Spinal 2-chloroprocaine: the effect of added fentanyl

Chloroprocaine is being investigated as a possible replacement for spinal lidocaine. Adding fentanyl to lidocaine increases the quality of spinal anesthesia without prolongation of block. We report the characteristics of 2-chloroprocaine (2-CP) spinal anesthesia with or without fentanyl in 8 volunteers receiving 40 mg 2-CP with saline or 20 micro g fentanyl in a double-blinded, randomized, crossover manner. Spinal anesthesia was successful for all subjects with complete block regression, ambulation, and void by 110 min. Itching occurred in all subjects receiving fentanyl, though medication was not required. No subject reported signs of transient neurological symptoms. Peak block with fentanyl averaged T5 (T3-7) and without fentanyl T9 (L1-T4) (P = 0.005). Regression to L1 was 78 +/- 7 min with fentanyl and 53 +/- 19 min without fentanyl (P = 0.02). Tourniquet was tolerated for 51 +/- 8 min with fentanyl and for 34 +/- 14 min without fentanyl (P = 0.02). Complete regression of block occurred at 104 +/- 7 min with fentanyl and by 95 +/- 9 min without fentanyl (P = 0.02). We conclude that 2-CP spinal anesthesia provides rapid onset and adequate potency, giving it a positive profile for ambulatory surgery. The addition of fentanyl lengthens regression to L1 and tourniquet tolerance while minimally lengthening block duration. IMPLICATIONS: Spinal 2-chloroprocaine (40 mg) provides rapid onset and reliable blockade without signs of transient neurological symptoms, giving it a positive profile for ambulatory surgical settings. The addition of fentanyl appears to lengthen the regression to L1 dermatome and tourniquet time while minimally lengthening duration of block.     

Spinal 2-chloroprocaine: the effect of added dextrose

Spinal 2-chloroprocaine is being investigated as an alternative short-acting spinal anesthetic to replace lidocaine for outpatient surgery. Adding dextrose increases the baricity of solutions and alters the characteristics of spinal anesthesia. In this study, we compared 2-chloroprocaine spinal anesthesia performed with or without the addition of dextrose (1.1%). Eight volunteers underwent 2 spinal anesthetics, receiving 40 mg 2-chloroprocaine (2 mL, 2%) with 0.25 mL saline with one and 0.25 mL 10% dextrose with the other in a double-blinded, randomized, balanced crossover manner. Pinprick anesthesia, tolerance to transcutaneous electrical stimulation, and tourniquet, motor strength measurements, and time to ambulation and void were assessed. Postvoid residual bladder volume was measured via ultrasound. Spinal anesthesia was successful in all subjects and regressed within 110 (80-110) min. There was no significant difference in peak height T4 (T7-C6), time to achieve peak block height (14 +/- 6 min), time for 2-segment regression (44 +/- 9 min), regression to L1 (66 +/- 12 min), tolerance of tourniquet (43 +/- 9 min), or return of motor function (81 +/- 14 min). Mean postvoid residual volume was larger with dextrose (74 +/- 67 mL versus 16 +/- 35 mL; P = 0.02). No subject reported signs of transient neurologic symptoms (TNS). In conclusion, spinal 2-chloroprocaine provides adequate potency with reliable regression, seemingly without TNS. Adding dextrose does not significantly alter spinal block characteristics but increases residual bladder dysfunction. Therefore, the addition of glucose to 2-chloroprocaine for spinal anesthesia is not necessary. IMPLICATIONS: Spinal chloroprocaine provides adequate potency with reliable regression, seemingly without concerns of transient neurologic symptoms, and hence an appealing profile for outpatient surgery. The addition of dextrose does not alter peak block height or tolerance of thigh tourniquet, and increases the degree of residual bladder dysfunction.     

Spinal 2-chloroprocaine: a dose-ranging study and the effect of added epinephrine

With the availability of preservative- and antioxidant-free 2-chloroprocaine (2-CP), there may be an acceptable short-acting alternative to lidocaine for spinal anesthesia. We examined the safety, dose-response characteristics, and effects of epinephrine with spinal 2-CP. Six volunteers per group were randomized to receive 30, 45, or 60 mg of spinal 2-CP with and without epinephrine. Intensity and duration of sensory and motor blockade were assessed. When 11 of the 18 volunteers complained of vague, nonspecific flu-like symptoms, breaking of the blind revealed that all spinal anesthetics associated with the flu-like symptoms contained epinephrine. There were no complaints of flu-like symptoms in the volunteers who received 2-CP without epinephrine. No further spinal anesthetics containing epinephrine were administered, resulting in 29 anesthetics (11 with epinephrine, 18 without epinephrine.) Plain 2-CP demonstrated a dose-dependent increase in peak block height and duration of effect at all variables except time to 2-segment regression and time to regression to T10. Time to complete sensory regression with plain 2-CP was 98 +/- 20, 116 +/- 15, and 132 +/- 23 min, respectively. 2-CP with epinephrine produced times to complete sensory regression of 153 +/- 25, 162 +/- 33, and 148 +/- 29 min, respectively. Preservative and antioxidant free 2-CP can be used effectively for spinal anesthesia in doses of 30-60 mg. Epinephrine is not recommended as an adjunct because of the frequent incidence of side effects. IMPLICATIONS: Hyperbaric spinal 2-chloroprocaine is effective and has an anesthetic profile appropriate for use in the surgical outpatient over the dose range of 30-60 mg without signs of transient neurologic symptoms. The addition of epinephrine is not recommended because of the frequent incidence of side effects.     

Spinal 2-chloroprocaine: minimum effective dose

BACKGROUND AND OBJECTIVES: Recent studies using preservative-free 2-chloroprocaine (2-CP) for spinal anesthesia have shown it to be a reliable short-acting agent in the 30-mg to 60-mg range. Investigations of doses below this range have not been performed. METHODS: To establish the minimum effective dose for spinal anesthesia, this randomized, double-blind, crossover study investigates the characteristics of spinal 2-CP 10 mg and 20 mg in 8 volunteers and compares the results with previous data obtained for 30 to 60 mg in the same human model. RESULTS: Peak block height, regression to L1, tolerance to tourniquet, and transcutaneous electrical stimulation all increased with increasing doses from 10 to 60 mg ( P <.0001). Likewise, time to complete block regression, ambulation, and micturition also increased with increasing spinal 2-CP dosage ( P <.0001). Degree of motor block generally increased with increasing doses from 10 to 60 mg; however, no differences existed between the 20-mg and 30-mg and between the 40-mg and 60-mg doses. CONCLUSIONS: Spinal 2-CP 40 mg and 60 mg provide rapid and reliable sensory and motor block. Although the 20-mg and 30-mg doses can produce sensory anesthesia adequate for brief surgical procedures, less motor block and some sacral sparing should be anticipated. Because the 10-mg dose produces only brief and inconsistent sensory anesthesia, it can be considered a no-effect dose.     

Spinal 2-chloroprocaine: effective dose for ambulatory surgery

Background: There is an interest in finding a safe, short-acting spinal anaesthetic, suitable for ambulatory surgery. In this prospective study, we evaluated the effective dose of plain 2-chloroprocaine (2-CP) for lower limb surgery, including knee arthroscopy and saphenectomy.
Methods: Sixty-four ASA physical status I–III patients undergoing elective lower limb surgery were randomly allocated to one of the four local anaesthetic groups for spinal anaesthesia in a double-blind manner. The patients ( n =16 patients in each group) received 35, 40, 45 or 50 mg of 10 mg/ml isobaric 2-CP.
Results: In all patients, anaesthesia was sufficient for the planned surgery. The median peak block height (T9) was similar in all four groups ( P =0.66). Time to complete sensory block regression was faster in the 35 mg group (111 min, mean) and in the 40 mg group (108 min) than in the 50 mg group (134 min, P =0.005). No differences in time to complete motor block regression were observed ( P =0.3). Home discharge time was faster in the 35 mg group (123 min) and in the 40 mg group (122 min) than in the 50 mg group (165 min, P =0.001). No complications related to spinal anaesthesia were observed and no transient neurologic symptoms (TNS) were reported at the 3-day follow-up.
Conclusion: Spinal 2-CP, 10 mg/ml 35, 40, 45 and 50 mg provide reliable sensory and motor block for ambulatory surgery, while reducing the dose of 2-CP to 35 and 40 mg resulted in a spinal block of faster ambulation.     

Spinal 2-chloroprocaine: a comparison with lidocaine in volunteers

Subarachnoid lidocaine has been the anesthetic of choice for outpatient spinal anesthesia. However, its use is associated with transient neurologic symptoms (TNS). Preservative-free formulations of 2-chloroprocaine are now available and may compare favorably with lidocaine for spinal anesthesia. In this double-blinded, randomized, crossover study, we compared spinal chloroprocaine and lidocaine in 8 volunteers, each receiving 2 spinal anesthetics: 1 with 40 mg 2% lidocaine and the other with 40 mg 2% preservative-free 2-chloroprocaine. Pinprick anesthesia, tolerance to transcutaneous electrical stimulation and thigh tourniquet, motor strength, and a simulated discharge pathway were assessed. Chloroprocaine produced anesthetic efficacy similar to lidocaine, including peak block height (T8 [T5-11] versus T8 [T6-12], P = 0.8183) and tourniquet tolerance (46 +/- 6 min versus 38 +/- 24 min, P = 0.4897). Chloroprocaine anesthesia resulted in faster resolution of sensory (103 +/- 13 min versus 126 +/- 16 min, P = 0.0045) and more rapid attainment of simulated discharge criteria (104 +/- 12 min versus 134 +/- 14 min, P = 0.0007). Lidocaine was associated with mild to moderate TNS in 7 of 8 subjects; no subject complained of TNS with chloroprocaine (P = 0.0004). We conclude that the anesthetic profile of chloroprocaine compares favorably with lidocaine. Reliable sensory and motor blockade with predictable duration and minimal side effects make chloroprocaine an attractive choice for outpatient spinal anesthesia. IMPLICATIONS: The spinal anesthetic profile of chloroprocaine (40 mg) compares favorably 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 chloroprocaine an attractive choice for outpatient spinal anesthesia.     

Spinal 2-chloroprocaine: a comparison with procaine in volunteers

Recent studies using preservative-free 2-chloroprocaine (2-CP) for spinal anesthesia have shown it to be a reliable short-acting drug that provides similar anesthesia to lidocaine. In this randomized, double-blind, crossover study, we compared the characteristics of spinal 2-CP (30 mg) with those of procaine (80 mg) in eight volunteers to determine whether either drug produces spinal anesthetic characteristics ideal for outpatient surgery. By using sensation to pinprick, transcutaneous electrical stimulation, tolerance to thigh tourniquet, and motor blockade as surrogates for surgical efficacy, 2-CP compared similarly to procaine. Peak block height (T9 [range, T6 to T12] versus T6 [T4 to T8]; P = 0.0796), time to two-segment regression (51 +/- 17 min versus 53 +/- 10 min; P = 0.7434), tourniquet time tolerance (37 +/- 16 versus 49 min +/- 17 min; P = 0.1755), and time to return of motor strength (Bromage scale: 54 +/- 23 min versus 55 +/- 44 min, P = 0.9366; return of 90% quadriceps strength: 78 +/- 9 min versus 98 +/- 30 min; P = 0.0721) were all similar. Procaine did produce overall longer sensory blockade (P = 0.0011) and motor blockade at the gastrocnemius (P = 0.0004) and quadriceps (P = 0.0146) muscles. Times until the resolution of sensory blockade (103 +/- 12 min versus 151 +/- 26 min; P = 0.0003), ambulation (103 +/- 12 min versus 151 +/- 26 min; P = 0.0003), and micturition (103 +/- 12 min versus 156 +/- 23 min; P < 0.0001) were all prolonged after procaine. In conclusion, at the doses tested, spinal 2-CP (30 mg) may be a better choice for short outpatient procedures because it provides anesthesia with similar efficacy as procaine (80 mg) but with more rapid fulfillment of discharge criteria.     

Spinal 2-chloroprocaine: a comparison with small-dose bupivacaine in volunteers

Ambulatory surgery continues to increase nationwide. Because spinal lidocaine is associated with transient neurologic symptoms, many clinicians have switched to small-dose bupivacaine for outpatient spinal anesthesia. However, bupivacaine often produces inadequate surgical anesthesia and has an unpredictable duration. Preservative-free 2-chloroprocaine (2-CP) has reemerged as an alternative for outpatient spinal anesthesia. We designed this double-blind, randomized, crossover, volunteer study to compare 40 mg of 2-CP with small-dose (7.5 mg) bupivacaine with measures of pinprick anesthesia, motor strength, tolerance to tourniquet and electrical stimulation, and simulated discharge criteria. Peak block height (2-CP average T7 [range T3-10]; bupivacaine average T9 [range T4-L1]), regression to L1 (2-CP 64 +/- 10 versus bupivacaine 87 +/- 41 min), and tourniquet tolerance (2-CP 52 +/- 11 versus bupivacaine 60 +/- 27 min) did not differ between drugs (P = 0.15, 0.12, and 0.40, respectively). However, time to simulated discharge (including time to complete block regression, ambulation, and spontaneous voiding) was significantly longer with bupivacaine (2-CP 113 +/- 14, bupivacaine 191 +/- 30 min, P = 0.0009). No subjects reported transient neurologic symptoms or other side effects. We conclude that spinal 2-CP provides adequate duration and density of block for ambulatory surgical procedures, and has significantly faster resolution of block and return to ambulation compared with 7.5 mg of bupivacaine.     

Spinal 2-chloroprocaine for surgery: an initial 10-month experience

Spinal 2-chloroprocaine (2-CP) is currently being investigated as a short-acting alternative to lidocaine, which frequently causes transient neurologic symptoms (TNS) in surgical patients. TNS has not been reported with 2-CP in volunteers in doses ranging from 30 to 60 mg and appears to provide an excellent level of surgical anesthesia. In this retrospective study, we describe the experience with spinal 2-CP in surgical patients during its first 10 mo of clinical use at our institution. Most patients had ambulatory surgery, including 39 orthopedic, 30 general surgical, 18 gynecologic, and 34 genitourinary procedures. Chloroprocaine 30 or 40 mg, with or without fentanyl (10-20 microg), was the most common (92%) dose combination used. Mean peak block height averaged T6 to T8. The surgical procedure time was 32.3 +/- 18.4 min. Time from placement of the block to the end of the surgical procedure was 53.1 +/- 20.7 min. Times to ambulation and discharge were 155.1 +/- 34.7 min and 207.9 +/- 69.4 min, respectively. 2-CP spinal anesthesia has proven to be a safe and effective alternative to lidocaine and procaine for ambulatory surgical procedures of < or =1 h, with a predictable regression of block height. No patients reported TNS after surgery.     

The dose-sparing effect of clonidine added to ropivacaine for labor epidural analgesia

To determine the effects of clonidine with ropivacaine during epidural labor analgesia, we studied 66 nulliparous women in early active labor. Women were randomized to receive ropivacaine 0.1% 8 mL plus 75 microg of clonidine (Group 1), ropivacaine 0.2% 8 mL plus 0.5 mL of NaCl 0.9% (Group 2), or ropivacaine 0.2% 8 mL plus 75 microg of clonidine (Group 3) 5 min after a bupivacaine 7.5 mg with epinephrine 15 microg test dose. Upon request, additional analgesia with ropivacaine 0.1% 8 mL followed by ropivacaine 0.2% 8 mL/h was administered. With clonidine, duration of analgesia was increased (132 +/- 48 min [Group 1] and 154 +/- 42 min [Group 3] versus 91 +/- 44 min [Group 2]; P < 0.05), and total ropivacaine dose over the first 4 h was significantly reduced (40.5 +/- 15 mg [Group 1] and 47.0 +/- 16 mg [Group 3] versus 72.5 +/- 18 mg [Group 2]; P < 0.01). The incidence of more profound motor block was more frequent in Group 2 (P < 0.05). Although there was a trend for more women receiving clonidine to require ephedrine for treatment of hypotension, this did not seem to have an impact on fetal outcome or incidence of cesarean deliveries for nonreassuring fetal heart rate tracings. This study demonstrates the dose-sparing effect of clonidine when added to ropivacaine. IMPLICATIONS: The effect of adding 75 microg of clonidine to ropivacaine for epidural labor analgesia was studied. Clonidine increased analgesia duration and produced dose sparing compared with ropivacaine alone. Despite a tendency for hypotension in women receiving clonidine, there was no apparent effect on delivery mode or neonatal outcome.     

Spinal alpha(2)-adrenoceptors are involved in the MACbar-sparing effect of systemic clonidine in rats

We evaluated the central or spinal mechanism involved in the MACbar-sparing effect of systemic clonidine by using intrathecal alpha-adrenergic antagonist administration. The minimum alveolar concentration of sevoflurane that blocks cardiovascular response to a noxious stimulus (MACbar(sevo)) was determined in rats after treatment with IV saline, IV clonidine 10 micro g/kg, intrathecal (IT) or IV phentolamine 50 micro g, IT or IV yohimbine 200 micro g, IT or IV prazosin 30 micro g, or the combination of IV clonidine and the different IT or IV alpha-adrenergic antagonists. In the studied model, the MACbar(sevo) of saline-treated controls was 2.10 +/- 0.8. After clonidine administration, it decreased to 1.07 +/- 0.4. The IT administration of phentolamine and yohimbine did not modify the MACbar(sevo) of na?ve rats, whereas in IV clonidine-treated animals, it totally suppressed the MAC-sparing effect of this drug (phentolamine) or even significantly increased (yohimbine) the MACbar(sevo) (2.78 +/- 1) when compared with controls (P < 0.05). IT prazosin alone significantly reduced the MACbar(sevo) (0.35 +/- 0.3; P< 0.05) and suppressed any hemodynamic reaction when combined with IV clonidine. The IV administration of the different alpha-adrenergic antagonists had no significant effect on the MACbar(sevo) of controls or IV clonidine-treated animals. These results argue for a spinal mechanism of action involved in the MACbar-sparing effect of systemic clonidine. Moreover, the spinally administered alpha-antagonists displayed different effects in rats under sevoflurane anesthesia than those reported in awake animals. IMPLICATIONS: Using intrathecal alpha-adrenergic antagonist administration, we demonstrated that a spinal mechanism is involved in the MACbar-sparing effect of systemic clonidine in rats.     

The half-life of 2-chloroprocaine

The purpose of this study was to examine the discrepancy between the reported in vitro half-life of chloroprocaine and the slower observed disappearance of the drug in maternal plasma. The study had two aims. The first was to redetermine the in vitro half-life of 2-chloroprocaine in maternal and fetal plasma. The second was to determine the apparent half-life of 2-chloroprocaine in vivo after intrapartum epidural anesthesia in obstetric patients. Gas chromatography or gas chromatography/mass spectrometry techniques were used to measure 2-chloroprocaine in maternal or fetal plasma. Mean in vitro half-lives of 11.2 +/- 2.8 and 15.4 +/- 5.2 sec were found for maternal and fetal plasma from nine patients, respectively. The maternal half-life was significantly shorter than the fetal half-life (P less than 0.05). The mean apparent in vivo half-life in maternal plasma was found to be 3.1 +/- 1.6 min. The results of this study show that the half-life in vitro is correctly measured in seconds. However, the apparent half-life in vivo after epidural anesthesia is 3.1 +/- 1.6 min and ranges from 1.5 to 6.4 min. The differences in the magnitude of the two findings is probably due to continuous uptake of the drug from the epidural space.     

Analgesic effect of clonidine added to bupivacaine 0.125% in paediatric caudal blockade

BACKGROUND: Caudals are a common method of providing pain relief in children undergoing surgery. Clonidine, an alpha(2) agonist, exhibits significant analgesic properties. The current investigation sought to determine whether caudal clonidine added to caudal bupivacaine would decrease pain in paediatric patients undergoing surgery. METHODS: Thirty-six children undergoing elective surgery were studied. Following anaesthetic induction, a caudal was placed (1 mg.kg(-1) bupivacaine 0.125%) with an equal volume of either clonidine (2 microg.kg(-1)) or saline. Perioperative analgesic requirements in the postanaesthesia care unit (PACU) and at home following hospital discharge, and parental pain scores were evaluated. RESULTS: There were no significant demographic, haemodynamic, or pain score differences between the groups. There was no difference in analgesic duration between groups. There were significantly more children who vomited during the first 24 postoperative hours in the clonidine group than in the saline group (eight in clonidine, two in saline; P < 0.05). CONCLUSION: We do not recommend adding clonidine (2 microg.kg(-1)) to a bupivacaine (0.125%) caudal block in children undergoing surgery.     

Paracervical block with 2-chloroprocaine

Thirty healthy term gravidas in active labor received a paracervical block (PCB) with the ester-type local anesthetic, 2-chloroprocaine (2CP). Good to excellent pain relief resulted in all but 1 case. The duration of action was short (mean 38.9 min), requiring repeat blocks in 6/30 cases. Fetal heart rate and uterine contractions were electronically monitored, and fetal acid-base status was periodically checked by fetal scalp pH measurements. PCB-related fetal bradycardia was observed in 3 cases, but in only 1 case was PCB the only cause for the bradycardia. Fetal acidosis was not observed. No instance of neonatal depression or acidosis as expressed by the 1- and 5-minute Apgar scores and cord blood acid-base evaluation was observed. No maternal complications were observed. It is concluded that paracervical block using 2CP is an effective though short-acting method of pain relief which, when properly monitored, is safe for both mother and fetus.     

The effect of pH and PCO2 on epidural analgesia with 2% 2-chloroprocaine

Increasing the pH of local anesthetics with sodium bicarbonate has been reported to hasten their onset of action. The purpose of this study was to compare the onset and duration of epidural analgesia with the use of sodium bicarbonate and tromethamine to increase the pH of 2% chloroprocaine (2CP). Five groups of patients were studied: Group I received 2CP; Group II received 2CP buffered to a pH of 7.1 with tromethamine; Group III received 2CP buffered to a pH of 7.1 with sodium bicarbonate; Group IV received 2CP buffered to a pH of 7.7 with tromethamine; and Group V received 2CP buffered to a pH of 7.7 with sodium bicarbonate. The final pH and PCO2 of each solution were measured. Time to onset of analgesia was significantly delayed with either of the tromethamine buffered groups (II [5.6 +/- 1.0 minutes] and IV [5.4 +/- 0.4 minutes]) when compared with data from the unbuffered control (I [4.4 +/- 0.1 minutes]) and the sodium bicarbonate buffered (III [4.5 +/- 0.8 minutes] groups and Group V [2.7 +/- 0.9 minutes]). Only when sodium bicarbonate buffer adjusted to pH 7.7 (Group IV) was onset significantly more rapid than the unbuffered 2CP (I) and tromethamine buffered 2CP (II and IV). Multiple regression analysis revealed that onset times were significantly related to both pH and PCO2. The coefficient of determination for this model was 0.5156.(ABSTRACT TRUNCATED AT 250 WORDS)     

不同剂量可乐定复合罗哌卡因硬膜外麻醉的效应

目的 评价不同剂量的可乐定复合罗哌卡因硬膜外麻醉的临床效应。方法 60例ASAⅠ-Ⅱ级妇科手术患者，硬膜外随机双盲接受不含或含50、100、150μg可乐定的0.75%罗哌卡因25ml，分为R、R－C50、R－C100、R－C150四组。记录感觉镇痛、运动阻滞起效时间及持续时间，术中镇痛质量及不良反应。结果 R－C100组、R－C150组运动阻滞起效时间缩短，术中内脏牵拉痛发生率及氯胺酮需要量减少，镇痛持续时间延长，寒战发生率降低。然而，R－C150组低血压发生率、麻黄碱需要量及输液量增加。结论 可乐定100μg与0.75％罗哌卡因25ml合用于硬膜外麻醉，可改善罗哌卡因阻滞特征而不增加低血压、心动过缓等副作用。