Predicting pain after Cesarean delivery: pressure algometry, temporal summation, three-item questionnaire.

PURPOSE: Approximately one in five women will experience severe postoperative pain after Cesarean delivery (CD). Previously, a bedside three-item questionnaire (3-IQ) has shown to predict women experiencing higher evoked pain intensity after CD, with an area under the receiver operator characteristics (ROC) curve of 0.72. We hypothesized that the addition of psychophysical pain tests to the existing 3-IQ would improve the ability to predict severe pain in women undergoing elective CD under spinal anesthesia METHODS: This was a prospective cohort study on women undergoing elective CD under spinal anesthesia. Women were assessed preoperatively using the 3-IQ, pressure algometry (PA) and mechanical temporal summation (TS) response. All women received standard perioperative care, including a multimodal analgesia regimen that included intrathecal fentanyl and morphine. A 0-100 mm visual analogue scale (VAS) was used to assess the severity of pain at rest (VASr) and on movement (VASm) at 24 and 48 hr after surgery. Patient satisfaction and opioid consumption were also recorded. We performed ROC curve analyses to assess whether we could improve the ability to predict our primary outcome of severe pain on movement at 24 hr (VASm24 ≥ 70). RESULTS: We studied 195 women. Median [interquartile range] VASm24 was 53 [32-72] and 28% of patients experienced a VASm24 ≥ 70. The ability to predict a VASm24 ≥ 70 assessed by the area under the ROC curve was 0.64 using the 3-IQ and 0.67 using the 3-IQ combined with TS and PA. CONCLUSION: The addition of PA and TS to the 3-IQ model resulted in a predictive model that performed similarly to the 3-IQ model alone. Further research is warranted in this area to better predict women at risk of severe pain post CD.

RéSUMé: OBJECTIF: Environ une femme sur cinq souffrira de douleur postopératoire sévère après un accouchement par césarienne. Un questionnaire à trois critères (Q3C) administré au chevet de la patiente a déjà été utilisé pour prédire quelles femmes éprouveraient une intensité de douleur évoquée plus élevée après une césarienne, avec une aire sous la courbe ROC de 0,72. Nous avons émis l'hypothèse que l'ajout de tests psychophysiques de douleur au Q3C existant améliorerait notre capacité à prédire la douleur sévère chez les femmes bénéficiant d'une césarienne élective sous rachianesthésie. MéTHODE: Il s'agissait d'une étude de cohorte prospective auprès de femmes bénéficiant d'une césarienne élective sous rachianesthésie. Les femmes ont été évaluées en préopératoire à l'aide du Q3C, de l'algométrie par pression (AP) et de la réponse à une sommation temporale (ST) mécanique. Toutes les femmes ont bénéficié des soins périopératoires standard, ainsi que d'un régime d'analgésie multimodal incluant fentanyl et morphine intrathécaux. Une échelle visuelle analogique (EVA) de 0 à 100 mm a été utilisée pour évaluer la sévérité de la douleur au repos (EVAr) et en mouvement (EVAm) à 24 et 48 heures après la chirurgie. La satisfaction des patientes et la consommation d'opioïdes ont également été enregistrées. Nous avons effectué des analyses de la courbe ROC pour déterminer s'il nous était possible d'améliorer notre capacité à prédire notre critère d'évaluation principal, soit la douleur sévère à la mobilisation à 24 heures (EVAm24 ≥ 70). RéSULTATS: Nous avons étudié 195 femmes. L'EVAm 24 médiane [écart interquartile] était de 53 [32-72] et 28 % des patientes ont noté un score sur l'EVAm24 ≥ 70. La capacité à prédire un score sur l'EVAm24 ≥ 70 tel qu'évalué par la surface sous la courbe ROC était de 0,64 en utilisant le Q3C et de 0,67 en utilisant le Q3C combiné à la ST et l'AP. CONCLUSION: L'ajout de l'AP et de la ST au modèle de Q3C a résulté en un modèle prédictif présentant une performance similaire au modèle de Q3C seul. D'autres recherches sont nécessaires dans ce domaine pour mieux prédire les femmes à risque de douleur sévères après une césarienne.

Comparison of Intermittent Intravenous Boluses of Phenylephrine and Norepinephrine to Prevent and Treat Spinal-Induced Hypotension in Cesarean Deliveries: Randomized Controlled Trial.

BACKGROUND: Phenylephrine (PE) is currently the vasopressor of choice to prevent and treat spinal-induced hypotension at cesarean delivery (CD). However, its use is often associated with reflex bradycardia. Norepinephrine (NE) has been put forward as an alternative vasopressor during CD due to its ability to treat hypotension while maintaining heart rate (HR). Recent studies have focused on the role of NE used as an infusion with favorable results compared to PE. No studies have compared equipotent bolus doses of PE and NE at CD. We hypothesized that when used in equipotent doses as an intermittent bolus regimen to prevent and treat spinal-induced hypotension, NE would result in a reduction in the incidence of bradycardia compared to PE. METHODS: This was a double-blind, randomized clinical trial of women undergoing elective CD under spinal anesthesia. Women were randomized to receive either PE 100 µg or NE 6 µg when the systolic blood pressure (SBP) was below baseline. In addition to the randomized treatment, ephedrine was given intravenously to both groups if the SBP was below baseline and the HR <60 bpm or if the SBP was <80% of baseline for 2 consecutive readings. The primary outcome was bradycardia (HR <50 bpm) in the predelivery period. Secondary outcomes included hypotension (SBP <80% of baseline), hypertension (SBP >120% of baseline), tachycardia (HR >120% of baseline), ≥2 episodes of bradycardia, nausea, vomiting, umbilical artery and vein blood gases, and Apgar scores. RESULTS: One hundred twelve patients were randomized. The incidence of bradycardia was lower in the NE group compared to the PE group (10.7% vs 37.5%; P < .001; difference [95% confidence interval {CI}], -26.8% [-41.8% to -11.7%]), implying an estimated 71% relative reduction (95% CI, 35%-88%). The distribution of the number of bradycardia episodes was also different between the 2 groups (P = .007). Further testing showed that the patients in the PE group had a higher risk of multiple bradycardia episodes (≥2 episodes) compared to the NE group (19.6% for PE versus 3.6% for NE; P = .008). The proportion of patients requiring rescue boluses of ephedrine was lower in the NE group compared to the PE group (7.2% for NE versus 21.4% for PE; P < .03; difference [95% CI], -14.3% [-27.0% to -1.6%]). No differences were observed between the 2 groups in the incidence of other secondary outcomes. CONCLUSIONS: When used as an intermittent bolus regimen to prevent and treat spinal-induced hypotension during CD, NE resulted in a significant reduction in the incidence of bradycardia as compared to an equipotent bolus regimen of PE. We conclude that the hemodynamic profile offered by NE during CD is superior to that of PE due to less fluctuations in HR and possibly cardiac output.

Histone deacetylase inhibitors and a functional potent inhibitory effect on human uterine contractility.

OBJECTIVE: This study was undertaken to investigate the effects of 3 histone deacetylase inhibitors on human uterine contractility. STUDY DESIGN: Biopsy specimens of human myometrium were obtained at elective cesarean section (n = 18). Dissected myometrial strips suspended under isometric conditions, undergoing spontaneous, and oxytocin-induced contractions, were subjected to cumulative additions of 3 histone deacetylase inhibitors: trichostatin A, suberic bishydroxamate (1 nmol/L-10 micromol/L) and valproic acid (100 nmol/L--1 mmol/L). Control experiments were run simultaneously. Integrals of contractile activity were measured by using the PowerLab hardware unit and Chart v3.6 software. Data were analyzed by using 1-way analysis of variance, followed by post hoc analysis. RESULTS: All 3 histone deacetylase inhibitor compounds exerted a potent and cumulative inhibitory effect on spontaneous (n = 18) and oxytocin-induced (n =18) contractility. The mean maximal inhibition values for the 3 compounds were as follows: trichostatin A, 46-54% (P < .05); valproic acid, 35-36% (P < .05); and suberic bishydroxamate, 53-65% (P < .05). CONCLUSION: The histone deacetylase inhibitors trichostatin A, valproic acid, and suberic bishydroxamate exerted a potent inhibitory effect on human uterine contractions. This raises the possibility that this new class of compounds may have tocolytic potential, in addition to their current clinical indications. We speculate that this inhibitory effect may be linked, at least in part, to the ability of histone deacetylase inhibitors to induce the expression of genes involved in maintaining myometrial quiescence via epigenetic mechanisms but may also potentially involve nonepigenetic pathways.