European Journal of Cardiovascular Medicine

Spinal anaesthesia in saddle-block technique directs a small bolus of local anaesthetic towards S4-S5 and coccygeal nerve roots. Saddle anaesthesia is one of the prominent techniques of anaesthesia for perianal surgeries as it is straightforward to perform, economical and associated with minimal hemodynamic alteration. It provides an effective surgical anaesthesia and postoperative analgesia with minimal side effects. It blunts operative pain and also autonomic, somatic and endocrine responses.1

Several local anaesthetics are commonly used for saddle anaesthesia. Hyperbaric bupivacaine (0.5%) in low dose is widely used local anaesthetic for saddle anaesthesia.2   although Bupivacaine may provide a prolonged postoperative analgesia.3 However, the prolonged duration of action may cause urine retention, delay hospital discharge, and impair the recovery of motor function.3,4   

Local anaesthetic with short duration of action is the need of hour for a safe and effective anaesthesia approach for perianal procedures. Recently 1% 2-chloroprocaine has been approved for intrathecal use for achieving subarachnoid block. We therefore plan this study to compare the effects of bupivacaine and 2-chloroprocaine while giving spinal anaesthesia with regards to block characteristics and hemodynamic stability. The primary objective of our study was to compare the efficacy of the study drugs with regards to onset of sensory and motor block, Time of two segmental regression, Duration of sensory and motor blocks.5,6,7

The current prospective randomised double-blind trial was carried out in the Department of Anaesthesiology and Critical Care, Pt. B.D. Sharma, PGIMS, Rohtak, following approval from the institutional ethical council (February 2020 to March 2021).

Eighty patients of either gender, 18-65 years old, belonging to ASA physical status I – II, scheduled for perianal surgeries were included. Patients who refused to give consent, Patients inability to maintain stillness during lumbar puncture, allergic to the local anaesthetic agent, with neurological disease, skin/soft tissue infection at the site of needle puncture, severe hypovolemia, coagulopathy, Heart block/dysrhythmia, Morbid obesity, Vertebral deformities, Pregnant and lactating female patients were excluded from the study.

All the patients were subjected to complete general physical and systemic examination prior to surgery. Patients were investigated according to the institutional protocol. The study's goal and protocol were described to all patients, and they provided informed written consent to participate.   

Patients fasted for 6 hours before surgery. Pre-medication included Alprazolam 0.25mg orally the night before and 2 hours prior to surgery, along with Omeprazole 20mg orally 2 hours pre-surgery. Upon arrival in the operating room, standard monitoring was initiated, and intravenous access was established with an appropriately sized intravenous cannula. Eighty patients were randomly assigned to two groups using a computer-generated randomization table.

Group B (n=40) received 7.5 mg of 0.5 % of bupivacaine (hyperbaric).

Group C (n=40) received 40 mg of 1% chloroprocaine (isobaric).

The study drug was loaded and administered by a fellow anaesthesiologist not involved in the study. The anaesthesiologist involved in data collection and analysis was blinded to the group allocation.

Anaesthesia technique

All patients were given Saddle block using a 25G Quincke spinal needle. As per the group assigned, the study drug was administered after obtaining a clear and free flow of CSF. The sitting position was maintained for 10 minutes, after which the lithotomy position was made. The level of sensory block was assessed by a  spirit swab and painful stimulus by non-toothed forceps. Loss of cold sensation in the sole of foot and numbness around the perianal area was considered adequate for surgery, i.e. sensory block covering at least coccygeal segment and the S5 dermatome (outer margin of S5 at 3 cm lateral to mucocutaneous junction). Surgery was allowed to commence once the sensory level was adequate. Sedation with 1mg midazolam intravenously was given to both groups. If the desired dermatomal level of anaesthesia was not achieved or the patient was apprehensive, then supplemental analgesia in the form of an intermittent bolus of (0.25mg/kg) ketamine was planned to be given, and the total dose was to be recorded till the start of surgery. Following surgery, patients were kept in the recovery area and checked for vital signs, any complications from anaesthesia or operation. Following observations were recorded: Demographic characteristics such as age, height, weight of all the patients were recorded.

Sensory block: The time it took to achieve sensory blockade to the S5 dermatomal level was recorded and was calculated as the interval between intrathecal drug delivery and the propagation of sensory block to the S5 dermatome. Maximum height of sensory block achieved was recorded. The time interval between intrathecal drug administration and maximum height of block was recorded and used to calculate the time to acquire maximum height of block. Time for two segment dermatomal regression was measured. The duration of the block was measured and defined as the time between intrathecal drug injection and regression to the point of S2 dermatome level. Surgery was authorized to begin once the sensory level was satisfactory.

Motor block: Onset time of motor blockade was recorded and was taken as the interval between intrathecal administration of drug till Bromage score 1 was achieved. Motor block was assessed at the same interval as the sensory block. Duration of block was noted and taken as the interval from intrathecal drug administration to the point at which Bromage score was back to zero. The degree of motor block was assessed using Modified Bromage Score, score 0 = no motor paralysis,1=unable to raise extended legs but able to flex knee and ankle, 2= unable to raise extended legs and flex the knees but able to move feet, 3= unable to flex ankles and feet.  Baseline reading of heart rate (HR), mean arterial pressure (MAP), SpO2 were noted, and observations were recorded at an interval of one minute till 5 minutes, then every 5 minutes for the next 15 minutes and then after every 10 minutes till the end of surgery. The time of completion of surgery was recorded. Pain score was recorded post-operatively using the visual analogue scale (VAS) Between 0 and 10 (0= no pain, 10 = most severe pain) for every ½ hour for 3 hours. Injection paracetamol 100 ml (i.v) was given as rescue analgesia when VAS > 4. Complications like bradycardia, hypotension, nausea and vomiting were to be recorded during the operating period.

1. Heart rate < 50 bpm or < 20% of basal value were to be recorded as bradycardia and treated with injection glycopyrrolate 0.2mg bolus.
2. Fall of mean arterial pressure (MAP) >20mm of Hg were to be recorded as hypotension and treated by giving injection ephedrine 5 mg IV bolus.
3. Episodes of nausea and vomiting were to be recorded and treated by injection ondansetron 4mg IV.

If there was an inadequate subarachnoid block, then the surgery was to be conducted at the discretion of the attending anaesthesiologist, and the case was to be counted as spinal anaesthesia failure and no further observation recorded.

 SENSORY BLOCK

Time For Onset of Sensory Block till S5 Dermatome

Table 1: Time for onset of sensory block till S5 dermatome. Group C had a mean onset of 95.08 ± 7.025 sec and Group B had a mean onset of 98.80 ± 10.498 sec. Both the groups showed no significant variation with respect to the time of onset of sensory block till S5 dermatome (p = 0.06). Thus, time for onset of sensory block was slightly earlier for Chloroprocaine but the difference was not significant.

Table 2: Maximum height of sensory block. 32.5% patients in Group C, attained a maximum height of sensory block of T7 dermatome, while in Group B, 32.5% patients attained a maximum height of T10 dermatome. Both the groups showed significant variation with respect to maximum height of sensory block (p <0.001). Thus, a higher level of sensory block was seen with Chloroprocaine compared to Bupivacaine.

TIME FOR TWO DERMATOMAL REGRESSIONS

Table 3: Time for two dermatomal regressions. Group C had a mean time of 50.43± 2.541 min and Group B had a mean time of 77.25 ± 6.916 min. Both the groups showed significant variation with respect to the time of two dermatomal regression (p=0.001). Thus, Chloroprocaine showed an earlier two dermatomal regressions compared to Bupivacaine

DURATION OF SENSORY BLOCK TILL S2 DERMATOME

Table 4: Duration of sensory block. Group C had a mean duration of 142.18 ± 7.789 min and Group B had a mean duration of 323.78 ± 12.538 min. Both the groups showed significant variation with respect to the duration of sensory block (p = 0.001). Thus, duration of sensory block of Chloroprocaine was shorter compared to Bupivacaine.

1. MOTOR BLOCK

ONSET OF MOTOR BLOCK

Table 5: Onset of motor block. Group C had a mean onset of 240.13 ± 26.192 sec and Group B had a mean onset of  364 ± 21.772 sec. Both the groups showed significant variation with respect to the time of onset of motor block (p = 0.001). Thus, the onset of motor block was faster with chloroprocaine compared to Bupivacaine.

DURATION OF MOTOR BLOCK

Table 5: Onset of motor block. Group C had a mean onset of 240.13 ± 26.192 sec and Group B had a mean onset of  364 ± 21.772 sec. Both the groups showed significant variation with respect to the time of onset of motor block (p = 0.001). Thus, the onset of motor block was faster with chloroprocaine compared to Bupivacaine.

DURATION OF MOTOR BLOCK

Table 6: Duration of motor block. Group C had a mean duration of 69.45  ± 5.411 min and Group B had a mean duration of 91.75  ± 3.726 min. Both the groups showed significant variation with respect to the duration of motor block  (p = 0.001). Thus, the duration of motor block with Chloroprocaine was shorter compared to Bupivacaine.

1. POST-OPERATIVE PERIOD

VAS SCORE

Table 7: VAS score . In both the groups, the VAS score at 90 min, 120 min, 150 min, 180 min are statistically significant (p<0.001). VAS score was comparable in the first 60 min. After 60 min VAS score was more with Chloroprocaine compared to Bupivacaine

The time for onset of sensory block till S5 dermatome in Group C was 95.08 ± 7.025 sec and Group B was 98.80 ± 10.498 sec. This implies that the time of onset of sensory block was slightly quicker with Chloroprocaine than Bupivacaine. However, this difference was statistically not significant (p = 0.06). The maximum height of sensory block level reached by most patients (32.5%) in Group C was T7 dermatome and 32.5 % attained T10 dermatome in Group B. This difference was statistically significant (p=0.001). Thus, greater height of sensory block was seen with Chloroprocaine (Median value T7) as compared to Bupivacaine (Median value T10). The time taken to attain maximum height of sensory block in Group C was 16.15±3.08 min and 17.33±2.45 min in Group B. This observation was statistically not significant (p=0.102). Thus, the time taken to attain maximum height of sensory block was similar for both Chloroprocaine and Bupivacaine. The duration of sensory block in Group C was 142.18±7.789 min and in Group B was 323±12.538 min. This observation was statistically significant (p <0.001). Thus, Chloroprocaine had a shorter sensory block duration than Bupivacaine and resulting in shorter stay in PACU. The motor block onset time was 240.13±26.19 sec in Group C and 364.75±21.77 Group B. The observation was statistically significant (p=0.001). Thus, Chloroprocaine had a faster onset of motor block then Bupivacaine. The duration of motor block in Group C was 69.45 ±5.411 min and Group B was 91.75±3.726 min. This was statistically significant (p value= 0.001). Thus, Chloroprocaine had an earlier resolution of motor block, thus patient could ambulate earlier. VAS score was comparable in the first 60 min. After 60 min VAS score was more with Chloroprocaine compared to Bupivacaine. During the first three hours after surgery, 12.5% of patients in group C and none in group B required rescue analgesia (p<0.001).VAS score and need for rescue analgesia was comparable up to the first 60 mins and then VAS score increased for the group receiving Chloroprocaine, showing that analgesia lasted up to 60 mins with Chloroprocaine while it is longer for Bupivacaine.

In our study we found that Chloroprocaine had a shorter sensory block duration than Bupivacaine (p <0.001) and we observed a shorter stay in PACU. The greater height of sensory block was seen with 2-Chloroprocaine (median sensory dermatomal block T7) as compared to Bupivacaine (median sensory dermatomal level T10) (p=0.001). The time required to reach the maximum height of the sensory block was similar for both Chloroprocaine and Bupivacaine.  The Chloroprocaine had a faster onset of motor block then Bupivacaine (p=0.001). The, Chloroprocaine had an earlier resolution of motor block, thus patient could ambulate earlier (p value= 0.001).  TheVAS score and need for rescue analgesia was comparable up to the first 60 mins and then VAS score increased for the group receiving Chloroprocaine, showing that analgesia lasted up to 60 mins with Chloroprocaine while it is longer for Bupivacaine.

The demographics profile in both the groups were comparable. This is similar to demographic profile chosen in the study of Kalra et al, where distribution age (p=0.52), sex (p=0.602), weight (p=0.632), height (0.855), ASA grade (0.197) and The duration of operation (0.821) was comparable across the two study groups.

In our study, time for onset of sensory block till S5 dermatome in Group C was 95.08 ± 7.025 sec and Group B was 98.80 ± 10.498 sec. Therefore, Chloroprocaine shows a slight early onset of sensory block than Bupivacaine, though it is not statistically significant. Our results were similar to the study conducted by Kalra et al12, where they observed that the onset of sensory block was 143 ±7.77 sec in Group A and 156.5 ±10.21 sec in Group B (p value=0.77). However, the mean time for the onset of sensory block in both groups of our study is less than that of Kalra et al. This is probably because we have used a different dermatome to assess the onset of sensory block. Our findings were likewise consistent with the outcomes of earlier studies by Khare et al10 and Tiwari et al.11

In our study, majority (32.5%) of patients in Group C attained a maximum height of the sensory block of T7 dermatome, and majority (32.5%) of patients in Group B attained T10 dermatome. Both groups showed a significant alteration with respect to the maximum height of the sensory block. Thus, greater height of sensory block was seen with Chloroprocaine (Median value T7) as compared to Bupivacaine (Median value T10).

Our results are similar to a study done by La casse et al, where the patients in Group 2-CP had a maximum height of sensory block of T7 and Group Bupivacaine T10  (p>0.05). 

In our study, the time to attain the maximum height of sensory block in Group C was 16.28±3.18 min and 17.33±2.443 min in Group B. Both the groups showed no significant variation with respect to time to reach maximum height of sensory block (p = 0.102). Our results are Consistent with the findings of La casse et al,8 in which the time to peak sensory block was 15±8 min in Group 2-CP and 18±11 min in Group Bupivacaine (p=0.15).  Our results were also consistent with the results of the previous studies by Kalra et al.12

In our study, the mean time for two dermatomal regressions in Group C was 50.43 ± 2.541 min and in Group B was 72.25±6.916 min. Both groups showed a significant variation with respect to the mean time for two dermatomal regressions (p=0.001). This shows that Chloroprocaine has an early regression of sensory block. Our results were consistent with a study done by Lacasse et al,8 where the mean time for two dermatomal regression was 50±18 min in Group 2CP and 75±37 min in Group Bupivacaine (p<0.001).

In our study, the duration of sensory block in Group  C was 142.18±7.79 min and in the Group B was 323±12.54 min (p<0.001).  Sensory block with Chloroprocaine is for shorter duration of time as compared to Bupivacaine. This shows that the patients receiving Chloroprocaine have a shorter stay in PACU. Our observation was consistent with the study by Lacasse et al. where the duration of sensory block was 146±38 min in Group 2-CP and 329±82 minutes in Group Bupivacaine (p<0.001). Our results were also consistent with the results of the previous studies by Teunkens et al.,9 Khare et al.,10Kalra et al.12

In our study, the motor block onset time was 240.13±26.19 sec in Group C and 364.75±21.77 sec in Group B (p <0.001). Both the groups showed significant variation with respect to the time of onset of motor block (p=0.001). Thus, the onset of motor block was earlier with Chloroprocaine. Our findings are also in line with those of Kalra et al.12 where the onset time of motor block was 3.87±0.75 min in Group A and 6.12±0.65 min in Group B (p<0.0001). Our results were also consistent with the previous studies of Lacasse et al and Khare et al.8,10

In our study, the duration of motor block in Group C was 69.45±5.411 min and Group B was 91.75±3.726 min. Both the groups showed significant variation with respect to the duration of motor block (p = 0.001). Thus, we observed that the mean duration of the motor block in group C was shorter than the group B. This shows that motor block with Chloroprocaine was of shorter duration compared to Bupivacaine. Thus, patients receiving Chloroprocaine could ambulate earlier. Our result was similar to the study done by Lacasse et al.8 where the duration of motor block was 76±25 minutes in Group 2-CP and 119±93 minutes in Group Bupivacaine (p=0.001).  Our result was also consistent with the results of the previous studies of Teunkens et al,9 Khare et al,10 Kalra et al.12

In our study, VAS score was comparable in the first 60 mins. After 60 mins VAS score was more with Chloroprocaine compared to Bupivacaine. During the first three hours after surgery, 12.5% of patients in group C and none in group B required rescue analgesia (p<0.001). Both the groups showed significant variation with respect to rescue analgesia (p=0.02). This shows that the VAS score and need for rescue analgesia was comparable up to the first 60 mins and then VAS score increased for the group receiving Chloroprocaine, showing that analgesia lasted up to 60 mins with Chloroprocaine while it is longer for Bupivacaine. Thus, we conclude that the duration of analgesia in Group B was more than that in Group C. The result of our study was consistent with the previous study by Kalra et al,12 where duration of analgesia in Group A was 114.31±2.15 min and 224.66±12.05 min in Group B (p<0.0001).

We, therefore conclude that Chloroprocaine is comparable to Bupivacaine in providing adequate anaesthesia for perianal surgeries and has the advantage of slightly early onset, blocks upto a desired level for a shorter duration and regresses faster

Chloroprocaine and Bupivacaine are both useful drugs for providing saddle block for doing perianal surgeries. Chloroprocaine is a good alternative to the time-tested Bupivacaine, as it has an advantage of slight early onset, attains adequately good height of sensory block, for a shorter duration, and regresses faster thus reducing stay in PACU. Moreover, it has the advantage of early onset and faster regression of motor block and thus patients can ambulate earlier. Therefore, chloroprocaine can be recommended for saddle block in perianal surgeries of short duration.

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