***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Background . The local anaesthetics used in day-case spinal anaesthesia should provide short recovery times . We aim ed 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 r and omized 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 BACKGROUND : In this prospect i ve , r and omized , double-blind study , we evaluated whether a very low dose of spinal bupivacaine could be sufficient for safe performance of short perianal surgery . METHODS : Eighty patients were r and omly assigned to receive hyperbaric bupivacaine doses of either 1.5 mg ( n = 40 ) or 6.0 mg ( n = 40 ) . RESULTS : The lower dose produced satisfactory anesthesia with a more limited block ( median S4 ; P < 0.01 ) , earlier time to ambulation ( 98 vs 147 min ; P < 0.01 ) , and hospital discharge ( 126 vs 249 min ; P < 0.01 ) , compared with the higher spinal dose . CONCLUSIONS : The use of 1.5 mg spinal bupivacaine can be successful for short perianal surgery Background : Spinal anesthesia for knee arthroscopy can be produced with a low dose of bupivacaine , but additional intrathecal drugs are often required to lower the risk of failed blocks . We investigated the effect of the addition of clonidine ( 0 , 15 or 30 μg ) to 5 mg hyperbaric bupivacaine on the duration of the motor block , analgesic quality and ability to void after the surgery in a r and omized controlled trial Background Given the current practice environment , it is important to determine the anesthetic technique with the highest patient acceptance and lowest associated costs . The authors compared three commonly used anesthetic techniques for anorectal procedures in the ambulatory setting . Methods Ninety-three consenting adult out patients undergoing anorectal surgery were r and omly assigned to one of three anesthetic treatment groups : group 1 received local infiltration with a 30-ml mixture containing 15 ml lidocaine , 2 % , and 15 ml bupivacaine , 0.5 % , with epinephrine ( 1:200,000 ) in combination with intravenous sedation using a propofol infusion , 25–100 & mgr;g · kg−1 · min−1 ; group 2 received a spinal subarachnoid block with a combination of 30 mg lidocaine and 20 & mgr;g fentanyl with midazolam , 1–2-mg intravenous bolus doses ; and group 3 received general anesthesia with 2.5 mg/kg propofol administered intravenously and 0.5–2 % sevoflurane in combination with 65 % nitrous oxide . In groups 2 and 3 , the surgeon also administered 10 ml of the previously described local anesthetic mixture at the surgical site before the skin incision . Results The mean costs were significantly decreased in group 1 ( $ 69 ± 20 compared with $ 104 ± 18 and $ 145 ± 25 in groups 2 and 3 , respectively ) because both intraoperative and recovery costs were lowest ( P < 0.05 ) . Although the surgical time did not differ among the three groups , the anesthesia time and times to oral intake and home-readiness were significantly shorter in group 1 ( vs. groups 2 and 3 ) . There was no significant difference among the three groups with respect to the postoperative side effects or unanticipated hospitalizations . However , the need for pain medication was less in groups 1 and 2 ( 19 % and 19%vs . 45 % for group 3;P < 0.05 ) . Patients in group 1 had no complaints of nausea ( vs. 3 % and 26 % in groups 2 and 3 , respectively ) . More patients in group 1 ( 68 % ) were highly satisfied with the care they received than in groups 2 ( 58 % ) and 3 ( 39 % ) . Conclusions The use of local anesthesia with sedation is the most cost-effective technique for anorectal surgery in the ambulatory setting BACKGROUND The effects of volume and baricity of spinal bupivacaine on block onset , height , duration , and hemodynamics were studied . METHODS Ninety patients undergoing endoscopic urologic procedures were r and omized to receive 10 mg of intrathecal bupivacaine at L2-L3 level in sitting position . In the operating room , commercial products were diluted as needed with NaCl 0.9 % to obtain isobaric solutions ( density , 1.005 - 1.008 ) or with NaC 10.9 % and glucose 30 % to obtain hyperbaric solutions ( density , 1.031 - 1.037 ) of 2 , 5 , or 10 ml ( six groups of 15 patients each ) . Three minutes after spinal injection the patients were placed in lithotomy position . Sensory blockade was assessed using pinprick and cold sensation tests , and motor blockade was assessed using a four-point scale . RESULTS Onset times to maximal cephalad spread of spinal blockade were similar with isobaric and hyperbaric solutions . A greater maximal cephalad spread of anesthesia was obtained with diluted isobaric bupivacaine but was not associated with more hypotension . Volume had no effect on cephalad extent of anesthesia with hyperbaric bupivacaine .  Times for regression of anesthesia to L2 and offset of motor block were longer with isobaric than with hyperbaric solutions of bupivacaine . The intensity of motor blockade was decreased with diluted hyperbaric bupivacaine . No patient reported back pain . CONCLUSION In this study , volume had no significant influence on either cephalad spread or duration of sensory blockade for either isobaric or hyperbaric bupivacaine . Time for offset of anesthesia was shorter with hyperbaric bupivacaine compared with isobaric solutions This study investigated whether the addition of 25 μg fentanyl to an ultra-low ( sub-anaesthetic ) dose of intrathecal bupivacaine provides adequate anaesthesia for out-patient anorectal surgery , without increasing side-effects or delaying hospital discharge . Patients were r and omly allocated to receive 2.5 mg 0.5 % bupivacaine plus 25 μg fentanyl ( group BF , n = 18 ) or 5 mg 0.5 % bupivacaine alone  ( group B , n = 17 ) . There were no significant differences in intra-operative outcomes , but mean recovery and discharge times were significantly shorter in group BF . There were no between-group differences in hypotension , bradycardia or respiratory depression and post-operative complications were comparable , apart from pruritus which was significantly more frequent in group BF . Fewer patients requested analgesic medication in the early post-operative period in group BF than in group B. In conclusion , 25 μg intrathecal fentanyl added to ultra-low dose ( 2.5 mg ) bupivacaine provided good- quality spinal anaesthesia and reduced post-operative analgesic requirement in patients undergoing ambulatory anorectal surgery The effect of adding epinephrine to small doses of spinal bupivacaine on the duration of sensory motor block has not been carefully investigated . Twelve volunteers underwent hyperbaric bupivacaine spinal anesthesia ( 7.5 mg ) with and without epinephrine ( 0.2 mg ) in a r and omized , double-blind , cross-over fashion .  Sensory block was assessed with  pinprick , transcutaneous electrical stimulation ( TES ) equivalent to surgical stimulation ( at umbilicus , pubis , knee , and ankle ) , and tolerance of a pneumatic thigh tourniquet .  Motor block was assessed with isometric force dynamometry . Discharge criteria were defined as return of pinprick sensation to dermatome S2 , ability to ambulate , and ability to urinate . Extent of sensory block to pinprick over time was unaffected by the addition of epinephrine . However , epinephrine prolonged tolerance of TES at the pubis , knee , and ankle ( 33 - 48 min , P < 0.05 ) and of thigh tourniquet ( 30 min , P < 0.01 ) . Motor block was prolonged by epinephrine at the quadriceps and gastrocnemius muscles ( by 23 and 51 min , respectively , P < 0.002 ) . Achievement of discharge criteria was prolonged by 48 min by the addition of epinephrine ( P < 0.01 ) . Thus , epinephrine may prolong surgical anesthesia for lower abdominal and lower extremity surgery and delay time until patients achieve discharge criteria . Implication s : Using a cross-over study design , 12 volunteers underwent bupivacaine spinal anesthesia with and without epinephrine . This study suggests that adding epinephrine to bupivacaine may prolong surgical anesthesia and also delay patients ' discharge . ( Anesth Analg 1998;86:973 - 7 In 60 patients undergoing inguinal hernia repair , we compared the clinical profile of unilateral spinal anesthesia produced with either 8 mg of hyperbaric bupivacaine 0.5 % ( n = 20 ) , 8 mg of hyperbaric levobupivacaine 0.5 % ( n = 20 ) , or 12 mg of hyperbaric ropivacaine 0.5 % ( n = 20 ) . The study drug was injected slowly through a 25-gauge Whitacre directional needle and patients maintained the lateral decubitus position for 15 min . The onset time and intraoperative efficacy were similar in the three groups . The maximal level of sensory block on the operative and nonoperative sides was T6 ( T12–5 ) and L3 ( /[no sensory level detectable]–T4 ) with bupivacaine , T8 ( T12–5 ) and L3 ( /–T3 ) with levobupivacaine , T5 ( T10–2 ) and T11 ( /–T3 ) with ropivacaine ( P = 0.11 , P = 0.23 , respectively ) . Complete regression of spinal anesthesia occurred after 166 ± 42 min with ropivacaine , 210 ± 63 min with levobupivacaine , and 190 ± 51 min with bupivacaine ( P = 0.03 and P = 0.04 , respectively ) ; however , no differences were observed in time for home discharge ( 329 ± 89 min with bupivacaine , 261 ± 112 min with levobupivacaine , and 332 ± 57 min with ropivacaine [ P = 0.28 ] ) . We conclude that 8 mg of levobupivacaine or 12 mg of ropivacaine are acceptable alternatives to 8 mg of bupivacaine when limiting spinal block at the operative side for inguinal hernia repair Background : Combination of local anesthetic and opioid enables the use of less spinal anesthetic and increases the success of anesthesia . Intrathecal opioid does not prolong motor recovery and thus should not delay discharge home . We hypothesized that 3 mg of hyperbaric bupivacaine with 10 µg of fentanyl permits fast‐tracking or shorter stay in post anesthesia care unit ( PACU ) , and earlier discharge home , compared with 4 mg of hyperbaric bupivacaine Background : We undertook this study to ascertain if a small dose of clonidine ( 30 μg 
    Output:
    
CONCLUSION Ambulatory surgery is possible under spinal anaesthesia with bupivacaine although the dose range that ensures reliable anaesthesia with duration short enough to guarantee ambulatory management is narrow