Dosage finding for low-dose spinal anaesthesia using hyperbaric prilocaine in patients undergoing perianal outpatient surgery

A comparison of 0.375% ropivacaine psoas compartment block and 2% prilocaine spinal anaesthesia in dogs undergoing tibial plateau levelling osteotomy

BACKGROUND

In dogs undergoing routine elective orthopaedic surgeries carried out as same-day surgeries regional anaesthetic techniques (RATs) should aim to produce analgesia but minimising the postoperative motor dysfunction. Our objective was to compare the perioperative analgesic effects and the time to motor recovery between spinal anaesthesia (SA) with hyperbaric solution of prilocaine 2% (mg = 4 x [0.3 × BW (kg) + 0.05 × SCL (cm)]) and morphine (0.03 mg/kg) and combined ultrasound (US) and electro stimulator-guided psoas compartment and ischiatic nerve block (PB) with ropivacaine 0.375% (0.45 mL/kg). Dogs undergoing tibial plateau levelling osteotomy (TPLO) were randomly assigned to receive either SA or PB. Procedural failure, perioperative rescue analgesia, motor block recovery and complications were recorded.

RESULTS

Procedural failure rate (PFR) was 19% (7 out of 36) for SA and 9% (3 out of 32) for PB (p = 0.31). Intraoperative rescue analgesia was administered to 6/29 (21%) SA group dogs and in 15/29 (52%) PB group dogs, respectively (p = 0.03). At 3 h after RAT, percentage of dogs with complete block recovery was 25/29 (86%) and 25/29 (86%) in group SA and PB, respectively (p = 1). Two cases of pruritus and one case of urinary retention were recorded in the SA group. Residual ischiatic nerve block was noted at 12 h after RAT in 2/15 (13%) of dogs in group PB; it completely resolved 24 h after RAT.

CONCLUSIONS

SA with prilocaine 2% and PB with ropivacaine 0.37% were found suitable for dogs undergoing same-day TPLO surgery. Pruritus and urinary retention in SA and residual block in both groups might occasionally delay the time of discharge.

Saddle block anesthetic technique for benign outpatient anorectal surgery

BACKGROUND

Current American Society of Colorectal Surgery Clinical Practice Guidelines for Ambulatory Anorectal Surgery endorse use of monitored anesthesia care, general anesthesia, or spinal anesthesia based on physician and patient preference. Although several studies support the use of monitored anesthesia care over general anesthesia, the literature regarding spinal anesthesia is limited and heterogenous due to small sample sizes and disparate spinal anesthesia techniques. Saddle block anesthesia is a form of spinal anesthesia that localizes to the lowermost sacral spinal segments allowing for preservation of lower extremity motor function and faster recovery. We accrued one of the largest reported cohort of anorectal procedures using saddle block anesthesia, as such, we sought to evaluate our institutional 12-year experience.

METHODS

Patients who underwent a benign anorectal procedure at our outpatient surgery center between July 2008-2020 were retrospectively reviewed. Demographics, surgical factors, perioperative times, and adverse events were collected from the electronic medical records. Saddle block anesthesia was generally performed in the preoperative area using a spinal needle (25-27 gauge) and a single injection technique of a 1:1 ratio local anesthetic mixed with 10% dextrose solution. Between 2.5-5 mg of hyperbaric anesthetic was injected intrathecally in the sitting position and the patient remained upright for 3-10 minutes. This technique of saddle block anesthesia provides analgesia for approximately 1-3 hours.

RESULTS

In the study, 859 saddle block anesthesia patients were identified, with a mean age of 44.6 years and American Society of Anesthesia score of 1.9; 609 (70.9%) were male. Surgical indications included lesion removal (27.1%), anal fistula (25.8%), hemorrhoidectomy (24.7%), pilonidal disease (6.3%), anal fissure (5.8%), and a combination of prior (10.2%). Prone jackknife positioning was used in 91.6% of procedures. Saddle block anesthesia most often was performed with bupivacaine (48.9%) or ropivacaine (41.7%). The median procedural saddle block anesthesia time was 11 minutes, surgery time was 17 minutes, anesthesia time was 42 minutes, and recovery time was 91 minutes. Patients spent a median of 3 hours and 53 minutes in the facility. Adverse events included urinary retention (1.9%), conversion to general anesthesia (1.8%), spinal headache (1.5%), hemodynamic instability (0.9%), and injection site reaction (0.3%).

CONCLUSION

Demonstrated using the largest known cohort of anorectal patients with saddle block anesthesia, saddle block anesthesia provides an effective method of analgesia to avoid general anesthesia with a low rate of adverse events.

Optimal local anesthetic regimen for saddle block in ambulatory anorectal surgery: an evidence-based systematic review

BACKGROUND

Ambulatory anorectal surgery requires an anesthetic of short duration but profound depth. Saddle block anesthesia (SBA) can provide dense sacral anesthesia with minimal motor blockade, but the ideal local anesthetic agent remains undefined. This systematic review aims to identify the optimal SBA regimen for ambulatory anorectal surgery.

METHODS

We sought randomized trials examining SBA for ambulatory anorectal surgery and stratified patients into four subgroups according to local anesthetic type and dose: (1) longer acting, higher dose; (2) longer acting, lower dose; (3) shorter acting, higher dose; and (4) shorter acting, lower dose. Longer acting agents included bupivacaine and levobupivacaine; shorter acting agents included chloroprocaine, mepivacaine, and prilocaine. Lower dose was defined as ≤5 mg and ≤20 mg for longer and shorter acting local anesthetics, respectively. The primary outcome was time to discharge; secondary outcomes included times to sensory and motor block regression, urine voiding, and ambulation, as well as block success.

RESULTS

A total of 11 trials (1063 patients) were included. Overall study quality and reporting consistency was poor. Doses ranged from 1.5-7.5 mg to 3-30 mg of longer and shorter acting local anesthetics, respectively. Hyperbaric local anesthetics were used in eight trials (953 patients, 86%). The median time to discharge appeared similar across all subgroups with an overall time of 182 (IQR 102) min. The use of long-acting, lower dose regimens was associated with a faster median time to motor block regression. Block success approached 99% among all trials.

CONCLUSIONS

There is presently insufficient qualitative and quantitative evidence to identify an optimal SBA regimen for ambulatory anorectal surgery. Nonetheless, we found that doses as low as 1.5 and 3 mg of longer and shorter acting hyperbaric local anesthetics, respectively, can achieve effective and reliable SBA with timely hospital discharge. Despite similar discharge times, longer acting, lower dose local anesthetics may produce faster motor block regression following SBA for ambulatory anorectal surgery.

Tailored Surgery in Inguinal Hernia Repair. The Role of Subarachnoid Anesthesia: A Retrospective Study

Safety and effectiveness evaluation of subarachnoid anesthesia implemented with hyperbaric Prilocaine in reduced dose (30mg) in combination with Fentanyl (20mcg), for the purpose of ensuring an optimal analgesia in open inguinal hernia repair. Although the local anesthesia is the first line treatment for open inguinal hernia repair, a minority of patients is not eligible because of obesity or big groin hernia, requiring a high dose of local anesthetic. Subarachnoid anesthesia implemented with hyperbaric Prilocaine in reduced dose in combination with Fentanyl may be a good alternative. Thirty patients were treated with intrathecal association of Prilocaine 30 mg and Fentanyl 20 mcg (group PF); they were compared to a group of fifty three ones, previously treated with a classic procedure with intrathecal Prilocaine 60 mg (group P). The sensitive blockage remained within an higher limit at T12 level in the patients of PF group, and a lower limit at S1 level 50 minutes after the anesthesia, while in the P group the anesthetic tended to migrate (p<0.0001). In PF group 70 minutes after the anesthesia 21 patients had a Bromage score equal to 0 and 9 patients equal to 9 (in P group, 19 patients had a score equal to 3, 8 to 2 and 3 to 1, p<0.0001). Subarachnoid anesthesia using Prilocaine 30 mg + Fentanyl 20 mcg could be stated as a viable alternative to local anesthesia in selected patients.

Influence of anxiolytic premedication on vasovagal reactions and home readiness following outpatient intrathecal anaesthesia-A retrospective analysis

BACKGROUND

Vasovagal reactions during application of intrathecal anaesthesia (IA) are associated with high anxiety levels. A high percentage of patients undergoing outpatient surgery suffer from anxiety. Anxiolytic premedication in day-surgery is suspected to delay recovery and discharge and is, therefore, not routinely used. The aim of this retrospective analysis was to detect the influence of anxiolytic premedication on the incidence of vasovagal reactions and time until discharge home.

METHODS

Anaesthesia records of all patients undergoing outpatient surgery under low-dose IA from January 2008 to June 2017 were analysed. Incidences of vasovagal reactions with a decrease in blood pressure and/or heart rate and need for cardiovascular activating medications were documented. Patients were categorised as having received an anxiolytic premedication or not. The time from intrathecal injection of the local anaesthetic until readiness for discharge was recorded.

RESULTS

The records of 2747 patients were analysed. One thousand two hundred and ninety-one of them received an anxiolytic premedication of 1-2 mg midazolam intravenously. Three hundred and fourteen patients had vasovagal incidents during application of IA (no premedication n = 217 [15.0%], premedication n = 97 [7.5%], P < 0.0001). Premedication did not prolong time to achieve readiness for discharge (mepivacaine: P = 0.5886, chloroprocaine: P = 0.1555). However, in the prilocaine group, premedication led to a significantly earlier achievement of readiness for discharge (P = 0.0002).

CONCLUSION

Anxiolytic premedication significantly reduces the incidence of vasovagal reactions during the application of IA and does not affect time until readiness for discharge.

Retrospective analysis of mepivacaine, prilocaine and chloroprocaine for low-dose spinal anaesthesia in outpatient perianal procedures

PURPOSE

Perianal procedures are carried out in an outpatient setting regularly. The purpose of this retrospective analysis was to investigate the impact of different local anaesthetics (LA) for spinal anaesthesia (SPA) on operating room (OR) efficiency (perioperative process times, turnaround times) and postoperative recovery. This study aims on the determination of the optimal LA for low-dose SPA in the specific setting of a high-volume day-surgery centre.

METHODS

Anaesthesia records of all patients undergoing perianal outpatient surgery under saddle-block SPA at the Mannheim University Medical Centre from 2008 until 2017 were analysed. Patients were categorized as having received prilocaine, mepivacaine or chloroprocaine.

RESULTS

Two thousand seven hundred forty-six patients were included. Postoperative recovery was faster for chloroprocaine 1% compared with both other LAs. Preoperative processes but not process times in the OR were shorter for chloroprocaine. In contrary, turnaround times were significantly prolonged when chloroprocaine had been used, leading to reduction of OR efficiency.

CONCLUSION

Low-dose SPA provides reliable blocks for perianal surgery. Considerations on the choice of LA for SPA must include not only the recovery profile, but also the impact on OR efficiency. Due to shorter turnaround times and a manageable prolonged duration of stay, prilocaine is the preferable LA for low-dose SPA in perianal outpatient surgery at a high-volume day-surgery centre.

Prilocaine hydrochloride 2% hyperbaric solution for intrathecal injection: a clinical review

Prilocaine is a local anesthetic characterized by intermediate potency and duration and fast onset of action. As hyperbaric formulation of 5% solution, it was introduced and has been successfully used for spinal anesthesia since 1960. A new formulation of 2% plain and hyperbaric solution is currently available in Europe. Because of its lower incidence of transient neurological symptoms, prilocaine is suggested as substitute to lidocaine and mepivacaine in spinal anesthesia for ambulatory surgery, as well as a suitable alternative to low doses of long-acting local anesthetics. The National Library of Medicine database, the Excerpta Medica database, the Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials database, were searched for the period 1970 to September 2016, with the aim to identify studies evaluating the intrathecal use of 2% prilocaine. A total of 13 randomized clinical trials (RCTs), 1 observational study, 2 dose finding, and 4 systematic reviews has been used for this review. The studies evaluated showed that 2% hyperbaric prilocaine due to a favorable anesthetic and safety profile is an alternative drug to lidocaine and mepivacaine for spinal anesthesia of intermediate or short duration. In comparison with plain solutions, hyperbaricity remarkably accelerates the onset and offset times of intrathecal 2% prilocaine. Literature suggests a dose ranging between 40 and 60 mg of prilocaine for lower extremities and lower abdominal procedures lasting up to 90 min, whereas a dose ranging from 10 to 30 mg is appropriate for perineal surgery. Readiness for discharge occurs in ~4 h from spinal administration.

Chloroprocaine 10 mg/ml for low-dose spinal anaesthesia in perianal surgery - a randomised dose finding study

BACKGROUND

Low-dose spinal anaesthesia is a safe and reliable anaesthesia technique in outpatient perianal surgery. Regarding its short duration of action and its trend to hyperbaric characteristics, plain chloroprocaine 10 mg/ml seems to be ideal to perform low-dose spinal anaesthesia. The aim of this trial was to determine the optimal dosage of chloroprocaine for this indication.

METHODS

Hundred and twenty patients undergoing perianal surgery were enrolled and randomly allocated to receive 10, 20 or 30 mg of chloroprocaine 10 mg/ml intrathecally. Patients had to sit upright for at least 10 min after injection. We measured the expansion of sensory and motor block and the times until voiding, walking without assistance and home discharge.

RESULTS

The expansion of the sensory (P ≤ 0.0059) and the motor block (P ≤ 0.0086) gained with increasing doses. At a dose of 30 mg the incidence of a profound, clinically relevant motor block was significantly higher compared to 10 and 20 mg (P ≤ 0.0004). In the 10 mg group two patients suffered from nociceptive pain due to an incomplete block and five patients announced discomfort during procedure. Doses of 10 and 20 mg led to a significantly earlier discharge compared to 30 mg (P = 0.0003; P = 0.0406).

CONCLUSION

Plain chloroprocaine 10 mg/ml can successfully be used for low-dose spinal anaesthesia in perianal outpatient surgery. Regarding the unfavourable motor block and later discharge-times in the 30 mg group on the one hand and the block-failures in the 10 mg group on the other, 20 mg can be recommended as the optimal dose.

Prilocaine spinal anesthesia for ambulatory surgery: A review of the available studies

Transient neurologic symptoms (TNS) led to the abandonment of intrathecal lidocaine. We reviewed the published literature for information about the duration of action and side effects of intrathecal prilocaine, which has been recently reintroduced in Europe. Medline and EMBASE databases were searched for the time period from 1966 to 2015. Fourteen prospective and one retrospective study were retrieved. The duration of the surgical block can be adjusted using doses between 40 and 80mg. Hyperbaric prilocaine in doses as low as 10mg can be used for perianal procedures. Four cases of TNS in 486 patients were reported in prospective studies, and none in 5000 cases in a retrospective data set. Spinal prilocaine appears to be safe and reliable for day case anesthesia. However, as chloroprocaine has a shorter duration and a lower risk of TNS and urinary retention, the indications for prilocaine remain to be defined.

Prophylactic Ondansetron for the Prevention of Intrathecal Fentanyl- or Sufentanil-Mediated Pruritus: A Meta-Analysis of Randomized Trials

BACKGROUND

Pruritus is a common side effect of intrathecal fentanyl or sufentanil that decreases patient satisfaction and may delay hospital discharge. There are conflicting reports about the efficacy of prophylactic ondansetron in reducing the incidence of pruritus. This meta-analysis aimed to assess the effect of prophylactic ondansetron on the incidence of intrathecal fentanyl- or sufentanil-mediated pruritus and the need for rescue treatment.

METHODS

A systematic search on PubMed, Medline, and the Cochrane Central Register of Controlled Trials from January 1, 1994, to January 1, 2014, was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Randomized controlled trials evaluating the efficacy of prophylactic ondansetron on pruritus associated with intrathecal fentanyl or sufentanil were included. The primary outcome was the incidence of pruritus, and the secondary outcome was patients' need for rescue therapy. Sensitivity analyses were conducted to assess the outcomes in obstetric and nonobstetric patients and in patients who received ondansetron before or after intrathecal opioid injection. Analyses used random-effect models.

RESULTS

Six randomized controlled trials involving 555 patients were included. In the overall analysis, prophylactic ondansetron did not significantly decrease the incidence of pruritus, but there was a trend toward reduced rescue medication use (risk ratio [RR], 0.57; 95% confidence interval [CI], 0.35-0.91; I = 0%; P = 0.02). Exploratory subgroups, including nonobstetric surgery patients and patients who received ondansetron before spinal opioid administration, also suggest a trend toward less rescue medication use (RR, 0.47; 95% CI, 0.26-0.85; P = 0.01; and RR, 0.62; 95% CI, 0.38-1.00; P = 0.05).

CONCLUSIONS

IV 8 mg prophylactic ondansetron does not decrease the incidence of fentanyl- or sufentanil-mediated pruritus but may decrease the need for pruritus rescue medication, particularly in specific subgroups. Randomized trials are needed to confirm these results.

Spinal anaesthesia with hyperbaric prilocaine in day-case perianal surgery: randomised controlled trial

Background. The local anaesthetics used in day-case spinal anaesthesia should provide short recovery times. We aimed to compare hyperbaric prilocaine and bupivacaine in terms of sensory block resolution and time to home readiness in day-case spinal anaesthesia. Methods. Fifty patients undergoing perianal surgery were randomized into two groups. The bupivacaine-fentanyl group (Group B) received 7.5 mg, 0.5% hyperbaric bupivacaine + 20 μg fentanyl in total 1.9 mL. The prilocaine-fentanyl group (Group P) received 30 mg, 0.5% hyperbaric prilocaine + 20 μg fentanyl in the same volume. Results. Time to L1 block and maximum block was shorter in Group P than in Group B (Group P 4.6 ± 1.3 min versus Group B 5.9 ± 01.9 min, P = 0.017, and Group P 13.2 ± 7.5 min versus Group B 15.3 ± 6.6 min, P = 0.04). The time to L1 regression and S3 regression of the sensorial block was significantly shorter in Group P than in Group B (45.7 ± 21.9 min versus 59.7 ± 20.9 min, P = 0.024, and 133.8 ± 41.4 min versus 200.4 ± 64.8 min, P < 0.001). The mean time to home readiness was shorter for Group P than for Group B (155 ± 100.2 min versus 207.2 ± 62.7 min (P < 0.001)). Conclusion. Day-case spinal anaesthesia with hyperbaric prilocaine + fentanyl is superior to hyperbaric bupivacaine in terms of earlier sensory block resolution and home readiness and the surgical conditions are comparable for perianal surgery.

ED50 and ED90 of intrathecal hyperbaric 2% prilocaine in ambulatory knee arthroscopy

PURPOSE

Hyperbaric 2% prilocaine (HP) is increasingly used for spinal anesthesia in day-case surgery. The aim of this prospective double-blind study was to determine the effective dose (ED)50 and the ED90 of HP for patients undergoing knee arthroscopy.

METHODS

Doses of HP were determined using an up-and-down sequential allocation technique. Sequences were analyzed by isotonic regression analysis. A subsequent observational study was performed with the calculated ED90 in 50 patients to confirm the initial result and to describe the induced blockade effects and side effects. Times corresponding to onset and duration of sensory and motor block, surgical data, and side effects were recorded.

RESULTS

The ED50 was estimated at 28.9 mg (95% confidence interval [CI]: 26.5 to 35.3) and the ED90 was estimated to be 38.5 mg (95% CI: 35.7 to 39.5). A 40 mg dose of HP provided efficient anesthesia in 46 patients (92%, 95% CI: 82 to 98). The average (SD) time to effective anesthesia was 14.5 (3.9) min. Complete sensory block at level T12 was obtained after ten minutes in 44 of 50 patients. The average (SD) duration of the sensory block was 205 (36.1) min. Maximal level of sensory block was obtained at the T8-T11 levels in 41 of 50 patients without hemodynamic instability. A Bromage 3 score was obtained in 40 of the 46 patients who achieved successful anesthesia after 30 min. Patients did not experience urinary retention, nor were any signs of transient neurologic symptoms observed.

CONCLUSION

This study determined the ED50 of HP is 28.9 mg and suggests that a 40-mg dose of HP is adequate to provide successful spinal anesthesia for outpatient knee arthroscopy.

Fluid therapy in critical illness: a special focus on indication, the use of hydroxyethyl starch and its different raw materials

PURPOSE OF REVIEW

Fluid therapy is a complex intervention with insufficient resuscitation, as well as overinfusion and fluid accumulation being associated with adverse outcomes. Early goal-directed therapy with later conservative fluid management (i.e. prevention of positive fluid balance and weight gain) appears to markedly improve the survival of patients with severe sepsis. The impact of colloids in resuscitation of patients with sepsis has been the topic of several recently published studies. The purpose of the present review is to outline the indication of fluid administration in critically ill patients, discuss the recent findings of trials involving hydroxyethyl starch (HES) solutions and highlight the impact of different raw materials for HES synthesis.

RECENT FINDINGS

Pragmatic trials of modern HES solutions versus crystalloids in critically ill patients show either no difference or adverse outcomes associated with HES infusion. However, fluid therapy was not protocolized in most of these studies and probably associated with overinfusion and hemodilution. Data on the use of waxy maize-derived 6% HES 130/0.4 during early goal-directed therapy show no evidence for harm and an improvement in microvascular blood flow. In addition, experimental data suggest that waxy maize-derived 6% HES 130/0.4 may have different biological effects compared to potato-derived 6% HES 130/0.42 with potentially reduced pulmonary inflammation.

SUMMARY

Adverse effects of fluid resuscitation in critically ill patients appear to be a consequence of dose and timing rather than the type of fluid itself. Modern waxy maize-derived 6% HES 130/0.4 may have advantages over crystalloids in the very early course of the disease. Clinical trials of early, goal-directed and protocolized therapy with innovative endpoints of resuscitation comparing balanced crystalloids and balanced, waxy maize-derived 6% HES 130/0.4 as the initial resuscitation fluid are warranted.