Local anaesthetics and additives for spinal anaesthesia--characteristics and factors influencing the spread and duration of the block

Regional anaesthesia: what surgical procedures, what blocks and availability of a “block room”?

PURPOSE OF REVIEW

With an expected rise in day care procedures with enhanced recovery programs, the use of specific regional anaesthesia can be useful. In this review, we will provide insight in the used regional block and medication so far known and its applicability in a day care setting.

RECENT FINDINGS

Regional anaesthesia has been improved with the aid of ultrasound-guided placement. However, it is not commonly used in the outpatient setting. Old, short acting local anaesthetics have found a second life and may be especially beneficial in the ambulatory setting replacing more long-acting local anaesthetics such as bupivacaine.To improve efficiency, a dedicated block room may facilitate the performance of regional anaesthesia. However, cost-efficacy for improved operating time, patient care and hospital efficiency has to be established.

SUMMARY

Regional anaesthesia has proven to be beneficial in ambulatory setting. Several short acting local anaesthetics are favourable over bupivacaine in the day care surgery. And if available, there are reports of the benefit of an additional block room used in a parallel (monitored) care of patients.

Spinal fentanyl vs. sufentanil for post-operative analgesia after C-section: a double-blinded randomised trial

BACKGROUND

Fentanyl and sufentanil are the most commonly administered intrathecal lipophilic opioids worldwide, although their relative efficacy when given by this route is not well characterised. The primary endpoint of this prospective, randomised, double-blind study was to compare effective analgesia duration of intrathecal administered fentanyl 25 μg and sufentanil 2.5 or 5 μg, Second endpoints were to compare post-operative morphine consumption and incidence of side effects between these opioids dosages.

METHODS

After IRB approval, 180 full-term parturients undergoing elective Caesarean section were randomly allocated into three groups, according to the opioid added to 10 mg intrathecal hyperbaric bupivacaine: fentanyl 25 μg, sufentanil 2.5 μg or sufentanil 5 μg. Total effective analgesia was defined as time from spinal injection (T0) to first IV morphine requirement (T1) administered with a patient controlled intravenous pump. Statistical data analysis included non-parametric tests and chi-squared. A P value < 0.05 was considered statistically significant. Data are presented as median [interquartile ranges 25-75].

RESULTS

Duration of analgesia was significantly longer with sufentanil 2.5 μg (214 min [189-251]) and 5 μg (236 min [190-372]) compared to fentanyl 25 μg (187 min [151-230]) (P < 0.01). Morphine consumption at T1 + 4 h was lower in the sufentanil groups (6 mg [3-9] and 6 mg [2-10]) than in the fentanyl group (9 mg [5-13]) (P < 0.01). Incidence of adverse effects was not different between groups.

CONCLUSION

In the conditions of our study, sufentanil 5 μg was the opioid of choice, associated with the best quality of anaesthesia without increased incidence of side effects.

A comparison of different densities of levobupivacaine solutions for unilateral spinal anaesthesia

BACKGROUND AND OBJECTIVES

The aim of the study was to compare the block characteristics and clinical effects of dextrose added to levobupivacaine solutions at different concentrations to provide unilateral spinal anaesthesia in lower extremity surgery.

METHODS

This prospective, randomised, double-blind study comprised 75 ASA I-II risk patients for whom unilateral total knee arthroscopy was planned. The patients were assigned to three groups: in Group I, 60mg dextrose was added to 7.5mg of 0.5% levobupivacaine, in Group II, 80mg and in Group III, 100mg. Spinal anaesthesia was applied to the patient in the lateral decubitus position with the operated side below and the patient was kept in position for 10min.

RESULTS

The time for the sensorial block to achieve T12 level was slower in Group I than in Groups II and III (p<0.05, p<0.00). The time to full recovery of the sensorial block was 136min in Group I, 154min in Group II and 170min in Group III. The differences were statistically significant (p<0.05). The mean duration of the motor block was 88min in Group I, 105min in Group II, and 139min in Group III and the differences were statistically significant (p<0.05). The time to urination in Group I was statistically significantly shorter than in the other groups (p<0.00).

CONCLUSIONS

The results of the study showed that together with an increase in density, the sensory and motor block duration was lengthened. It can be concluded that 30mg mL(-1) concentration of dextrose added to 7.5mg levobupivacaine is sufficient to provide unilateral spinal anaesthesia in day-case arthroscopic knee surgery.

[A comparison of different densities of levobupivacaine solutions for unilateral spinal anaesthesia]

BACKGROUND AND OBJECTIVES

The aim of the study was to compare the block characteristics and clinical effects of dextrose added to levobupivacaine solutions at different concentrations to provide unilateral spinal anaesthesia in lower extremity surgery.

METHODS

This prospective, randomised, double-blind study comprised 75 ASA I-II risk patients for whom unilateral total knee arthroscopy was planned. The patients were assigned to three groups: in Group I, 60mg dextrose was added to 7.5mg of 0.5% levobupivacaine, in Group II, 80mg and in Group III, 100mg. Spinal anaesthesia was applied to the patient in the lateral decubitus position with the operated side below and the patient was kept in position for 10min.

RESULTS

The time for the sensorial block to achieve T12 level was slower in Group I than in Groups II and III (p<0.05, p<0.00). The time to full recovery of the sensorial block was 136min in Group I, 154min in Group II and 170min in Group III. The differences were statistically significant (p<0.05). The mean duration of the motor block was 88min in Group I, 105min in Group II, and 139min in Group III and the differences were statistically significant (p<0.05). The time to urination in Group I was statistically significantly shorter than in the other groups (p<0.00).

CONCLUSIONS

The results of the study showed that together with an increase in density, the sensory and motor block duration was lengthened. It can be concluded that 30mgmL(-1) concentration of dextrose added to 7.5mg levobupivacaine is sufficient to provide unilateral spinal anaesthesia in day-case arthroscopic knee surgery.

Comparison of the effects of pre-anesthetic administration of normal saline, ringer and voluven on the spread of sensory block with hyperbaric bupivacaine spinal anesthesia

BACKGROUND

Spinal anesthesia is an important and commonly used method for surgical anesthetic in operating rooms. However, even with identical drug dosage and administration mode, the extent of drug distribution in vivo is highly variable and difficult to control. Preanesthetic administration of fluids immediately before spinal anesthesia (preload) is normal practice. The choice of fluid type may affect drug distribution as well as the duration and level of the block.

OBJECTIVES

We examined whether preloads of normal saline, Ringer, or hydroxyethyl starch has different effects on the time it takes to reach maximum block, and the distribution and duration of spinal block level.

PATIENTS AND METHODS

This was a randomized trial and the 150 patients selected were evenly divided into three groups and given; normal saline, Ringer, or hydroxyethyl starch 130/0.4f luids. Preload was given at 10 mL/kg for the normal saline and Ringer groups, and 5 mL/kg for the hydroxyethyl starch group, 10 min before the spinal anesthesia. Sensory block levels were recorded every 5 min until 30 min after spinal anesthesia and then at 60 and 90 min. Time taken to reach maximum and median sensory block, maximum and median level of block, duration of block, and hemodynamic status were recorded.

RESULTS

There were no statistically significant differences in the demographic characteristics between the three groups. Maximum block was higher in normal saline compared to Ringer (P = 0.029). Time taken to reach maximum block was greater in Ringer compared to both normal saline (P = 0.001) and hydroxyethyl starch (P = 0.003). Normal saline had a longer duration of sensory block T10 compared to Ringer and hydroxyethyl starch (P = 0.03).

CONCLUSIONS

Preload fluids have an impact on the level, distribution and duration of sensory block in spinal block. Of the three fluids, normal saline produced the greatest maximum and longest duration of block, whereas time taken to reach maximum block was longer in the Ringer group.

Comparison of postoperative analgesic effect of intrathecal clonidine and fentanyl added to bupivacaine in patients undergoing cesarean section: a prospective randomized double-blind study

Objectives. To compare the analgesic efficacy of intrathecal clonidine and fentanyl added to bupivacaine after cesarean section. Methods. Ninety patients scheduled for cesarean section under spinal anesthesia were randomly allocated to one of the three following groups to receive bupivacaine 10 mg combined with 75 µg clonidine (group C), bupivacaine 10 mg combined with 0.5 mL fentanyl (group F), and bupivacaine 10 mg combined with 0.5 mL distilled water (group P), intrathecally. The time to first analgesic request, analgesic requirement in the first 24 hours after surgery, sensory and motor blockade onset time, duration of sensory and motor blockade, the incidence of hypotension, ephedrine requirements, bradycardia, and hypoxemia were recorded. Results. The duration of anesthesia in clonidine group (275.10 ± 96.09) was longer compared to the placebo (211.73 ± 74.80) and fentanyl (192.33 ± 30.36) groups. This difference between group C versus F (P = 0.006) and P groups (P < 0.001) was significant. Similarly, the mean time to first analgesic request was also longer in group C (519.44 ± 86.25) than in groups F (277.88 ± 94.25) and P (235.43 ± 22.35 min). This difference between group C versus F (P < 0.001) and P groups (P < 0.001) was significant. Conclusion. Intrathecal clonidine 75 µg with bupivacaine prolonged the time to first analgesic request compared to fentanyl; however, the total analgesic consumption within the first 24 h postoperative was similar in fentanyl and clonidine groups following cesarean section. This trial is registered with ACTRN12611000909921 and ClinicalTrials.gov NCT01425658.

Comparison of Maternal and Neonatal Effects of Combined Spinal Epidural Anaesthesia in Either the Sitting or Lateral Position During Elective Cesarean Section

OBJECTIVE

Our goal was to demonstrate which position would be hemodynamically and technically better by comparing the effects of combined spinal epidural (CSE) in the sitting or lateral decubitus position for elective cesarean deliveries on maternal and neonatal parameters and ephedrine requirement.

METHODS

Sixty parturients were randomly assigned into two groups to perform CSE in the sitting (Group I, n=30) or right lateral decubitus position (Group II, n=30) using hyperbaric 10 mg bupivacaine and 20 μg fentanyl. Mean arterial pressure (MAP), heart rate (HR), and characteristics of sensory and motor block were recorded from intrathecal drug administration until the end of surgery. Ephedrine and 1(st) analgesic requirement, number of attempts to perform CSE, incidence of paresthesia during spinal needle insertion, and Apgar scores were recorded.

RESULTS

Ephedrine requirements and HR changes were similar in both groups. However, MAP values at 45 min in Group II were significantly less than in Group I. Maximum sensory block levels in Group II were significantly higher than in Group I. Despite similar motor block recovery times in both groups, regression times of sensory block and 1st analgesic requirement in Group II were significantly longer than in Group I. Incidence of paresthesia due to spinal needle (3.3% versus 20% in Groups I and II, respectively) and number of attempts to perform CSE (26.7% versus 60% in Groups I and II, respectively) were significantly higher in Group II. Apgar scores were similar in both groups.

CONCLUSION

Performing CSE in the sitting position would be safer and easier because higher and earlier onset of sensory block, and a greater number attempts at epidural insertion and paresthesia develop to spinal needle insertion in the right lateral position.

Effects of baricity of 0.5% or 0.75% levobupivacaine on the onset time of spinal anesthesia: a randomized trial

PURPOSE

Levobupivacaine has been extensively evaluated for spinal anesthesia. Its pharmacologic properties are similar to those of bupivacaine, but differences in density between two commercially-available preparations of plain levobupivacaine might lead to different block profiles. We examined the characteristics of spinal anesthesia using the same dose of 0.5% and 0.75% plain levobupivacaine.

METHODS

In this randomized, controlled, double-blind clinical trial, 60 ASA I-III patients, scheduled for hip fracture surgery, were randomly allocated to receive spinal anesthesia with 15 mg of either 0.5% (group Levo-0.5), or 0.75% (group Levo-0.75) plain levobupivacaine. Onset time (primary outcome), sensory block height level by pinprick, motor block using a modified Bromage scale, and hemodynamic variables were recorded.

RESULTS

In group Levo-0.5 (n = 29), surgical anesthesia was obtained within 15 (10-20) min, compared to 12 (7-21) min in group Levo-0.75 (n = 31) (p = 0.409). The highest sensory block level was T11 (T6-T12) in group Levo-0.5, and T10 (T8 - T12) in group Levo-0.75 (p = 0.759). Mean duration of anesthesia was 285 (224-303) min in group Levo-0.5, and 318 (243-375) min in group Levo-0.75 (p = 0.117). The groups were similar in regards to the number of failed blocks requiring general anesthesia, and the number of patients requiring vasopressors.

CONCLUSIONS

In this population of elderly patients, spinal anesthesia with 15 mg of either 0.5% or 0.75% plain levobupiva-caine resulted in similar onset of pharmacological actions, and outcomes. Potential differences in baricity did not appear to be clinically relevant in this setting.

[Spinal anaesthesia]

In spinal anaesthesia, surgical analgesia and in most cases motor block is achieved by injecting one or more drugs into the cerebrospinal fluid. As one of the earliest methods of anaesthesia it was introduced into clinical practice in the late nineteenth century. Although later on it was more or less replaced by "modern" general anaesthesia, it has regained popularity due to its benefits for certain patient populations. In spite of being a technically simple procedure, performing spinal anaesthesia requires a sound knowledge of applied physiology and pharmacology, especially in high-risk groups such as pregnant women or former preterm babies. For some patients even under anticoagulant therapy, spinal anaesthesia might be the best option, considering the individual risk of alternative methods.

Antibacterial Activity of Clonidine and Neostigmine In Vitro

We conducted an in vitro study to investigate the antibacterial activity of clonidine and neostigmine on common microorganisms encountered during infectious complications after regional anesthesia. Standardized suspensions of Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli were incubated during 1, 3, 6, and 24 h at 37 degrees C with concentrations of 37.5, 75, and 150 microg/mL of clonidine and 125, 250, and 500 microg/mL of neostigmine. After 24 h incubation at 37 degrees C, the colony counts were compared by two-way analysis of variance. The mean colony counts for S. aureus decreased significantly from control as the exposure to clonidine increased (P < 0.05), with a approximately 100% kill at 6 h for the largest concentration (150 microg/mL) and at 24 h for the intermediate concentration (75 microg/mL). Similar results were observed for S. epidermidis, with a approximately 100% kill at 6 h for the largest concentrations (75 and 150 microg/mL). No bactericidal activity of clonidine was observed for E. coli and no bactericidal activity of neostigmine was observed for any of the tested strains. In the conditions of this experiment, clonidine, but not neostigmine, exhibited a concentration-dependent and time-dependent bactericidal activity in vitro on the microorganisms most frequently encountered in infectious complications after regional anesthesia.

The Effect of Posture and Baricity on the Spread of Intrathecal Bupivacaine for Elective Cesarean Delivery

Posture and baricity during induction of spinal anesthesia with intrathecal drugs are believed to be important in determining spread within the cerebrospinal fluid. In this double-blind prospective study, 150 patients undergoing elective cesarean delivery were randomized to receive a hyperbaric, isobaric, or hypobaric intrathecal solution of 10 mg bupivacaine during spinal anesthesia induced in either the sitting or right lateral position. After an intrathecal injection using a combined-spinal technique patients were placed in the supine wedged position. We determined the densities of the three intrathecal solutions from a previously validated formula and measured using a DMA-450 density meter. Data collection included sensory level, motor block, episodes of hypotension, and ephedrine use. Statistical analysis included analysis of variance and Cuzick's trend. In the lateral position, baricity had no effect on the spread of sensory levels for bupivacaine compared to the sitting position, where there was a statistically significant difference in spread with the hypobaric solution producing higher levels of analgesia than the hyperbaric solution (P = 0.002). However, the overall differences in maximal spread only differed by one dermatome, with the hyperbaric solution achieving a median maximum sensory level to T3 compared with T2 for the isobaric and hypobaric solutions. Motor block was significantly (P = 0.029) reduced with increasing baricity and this trend was significant (P = 0.033) for the lateral position only. Hypotension incidence and ephedrine use increased with decreasing baricity (P = 0.003 and 0.004 respectively), with the hypobaric sitting group having the most frequent incidence of hypotension (76%) as well as cervical blocks (24%; P = 0.032).

The combination of epidural clonidine and S(+)-ketamine did not enhance analgesic efficacy beyond that for each individual drug in adult orthopedic surgery

STUDY OBJECTIVES

To evaluate the benefit of epidural clonidine and S(+)-ketamine combination through the epidural route in adult orthopedic surgery.

DESIGN

Randomized double-blinded study.

SETTING

Teaching hospital.

PATIENTS

Scheduled to undergo knee surgery, 56 American Society of Anesthesiologists physical status 1 and 2 adult patients.

INTERVENTIONS

Patients were randomized to 1 of 4 groups to receive the combined epidural-intrathecal technique. A 10-mL epidural injection of either study drug or normal saline was first administered to all patients. Intrathecal anesthesia was performed with 15 mg of bupivacaine. The control group (CG) received epidural saline. The 0.1-mg/kg S(+)-ketamine epidural group received 0.1 mg/kg epidural S(+)-ketamine. The 0.5-microg/kg clonidine epidural group received 0.5 microg/kg epidural clonidine. The S(+)-ketamine/clonidine group received 0.1 mg/kg epidural S(+)-ketamine plus 0.5 microg/kg epidural clonidine.

MEASUREMENTS AND MAIN RESULTS

Pain and adverse effects were evaluated by visual analog scale. Rescue analgesics were available to patients. The groups were demographically similar. Sensory level to pinprick, surgical and anesthetic time, and visual analog scale scores for pain at first rescue medication were similar among the groups. The time to first rescue analgesic (minute) was lowest in CG (P < .005). The CG required more rescue analgesics in 24 hours than any of the other groups (P < .0005). Patients who received either epidural clonidine, S(+)-ketamine, or both displayed similar analgesia. The frequency of adverse effects was similar among groups (P > .05).

CONCLUSIONS

The association of epidural clonidine or S(+)-ketamine did not result in a greater analgesic effect in the model of acute postoperative pain studied, although the interaction of epidural clonidine and S(+)-ketamine is not attributable to sharing of a common second messenger system.