human
***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Fifty patients undergoing thoracotomy was studied to compare the effects of cryoanalgesia combined with intravenous continuous analgesia ( IVCA ) .  Patients were r and omized into two groups : IVCA group and IVCA-cryo group .  Subjective pain intensity was assessed on a visual analogue scale at rest ( VAS-R ) and during movement ( VAS-M ) . Analgesic requirements were evaluated over the 7 days following surgery . Forced vital capacity ( FVC ) and forced expiratory volume in 1 sec ( FEV1 ) were measured before operation , on the 2nd and 7th postoperative days ( POD ) . We interviewed patients by telephone to evaluate the prevalence of post-thoracotomy pain at the 1st , 3rd , and 6th months postoperatively . No significant differences were observed between the two groups with respect to postoperative pain , analgesic requirements , side effects , respiratory complications , or prevalence of post-thoracotomy pain . However , a significant increase in FVC and FEV1 was observed on the 7th POD in IVCAc-ryo group . The incidence of the post-thoracotomy pain at the 1st , 3rd , and 6th months postoperatively was 68 , 60 , and 44 % in IVCA group , and 88 , 68 , and 28 % in IVCA-cryo group , respectively . Our study showed that cryoanalgesia combined with IVCA effectively restore respiratory function on 7th POD , but that it was not effective at reducing the incidence of post-thoracotomy pain Background Despite major advances in the underst and ing of the neurobiologic mechanisms of pain , the wide variation in acute pain experience has not been well explained . Therefore , the authors investigated the potential of a preoperatively induced heat injury to predict subsequent postoperative pain ratings in patients undergoing knee surgery . Methods Twenty patients were studied . The burn injury was induced 6 days before surgery with a contact thermode ( 12.5 cm2 , 47 ° C for 7 min ) . The sensory testing , before and 1 h after the injury , included pain score during induction of the burn , secondary hyperalgesia area , thermal and mechanical pain perception , and pain thresholds . Postoperative analgesia consisted of ibuprofen and acetaminophen . Pain ratings ( visual analog scale ) at rest and during limb movement were followed for 10 days after surgery . Results The burn injury was associated with development of significant hyperalgesia . There was a significant correlation between preoperative pain ratings during the burn injury and early ( 0–2 days , area under the curve ) and late ( 3–10 days , area under the curve ) postoperative dynamic pain ratings during limb movement . Conclusion The results of this study suggest that the pain response to a preoperative heat injury may be useful in research in predicting the intensity of postoperative pain . These findings may have important implication s to identify patients at risk for development of chronic pain and to stratify individuals for investigations of new analgesics Background : Ketamine potentiates intravenous or epidural morphine analgesia . The authors hypothesized that very-low-dose ketamine infusion reduces acute and long-term postthoracotomy pain . Methods : Forty-nine patients scheduled to undergo open thoracotomy were r and omly assigned to receive one of two anesthesia regimens : continuous epidural infusion of ropivacaine and morphine , along with intravenous infusion of ketamine ( 0.05 mg · kg−1 · h−1 [ approximately 3 mg/h ] , ketamine group , n = 24 ) or placebo ( saline , control group , n = 25 ) . Epidural analgesia was continued for 2 days after surgery , and infusion of ketamine or placebo was continued for 3 days . Pain was assessed at 6 , 12 , 24 , and 48 h after surgery . Patients were asked about their pain , abnormal sensation on the wound , and inconvenience in daily life at 7 days and 1 , 3 , and 6 months after surgery . Results : The visual analog scale scores for pain at rest and on coughing 24 and 48 h after thoracotomy were lower in the ketamine group than in the control group ( pain at rest , 9 ± 11 vs. 25 ± 20 and 9 ± 11 vs. 18 ± 13 ; pain on coughing , 26 ± 16 vs. 50 ± 17 and 30 ± 18 vs. 43 ± 18 , mean ± SD ; P = 0.002 and P = 0.01 , P < 0.0001 and P = 0.02 , respectively ) . The numerical rating scale scores for baseline pain 1 and 3 months after thoracotomy were significantly lower in the ketamine group ( 0.5 [ 0–4 ] vs. 2 [ 0–5 ] and 0 [ 0–5 ] vs. 1.5 [ 0–6 ] , median [ range ] , respectively ; P = 0.02 ) . Three months after surgery , a higher number of control patients were taking pain medication ( 2 vs. 9 ; P = 0.03 ) . Conclusions : Very-low-dose ketamine ( 0.05 mg · kg−1 · h−1 ) potentiated morphine-ropivacaine analgesia and reduced postthoracotomy pain Background : Women scheduled to undergo hysterectomy for benign indications frequently have preoperative pelvic pain , but it is largely unknown why pain in some cases persists or even develops after surgery . This nationwide question naire and data base study describes pain and identifies risk factors for chronic  postsurgical pain  1 yr after hysterectomy for benign indications . Methods : A pain question naire was mailed to 1,299 women 1 yr after hysterectomy .  The response rate was 90.3 % , and the presence of persistent pain was correlated to indication for surgery , surgical procedure , type of anesthesia , and other perioperative data . Results : Pain was reported by 31.9 % 1 yr after hysterectomy ( chronic pain ) , and 13.7 % had pain more than 2 days a week . Pain was not present before surgery in 14.9 % of women with chronic postsurgical pain . Risk factors for chronic pain were preoperative pelvic pain ( odds ratio [ OR ] , 3.25 ; 95 % confidence interval [ CI ] , 2.40–4.41 ) , previous cesarean delivery ( OR , 1.54 ; CI , 1.06–2.26 ) , pain as the main indication for surgery ( OR , 2.98 ; CI , 1.54–5.77 ) , and pain problems elsewhere ( OR , 3.19 ; CI , 2.29–4.44 ) . Vaginal hysterectomy versus total abdominal hysterectomy was not significantly associated with a lower risk of chronic pain ( OR , 0.70 ; CI , 0.46–1.06 ) . Importantly , spinal versus general anesthesia was associated with less chronic pain ( OR , 0.42 ; CI , 0.21–0.85 ) . Conclusions : Thirty-two percent had chronic pain after hysterectomy , and risk factors were comparable to those seen in other operations . Interestingly , spinal anesthesia was associated with a lower frequency of chronic pain , justifying prospect i ve study of spinal anesthesia for patients with a high risk for development of chronic postsurgical pain In this clinical , r and omized , prospect i ve study , we compared the effects of three different analgesia techniques ( thoracic epidural analgesia [ TEA ] with and without preoperative initiation and IV patient-controlled analgesia [ IV-PCA ] ) on postthoracotomy pain in 69 patients . In two groups , a thoracic epidural catheter was inserted preoperatively . Group Pre-TEA had bupivacaine and morphine solution preoperatively and intraoperatively . Postoperative analgesia was maintained with epidural PCA with a similar solution . Group Post-TEA , with no intraoperative medication , had the same postoperative analgesia as Group Pre-TEA plus the bolus dose . Group IV-PCA received only IV-PCA with morphine for postoperative analgesia . Pain was evaluated every 4 h during the first 48 h at rest , cough , and movement . Pre-TEA was associated with decreased pain compared with the other groups . Six months later , the patients were asked about their pain . The incidence and the intensity of pain were most frequent in Group IV-PCA ( 78 % ) and were the least in Group Pre-TEA ( 45 % ) ( Group Pre-TEA versus Group IV-PCA , P = 0.0233 ; Group Pre-TEA versus Group IV-PCA , P = 0.014 ) . Patients having pain on the second postoperative day had 83 % chronic pain . TEA with preoperative initiation is a preferable method in preventing acute and long-term thoracotomy pain BACKGROUND Thoracotomy is associated with significant pain and morbidity . METHODS We performed a prospect i ve r and omized trial over 4 months . Patients were r and omized to a st and ard posterior-lateral thoracotomy or an identical procedure , except an intercostal muscle was harvested from the lower rib ( to protect the intercostal nerve ) before chest retraction . To ensure an equal distribution among both groups , patients were stratified by race , sex , and type of pulmonary resection . All patients received similar pain management . Pain was assessed by using multiple pain scores during hospitalization and after discharge . Outcomes assessed were pain scores , spirometric values , analgesic use , and activity level . RESULTS There were 114 patients . The median time for intercostal muscle harvesting was 3.7 minutes . The numeric pain scores were lower for the intercostal muscle group on postoperative days 1 and 2 and at weeks 1 , 2 , 3 , 4 , 8 , and 12 ( P < .05 for all ) . In addition , patients in the intercostal muscle group had a smaller decrease in spirometric values , were less likely to be using analgesics , and were more likely to have returned to normal activity . CONCLUSIONS The harvesting of an intercostal muscle flap before chest retraction decreases the pain of thoracotomy and leads to a lower decrease in spirometry . In addition , patients have less pain at 1 , 2 , 3 , 4 , 8 , and 12 weeks postoperatively and are less likely to be using narcotics . Finally , it offers a pedicled muscle flap that takes little time to harvest and is able to buttress all bronchi after lobectomy OBJECTIVE Long-term pain is a common sequela of thoracotomy , occurring in approximately 50 % of patients 2 years after thoracic surgery . Despite this alarming statistic , little is known about the factors responsible for the transition of acute to chronic pain . The aim of the present study is to identify predictors of long-term post-thoracotomy pain . DESIGN Follow-up was for 1.5 years for patients who had participated in a prospect i ve , r and omized , controlled trial of preemptive , multimodal analgesia .  SETTING Subjects were recruited from a tertiary care center . PATIENTS Thirty patients who had undergone lateral thoracotomy  were followed up by telephone , administered a structured interview , and classified according to long-term pain status . MAIN OUTCOME MEASURES Present pain status was measured by a verbal rating scale ( VAS ) . Measures obtained within the first 48 h after surgery were compared between patients with and without pain 1.5 years later . These include VAS pain scores at rest and after movement , McGill Pain Question naire data , patient-controlled morphine consumption ( mg ) , and pain thresholds to pressure applied to a rib contralateral to the thoracotomy incision . RESULTS Fifty-two percent of patients reported long-term pain . Early postoperative pain was the only factor that significantly predicted long-term pain . Pain intensity 24 h after surgery , at rest , and after movement was significantly greater among patients who developed long-term pain compared with pain-free patients . A significant predictive relationship was also found at 24 and 48 h using the McGill Pain Question naire . Cumulative morphine was comparable for the two groups . Pain thresholds to pressure applied to a rib contralateral to the incision did not differ significantly between the groups . CONCLUSION Aggressive management of early postoperative pain may reduce the likelihood of long-term post-thoracotomy pain Thoracotomy causes severe postoperative pain , which is difficult to manage since the use of systemic analgesics often causes respiratory depression . Cryoanalgesia of the intercostal nerves has been advocated as an effective means of local analgesia without serious side effects . A prospect i ve r and omised blind trial to investigate the efficacy of the technique was carried out . A total of 53 patients undergoing thoracotomy  were allocated to either the trial or a control group . At thoracotomy the surgeon was informed of the patient 's trial allocation . The trial group received one minute of direct cryotherapy to at least five intercostal nerves related to the incision . All patients received methadone via the lumbar epidural route in a dose calculated according to their weight . A linear analogue assessment of postoperative pain was made by the patients as soon as they were sufficiently awake . An independent record of all postoperative analgesia was kept . After discharge from hospital further assessment s were made at least six weeks after operation . Statistical analysis of the scores of postoperative pain and analgesic consumption showed that there was no significant difference between the trial and the control group . There was , however , a suggestion of an increase in the long term morbidity , although these figures were not amenable to statistical analysis . Thus is has not been possible to demonstrate a role for cryoanalgesia in the control of post thoracotomy 
    Output:
    
agent
However , intercostal nerve injury seems to be the most important pathogenic factor .
***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Fifty patients undergoing thoracotomy was studied to compare the effects of cryoanalgesia combined with intravenous continuous analgesia ( IVCA ) .  Patients were r and omized into two groups : IVCA group and IVCA-cryo group .  Subjective pain intensity was assessed on a visual analogue scale at rest ( VAS-R ) and during movement ( VAS-M ) . Analgesic requirements were evaluated over the 7 days following surgery . Forced vital capacity ( FVC ) and forced expiratory volume in 1 sec ( FEV1 ) were measured before operation , on the 2nd and 7th postoperative days ( POD ) . We interviewed patients by telephone to evaluate the prevalence of post-thoracotomy pain at the 1st , 3rd , and 6th months postoperatively . No significant differences were observed between the two groups with respect to postoperative pain , analgesic requirements , side effects , respiratory complications , or prevalence of post-thoracotomy pain . However , a significant increase in FVC and FEV1 was observed on the 7th POD in IVCAc-ryo group . The incidence of the post-thoracotomy pain at the 1st , 3rd , and 6th months postoperatively was 68 , 60 , and 44 % in IVCA group , and 88 , 68 , and 28 % in IVCA-cryo group , respectively . Our study showed that cryoanalgesia combined with IVCA effectively restore respiratory function on 7th POD , but that it was not effective at reducing the incidence of post-thoracotomy pain Background Despite major advances in the underst and ing of the neurobiologic mechanisms of pain , the wide variation in acute pain experience has not been well explained . Therefore , the authors investigated the potential of a preoperatively induced heat injury to predict subsequent postoperative pain ratings in patients undergoing knee surgery . Methods Twenty patients were studied . The burn injury was induced 6 days before surgery with a contact thermode ( 12.5 cm2 , 47 ° C for 7 min ) . The sensory testing , before and 1 h after the injury , included pain score during induction of the burn , secondary hyperalgesia area , thermal and mechanical pain perception , and pain thresholds . Postoperative analgesia consisted of ibuprofen and acetaminophen . Pain ratings ( visual analog scale ) at rest and during limb movement were followed for 10 days after surgery . Results The burn injury was associated with development of significant hyperalgesia . There was a significant correlation between preoperative pain ratings during the burn injury and early ( 0–2 days , area under the curve ) and late ( 3–10 days , area under the curve ) postoperative dynamic pain ratings during limb movement . Conclusion The results of this study suggest that the pain response to a preoperative heat injury may be useful in research in predicting the intensity of postoperative pain . These findings may have important implication s to identify patients at risk for development of chronic pain and to stratify individuals for investigations of new analgesics Background : Ketamine potentiates intravenous or epidural morphine analgesia . The authors hypothesized that very-low-dose ketamine infusion reduces acute and long-term postthoracotomy pain . Methods : Forty-nine patients scheduled to undergo open thoracotomy were r and omly assigned to receive one of two anesthesia regimens : continuous epidural infusion of ropivacaine and morphine , along with intravenous infusion of ketamine ( 0.05 mg · kg−1 · h−1 [ approximately 3 mg/h ] , ketamine group , n = 24 ) or placebo ( saline , control group , n = 25 ) . Epidural analgesia was continued for 2 days after surgery , and infusion of ketamine or placebo was continued for 3 days . Pain was assessed at 6 , 12 , 24 , and 48 h after surgery . Patients were asked about their pain , abnormal sensation on the wound , and inconvenience in daily life at 7 days and 1 , 3 , and 6 months after surgery . Results : The visual analog scale scores for pain at rest and on coughing 24 and 48 h after thoracotomy were lower in the ketamine group than in the control group ( pain at rest , 9 ± 11 vs. 25 ± 20 and 9 ± 11 vs. 18 ± 13 ; pain on coughing , 26 ± 16 vs. 50 ± 17 and 30 ± 18 vs. 43 ± 18 , mean ± SD ; P = 0.002 and P = 0.01 , P < 0.0001 and P = 0.02 , respectively ) . The numerical rating scale scores for baseline pain 1 and 3 months after thoracotomy were significantly lower in the ketamine group ( 0.5 [ 0–4 ] vs. 2 [ 0–5 ] and 0 [ 0–5 ] vs. 1.5 [ 0–6 ] , median [ range ] , respectively ; P = 0.02 ) . Three months after surgery , a higher number of control patients were taking pain medication ( 2 vs. 9 ; P = 0.03 ) . Conclusions : Very-low-dose ketamine ( 0.05 mg · kg−1 · h−1 ) potentiated morphine-ropivacaine analgesia and reduced postthoracotomy pain Background : Women scheduled to undergo hysterectomy for benign indications frequently have preoperative pelvic pain , but it is largely unknown why pain in some cases persists or even develops after surgery . This nationwide question naire and data base study describes pain and identifies risk factors for chronic  postsurgical pain  1 yr after hysterectomy for benign indications . Methods : A pain question naire was mailed to 1,299 women 1 yr after hysterectomy .  The response rate was 90.3 % , and the presence of persistent pain was correlated to indication for surgery , surgical procedure , type of anesthesia , and other perioperative data . Results : Pain was reported by 31.9 % 1 yr after hysterectomy ( chronic pain ) , and 13.7 % had pain more than 2 days a week . Pain was not present before surgery in 14.9 % of women with chronic postsurgical pain . Risk factors for chronic pain were preoperative pelvic pain ( odds ratio [ OR ] , 3.25 ; 95 % confidence interval [ CI ] , 2.40–4.41 ) , previous cesarean delivery ( OR , 1.54 ; CI , 1.06–2.26 ) , pain as the main indication for surgery ( OR , 2.98 ; CI , 1.54–5.77 ) , and pain problems elsewhere ( OR , 3.19 ; CI , 2.29–4.44 ) . Vaginal hysterectomy versus total abdominal hysterectomy was not significantly associated with a lower risk of chronic pain ( OR , 0.70 ; CI , 0.46–1.06 ) . Importantly , spinal versus general anesthesia was associated with less chronic pain ( OR , 0.42 ; CI , 0.21–0.85 ) . Conclusions : Thirty-two percent had chronic pain after hysterectomy , and risk factors were comparable to those seen in other operations . Interestingly , spinal anesthesia was associated with a lower frequency of chronic pain , justifying prospect i ve study of spinal anesthesia for patients with a high risk for development of chronic postsurgical pain In this clinical , r and omized , prospect i ve study , we compared the effects of three different analgesia techniques ( thoracic epidural analgesia [ TEA ] with and without preoperative initiation and IV patient-controlled analgesia [ IV-PCA ] ) on postthoracotomy pain in 69 patients . In two groups , a thoracic epidural catheter was inserted preoperatively . Group Pre-TEA had bupivacaine and morphine solution preoperatively and intraoperatively . Postoperative analgesia was maintained with epidural PCA with a similar solution . Group Post-TEA , with no intraoperative medication , had the same postoperative analgesia as Group Pre-TEA plus the bolus dose . Group IV-PCA received only IV-PCA with morphine for postoperative analgesia . Pain was evaluated every 4 h during the first 48 h at rest , cough , and movement . Pre-TEA was associated with decreased pain compared with the other groups . Six months later , the patients were asked about their pain . The incidence and the intensity of pain were most frequent in Group IV-PCA ( 78 % ) and were the least in Group Pre-TEA ( 45 % ) ( Group Pre-TEA versus Group IV-PCA , P = 0.0233 ; Group Pre-TEA versus Group IV-PCA , P = 0.014 ) . Patients having pain on the second postoperative day had 83 % chronic pain . TEA with preoperative initiation is a preferable method in preventing acute and long-term thoracotomy pain BACKGROUND Thoracotomy is associated with significant pain and morbidity . METHODS We performed a prospect i ve r and omized trial over 4 months . Patients were r and omized to a st and ard posterior-lateral thoracotomy or an identical procedure , except an intercostal muscle was harvested from the lower rib ( to protect the intercostal nerve ) before chest retraction . To ensure an equal distribution among both groups , patients were stratified by race , sex , and type of pulmonary resection . All patients received similar pain management . Pain was assessed by using multiple pain scores during hospitalization and after discharge . Outcomes assessed were pain scores , spirometric values , analgesic use , and activity level . RESULTS There were 114 patients . The median time for intercostal muscle harvesting was 3.7 minutes . The numeric pain scores were lower for the intercostal muscle group on postoperative days 1 and 2 and at weeks 1 , 2 , 3 , 4 , 8 , and 12 ( P < .05 for all ) . In addition , patients in the intercostal muscle group had a smaller decrease in spirometric values , were less likely to be using analgesics , and were more likely to have returned to normal activity . CONCLUSIONS The harvesting of an intercostal muscle flap before chest retraction decreases the pain of thoracotomy and leads to a lower decrease in spirometry . In addition , patients have less pain at 1 , 2 , 3 , 4 , 8 , and 12 weeks postoperatively and are less likely to be using narcotics . Finally , it offers a pedicled muscle flap that takes little time to harvest and is able to buttress all bronchi after lobectomy OBJECTIVE Long-term pain is a common sequela of thoracotomy , occurring in approximately 50 % of patients 2 years after thoracic surgery . Despite this alarming statistic , little is known about the factors responsible for the transition of acute to chronic pain . The aim of the present study is to identify predictors of long-term post-thoracotomy pain . DESIGN Follow-up was for 1.5 years for patients who had participated in a prospect i ve , r and omized , controlled trial of preemptive , multimodal analgesia .  SETTING Subjects were recruited from a tertiary care center . PATIENTS Thirty patients who had undergone lateral thoracotomy  were followed up by telephone , administered a structured interview , and classified according to long-term pain status . MAIN OUTCOME MEASURES Present pain status was measured by a verbal rating scale ( VAS ) . Measures obtained within the first 48 h after surgery were compared between patients with and without pain 1.5 years later . These include VAS pain scores at rest and after movement , McGill Pain Question naire data , patient-controlled morphine consumption ( mg ) , and pain thresholds to pressure applied to a rib contralateral to the thoracotomy incision . RESULTS Fifty-two percent of patients reported long-term pain . Early postoperative pain was the only factor that significantly predicted long-term pain . Pain intensity 24 h after surgery , at rest , and after movement was significantly greater among patients who developed long-term pain compared with pain-free patients . A significant predictive relationship was also found at 24 and 48 h using the McGill Pain Question naire . Cumulative morphine was comparable for the two groups . Pain thresholds to pressure applied to a rib contralateral to the incision did not differ significantly between the groups . CONCLUSION Aggressive management of early postoperative pain may reduce the likelihood of long-term post-thoracotomy pain Thoracotomy causes severe postoperative pain , which is difficult to manage since the use of systemic analgesics often causes respiratory depression . Cryoanalgesia of the intercostal nerves has been advocated as an effective means of local analgesia without serious side effects . A prospect i ve r and omised blind trial to investigate the efficacy of the technique was carried out . A total of 53 patients undergoing thoracotomy  were allocated to either the trial or a control group . At thoracotomy the surgeon was informed of the patient 's trial allocation . The trial group received one minute of direct cryotherapy to at least five intercostal nerves related to the incision . All patients received methadone via the lumbar epidural route in a dose calculated according to their weight . A linear analogue assessment of postoperative pain was made by the patients as soon as they were sufficiently awake . An independent record of all postoperative analgesia was kept . After discharge from hospital further assessment s were made at least six weeks after operation . Statistical analysis of the scores of postoperative pain and analgesic consumption showed that there was no significant difference between the trial and the control group . There was , however , a suggestion of an increase in the long term morbidity , although these figures were not amenable to statistical analysis . Thus is has not been possible to demonstrate a role for cryoanalgesia in the control of post thoracotomy 
    Output:
    