaching the operation theatre, baseline recordings of pulse, non-invasive blood pressure, electrocardiogram, and oxygen saturation were monitored (Cardiocap, Datex Ohmeda, Helsinki, Finland) and parturients were appropriately positioned according to the groups allocated. During the procedure, an assistant helped in positioning of the patients. For the left lateral position, the legs were flexed on the abdomen and the chin on the chest. For the sitting position, the legs were placed over the edge of the operating table and the feet supported by a stool; a pillow was placed on her lap, and the arms wrapped around the pillow, resting on the flexed lower extremity. The Oxford position is a modification of the left lateral position with the head-end of the table slightly down (~10°) and a pillow supporting the head and a 3 liter IV infusion bag below the left shoulder to limit the cephalad drug spread.
After sterile preparation, the combined spinal epidural (CSE) set (Espocan, B Braun) was used to put an 18 G Touhy needle in the epidural space using the loss of resistance technique. Once the epidural space was identified, a 27 G spinal needle present in the set was threaded through the Touhy needle to puncture the dura mater. Free flow of the cerebrospinal fluid was ascertained and 2.2 ml of 0.5% bupivacaine heavy was injected intrathecally. The spinal needle was withdrawn, and the epidural catheter (20 G, 0.45 mm × 0.85 mm × 1000 mm) was threaded in the cephalad direction to lie 2-3 cm inside the epidural space. Then, a test dose containing 2 ml of 2% xylocaine with 1:200,000 adrenaline was given epidurally to check for any inadvertent vascular placement recognized by tachycardia or intrathecal placement recognized by worsening motor blockade. The catheter was securely fixed and the patient turned to the supine position. The sensory block was tested by the loss of sensation to cotton wool touch. Motor blockade was assessed by modified Bromage scale (0 = no motor paralysis; 1 = unable to raise extended legs but able to flex knee and ankles; 2 = unable to raise extended legs and flex the knees but able to move feet; 3 = not able to flex ankles or feet). If the sensory block level up to T 4 dermatome level was not reached within 15 min, 3 ml of 0.25% plain bupivacaine was injected epidurally over 1-2 min. The time taken from the intrathecal injection to sensory blockade up to T 4 dermatome was recorded. The number of patients requiring epidural supplementation was also recorded. Intraoperative hemodynamic changes were recorded every 2 min till the delivery of the baby and then every 5 min till the end of surgery. Intraoperative hypotension was defined as a fall in systolic blood pressure (SBP) > 30% of the baseline or SBP < 90 mm Hg. Injection mephenteramine 3 mg IV increments were used to return SBP > 100 mmHg and the total amount of mephenteramine consumed was recorded. The results obtained from the study were statistically analyzed using one way ANOVA for continuous data and Chi-square test for categorical data using SPSS version 16 (SPSS 16.0, Rel. 16.0.2007, Chicago: SPSS Inc.). A P value of <0.05 was considered significant.
| Results|| |
All the three groups had comparable demographic profile [Table 1]. Intraoperative hemodynamics changes (heart rate and SBP) are shown in [Figure 1] and [Figure 2]. The changes in the heart-rate follow the same trend without significant differences [Figure 1]. However, SBP decreased significantly (P = 0.001) to a minimum by 8 min in all the groups and thereafter, increased slowly towards the baseline although the differences remain significant up to the 45 min observation. The SBP was lowest in Group A compared with Group B (t = 2.45; P = 0.01) or Group C (t = 2.30; P = 0.01). However, there were no significant differences between Group B and Group C (t = 0.03; P = 0.98).
|Table 1: Demographic profile-continuous data are expressed as mean±SD and categorical data are expressed as ratios|
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The incidence of hypotension was highest in Group A followed by Group B and C respectively [Table 2]. Mephenteramine consumption was also significantly higher in Group A. Both sensory and motor blockade was faster in Group A as well as the number of patients having maximum motor blockade.
|Table 2: Incidence of hypotension, mephenteramine consumption and pattern of sensory and motor blockade in the three groups|
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Epidural supplementation was required in two patients (4%) in Group A, nine patients (18%) in Group B, and four patients (8%) in Group C [Figure 3]. Differences between Group A and B was significant (χ2 = 5.06; P = 0.03). However, the differences between Group A and C (χ2 = 0.71; P = 0.40) or between Group B and C (χ2 = 2.21; P = 0.14) were not significant. Five patients (10%) in Group A, one patient (2%) in Group B and none in Group C had unintentional sensory block up to T 3 . Three out of 5 (3/5) patients in Group A, one patient in Group B having sensory block up to T 3 did not receive epidural supplementation. The left lateral position had greater risk of accidental higher block when compared with the Oxford position (χ2 = 7.33; P = 0.03) or the sitting position (χ2 = 5.77; P = 0.05). We did not come across accidental dural puncture or epidutral related side effects in this study.
|Figure 3: Bar diagram. Showing the number of patients requiring epidural supplementation|
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| Discussion|| |
CSEA for caesarean section is associated with low failure rates and high acceptability.  Hypotension, a common complication of spinal and CSEA may be due to the cephalad spread of the local anesthetic in the subarachnoid space and also aortocaval compression by the gravid uterus. Both these factors are influenced by the parturient posture during and immediately after the subarachnoid injection. By influencing the spread of the local anesthetic, maternal posture may affect the spread of onset of the sensory blockade. The position used for CSE placement varies among the anesthesiologists.  Regional anesthesia may be conducted with the parturient in the sitting position or lateral position. Parturients who were favorable for the lateral recumbent position tended to be leaner than those who preferred the sitting position for the procedure.  However, inability to perform the spinal puncture because of the lateral placement of the epidural needle is common when CSEA is performed in the lateral position.  The sitting position facilitates identification of the midline structures  and allows better spinal flexion,  thus making it preferable for obese patients or when technical difficulty in performing the block is anticipated. Oxford position is a modification of the lateral position whereby an upward slope is created in the thoracic region and supine position is avoided until just before the surgery. It aims at protecting the upper thoracic nerve roots from exposure to the local anesthetics and to minimize the aortocaval compression.  In the present study, hypotension was found to be maximum in the left lateral group compared to the Oxford position and the sitting position (42%, 30% and 26% respectively, χ2 = 6.0, P = 0.199). Other investigators ,, also found higher incidence of hypotension in the left lateral position compared to the sitting position. These opinions are in contrast to the opinion held by some others. ,,, In the present study, the need for mephenteramine to correct hypotension was also more in the left lateral position compared to the Oxford position and sitting position. Besides position and the effect of baracity of the solution, the additional time taken to thread and secure the epidural catheter might account for these findings. However, one advantage of the left lateral position might be the lower risk of orthostatic hypotension and syncope. ,
In this study, Group A had the minimum time to reach the T 4 dermatome block level. Five (10%) parturient in Group A and 1 (2%) parturient in Group B had unintentional block up to T 3 and this occurred without epidural supplementation in 3 parturients in Group A and a single parturient in Group B, implying that epidural supplementation is not necessarily the reason for accidental high block. Our findings is agreement with those of other studies, ,, while others  found no significant differences in the time required to block up to T 5 level in all the three positions. Differences in the body contour, (e.g., more cephalic spread with pendulous abdomen) and the non-uniform need for epidural supplementation might account for these differences. In the present study, 2 parturients (4%) in the left lateral position group, 9 parturients (18%) in the Oxford position group, and 4 parturients (8%) in the sitting position group required epidural supplementation. This non-uniform requirement for epidural supplementation was observed in other studies as well. ,,,, Time to maximum Bromage score was lowest in the left lateral position followed by the Oxford position and sitting position in the present study.
Limitations of the present study:
- The need for epidural supplementation is based on clinical assessment and subject to inter individual variations. It was not done on a uniform protocol for every patient. Moreover, we could not predict which patient would require epidural supplementation, and unintentional block up to T 3 was not necessarily related to epidural supplementation.
- As most caesarean sections are possible with block level up to T 6 level, our target to block up to T 4 level might not offer additional advantage.
- Most caesarean sections are possible within 1 h. If prolongation of the anesthesia is the sole criteria (without consideration for post-operative analgesia), intrathecal opioid plus bupivacaine combination might provide the same advantage. However, we did not include this aspect in our study.
| Conclusion|| |
In conclusion, this study has highlighted that the left lateral position had the least requirement for epidural supplementation. However, more vigilance is required because of the faster and higher block and tendency for more episodes of hypotension.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]