Peter H. Pan

severity of acute pain after childbirth, but not type of delivery, predicts persistent pain and postpartum depression

Abstract Cesarean delivery rates continue to increase, and surgery is associated with chronic pain, often co‐existing with depression. Also, acute pain in the days after surgery is a strong predictor of chronic pain. Here we tested if mode of delivery or acute pain played a role in persistent pain and depression after childbirth. In this multicenter, prospective, longitudinal cohort study, 1288 women hospitalized for cesarean or vaginal delivery were enrolled. Data were obtained from patient interviews and medical record review within 36 h postpartum, then via telephone interviews 8 weeks later to assess persistent pain and postpartum depressive symptoms. The impact of delivery mode on acute postpartum pain, persistent pain and depressive symptoms and their interrelationships was assessed using regression analysis with propensity adjustment. The prevalence of severe acute pain within 36 h postpartum was 10.9%, while persistent pain and depression at 8 weeks postpartum were 9.8% and 11.2%, respectively. Severity of acute postpartum pain, but not mode of delivery, was independently related to the risk of persistent postpartum pain and depression. Women with severe acute postpartum pain had a 2.5‐fold increased risk of persistent pain and a 3.0‐fold increased risk of postpartum depression compared to those with mild postpartum pain. In summary, cesarean delivery does not increase the risk of persistent pain and postpartum depression. In contrast, the severity of the acute pain response to childbirth predicts persistent morbidity, suggesting the need to more carefully address pain treatment in the days following childbirth.

Multifactorial Preoperative Predictors for Postcesarean Section Pain and Analgesic Requirement

Background: The study aimed to determine predictive factors for postcesarean pain and analgesia using an assessment of pain threshold and suprathreshold thermal stimuli as well as degree of somatization and anxiety. Methods: Thirty-four healthy parturients scheduled for cesarean delivery under subarachnoid anesthesia were enrolled. Preoperative thermal pain threshold, intensity, and unpleasantness to heat stimuli applied to arm and lower back, State Trait Anxiety Inventory, and patient expectation for postoperative pain and need for analgesia were assessed. After surgery, overall, resting, and movement pain and analgesic consumption were recorded. Prediction of pain and analgesic use outcomes was made by principal component factor analysis, followed by stepwise linear regression. Results: Resting pain was predicted by two factors, thermal pain and unpleasantness and patient expectation (r2 = 0.26, P < 0.01), evoked pain by thermal pain threshold in the back (r2 = 0.20, P < 0.009), composite pain by thermal pain and unpleasantness and preoperative blood pressure (r2 = 0.28, P < 0.008), intraoperative analgesic need by preexisting pain (r2 = 0.22, P < 0.006), recovery room analgesia by thermal pain threshold and State Trait Anxiety Inventory (r2 = 0.27, P < 0.01), and total analgesic need by State Trait Anxiety Inventory (r2 = 0.22, P < 0.01). These models predicted the upper twentieth percentile of composite pain scores and analgesic requirement with sensitivity of 0.71 to 0.80 and specificity of 0.76 to 0.80. Conclusions: The authors’ results suggest a meaningful combination of preoperative patient responses from physical and psychological tests yields a valid multifactorial predictive model for postoperative pain and analgesic requirement with significant improvements over individual predictive variables.

Resolution of pain after childbirth.

Background:Chronic pain after surgery occurs in 10–40% of individuals, including 5–20% of women after cesarean delivery in previous reports. Pain and depression 2 months after childbirth are independently associated with more severe acute post-delivery pain. Here we examine other predictors of pain at 2 months and determine the incidence of pain at 6 and 12 months after childbirth. Methods:Following Institutional Review Board approval, 1228 women were interviewed within 36 h of delivery. Of these, 937 (76%) were successfully contacted by telephone at 2 months, and, if they had pain, at 6 and 12 months after delivery. The primary outcome measure was presence of pain which began at the time of delivery. We also generated a model of severity of acute post-delivery pain and 2 month pain and depression. Results:Pain which began at the time of delivery was remarkably rare 6 and 12 months later (1.8% and 0.3% [upper 95% confidence limit, 1.2%], respectively). Past history of pain and degree of tissue damage at delivery accounted for 7.0% and 16.7%, respectively, of one aspect in the variability in acute post-delivery pain. Neither of these factors was associated with incidence of pain 2 months later. Conclusions:Using a definition of new onset pain from delivery, we show a remarkably low incidence of pain 1 yr after childbirth, including those with surgical delivery. Additionally, degree of tissue trauma and history of chronic pain, risk factors for pain 2 months after other surgery, were unimportant to pain 2 months after cesarean or vaginal delivery.

Intraoperative antiemetic efficacy of prophylactic ondansetron versus droperidol for cesarean section patients under epidural anesthesia

The efficacy of ondansetron and droperidol were evaluated for prophylactic treatment of nausea and vomiting in cesarean section patients under epidural anesthesia.Forty-eight ASA physical status I-II parturients requiring nonemergent cesarean section gave their consent and were randomly assigned into one of three treatment groups (n = 16 each) according to a double-blind, placebo-controlled protocol. When the fetal umbilical cord was clamped, patients received intravenously 8 mg of ondansetron or 0.625 mg of droperidol or saline depending on their treatment group. Ninety-four percent of the ondansetron group, 88% of the droperidol group, and 56% of the placebo group were emesis free. Sixty-nine percent of the ondansetron group, 75% of the droperidol group, and 31% of the placebo group were nausea free. This study showed a significantly lower incidence of nausea and vomiting and a tendency toward less severe emetic symptoms in the ondansetron and the droperidol groups than in the placebo group, but the ondansetron group was not statistically different from the droperidol group. This study is the first to report the antiemetic efficacy of prophylactic ondansetron in cesarean section patients or in patients under epidural anesthesia for abdominal surgery. Both prophylactic ondansetron and droperidol were similarly effective, and significantly better than placebo, in reducing the incidence and severity of intraoperative emetic symptoms in cesarean section patients under epidural anesthesia. (Anesth Analg 1996;83:982-6)

Antiemetic Prophylaxis for Postdischarge Nausea and Vomiting and Impact on Functional Quality of Living During Recovery in Patients with High Emetic Risks: A Prospective, Randomized, Double-Blind Comparison of Two Prophylactic Antiemetic Regimens

BACKGROUND: We compared two antiemetic prophylaxis regimens, their efficacy for preventing postdischarge nausea and vomiting, and their impact on quality of living, during recovery. METHODS: Sixty-four women undergoing outpatient gynecological surgery and at high risk for emesis were randomized into one of two groups. The study group received intraoperative IV dexamethasone 8 mg and ondansetron 4 mg, followed with an 8 mg oral disintegrating ondansetron tablet, to be taken on discharge and in the morning of postoperative days 1 and 2. The control group received only the IV ondansetron 4 mg intraoperatively. The incidence and severity of emetic symptoms and pain were assessed while patients were in the recovery room and via telephone and patient diary for 5 days after discharge. A modified functional living index of emesis was used to assess the impact on quality of living during recovery. RESULTS: Sixty patients, 30 in each group, completed the study. The incidences for postdischarge nausea were 57% and 20%, and for postdischarge vomiting 20% and 3% in the control and study groups, respectively, for the period between the 8th and 120th hours postanesthesia (P < 0.05). Thirty-three percent of the study and 60% of the control group reported that emetic symptoms negatively affected their quality of living (P < 0.05). CONCLUSIONS: When compared with a single dose of intraoperative IV ondansetron prophylaxis, our study regimen of additional intraoperative dexamethasone and once a day ondansetron significantly reduced the incidence of postdischarge nausea and vomiting and its negative impact on quality of living during the first 5 days of recovery.

Dural puncture with a 27-gauge Whitacre needle as part of a combined spinal-epidural technique does not improve labor epidural catheter function.

Background:This prospective, double-blind, randomized study was designed to examine whether the combined spinal–epidural technique without subarachnoid drug administration improved epidural catheter function when compared with the traditional epidural technique. Methods:After institutional review board approval and informed consent, 251 healthy laboring parturients were randomly assigned to either group DP (combined spinal–epidural technique with 27-gauge Whitacre needle dural puncture but without subarachnoid drug administration) or group NoDP (traditional epidural technique). Patient-controlled epidural analgesia was initiated with 0.11% bupivacaine and 2 &mgr;g/ml fentanyl. Top-up doses in 5-ml increments of 0.25% bupivacaine were administered if needed. Previous power analysis revealed that a sample size of 108 patients/group was needed to show a clinically useful reduction of the catheter manipulation rate from 32% to 15%. Results:In groups DP and NoDP, 107 and 123 evaluable patients, respectively, completed the study. Demographics and outcome variables measured, including epidural catheter manipulation and replacement rate, sacral sparing, unilateral block, number of top-up doses, average hourly epidural drug usage, highest sensory blockade level, and labor analgesia quality, were not different between groups. A subgroup of 18 patients without cerebral spinal fluid return during dural puncture had a higher catheter replacement rate than those of groups DP and NoDP, but it did not reach statistical significance. Conclusions:Dural puncture with a 27-gauge Whitacre needle without subarachnoid drug administration during combined spinal–epidural labor analgesia did not improve epidural labor analgesia quality or reduce catheter manipulation or replacement rate when compared with a traditional epidural technique.

Role of Spinal Cyclooxygenase in Human Postoperative and Chronic Pain

Background:Nonsteroidal antiinflammatory drugs are commonly used to treat postoperative and chronic pain. Animal studies suggest that these drugs act, in part, by blocking prostaglandin production in the spinal cord. The authors tested intrathecal ketorolac in patients with chronic or postoperative pain. Methods:After approval of the institutional review board and the Food and Drug Administration, three clinical studies were performed. First, 15 patients receiving chronic intrathecal morphine received 0.5–2.0 mg of intrathecal ketorolac. Second, 12 patients receiving chronic intrathecal morphine received, in a double-blinded, randomized, cross-over design, intrathecal saline or 2.0 mg of ketorolac, with pain intensity as the primary outcome measure. Third, 30 patients undergoing total vaginal hysterectomy received, in a double-blinded, randomized, controlled design, intrathecal saline or 2.0 mg of ketorolac, with bupivacaine with time to first morphine dose after surgery as the primary outcome measure. Results:Patients with chronic pain had many symptoms before intrathecal injection, without worsening of these symptoms from ketorolac. Pain intensity was reduced by intrathecal ketorolac, but this did not differ from placebo. In the first study, pain was reduced by intrathecal ketorolac in patients with high cerebrospinal fluid prostaglandin E2 concentrations but not in those with normal concentrations. Intrathecal ketorolac did not alter time to first morphine after surgery. Conclusions:Intrathecal ketorolac did not relieve chronic pain or extend anesthesia or analgesia from intrathecal bupivacaine administered at the beginning of surgery. Under the conditions of these studies, it seems that spinal cylcooxygenase activity does not contribute to chronic or postoperative pain.

Chronobiology of Subarachnoid Fentanyl for Labor Analgesia

Background:Chronobiology studies the recurrent biologic rhythms that directly affect how an organism interacts with its environment and how its environment affects the organism. The purpose of this study is to determine whether the time of administration influences the analgesic duration of the commonly used subarachnoid fentanyl for labor analgesia. Methods:After institutional review board approval and informed consent were obtained, 77 healthy nulliparous women in active labor requesting neuraxial analgesia were assigned to one of two groups, based on the time of combined spinal–epidural analgesia placement: the day group, for the time period from 12:00 to 18:00, and the night group, for the period from 20:00 to 02:00. Combined spinal–epidural analgesia was performed with 20 &mgr;g subarachnoid fentanyl. An epidural catheter was inserted but not dosed until patients requested further analgesia. Dynamic data were recorded at 5-min intervals for 20 min initially and then every 15 min. The analgesic duration was defined as the time from subarachnoid fentanyl injection to the time the patient requested further analgesia. Results:Seventy evaluable patients completed the study, with 35 per group. Patient demographics, visual analog pain scale scores, and labor characteristics were similar between groups, but the duration (mean ± SD) for subarachnoid fentanyl labor analgesia was 92 ± 34 min for the day group and 67 ± 21 min for the night group (P < 0.001). Conclusions:The results indicate that chronobiology of subarachnoid fentanyl plays a significant role of up to 27% difference in labor analgesic duration between the two administration time periods studied. Chronobiology should be incorporated in future comparative studies or analysis of previous studies on subarachnoid fentanyl.

Success of spinal and epidural labor analgesia: comparison of loss of resistance technique using air versus saline in combined spinal-epidural labor analgesia technique.

Background:Comparison of air versus saline for loss of resistance technique (LORT) in combined spinal epidural labor analgesia (CSE) has not been evaluated, and neither has the relation between CSE characteristics (the presence/absence of initial spontaneous clear fluid return or upon aspiration) and spinal/epidural analgesia outcomes. The authors hypothesized that there is no difference in the spinal analgesia success or epidural catheter efficacy between using air versus saline LORT for CSE. Methods:A total of 360 patients were randomized to air or saline LORT for CSE. Primary outcome was spinal analgesia success as defined by verbal pain score of no more than 3 at 15 min after spinal dose administration. Secondary outcomes were CSE characteristics, catheter replacement, and average hourly epidural drug consumption. Results:Results from 345 patients were analyzed. Spinal analgesia success, epidural catheter replacement, and drug consumption were not different between using air or saline LORT and were also independent of the presence/absence of fluid return on aspiration if initial spontaneous fluid returned to the spinal needle. However, epidural catheters inserted in absence of initial fluid return had a significantly higher catheter replacement rate (28.6%) than the 4.1% among those with initial fluid return (P < 0.03). Conclusions:Spinal analgesia success rate and epidural efficacy are independent of whether air or saline is used for LORT during CSE. Practice of aspiration for fluid after observing initial fluid return may be unnecessary because this practice does not alter spinal/epidural analgesia outcomes. However, epidural catheters inserted with the absence of initial fluid returned to spinal needle may pose a high failure risk.

Predicting Acute Pain after Cesarean Delivery Using Three Simple Questions

Background:Interindividual variability in postoperative pain presents a clinical challenge. Preoperative quantitative sensory testing is useful but time consuming in predicting postoperative pain intensity. The current study was conducted to develop and validate a predictive model of acute postcesarean pain using a simple three-item preoperative questionnaire. Methods:A total of 200 women scheduled for elective cesarean delivery under subarachnoid anesthesia were enrolled (192 subjects analyzed). Patients were asked to rate the intensity of loudness of audio tones, their level of anxiety and anticipated pain, and analgesic need from surgery. Postoperatively, patients reported the intensity of evoked pain. Regression analysis was performed to generate a predictive model for pain from these measures. A validation cohort of 151 women was enrolled to test the reliability of the model (131 subjects analyzed). Results:Responses from each of the three preoperative questions correlated moderately with 24-h evoked pain intensity (r = 0.24–0.33, P < 0.001). Audio tone rating added uniquely, but minimally, to the model and was not included in the predictive model. The multiple regression analysis yielded a statistically significant model (R2 = 0.20, P < 0.001), whereas the validation cohort showed reliably a very similar regression line (R2 = 0.18). In predicting the upper 20th percentile of evoked pain scores, the optimal cut point was 46.9 (z =0.24) such that sensitivity of 0.68 and specificity of 0.67 were as balanced as possible. Conclusions:This simple three-item questionnaire is useful to help predict postcesarean evoked pain intensity, and could be applied to further research and clinical application to tailor analgesic therapy to those who need it most.