European Journal of Cardiovascular Medicine

Daycare surgeries have surged due to their cost-effectiveness, lower infection risk, and improved patient turnover. Anaesthetic techniques for such surgeries must offer rapid onset and predictable offset to facilitate same-day discharge. Spinal anaesthesia, while commonly employed, requires local anaesthetics with brief durations to align with daycare requirements.

Chloroprocaine, an ester-type local anesthetic, historically used for epidural anaesthesia^1,2, has recently found renewed interest for intrathecal use due to its rapid onset and short duration of action. Its metabolism by plasma cholinesterase ensures swift elimination, thus reducing the risk of prolonged motor block and urinary retention, key factors in outpatient surgeries³.

Lateral anal sphincterotomy, typically performed for chronic anal fissures, is ideally suited for daycare settings. Anaesthesia for such perianal procedures demands limited sensory blockade, quick onset, and rapid post-operative recovery. Although chloroprocaine's dose-dependent properties are well-recognized, the optimal intrathecal dose for balancing efficacy and rapid recovery in such procedures remains underexplored.

This study aims to compare 20 mg and 30 mg intrathecal chloroprocaine doses, both combined with 25 mcg fentanyl, to determine which provides better anaesthetic quality and recovery profiles for daycare lateral anal sphincterotomy under spinal anaesthesia.

STUDY DESIGN: This prospective, randomized, double-blind clinical study was conducted in a tertiary care teaching hospital following Institutional Ethics Committee approval. The study adhered to the Declaration of Helsinki guidelines. Based on results of pilot study, the duration of motor block with 30 mg was 90min to detect a 10% difference in duration of motor block with 90% power and 95% confidence interval; we needed 19 patients in each group. We included 30 patients in each group.

 Total sixty patients of either gender aged between 18-65 yrs belonging to ASA I and ASA II planned for elective lateral anal sphincterotomy were included in the study. Patients who refused consent for spinal anesthesia, who are allergic to local anesthetics, skin and soft tissue infection at injection site, who have coagulopathy, neurologic disorder, morbidly obese(BMI>35) , patients requiring sedation and conversion to general anesthesia were excluded from the study.

All patients were subjected to general physical examination and underwent surgical profile before surgery. All patients were kept nil per oral for 8 hrs before surgery and received 0.25 mg alprazolam on the night before surgery and 4 hrs prior to surgery. In the operation theater ASA standard monitoring SPO₂, NIBP, three lead ECG connected and baseline values were recorded. IV access was secured and 10 ml /kg of Ringer lactate loading was administered.

Patients were allocated to group A & B based on computer generated random allocation.

Group A received inj 1%Chlorprocaine 20 mg(2ml) + 25 mcg(0.5ml) intrathecally, volume adjusted to 3.5 ml by adding 1ml of normal saline to aid in blinding

Group B received inj 1%Chlorprocaine 30 mg(3ml) + 25 mcg(0.5ml) intrathecally, total of 3.5 ml.

Study drug was loaded by fellow anesthesiologist, not involved in the study and patient follow up in the postoperative period.

Anesthesia technique:

Spinal anesthesia was performed at L3-L4 Intervertebral space using a 26G wittacre needle in the lateral position. After confirming free flow of CSF, the study drug was injected slowly. After injecting patients are made to lie supine. After adequate sensory level is achieved, patients are put in lithotomy position. The level of sensory block was assessed using spirit swab and pain to 23G hypodermic needle.

Sensory block: Interval between the intrathecal drug delivery and achieving S1-S5 sensory block was taken as onset of sensory block. Sensory dermatomal levels were tested every 1 minute for the first 5 min, then at 5-min intervals for next 60 minutes and at every 10 minutes intervals until complete resolution of sensory anesthesia. Time of onset, highest level of sensory block and duration of sensory block was recorded.  The duration of the block is defined as the time between intrathecal drug injection and regression to the point of S2 dermatome level.

Motor block was assessed by modified Bromage scale. It is assessed every 1 minute for the first 5 min, then at 5-min intervals for next 60 minutes and at every 10 minutes intervals until complete resolution of motor anesthesia. Time of onset, highest level of motor block and duration of motor block was recorded. 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 after subarachnoid block 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 > 3. Complications like bradycardia, hypotension, pruritis nausea and vomiting were recorded during the operating period and postoperative period till patient is stepped out of PACU.

1. Heart rate < 50 bpm was considered as bradycardia and treated with injection Atropine 0.6mg bolus.
2. Fall of mean arterial pressure (MAP) >20mm of Hg was considered as hypotension and treated by giving injection ephedrine 5 mg IV bolus.
3. Episodes of nausea and vomiting were 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.

Demographic and Baseline Parameters 

A total of 60 patients were enrolled and completed the study, with no dropouts. Demographic variables including age, height and body mass index (BMI) were comparable between Group A (20 mg chloroprocaine + fentanyl 25 mcg) and Group B (30 mg chloroprocaine + fentanyl 25 mcg), indicating proper randomization and baseline homogeneity. There were no statistically significant differences observed in any of these variables (p > 0.05), ruling out confounding due to demographic variations. The duration of surgery is also comparable between the groups.

Data Represented as mean ± slandered deviation (SD) and unpaired students T test was used for intergroup comparison. P value <0.05 is taken as significant.

BMI – body mass index

Table 2: Subarachnoid Block characteristics:

P value<0.05 is considered significant

Onset of Sensory and Motor Block 

Group B exhibited a statistically faster onset of sensory block, with a mean onset time of   2.8 ± 0.7 minutes, compared to   3.6 ± 0.8 minutes   in Group A (p = 0.001). A similar trend was noted in the motor block onset, where Group B demonstrated quicker onset times, although the difference was not as pronounced. The faster onset in Group B can be attributed to the higher concentration and volume of Chlorprocaine, resulting in more rapid saturation of spinal nerve roots.

Duration of Sensory and Motor Block 

The duration of sensory block was significantly longer in Group B (112.2 ± 12.5 minutes) compared to Group A (85.7 ± 10.3 minutes, p < 0.001). Similarly, the motor block persisted longer in Group B (72.6 ± 7.4minutes) than in Group A (64.5 ± 8.9 minutes, p < 0.01). While the extended duration in Group B may be beneficial in longer surgical procedures, it could be a limiting factor in ambulatory settings where early mobilization and discharge are critical.

Time to Ambulation and Discharge Readiness 

Group A demonstrated a significantly shorter time to ambulation (102.4 ± 11.3 minutes) compared to Group B (116.7 ± 14.1 minutes, p = 0.03). Discharge readiness, defined by complete motor recovery, stable vitals, ability to ambulate, urinate, and minimal nausea was achieved earlier in Group A (150.5 ± 16.8 minutes) than in Group B (172.2 ± 20.4 minutes, p = 0.02). This finding is particularly relevant in the context of daycare surgery, where early turnover is beneficial for both patients and healthcare resources.

P value<0.05 is considered significant

Intraoperative Conditions and Analgesic Efficacy.

Intraoperative anaesthesia was sufficient in all patients. No conversions to general anaesthesia were required, and no patients in either group reported inadequate anaesthetic depth or discomfort requiring intervention. This affirms that both 20 mg and 30 mg doses of chloroprocaine, when augmented with fentanyl, can reliably provide adequate anaesthesia for lateral anal sphincterotomy procedures, typically lasting 20–30 minutes.

Postoperative pain scores were measured using the Visual Analogue Scale (VAS). Mean VAS scores remained <3 for the first two hours in both groups. At the third postoperative hour, Group A showed a slight but non-significant increase in pain scores compared to Group B. Four patients in Group A (13.3%) required rescue analgesia within four hours, versus two patients in Group B (6.6%), though this difference did not reach statistical significance (p = 0.39).

Adverse Effects and Safety 

Few side effects like hypotension, bradycardia, nausea /vomiting observed in both groups but incidence is not significant and there is no statistically significant difference observed between the groups. No neurological complications were observed in either group.  Perioperative pruritis was reported in 3 patients (10%) and 4 patients in group(13.3%), incidence is within the range in various previous studies with intrathecal opioids.

Patient Satisfaction 

Patient satisfaction, measured using a 5-point Likert scale (1 = very dissatisfied, 5 = very satisfied), was high across both groups. The mean satisfaction scores were   4.6 ± 0.4   in Group A and   4.7 ± 0.3   in Group B, with no statistically significant difference (p = 0.45). Patients appreciated the prompt recovery, minimal discomfort, and the ability to resume activities within hours of the procedure.

The present study sought to determine the optimal dose of intrathecal chloroprocaine for daycare lateral anal sphincterotomy procedures, comparing 20 mg and 30 mg dosages, each combined with 25 mcg fentanyl. The rationale behind exploring this dosing range lies in the need to achieve an effective surgical block while preserving the ability to achieve early ambulation and discharge, hallmarks of successful ambulatory anaesthesia.

Chloroprocaine is an ester-type local anaesthetic with an ultra-short duration of action due to rapid hydrolysis by plasma cholinesterases. Its pharmacokinetics make it an ideal agent for ambulatory spinal anaesthesia, contrasting with longer-acting agents such as Bupivacaine⁵, Ropivacaine⁶ . these long-acting drugs even in smaller doses can result in delayed mobilization, increased risk of urinary retention and delayed discharge. The spinal anesthetic profile of chlorprocaine (40 mg) compares favourably with the same dose of spinal lidocaine. Reliable sensory and motor blockade with predictable duration and minimal side effects and without signs of transient neurological symptoms make chlorprocaine an attractive choice for outpatient spinal anesthesia². However, the ideal dose for perianal surgeries has not been firmly established, warranting further exploration.

Our findings align with previous studies that have demonstrated chloropropane’s efficacy in ambulatory lower limb, urological, and perianal surgeries. Notably, the   Ghisi et al.⁵   study (2016) comparing levobupivacaine and Chloroprocaine showed faster recovery with the latter, reinforcing its suitability for short procedures. Similarly, Kallio et al. ⁴ (2012) found both 40 mg and 60 mg doses effective for intrathecal use but suggested that higher doses may unnecessarily prolong recovery.

In our study, the   30 mg dose provided a marginally faster onset and significantly longer duration of block, which may be preferable in surgeries expected to be prolonged or technically complex. However, this advantage is offset by delayed ambulation and discharge, critical metrics in the outpatient surgical workflow. For lateral anal sphincterotomy, a relatively brief and superficial procedure, the 20 mg dose with fentanyl appears to strike a better balance between efficacy and recovery profile.

A key strength of this study is the inclusion of   fentanyl, a lipophilic opioid that augments both sensory and analgesic effects without contributing significantly to motor blockade or prolonging recovery time^8,9. Its synergistic effect with Chloroprocaine enhances intraoperative comfort and postoperative pain control, reducing the need for systemic analgesics⁷.

The   shorter ambulation and discharge times in the 20 mg group   have practical implications. Early recovery reduces postoperative complications such as urinary retention and orthostatic hypotension and improves patient satisfaction. Moreover, in high-volume surgical centers, shorter hospital stays translate into better resource allocation and patient satisfaction.

Patient satisfaction scores   were uniformly high in both groups, underscoring that a lower dose does not compromise the subjective experience when combined with adequate intraoperative monitoring and communication. These findings are crucial as patient-reported outcomes increasingly guide an anaesthetic practice decision.

Despite the positive findings, certain limitations must be acknowledged. The study was   limited to a single Center with a modest sample size, which may affect the generalizability of results. Additionally, long-term neurological follow-up   was not performed, although prior studies have found intrathecal preservative free Chloroprocaine to be safe in this regard, especially when preservative-free formulations are used.

We also did not explore the effects of   other adjuvants or sedation strategies, which might influence the overall experience in different patient populations. Furthermore, the subjective nature of pain and satisfaction assessments introduces potential biases despite efforts to blind the investigators.

Clinical Implications and Future Directions 

The results of this study suggest that   20 mg of intrathecal chloroprocaine with 25 mcg fentanyl   offers a safe, effective, and efficient anaesthetic profile for lateral anal sphincterotomy, optimizing both surgical conditions and postoperative recovery. Given the trend toward increasing ambulatory surgeries, this combination could serve as a   standardized protocol   for similar anorectal procedures.

Future research could explore:

Head-to-head comparisons with other local anaesthetics such as prilocaine or low-dose bupivacaine. The utility of adjuncts like clonidine or dexmedetomidine with chlorprocaine. Evaluation of dosing in obese, elderly, or high-risk populations. Cost-effectiveness analysis comparing chlorprocaine protocols to general anaesthesia in daycare settings.

1. Chlorprocaine Spinal Anaesthesia: Back to the Future? Drasner, Kenneth MD Editor(s): Horlocker, Terese T Anaesthesia & Analgesia 100(2):p 549-552, February 2005.
2. Yoos JR, Kopacz DJ. Spinal 2-chloroprocaine: A comparison with lidocaine in volunteers. Anesth Analg. 2005;100(2):566–572.
3. Chloroprocaine Provides Safe, Effective, Short-Acting Spinal Anaesthesia Ideal for Ambulatory Surgeries: A Retrospective Review
4. David H Kim, Richard Kahn  Andrew Lee , Phuong Dinh Mac, Yu-fen Chiu, Jacques Yadeau , Jiabin Liu. HSS J 2019 Aug 26;16(Suppl 2):280–284. doi: 1007/s11420-019-09713-y
5. Kallio H, Snäll EV, Kero MP, Rosenberg PH. Intrathecal chloroprocaine: A comparison of 40 and 60 mg doses in ambulatory surgery. Anesth Analg. 2012;115(3):607–614.
6. Ghisi D, Bonarelli S, Ambrosoli AL, et al. Levobupivacaine or chloroprocaine for intrathecal anaesthesia in ambulatory surgery: a randomized controlled trial. Br J Anaesth. 2016;116(5):752–758.
7. Ganesh A, Maxwell LG. Pathophysiology and management of opioid-induced pruritus. Drugs. 2007; 67:2323–2333. doi: 10.2165/00003495-200767160-00003. 
8. A randomized prospective comparative study between intrathecal chloroprocaine 1% and ropivacaine 0.5% for short duration surgery.Vivek Prakash,Payal Jain,Mukesh Kumar Prasad
9. Anesthesia, pain & intensivecare vol 27 NO 4(2023) AUG2023
10. Spinal 2-Chloroprocaine: The Effect of Added Fentanyl Vath, Julie S. MD; Kopacz, Dan J. Anesthesia & Analgesia 98(1):p 89-94, January 2004.
11. Comparison of analgesic efficacy of intrathecal 1% 2-chloroprocaine with or without fentanyl in elective caesarean section.A prospective, double-blind, randomised study
12. Singariya, Geeta; Choudhary, Kusum; Kamal, Manoj; Bihani, Pooja; Pahuja, Himani; Saini, Pradeep Indian Journal of Anaesthesia 65(2):p 102-107, February 2021.
13. Swain A, Nag DS, Sahu S, Samaddar DP. Adjuvants to local anesthetics: Current understanding and future trends World J Clin Cases. 2017;5:307–23
14. Hejtmanek MR, Pollock JE. Chloroprocaine for spinal anesthesia: A retrospective analysis Acta Anaesthesiol Scand. 2011;55:267–72
15. Chloroprocaine for spinal anesthesia: a retrospective analysis M R Hejtmanek¹, J E Pollock. Acta Anesthesolgica scandnavica 2011 Mar;55(3):267-72.
16. Conversion of Labour Epidural Analgesia to Anaesthesia for Caesarean Delivery Dr Shweta S. Mogal, Dr Manokanth Madapu, Obstetric Anesthesia tutorial 484, nov 2022.