Study of quality and extent of intrathecal bupivacaine block by extradural injection of bupivacaine or normal saline in combined spinal epidural technique.

AIMS: The aim of the present study is to substantiate and compare the quality and extent of nerve block by using intrathecal bupivacaine or extradural bupivacaine alone and in combined spinal-epidural (CSE) technique using smaller dose of intrathecal bupivacaine and extradural injection of a smaller dose of bupivacaine or normal saline. SETTING AND
DESIGN: A prospective study design was set up with 60 adult patients scheduled for vaginal and lower abdominal operation under CSE technique and single spinal or epidural technique.
MATERIALS AND METHODS: 60 patients undergoing infra-umbilical surgery were divided into three groups (Group). Group A1 (control) 10 patients received 3 ml of intrathecal heavy bupivacaine. A2-10 patients received 16 ml isobaric bupivacaine extradurally Group B (n = 20) patients received 2 ml intrathecal heavy bupivacaine and 10 ml normal saline extradurally. Group C patients (n = 20) received 2 ml heavy bupivacaine intrathecally and 10 ml isobaric bupivacaine extradurally. A total duration of this study was 18 months. Duration of motor block, sensory block, analgesia, onset of sensory block and cephaloid extent of sensory block and side-effects noted among patients. Visual analog scale in the post-operative period was recorded. STATISTICAL ANALYSIS: The results were analyzed statistically by applying analysis of variable, odds ratio and Chi-square test.
RESULTS: Patients were comparable regarding the onset time and height and duration of sensory block with a significant difference, though there was no difference in duration of motor block and analgesia. The side-effects in the control group are higher than the other two groups.
CONCLUSION: Quality of nerve block in combined technique using bupivacaine both intrathecally and extradurally is better and associated with lower side-effect compared with intrathecal heavy bupivacaine or extradural isobaric bupivacaine alone.

RCT Entities:   Population Interventions Outcomes

INTRODUCTION

New drugs, new needle designs and development in catheter technology have contributed to improve the quality and safety of regional anesthesia. New regional anesthesia technique, like combined spinal epidural (CSE) anesthesia and analgesia have introduced in the recent past.[12]

The CSE technique has attained widespread popularity for patients undergoing major surgery below the umbilical level who require prolonged and effective post-operative analgesia.[34]

Both spinal and epidural techniques have their own advantages and disadvantages.[34] Spinal anesthesia is simple to perform and require small dose of local anesthetic to provide reliable and intense block and at the same time high incidence of nausea, vomiting, hypotension, post-operative headache are common after spinal analgesia.[34]

Epidural anesthesia, though less reliable and predictable than spinal anesthesia, it provides a better control of analgesia by using an epidural catheter. Epidural anesthesia requires higher doses of local anesthetic and associated with significant systemic absorption, chance of toxicity and slower onset of action.[34]

However, combined technique has eliminated the many disadvantages to a significant extent.[34] Subarachnoid block provides rapid onset of reliable block with low dose of local anesthetic agent and desired level of sensory block achieved by epidural injection of local anesthetic.[56] Drug used bupivacaine, like other local anesthetic, blocks nerve conduction by decreasing the entry of sodium (Na+) ions during the upstroke of action potential. It is highly lipid soluble. Thus, it has got higher potency, 3-4 times as potent as lignocaine. It has got a high protein binding capacity of about 95%. High protein binding is associated with prolonged duration of action. The total duration of effect is between 5 and 16 h.[78]

MATERIALS AND METHODS

The present study design utilized following inclusion criteria.

A total of 60 adult patients of either sex or age ranging between 18 and 60 years and belonging to American society for Anesthesiologists (ASA) physical status 1 and 2, scheduled for lower abdominal, gynecological and urological operation to be carried out under regional anesthesia were selected. An informed consent was taken from patient.

ASA 1-The patient has no organic, physiological, biochemical or psychiatric disturbance. The pathological process for which operation is to be performed is localized and does not entail a systemic disturbance.

ASA 2-Mild to moderate systemic disturbance caused by the condition to be treated surgically or by other pathophysiological processes such as mild organic heart disease, diabetes, mild hypertension, anemia, old age, obesity, anemia, mild chronic bronchitis

The study design was prospective in nature and was conducted over 18 months.

The exclusion criteria of this study were known allergy or contraindication to any of the test drug or spinal analgesia (for example, coagulation defect, infection at the puncture site and pre-existing neurological deficit in the lower extremities). Patient with evidence of major cardiovascular pulmonary, hepatic, renal, hematological, endocrine or metabolic disorder or history of motion sickness were also excluded.

Patients were divided into three broad groups, A, B and C, (each consisting of 20 patients). Matching of age, sex and surgical conditions were done categorically among the patients of three groups of the presently designed study.

Group A: Subdivided into two groups:

10 patients received 3 ml of 0.5% hyperbaric bupivacaine intrathecally

10 patients received 16 ml of 0.5% isobaric bupivacaine extradurally.

Group A: Patients also served as control. Matching between control and cases were also done as above said standardized techniques.

Group B: 20 patients received 2 ml of 0.5% hyperbaric bupivacaine intrathecally + 10 ml of 0.9% saline extradurally.

Group C: 20 patients received 2 ml of 0.5% hyperbaric bupivacaine intrathecally + 10 ml of 0.5% isobaric bupivacaine extradurally.

Routine pre-operative investigation carried out in all patients-routine hemogram, estimation of blood glucose, urea, creatinine, chest X-ray and electrocardiogram (ECG).

All patients were fasted adequately (for solid food – 6 h, clear fluid intake – 4 h.)

In the operation theater, all patients had an intravenous (IV) line using 18 gauge (G) cannula, proper checking of anesthesia machine was done. Monitoring of oxygen saturation (SpO2), non-invasive blood pressure (BP), pulse and ECG was started.

All patients were received preloading with 1000 ml Ringer lactate solution.

Patient was kept in the supine position and proper cleaning of the back with antiseptic lotion, i.e., Betadine lotion was performed. After proper identification of interspinous space, local anesthesia was done by infiltration of 1.5 ml injection lignocaine (2%). An epidural needle, Tuohy needle (16G), was administered at Lumber 2-3(L2-L3) interspace and catheter (18G) was threaded on through the needle. Bupivacaine and normal saline administered through the catheter after removal of the needle. Lumbar puncture was done at L3-L4 interspace with 25G spinal needle. After establishing free flow of cerebrospinal fluid – drugs were administered. Then, spinal needle was withdrawn and the puncture site was sealed with sterile gauge and adhesive tape.

Drugs were administered according to the group of patients:

A1-10 patients received 3 ml of heavy bupivacaine intrathecally in L3-L4 interspace

A2-10 patients received 16 ml of isobaric bupivacaine extradurally in L2-L3 interspace.

Group B: 20 patients received 2 ml of hyperbaric bupivacaine. Intrathecally in L3-L4 interspace of 10 ml extradurally normal saline in L2-L3 interspace.

Group C: 20 patients received 2 ml heavy bupivacaine intrathecally in L3-L4 space and 10 cc isobaric bupivacaine extradurally in L2-L3 space.

The patients were made supine and Oxygen (O2) administered to patients. Intraoperative monitoring of SpO2, ECG, Pulse, non-invasive BP done as per normal routine.

Pulse rate, BP, SpO2 monitored at 0, 5, 10, 15 and 30 min and thereafter every 30 min.

Motor block was assessed by modified Bromage score.[9] Height and time of onset of sensory block was assessed by pin prick.

Any fall in BP below 20% of baseline value or <90 mm of Mercury (Hg) of systolic pressure was treated with IV fluid and vasopressor mephentermine IV.

Reduction of pulse rate <50 beats/min, was treated with injection atropine (0.6 mg) IV.

Post-operative assessment for pain was carried out by visual analog scale (VAS) scoring at the interval of 3, 6, 9 and 12 h.

Any side-effects such as nausea, vomiting and shivering, back pain were noted during surgery and in the post-operative period.

Statistical analysis

The data were subjected to statistical analysis by applying analysis of variable, odds ratio, Chi-square test and two-way analysis of variance. Descriptive statistics including mean and standard deviation were calculated for relevant measurements.

RESULT

There is a significant difference in the onset of sensory block among three broad groups. P <0.01 [Table 1].

Table 1

Time of onset of sensory block in three broad groups

In the Table 2, Group C show higher level of sensory block compared with other two groups. Group B patient achieved higher sensory block than Group A1 and A2, but less than Group C.

Table 2

Height of sensory block in in thoracic level (t) in three groups

Duration of sensory block on statistical analysis – there is a significant difference [Table 3] among three groups P < 0.01.

Table 3

Duration of sensory block in three groups

On statistical analysis, there is no significant difference in mean duration of motor block among three groups P > 0.05 [Table 4].

Table 4

Duration of motor block in three groups

Table 5 shows the mean duration of analgesia in three groups. On statistical analysis, there is no significant difference in mean duration of analgesia among three groups P > 0.05.

Table 5

Duration of analgesia among three groups

The pulse rate of patients was maintained close to pre-operative level throughout the operation.

The mean arterial pressure (MAP) in Group A1 (control) at 15 min and Group A2 (control) at 30 min were very much lower than pre-operative level, but MAP in other time interval during intraoperative period among all group of patients are maintained close to pre-operative level.

The four group of the patients were comparable without any significant difference using VAS, VAS 0 = no pain, 10 = worst pain.

Table 6 shows side-effects in Group A are higher when compared with other groups.

Table 6

Occurrence of side effects

DISCUSSION

The idea of combined spinal epidural analgesia originated to reduce the dosage of local anesthetic agents. Epidural injection enhances spinal analgesia in CSE technique. Saline and local anesthetics have a volume effect elevating sensory level when supplementing a volume into the epidural space.[1]

Singh in the year 2000 reported that subarachnoid and epidural blockade attenuates the surgery induced increase in plasma concentration of catecholamine, adrenocorticotrophic hormone, cortisol, renin, prolactin.[10]

Hody in 1994 found that CSE block has proved its efficacy in skilled hands and this technique provides advantages of spinal anesthesia regarding its speed of action, intensity of motor blockade and advantage of post-operative analgesia by epidural route.[11]

Lyons et al. reported in 1992 that CSE anesthesia for operation is more successful if each procedure is performed using separate spaces compared with needle through needle technique.[12]

Albright and Forster[5] mentioned the risk of CSE technique include the accidental passage of the epidural catheter through the dural puncture, possibility of extensive spinal block because of leaking of epidural local anesthetic solution through the hole in the dura into the subarachnoid space.

Present study appropriately demonstrated the extent, quality of the block and side-effect using intrathecal bupivacaine singly and extradural bupivacaine singly and to compare the effectiveness of block in combined technique using smaller dose of intrathecal bupivacaine and extradural bupivacaine or normal saline.

Results of Table 1 show that mean time of onset of sensory block among four groups (including subgroups). It was 4.5 min in Group A1, 8.60 min in Group A2, 3.35 min in Group B and 4.63 min in Group C. There was a significant difference between Group A1, B and C with Group A2.

Table 2 elaborates that highest level of sensory block was found in Group C patients, which reached T4, which was greater than level of sensory block in Group B (i.e., T7-T8) and Group A patients (i.e., T9 level).

Table 3 shows the mean duration of sensory block in three groups. It was 126.7 min in Group A1, 141.9 min in Group A2 and 146 min in Group C. Supplementation with general anesthesia was required in Group B patients and hence the duration of sensory block could not be calculated.

Table 4 shows the mean duration of motor block in three groups of patients. It was 120.8 min in Group A1, 121.8 min in Group A2, 129.9 min Group C case. Supplementation with general anesthesia was required for Group B patients and hence duration of motor block could not be estimated. On statistical analysis, there was no significant difference in mean duration of motor block among three groups.

Table 5 shows mean duration of analgesia in three groups. It was 163.5 min in Group A1, 167.3 min in Group A2 and 160 min in Group C patients and the findings are not statistically significant among three groups (P > 0.05).

Table 6 shows the occurrence of side-effects among three groups during operation. This table shows that side-effects in Group A were higher when compared with other two groups. The difference in side-effects in the control group, i.e. Group A was statistically significant, but among the other two groups, i.e. Group B and C, there was no statistically significant difference in side-effects.

Hence, present study clearly demonstrated that an epidural injection of normal saline elevated the sensory level for short duration, which was not adequate enough for the completion of surgical procedure.[6] Whereas, the epidural injection of local anesthetics enhanced the spinal block and sustained the block.

We also observed from the study that there is a difference in the onset of sensory block among three groups of patients and height of sensory block is maximum in Group C patient. Duration of sensory block is most in Group C patient, but no difference in duration of motor block and analgesia is seen among the three Groups.

Furthermore, occurrence of side-effects is higher in Group A patient than the other two groups.

CONCLUSION

Our study shows that there is an extension of sensory level of hyperbaric intrathecal bupivacaine block by extradural injection of both normal saline and local anesthetic agents. However, there is no prolongation of sensory block after extradural normal-saline injection.

On the other hand, extradural injection of local anesthetic provides effective and sustained cephaloid extension of sensory level after intrathecal hyperbaric bupivacaine injection as compared to intrathecal hyperbaric bupivacaine or extradural isobaric bupivacaine injection alone.

Regarding the quality of nerve block, the combined technique (CSE) using both hyperbaric bupivacaine intrathecally and isobaric bupivacaine extradurally, is associated with a lower incidence of side-effects as compared to intrathecal heavy bupivacaine or extradural isobaric bupivacaine alone.