Comparison of hemodynamic stability of combined spinal anesthesia with low dose spinal anesthesia and epidural volume extension by saline as compared to epidural anaesthesia for patients undergoing elective lower limb surgery

 

Sri Devi S¹, Sanjeev G M^2*, Darshan M S³

 

^1,3Assistant Professor, ²Professor and HOD, Department of Anesthesiology, CIMS Chamarajanagar.Yadapura, Karnataka 571313 INDIA.

Email: darshanms_jss@yahoo.com

 

Abstract               Administration of saline in epidural space following intrathecal drug administration constitutes Epidural Volume Extension. In our study we involved 40 patients who were planned to undergo elective lower limb surgery, who were randomized into two groups of 20 each. 20 patients in Group EV received low dose of spinal anesthesia with epidural volume extension by saline, and 20 patients in Group E received conventional epidural anesthesia. From our study it was seen that the patients in Group EV had quicker onset of sensory block, and stable hemodynamic parameters as compared to patients in Group E.

Key Words: Hemodynamic Stability, Elective lower limb surgeries, Epidural Anesthesia, Epidural Volume Extension.

 

 

INTRODUCTION

Administration of saline in epidural space following intrathecal drug administration constitutes Epidural Volume expansion. Spinal anesthesia is known to cause autonomic block and hence corresponding changes in vital parameters, which is of lesser extent when epidural anesthesia is used as a sole anesthetic modality. Epidural anesthesia since consumes significantly larger volume of local anesthetic drug and it is associated with separate complication of its own. Dosage of spinal anesthesia being directly correlating factor for level of spinal blockade and hence the autonomic blockade, our study wanted to compare low volume spinal anesthesia over epidural anesthesia for hemodynamic stability.

 

MATERIALS AND METHODS

Institutional ethics committee approval was obtained prior to the study. 40 patients undergoing elective lower limb surgery were chosen for the study.

Inclusion Criteria

• ASA I and II group of patient who gave consent for the study
• Age between 18-80 years
• No comorbid illness
• Patient weighing 50-70 kg
• Elective lower limb surgery

Exclusion Criteria

• Denial of consent
• ASA III and IV
• Known allergy to study drugs
• Uncontrolled bleeding diathesis
• Infection at injection site
• Valvular heart disease
• Raised intracranial and intra-abdominal pressure
• Emergency surgery
• Sepsis, Shock and hypervolemia

All patients were preoperatively assessed and consent for the study was obtained, they were advised to take Tab. Ranitidine 150 mg and Tab. Alprazolam 0.5 mg at night on the day before surgery. On the day of surgery they were shifted to operating room and basal vital parameters like Systolic Blood Pressure, Diastolic blood pressure and pulse rate and oxygen saturation were noted by connecting the patient to multipara monitor (time pre op). All the patients were premedicated with Inj Ranitidine 50 mg and Inj. Ondansetron 8 mg (given slow iv) and were pre-loaded with 500 ml of Ringers Lactate over a period of 30 minutes, the vital parameters of the patient were noted during this period. Patients were divided into two groups of 20 patients each by computer generated randomization charts. Epidural catheterisation was done by experienced anaesthesiologist who was not involved in the study. The patients were shifted to operating room and all the patients received epidural catheterisation in sitting position with 18G Tuohy needle at L2-L3 interspace and epidural catheter was directed cephalad, 4 cm of epidural catheter was threaded in space.3 ml of Inj. Lignocaine with Adrenaline 1.5% was given after negative aspiration for blood and CSF as epidural test dose. Patients in Group EV received 0.8ml of 0.5% hyperbaric Inj. Bupivacaine intrathecally by lumbar puncture at L3-L4 space and once when the patient was placed in supine position they received 15 ml of normal saline through epidural catheter. Patient in Group E received 15 ml of 0.5%Inj. Bupivacaine through epidural catheter after placing the patients in supine position. The Hemodynamic parameters of the patient were monitored at time 0 (just before regional anesthesia), time 5 (just after completing the epidural drug administration) and every 5 minutes thereafter for 20 minutes. Sensory block was assessed by blunt pinprick method, at T10 dermatome after the end of drug administration at interval of 2 minutes and the time of onset of sensory block at T10 was taken as sensory onset time. At end of 20 minutes sensory block was assessed and level of analgesia obtained was noted in each group. The motor block was assessed by Modified Bromage scale ((0 = able to move hip, knee and ankle; 1 = unable to move hip, able to move knee and ankle; 2 = unable to move hip and knee, able to move ankle; 3 = unable to move hip, knee and ankle) at end of 20 minutes.  For patients whose heart rate dropped to 50 beats per minute or less received 0.6mg of Inj atropine, and patients in whom the mean blood pressure dropped to less than 60 received 6mg of Inj Ephedrine, requirement of above drug were tabulated. Surgery was allowed to be started after 20 minutes in patients who achieved the required level of block. Patients who had not achieved sensory block of T10 or those had not achieved motor block of at least grade two were considered failure, Such patients in Group E were converted to general anesthesia, those in Group EV were given conventional epidural anesthesia, if they failed to achieve required level of anesthesia they were also converted to general anesthesia.

Statistical Analysis: Quantitative data were represented as means, and for qualitative data, numbers and percentages were used. Students’t-test was used as test of significance to find an association for quantitative data. Chi-square test was used as test of significance to find the association for qualitative data. P < 0.05 was considered statistically significant.

 

 

RESULTS

Study included 40 patients, and there were no failure in technique and data loss during the study period. Both the groups were comparable on the basal demographic parameters like age, height and weight. The variations between the groups were not statistically significant.

 

Table 1:

 

There were 4 female patients in Group EV and 5 female patients in group E. 16 male patients in Group EV and 15 male patients in Group E, the above variation between groups was not statistically significant (p=0.705)

 

Table 2:

 

Patient classification according to ASA risk stratification is as tabulated below and it had p value of 0.752 which was not statistically significant.

 

Table 3:

Classification of patients between the groups based on the surgery they underwent is tabulated below and the variation between the groups had p value of 0.937, which is not statistically significant.

 

Table 4:

 

The mean time for onset of sensory block at T-10 dermatome in Group EV was 1.15 minutes and that in group E was 6.45 minutes with p value of 0.00 which was statistically significant.

 

Table 5:

 

The maximum motor block assessed on Modified Bromage Scale at end of 20 minutes is tabulated and the variation showed the p value of 0.035 and was statistically significant.

 

Table 6:

 

Pre-operative pulse, systolic blood pressure and diastolic blood pressure were comparable between the groups and p value greater than 0.05 and variations were statistically insignificant.

 

Table 7:

 

The mean pulse rate at 0minutes, 5 minutes, 10 minutes, 15 minutes and 20 minutes were tabulated and it was found that pulse rate at 20 min in group E was lower than Group EV and the preoperative pulse rate; this was statistically significant with p value of 0.05.The mean Systolic blood pressures were tabulated at similar timings and it was found that Systolic blood pressures at 5 minutes were significantly lower in Group EV as compared to Group E, and Systolic blood pressure at 15 and 20 minutes were significantly lower in Group E.Similarly the mean diastolic blood pressure variation between the groups showed that diastolic blood pressure at 5 minutes was significantly lower in Group EV and diastolic blood pressures at 10 minutes, 15 minutes and 2 and 20 minutes were significantly lower in Group E.

 

Table 8:

 

Table 9:

 

Table 10:

 

Table 11:

 

Table 12:

 

None of the patients in study groups required atropine. 4 patients in Group E required pressor agent in form of Inj. Ephidrine and this variation was statistically significant.

 

Table 13:

 

DISCUSSION

Our study showed that epidural volume extension by saline as adjunct to low volume of spinal anesthesia showed to have quicker onset of sensory block, and stable hemodynamic parameters as compared to sole epidural anesthesia. Even though the intensity of motor blockade was less dense in epidural volume extension group none of the surgeons requested for additional relaxation for surgery.Our study groups were comparable based on the demographic parameters, and the block parameters achieved in our study is similar compared to previous studies showing quicker onset of sensory and motor block, higher level of sensory block¹.Elective lower limb surgery by regional anesthesia is a common practice by anesthesiologists. Epidural anesthesia carries its advantage over spinal anesthesia by its better hemodynamic profile. But the volume requirement of local anesthetic agent for conventional epidural anesthesia is larger; this has its own systemic effects which are of concern to anesthesiologist.Epidural volume extension after spinal anesthesia was found to have its effect by volume effect, where in compression of theca causes the extensive spread of CSF with local anesthetic to higher level^1-7.Epidural volume extension is said to have a distinct mechanism of action from that of epidural top up by local anesthetic in epidural anesthesia, the volume extension has a time dependent action and does not prolong the duration of spinal/ epidural anesthesia. After 30 minutes of spinal anesthesia epidural volume extension does not work and is rather said to enhance the spinal block regression^8-12.Epidural volume extension method has reliability and rapidity of spinal anesthesia and yet has the flexibility of epidural anesthesia. The patients with epidural volume extension have lower blood concentration of local anesthetic, early motor and sensory recovery, enhanced patient satisfaction and early ambulation from PACU hence reducing the economic burden of the patients¹³. Many studies have showed the dose sparing effect of epidural volume extension to local anesthetic drugs. Epidural volume extension by virtue of lower consumption of local anesthetic drug causes lesser sympathetic block and hence lesser hemodynamic instabilities¹⁴.From our study we could conclude that Epidural volume extension with saline can be used as novel modality of regional anesthesia which has rapidity of spinal anesthesia, flexibility of epidural anesthesia and better hemodynamic stability than that of epidural or spinal anesthesia.

 

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