Lower abdominal and lower limb surgeries may be performed under local, regional (spinal or epidural) or general anaesthesia.[1] Spinal block is the first choice because of its cost-effectiveness, rapid onset of action, superior blockade, low risk of infection and less failure rates.[2] Spinal lidocaine has been the local anaesthetic of choice for outpatient surgery because of its faster onset and short duration of action. However, transient neurological symptoms such as back pain with irradiation to the lower extremities, have been reported.[3, 4] Hence, as an alternative, low dose hyperbaric bupivacaine, a long-acting local anaesthetic was used in the ambulatory setting. However, prolonged duration of the block and urinary retention delaying the time of discharge are the shortcomings associated with bupivacaine.[5, 6]

Over the recent years, 2-chloroprocaine, an ester type local anaesthetic that has gained popularity is indicated for neuraxial anaesthesia and peripheral nerve blocks and obstetric anaesthesia.[7, 8] 2-chloroprocaine was withdrawn previously because of concerns about neurotoxicity.[9] However, the new formulation without preservatives has no longer been associated with neurotoxicity.[9] The United States Food and Drug Administration recently approved a preservative-free chloroprocaine to provide spinal anesthesia for adults undergoing short-duration lower extremity and lower abdominal surgery.[7]

It was reported that rapid onset of action (5–10 minutes), speedy recovery time (70–150 minutes), duration of anaesthesia up to 100 minutes are the characteristics of 2-chloroprocaine.[9, 10] However, there has been little clinical research on spinal 2-chloroprocaine, mainly dose comparisons and block characteristics in short-duration surgeries.[11-13] Thus, the study was designed to investigate 2-chloroprocaine with bupivacaine for spinal anaesthesia in lower abdominal and lower extremity surgeries.

Study design and setting

The case-control study (August 2017 to May 2018) included patients scheduled to undergo lower abdominal surgeries and lower extremity surgeries at the Department of Anaesthesia in a tertiary care centre in Bangalore, Karnataka. An informed written consent was taken from the patients at the time of pre-anaesthetic check-up and institutional ethical committee clearance was sought from the study before the study commencement.

A total of 66 patients of either sex aged 18-60 years, American Society of Anesthesiologists (ASA) physical status I and II undergoing lower limb and lower abdominal surgery of short duration (<60 min) under spinal anaesthesia were included. While patients with International normalized ratio >1.3, Platelets <75,000/ml, neurologic disease (multiple sclerosis, symptomatic lumbar herniated disc, spinal stenosis), fluid restriction (cardiac or renal insufficiency), severe cardiac disease (severe AS, severe MS, hypertrophic obstructive cardiomyopathy, CHF etc), sepsis, lung disease (diaphragm weakness, pleural effusion) were excluded. Also, patients who were on anticoagulant drug, allergy, or intolerance to local anaesthetics or para-aminobenzoic acid, atypical plasma cholinesterase excluded.

Based on et al. Lacasse et al. study[8], 66 patients (33 per group) were required to have a 90% chance of detecting (β), as significant at the 5% level (α), a decrease in the average time to complete sensory regression from 329 min in the control group to 146 min in the experimental group. Recruited patients were received either preservative free 1% 2-chloroprocaine 40 mg (4 ml; n = 33) or 0.5% hyperbaric bupivacaine 10 mg (2 ml; n = 33) without any adjuvant medication such as fentanyl or epinephrine.

Study procedure

Pre-anaesthetic check-up was performed one day prior to the surgery and all the patients participating in were kept nil per orally for at least 6 h. After arrival to operating room, a 20G peripheral intravenous catheter was inserted into the patient’s forearm, and approximately 10 mL/kg of crystalloid was infused. Standard monitoring was used throughout the surgery, including non-invasive arterial blood pressure, electrocardiogram (three leads), and pulse oximetry. Spinal anaesthesia was performed under sterile conditions after local infiltration of the skin with 2% lidocaine. With the patient in the sitting position, the subarachnoid space was entered at the L3-4, or L4-5 inter space via the midline approach using a 25 or 26G Quinke’s spinal needle. After the completion of the spinal injection, the patients were immediately placed supine. The sensory level of the block was assessed in a caudal to cephalad direction using pin prick method. The motor block was assessed using the modified Bromage scale (0 = no block, full straight leg raises possible; 1 = unable to straight leg raise, able to flex knee; 2 = unable to flex knee, able to flex ankle; 3 = no motor movement, complete motor block).

Readiness for surgery was defined as loss of pin prick sensation >= T10. During surgery, the patient’s blood pressure (systolic and diastolic), electrocardiogram, and pulse oximetry were recorded. During surgery, evaluation of the motor block was suspended until the end of the procedure. If the patient complained of pain, fentanyl 25 to 100 micro gm iv was administered. If additional sedation was needed, midazolam 0.025 to 0.05 mg/kg iv was given. The total dose of any given medication was recorded. If the patient still complained of pain, general anaesthesia was provided, and the protocol was stopped.

The incidence of hypotension (systolic arterial blood pressure < 25% from baseline) was treated with ephedrine or phenylephrine. Bradycardia (heart rate<50 beats/min) was treated with atropine or ephedrine. Ondansetron 4 mg iv was given for nauseous patients. Patients were discharged from the post anaesthesia care unit when they attained all the following criteria: A minimum 60-min stay, stable vital signs, normal consciousness, and signs of regression of the motor block (Bromage 0 to 1).

Parameters assessment

After discharge, the nurse was asked to note down the time when the patient starts to ambulate without assistance and time to micturate. Sensory and motor blockade-highest level of sensory blockade, regression of sensory to S2 (duration of sensory block) and regression of motor block to bromage score 0 or 1 in PACU (duration of motor block). Hemodynamic parameters such as heart rate and blood pressure changes were noted. Side effects/complications like hypotension and bradycardia, were also recorded.

Statistical analysis

SPSS v.23 (Armonk, NY: IBM Corp.) was used for data analysis. Continuous or parametric variables were represented in the form of mean, standard deviation (SD) and analyzed using Student t-test. Non-parametric or categorical variables were represented in the form of the number and analyzed using Chi-square (χ2)/Freeman-Halton Fisher exact test. P<0.05 was considered as significant.

The mean age, gender, weight, height, ASA status, and type of surgery were comparable between cases and controls (P>0.05; Table 1).

Table 1: Demographic and clinical data of patients assigned to either

*Significant

The number of patients who achieved highest level of sensory block was higher in cases when compared to controls at T6 level (87.9% vs. 54.5%; P=0.003). The mean duration of sensory block and motor block, and the mean time to ambulation and micturition were significantly higher in controls when compared to cases (P<0.001). Hypotension was seen in 6.1% of the patients in cases, wherein controls showed 9.1%. Bradycardia was seen in 3% in cases and none in the controls in our study. However, there were no significant comparable side effects between cases and controls (P=0.549; Table 2).

Table 2: Clinical Characteristics of Spinal Anesthesia

*Significant

Heart rate, diastolic blood pressure, and systolic blood pressure were comparable between cases and controls (P>0.05).

Table 3: Comparison of hemodynamic parameters between the groups

Spinal anesthesia technique involves injecting a local anaesthetic solution into the cerebrospinal fluid to temporarily halt the transmission of nerve impulses within the subarachnoid space.[1, 3] It is easy to administer and offers a high level of post-anaesthesia satisfaction for patients undergoing lower abdomen, perineum, and lower extremities surgeries.[3] Hence, we compared 2-chloroprocaine with bupivacaine for spinal anaesthesia in lower abdominal and lower limb surgeries. Our principal finding was that spinal anaesthesia with 2-chloroprocaine provide a satisfactory surgical block with rapid regression of the sensory and motor block, which helps patients ambulate and micturate fast allowing earlier hospital discharge.

In our study, majority of patients were middle aged in both the groups. Furthermore, parameters such as gender distribution, BMI, types of surgeries performed were also kept identical in both groups to avoid variations in intraoperative and postoperative outcome of patients.

Literature has reported that 40 mg of chloroprocaine was found to be the ideal dose because  increasing this dose resulted in an increased time for block recovery and lowering this dose resulted in insufficient duration of anaesthesia.[12] While 7.5 mg bupivacaine was shown to be the most ideal dose for providing clinical anaesthetic efficacy.[14] These findings have led to fix the drug doses in our study to achieve spinal anaesthesia in patients undergoing lower limb and abdominal surgeries of shorter duration.

In our study patients in 1% 2-chloroprocaine group achieved significantly rapid sensory block (146 min vs. 329 min) and motor block (76 min vs. 124.5 min), early ambulation (223 min vs. 262 min) and micturition (269 min vs. 339 min) than those in 0.5% bupivacaine group. Yoos et al. reported spinal 2-chloroprocaine achieved 1.7 times faster regression of the sensory block than small dose bupivacaine.[11] Further, 2-chloroprocaine spinal anaesthesia associated with faster resolution of block, shorter ambulation and voiding.[11] Camponovo et al. demonstrated that 1% chloroprocaine achieved significantly faster resolution of sensory (105 vs. 225 min) and motor (100 min vs. 210 min) blocks, unassisted ambulation (142.5 vs. 290.5 min), first analgesic requirement (120 min vs. 293.5 min), and early discharge from hospital (150 vs. 325 min) than plain 0.5% bupivacaine.[15] Lacasse et al. has shown that average time for complete regression of the sensory block was 146 min in 2- chloroprocaine group and 329 min in bupivacaine group.[8] Ben Gys et al. demonstrated 2-Chloroprocaine reported fast and complete sensory recuperation and motor regression facilitating faster voiding and ambulation than with prilocaine or bupivacaine in patients who underwent ambulatory abdominal wall herniorrhaphy.[16] The indicates that spinal 2-chloroprocaine provides adequate duration and depth of surgical anaesthesia with the advantages of faster block resolution and earlier hospital discharge compared with spinal bupivacaine.

In our study the hemodynamic parameters such as heart rate, systolic blood pressure, diastolic blood pressure was comparable between the groups. These findings were consistent with the similar studies.[8, 11, 15] While side effects noted in our study was consistent with other similar studies, which reported the incidence of hypotension, bradycardia, pain requiring analgesia, transient neurologic symptom rate, total dose of fentanyl given, patient satisfaction were similar between the groups during the surgery.[8, 15, 17]

The finding that shows the most significant advantage is the time for regression of the sensory block to S2, as 2-chloroprocaine showed faster regression of the block, resulting in earlier ambulation and earlier voiding. Nevertheless, like other studies, the present study also poses several limitations that need to be put forth. The size of the study group is not large enough to reliably account for all important variables or draw firm conclusions about absence of relationships. Further studies with large sample size might be needed to validate the findings of our study before any guidelines or recommendations are promulgated. As this is a case-control study, there is possibility of bias in recollection and the conclusions drawn need to verified by replication in other study designs such as prospective cohort studies.

Intrathecal preservative-free 1% 2-chloroprocaine provides adequate duration and depth of surgical anaesthesia with the advantages of highest sensory block at T6 level, faster regression of sensory and motor block, and less time to ambulation and micturition compared with 0.5% bupivacaine for lower abdominal and lower limb surgeries of short duration (<60 mins). Therefore 2- chloroprocaine can be used successfully for lower abdomen and lower extremity surgeries of short duration which further facilitates early hospital discharge.

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