ORIGINAL ARTICLE
Severe pain during local infiltration for spinal anaesthesia predicts post-caesarean pain S. Orbach-Zinger1, A. Aviram2, S. Fireman1, T. Kadechenko1, Z. Klein1, N. Mazarib1, A. Artiuch1, A. Reuveni1, A. Ioscovich3, L.A. Eidelman1, R. Landau4 1 2 3 4
Department Department Department Department
of of of of
Anaesthesia, Rabin Medical Center, Beilinson Hospital, Petach Tikvah, Israel Obstetrics Gynecology, Rabin Medical Center, Beilinson Hospital, Petach Tikvah, Israel Anaesthesia, Shaare Zedek Medical Center, Hebrew University, Jerusalem, Israel Anesthesia, Columbia University College of Physicians and Surgeons, New York, USA
Correspondence Sharon Orbach-Zinger E-mail: [email protected] Funding sources All funding for this study was departmental. Conflicts of interest None declared.
Accepted for publication 2 May 2015 doi:10.1002/ejp.737
Abstract Background: Quantitative sensory testing (QST) measures response to painful stimuli and has been used to predict post-caesarean pain. Pain reported upon intravenous cannulation was shown to predict epidural analgesic use and pain intensity during labour. We hypothesized that pain intensity reported by women upon local anaesthesia injection (ILA) for spinal anaesthesia may predict acute pain after caesarean delivery (CD). Methods: In a prospective observational trial, 229 women undergoing elective CD under spinal anaesthesia were enrolled. Using standardized script before ILA, women received ILA (lidocaine 1% 2.5 mL via 25 G needle), and provided an ILA score after the injection [verbal numeric pain scale (VNPS); 0–100]. Demographic data, average, peak pain (at rest, with movement and uterine cramping) and analgesic requests were recorded for the first 24 h. Results: Fourteen percent of women experienced severe pain (VNPS ≥70) upon ILA. Good correlation was noted between ILA and pain scores at rest and upon mobilization during the 24 h following surgery (average resting pain r = 0.529, p < 0.001, average pain at mobilization r = 0.483, p < 0.0001). Severe acute postoperative pain (VNPS ≥70) was predicted by severe ILA pain with a sensitivity of 91.6% and specificity of 93.3%. Conclusion: This is the first study evaluating a clinical measure to predict post-caesarean pain. Our main findings were that 14% of women experience severe pain upon ILA, which was associated with increased pain during the first 24 h. For this article, a commentary is available at the Wiley Online Library.
1. Introduction More than 1.2 million caesarean deliveries are performed annually in the United States, representing 33% of all births (Martin et al., 2013). Despite widespread use of multimodal analgesia, up to 85% of women undergoing caesarean deliveries report moderate to severe acute pain that interferes with one or
1382 Eur J Pain 19 (2015) 1382--1388
more daily activities (Eisenach et al., 2008). Severe acute pain was associated with persistent pain (Kainu et al., 2010; Vermeils et al., 2010) and postpartum depression (Eisenach et al., 2008). Several studies have attempted to apply preoperative experimental and clinical tests in women undergoing a planned caesarean delivery to identify those at risk for severe acute post-caesarean and potentially chronic pain (Granot et al., 2003; Hsu et al.,
© 2015 European Pain Federation - EFICâ
S. Orbach-Zinger et al.
What’s already known about this topic? • Attempts have been made to predict postoperative pain after caesarean delivery, however, a simple clinical tool that can be performed in a clinical setting has yet to be found.
Pain during local anaesthesia infiltration predicts post-caesarean pain
were under 18 years of age, unable to undergo spinal anaesthesia, allergic to non-steroidal anti-inflammatory drugs or acetaminophen or did not understand the Hebrew language.
2.1 Ethics What does this study add? • We found that 14% of women experience severe pain during local anaesthetic infiltration, and severe pain predicted higher pain scores after caesarean delivery.
2005; Pan et al., 2006, 2013; Carvalho et al., 2007; Nielsen et al., 2007; Strulov et al., 2007). These tests are not currently applied in clinical practice as they are time-consuming and cannot readily be performed in a clinical setting. A recent study found that pain intensity reported by women during intravenous cannulation before induction of labour was correlated with time to epidural request during labour (Carvalho et al., 2013). Local anaesthesia infiltration is performed immediately prior to the spinal anaesthetic and since it is performed by the anaesthetist providing the anaesthetic solution it could potentially serve as a clinical test to guide intraoperative and postoperative pain management. In a study comparing different solutions for local anaesthesia infiltrations before neuraxial anaesthesia, pain upon injection of lidocaine 1.5% 2.5 mL was 3.6 2.2 (VNPS 0–10, mean standard deviation) (Carvalho et al., 2007), and intradermal injection of lidocaine 1% in healthy volunteers was 4.9 0.4 (VNPS 0–10, mean standard deviation) (Christoph et al., 1988). We therefore hypothesized that women reporting severe pain scores upon local anaesthesia infiltration prior to spinal anaesthesia will more likely report high post-caesarean pain scores, and conducted a prospective observational study in a cohort of healthy women undergoing a planned caesarean delivery to examine the validity of this simple clinical test to predict acute post-operative pain.
2. Methods The study was conducted at the Rabin Medical Center (Beilinson Campus), Petach Tikva, Israel, a tertiary university affiliated hospital, between May 2013 and June 2014. The Institutional Review Board approved this study and all participants provided written informed consent. Women were not included if they © 2015 European Pain Federation - EFICâ
Ethical approval for this study (Ethical Committee number 5245) was provided by the Ethical Committee of Rabin Medical Center-Beilinson Hospital, Petach Tikvah, Israel (Chairperson Professor Meir Lahav) on January 8, 2013. The study was registered on clinicaltrials.gov (Clinical Trial identifier NCT 02033304). Women were approached for enrolment during the preoperative consultation 4–6 weeks before the scheduled caesarean delivery. Informed consent was obtained during this consultation by an anaesthetist involved in the study, according to the hospital ethical committee requirement that all subjects are approached for consent at least 24 h prior to surgery. 2.1.1 Study procedure – pain upon injection of local anaesthesia Spinal anaesthesia was performed in the sitting position at the L3-L4 or L4-L5 interspace. After sterile preparation with chlorhexidine and draping, the anaesthetist performed ILA in a standardized method. Since it has been proven that words used during ILA influence the subjective experience of pain (noceboinduced hyperalgesia) (Varelmann et al., 2010), the anaesthetist performing the procedure used a standardized script to inform that ILA was about to occur: ‘I am now giving you the numbing dose’. ILA was standardized as follows: lidocaine 1% drawn up in a 10 mL syringe was injected using a 25 G needle and a total of 2.5 mL were given over 30 s, initially as an intradermal wheal and then injected deeper. After the injection was completed and the needle was removed the anaesthetist waited 10 s and then used a standardized script ‘From 0–100 where 0 is no pain and 100 is worst pain imaginable, how much did this procedure hurt?’ All the procedures (ILA) were performed by the same investigators who each underwent formal training by the principal investigator. A spinal anaesthetic was then provided, using a Whitacre needle 26 G with a 22 G introducer (Temena, France). The spinal solution contained 10–12 mg hyperbaric bupivacaine (AstraZeneca), 20 lg fentanyl (Jannsen) and 100 lg preservative-free morphine (Rafa). Eur J Pain 19 (2015) 1382--1388
1383
Pain during local anaesthesia infiltration predicts post-caesarean pain
Cases were excluded from further analysis if the spinal anaesthetic solution failed to provide an adequate surgical block (with a dermatomal level of T2 to cold) or if rescue IV medication was needed to manage breakthrough pain during the caesarean delivery. 2.1.1.1 Postoperative analgesia protocol
In the postoperative care unit, all women received intramuscular diclofenac 75 mg and intravenous acetaminophen 1 g. In the postpartum unit, women received oral medication per request. As per standard care in our institution, dipyrone (metamizole; Teva, Hungary) 1 g was given upon first request, 500 mg acetaminophen upon 2nd request and ibuprofen 600 mg upon 3rd request for analgesic medication. This regimen was repeated during subsequent requests up to a maximum dosing interval of 4 times daily for acetaminophen and dipyrone and 3 times daily for ibuprofen. Dipyrone is commonly used in Europe to manage mild to moderate pain with a half life of 2–3 h and an analgesic equivalency of ibuprofen 800 mg. Women were encouraged to request analgesic medication at any time, as guided by the postoperative analgesia protocol, but analgesics were not given at standard times. Nurses recorded VNPS at the time of analgesic request but this did not influence analgesic administration. Pain scores recorded by participation in the study did not result in medication intake if the participant did not request any analgesics. 2.1.1.2 Postoperative pain outcomes
All women were evaluated at 24 h postoperatively. An anaesthetist blinded to the results of the ILA injection made the assessments using a standardized script. Pain scores were assessed using a VNPS from 0 to 100 (with 0 indicating no pain and 100 indicating the worst pain imaginable). Average and peak pain at rest, upon movement and uterine cramping were measured during the 24 h. Analgesic consumption was also recorded.
2.2 Statistical analysis The cohort was divided into three groups according to women’s ILA pain score: Group 1 – mild ILA (0–30), Group 2 – moderate ILA (31–69) and Group 3 – severe ILA (70–100), based on International Association for the Study of Pain classification of mild, moderate and severe pain, and as used in our previous study identifying clinical predictors for acute post-caesarean pain (Ortner et al., 2013). Comparisons between the groups were performed using Kruskal–Wallis test 1384 Eur J Pain 19 (2015) 1382--1388
S. Orbach-Zinger et al.
because the groups were unequal; indeed there were with significantly more women reporting mid (48%) and moderate (38%) pain upon ILA than women reporting severe pain (14%). Spearman correlation was calculated to assess the correlation between ILA pain score and each examined post-caesarean pain score. Regression analysis was performed to account for different confounders and determine the predictability of post-caesarean pain scores by ILA pain score. The main outcome measure was postoperative average resting pain. Sensitivity and specificity were calculated using a cut off of ILA VNPS ≥70 based on previous similar analysis by our group (Ortner et al., 2013). p value of
Severe pain during local infiltration for spinal anaesthesia predicts post-caesarean pain S. Orbach-Zinger1, A. Aviram2, S. Fireman1, T. Kadechenko1, Z. Klein1, N. Mazarib1, A. Artiuch1, A. Reuveni1, A. Ioscovich3, L.A. Eidelman1, R. Landau4 1 2 3 4
Department Department Department Department
of of of of
Anaesthesia, Rabin Medical Center, Beilinson Hospital, Petach Tikvah, Israel Obstetrics Gynecology, Rabin Medical Center, Beilinson Hospital, Petach Tikvah, Israel Anaesthesia, Shaare Zedek Medical Center, Hebrew University, Jerusalem, Israel Anesthesia, Columbia University College of Physicians and Surgeons, New York, USA
Correspondence Sharon Orbach-Zinger E-mail: [email protected] Funding sources All funding for this study was departmental. Conflicts of interest None declared.
Accepted for publication 2 May 2015 doi:10.1002/ejp.737
Abstract Background: Quantitative sensory testing (QST) measures response to painful stimuli and has been used to predict post-caesarean pain. Pain reported upon intravenous cannulation was shown to predict epidural analgesic use and pain intensity during labour. We hypothesized that pain intensity reported by women upon local anaesthesia injection (ILA) for spinal anaesthesia may predict acute pain after caesarean delivery (CD). Methods: In a prospective observational trial, 229 women undergoing elective CD under spinal anaesthesia were enrolled. Using standardized script before ILA, women received ILA (lidocaine 1% 2.5 mL via 25 G needle), and provided an ILA score after the injection [verbal numeric pain scale (VNPS); 0–100]. Demographic data, average, peak pain (at rest, with movement and uterine cramping) and analgesic requests were recorded for the first 24 h. Results: Fourteen percent of women experienced severe pain (VNPS ≥70) upon ILA. Good correlation was noted between ILA and pain scores at rest and upon mobilization during the 24 h following surgery (average resting pain r = 0.529, p < 0.001, average pain at mobilization r = 0.483, p < 0.0001). Severe acute postoperative pain (VNPS ≥70) was predicted by severe ILA pain with a sensitivity of 91.6% and specificity of 93.3%. Conclusion: This is the first study evaluating a clinical measure to predict post-caesarean pain. Our main findings were that 14% of women experience severe pain upon ILA, which was associated with increased pain during the first 24 h. For this article, a commentary is available at the Wiley Online Library.
1. Introduction More than 1.2 million caesarean deliveries are performed annually in the United States, representing 33% of all births (Martin et al., 2013). Despite widespread use of multimodal analgesia, up to 85% of women undergoing caesarean deliveries report moderate to severe acute pain that interferes with one or
1382 Eur J Pain 19 (2015) 1382--1388
more daily activities (Eisenach et al., 2008). Severe acute pain was associated with persistent pain (Kainu et al., 2010; Vermeils et al., 2010) and postpartum depression (Eisenach et al., 2008). Several studies have attempted to apply preoperative experimental and clinical tests in women undergoing a planned caesarean delivery to identify those at risk for severe acute post-caesarean and potentially chronic pain (Granot et al., 2003; Hsu et al.,
© 2015 European Pain Federation - EFICâ
S. Orbach-Zinger et al.
What’s already known about this topic? • Attempts have been made to predict postoperative pain after caesarean delivery, however, a simple clinical tool that can be performed in a clinical setting has yet to be found.
Pain during local anaesthesia infiltration predicts post-caesarean pain
were under 18 years of age, unable to undergo spinal anaesthesia, allergic to non-steroidal anti-inflammatory drugs or acetaminophen or did not understand the Hebrew language.
2.1 Ethics What does this study add? • We found that 14% of women experience severe pain during local anaesthetic infiltration, and severe pain predicted higher pain scores after caesarean delivery.
2005; Pan et al., 2006, 2013; Carvalho et al., 2007; Nielsen et al., 2007; Strulov et al., 2007). These tests are not currently applied in clinical practice as they are time-consuming and cannot readily be performed in a clinical setting. A recent study found that pain intensity reported by women during intravenous cannulation before induction of labour was correlated with time to epidural request during labour (Carvalho et al., 2013). Local anaesthesia infiltration is performed immediately prior to the spinal anaesthetic and since it is performed by the anaesthetist providing the anaesthetic solution it could potentially serve as a clinical test to guide intraoperative and postoperative pain management. In a study comparing different solutions for local anaesthesia infiltrations before neuraxial anaesthesia, pain upon injection of lidocaine 1.5% 2.5 mL was 3.6 2.2 (VNPS 0–10, mean standard deviation) (Carvalho et al., 2007), and intradermal injection of lidocaine 1% in healthy volunteers was 4.9 0.4 (VNPS 0–10, mean standard deviation) (Christoph et al., 1988). We therefore hypothesized that women reporting severe pain scores upon local anaesthesia infiltration prior to spinal anaesthesia will more likely report high post-caesarean pain scores, and conducted a prospective observational study in a cohort of healthy women undergoing a planned caesarean delivery to examine the validity of this simple clinical test to predict acute post-operative pain.
2. Methods The study was conducted at the Rabin Medical Center (Beilinson Campus), Petach Tikva, Israel, a tertiary university affiliated hospital, between May 2013 and June 2014. The Institutional Review Board approved this study and all participants provided written informed consent. Women were not included if they © 2015 European Pain Federation - EFICâ
Ethical approval for this study (Ethical Committee number 5245) was provided by the Ethical Committee of Rabin Medical Center-Beilinson Hospital, Petach Tikvah, Israel (Chairperson Professor Meir Lahav) on January 8, 2013. The study was registered on clinicaltrials.gov (Clinical Trial identifier NCT 02033304). Women were approached for enrolment during the preoperative consultation 4–6 weeks before the scheduled caesarean delivery. Informed consent was obtained during this consultation by an anaesthetist involved in the study, according to the hospital ethical committee requirement that all subjects are approached for consent at least 24 h prior to surgery. 2.1.1 Study procedure – pain upon injection of local anaesthesia Spinal anaesthesia was performed in the sitting position at the L3-L4 or L4-L5 interspace. After sterile preparation with chlorhexidine and draping, the anaesthetist performed ILA in a standardized method. Since it has been proven that words used during ILA influence the subjective experience of pain (noceboinduced hyperalgesia) (Varelmann et al., 2010), the anaesthetist performing the procedure used a standardized script to inform that ILA was about to occur: ‘I am now giving you the numbing dose’. ILA was standardized as follows: lidocaine 1% drawn up in a 10 mL syringe was injected using a 25 G needle and a total of 2.5 mL were given over 30 s, initially as an intradermal wheal and then injected deeper. After the injection was completed and the needle was removed the anaesthetist waited 10 s and then used a standardized script ‘From 0–100 where 0 is no pain and 100 is worst pain imaginable, how much did this procedure hurt?’ All the procedures (ILA) were performed by the same investigators who each underwent formal training by the principal investigator. A spinal anaesthetic was then provided, using a Whitacre needle 26 G with a 22 G introducer (Temena, France). The spinal solution contained 10–12 mg hyperbaric bupivacaine (AstraZeneca), 20 lg fentanyl (Jannsen) and 100 lg preservative-free morphine (Rafa). Eur J Pain 19 (2015) 1382--1388
1383
Pain during local anaesthesia infiltration predicts post-caesarean pain
Cases were excluded from further analysis if the spinal anaesthetic solution failed to provide an adequate surgical block (with a dermatomal level of T2 to cold) or if rescue IV medication was needed to manage breakthrough pain during the caesarean delivery. 2.1.1.1 Postoperative analgesia protocol
In the postoperative care unit, all women received intramuscular diclofenac 75 mg and intravenous acetaminophen 1 g. In the postpartum unit, women received oral medication per request. As per standard care in our institution, dipyrone (metamizole; Teva, Hungary) 1 g was given upon first request, 500 mg acetaminophen upon 2nd request and ibuprofen 600 mg upon 3rd request for analgesic medication. This regimen was repeated during subsequent requests up to a maximum dosing interval of 4 times daily for acetaminophen and dipyrone and 3 times daily for ibuprofen. Dipyrone is commonly used in Europe to manage mild to moderate pain with a half life of 2–3 h and an analgesic equivalency of ibuprofen 800 mg. Women were encouraged to request analgesic medication at any time, as guided by the postoperative analgesia protocol, but analgesics were not given at standard times. Nurses recorded VNPS at the time of analgesic request but this did not influence analgesic administration. Pain scores recorded by participation in the study did not result in medication intake if the participant did not request any analgesics. 2.1.1.2 Postoperative pain outcomes
All women were evaluated at 24 h postoperatively. An anaesthetist blinded to the results of the ILA injection made the assessments using a standardized script. Pain scores were assessed using a VNPS from 0 to 100 (with 0 indicating no pain and 100 indicating the worst pain imaginable). Average and peak pain at rest, upon movement and uterine cramping were measured during the 24 h. Analgesic consumption was also recorded.
2.2 Statistical analysis The cohort was divided into three groups according to women’s ILA pain score: Group 1 – mild ILA (0–30), Group 2 – moderate ILA (31–69) and Group 3 – severe ILA (70–100), based on International Association for the Study of Pain classification of mild, moderate and severe pain, and as used in our previous study identifying clinical predictors for acute post-caesarean pain (Ortner et al., 2013). Comparisons between the groups were performed using Kruskal–Wallis test 1384 Eur J Pain 19 (2015) 1382--1388
S. Orbach-Zinger et al.
because the groups were unequal; indeed there were with significantly more women reporting mid (48%) and moderate (38%) pain upon ILA than women reporting severe pain (14%). Spearman correlation was calculated to assess the correlation between ILA pain score and each examined post-caesarean pain score. Regression analysis was performed to account for different confounders and determine the predictability of post-caesarean pain scores by ILA pain score. The main outcome measure was postoperative average resting pain. Sensitivity and specificity were calculated using a cut off of ILA VNPS ≥70 based on previous similar analysis by our group (Ortner et al., 2013). p value of
