Aims and objectives.  This review aims to explore the research available relating to three commonly used pain rating scales, the Visual Analogue Scale, the Verbal Rating Scale and the Numerical Rating Scale. The review provides information needed to understand the main properties of the scales.

Background.  Data generated from pain-rating scales can be easily misunderstood. This review can help clinicians to understand the main features of these tools and thus use them effectively.

Method.  A MedLine review via PubMed was carried out with no restriction of age of papers retrieved. Papers were examined for methodological soundness before being included. The search terms initially included pain rating scales, pain measurement, Visual Analogue Scale, VAS, Verbal Rating Scale, VRS, Numerical/numeric Rating Scale, NRS. The reference lists of retrieved articles were used to generate more papers and search terms. Only English Language papers were examined.

Conclusions.  All three pain-rating scales are valid, reliable and appropriate for use in clinical practice, although the Visual Analogue Scale has more practical difficulties than the Verbal Rating Scale or the Numerical Rating Scale. For general purposes the Numerical Rating Scale has good sensitivity and generates data that can be statistically analysed for audit purposes. Patients who seek a sensitive pain-rating scale would probably choose this one. For simplicity patients prefer the Verbal Rating Scale, but it lacks sensitivity and the data it produces can be misunderstood.

Relevance to clinical practice.  In order to use pain-rating scales well clinicians need to appreciate the potential for error within the tools, and the potential they have to provide the required information. Interpretation of the data from a pain-rating scale is not as straightforward as it might first appear.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2702.2005.01121.x

Pain: a review of three commonly used pain rating scales.

On-line monitoring of volatile organic compounds at pptv levels by means of proton-transfer-reaction mass spectrometry (PTR-MS) medical applications, food control and environmental research

We have examined the effects of pregnancy and sex hormones on calcium-dependent and calcium-independent nitric oxide synthases (NOSs) in the guinea pig. Pregnancy (near term) caused a > 4-fold increase in the activity of calcium-dependent NOS in the uterine artery and at least a doubling in the heart, kidney, skeletal muscle, esophagus, and cerebellum. The increase in NOS activity in the cerebellum during pregnancy was inhibited by the estrogen-receptor antagonist tamoxifen. Treatment with estradiol (but not progesterone) also increased calcium-dependent NOS activity in the tissues examined from both females and males. Testosterone increased calcium-dependent NOS only in the cerebellum. No significant change in calcium-independent NOS activity was observed either during pregnancy or after the administration of any sex hormone. Both pregnancy and estradiol treatment increased the amount of mRNAs for NOS isozymes eNOS and nNOS in skeletal muscle, suggesting that the increases in NOS activity result from enzyme induction. Thus both eNOS and nNOS are subject to regulation by estrogen, an action that could explain some of the changes that occur during pregnancy and some gender differences in physiology and pathophysiology.

https://www.pnas.org/content/pnas/91/11/5212.full.pdf

Induction of calcium-dependent nitric oxide synthases by sex hormones

Diagnosis and management of gestational hypertension and preeclampsia.

ACOG practice bulletin: Clinical management guidelines for obstetrician-gynecologists

Part 1 Basic considerations: physiologic changes of pregnancy anaesthesia and uteroplacental blood flow spinal and epidural anaesthesia local anaesthetics - physiology and pharmacology drugs during pregnancy and lactation. Part 2 The foetus and the neonate: foetal physiology antepartum foetal assessment and therapy intrapartum foetal assessment and therapy neonatal assessment and resuscitation. Part 3 Labour and vaginal delivery: approach to the pregnant patient obstetric management of labour and vaginal delivery childbirth preparation and non-pharmacologic analgesia systemic opioid analgesia inhalation analgesia and ketamine paracervical block, pudendal block and perineal infiltration lumbar and caudal epidural analgesia/anesthesia epidural analgesia, the progress of labour and the method of delivery spinal analgesia/anaesthesia trial of labour after previous Cesarean section. Part 4 Cesarean section: epidural and spinal anaesthesia for Cesarean section general anaesthesia for Cesarean section anaesthesia for foetal distress the patient with a difficult airway post-operative analgesia - systemic opioid techniques post-operative analgesia - epidural and spinal techniques. Part 5 Anaesthetic complications: medicolegal risks in obstetric anaesthesia standards and guidelines in obstetric anaesthesia intrapartum complications of regional anaesthesia dural puncture headache neurologic complications of regional anaesthesia. Part 6 Obstetric complications: preterm labour and delivery breech presentation and multiple gestation the patient with fever and/or infection antepartum and post partum haemorrhage shoulder dystocia, uterine inversion and retained placenta embolic phenomena. Part 7 The parturient with systemic disease: cardiovascular disease endocrine disorders haematologic disorders hepatic and renal disease human immunodeficiency virus hypertensive disorders of pregnancy immunologic disorders malignant hyperthermia neurologic and neuromuscular disorders obesity orthopaedic disorders respiratory disorders substance abuse trauma. Part 8 Non-obstetric surgery before, during and after pregnancy: "in vitro" fertilization problems of early pregnancy non-obstetric surgery during pregnancy postpartum tubal sterilization.

Obstetric Anesthesia: Principles and Practice

BackgroundA common type of study performed by anesthesiologists determines the effect of an intervention on pain reported by groups of patients. The goal of this study was to evaluate the effectiveness of t, analysis of variance (ANOVA), Mann-Whitney, and Kruskal-Wallis tests to compare visual analo

Analysis of statistical tests to compare visual analog scale measurements among groups.

The analgesic efficacy of the continuous epidural infusion of 0.0625% bupivacaine/0.0002% fentanyl was compared with the infusion of 0.125% bupivacaine alone in a randomized, double-blind study of nulliparous women. Each patient received, in sequence: 1)3 ml of 0.5% bupivacaine with 1:200,000 epinep

Continuous Infusion Epidural Analgesia during Labor: A Randomized, Double-blind Comparison of 0.0625% Bupivacaine / 0.0002% Fentanyl Versus 0.125% Bupivacaine

Background Some studies suggest that epidural analgesia prolongs labor and increases the incidence of cesarean section, especially if it is administered before 5 cm cervical dilation. The purpose of the current study was to determine whether early administration of epidural analgesia affects obstetric outcome in nulliparous women who are in spontaneous labor. Methods Informed consent was obtained from 344 healthy nulliparous women with a singleton fetus in a vertex presentation, who requested epidural analgesia during spontaneous labor at at least 36 weeks' gestation. Each patient was randomized to receive either early or late epidural analgesia. Randomization occurred only after the following conditions were met: (1) the patient requested pain relief at that moment, (2) a lumbar epidural catheter had been placed, and (3) the cervix was at least 3 cm but less than 5 cm dilated. Patients in the early group immediately received epidural bupivacaine analgesia. Patients in the late group received 10 mg nalbuphine intravenously. Late-group patients did not receive epidural analgesia until they achieved a cervical dilation of at least 5 cm or until at least 1 h had elapsed after a second dose of nalbuphine. Ten of the 344 patients were excluded because of a protocol violation or voluntary withdrawal from the study. Results Early administration of epidural analgesia did not increase the incidence of oxytocin augmentation, prolong the interval between randomization and the diagnosis of complete cervical dilation, or increase the incidence of malposition of the vertex at delivery. Also, early administration of epidural analgesia did not result in an increased incidence of cesarean section or instrumental vaginal delivery. Seventeen (10%) of 172 women in the early group and 13 (8%) of 162 women in the late group underwent cesarean section (relative risk for the early group 1.22; 95% confidence interval 0.62-2.40). Patients in the early group had lower pain scores between 30 and 150 min after randomization. Infants in the late group had lower umbilical arterial and venous blood pH and higher umbilical venous blood carbon dioxide tension measurements at delivery. Conclusions Early administration of epidural analgesia did not prolong labor, increase the incidence of oxytocin augmentation, or increase the incidence of operative delivery, when compared with intravenous nalbuphine followed by late administration of epidural analgesia, in nulliparous women who were in spontaneous labor at term.

Does early administration of epidural analgesia affect obstetric outcome in nulliparous women who are in spontaneous labor

The updated fourth edition of this comprehensive, highly respected reference covers all you need to know about obstetric anesthesia - from basic science to various anesthesia techniques to complications. The editorial team of leading authorities in the field now features Drs. Linda S. Polley, Lawrence C. Tsen, and Cynthia A. Wong and presents the latest on anesthesia techniques for labor and delivery and medical disorders that occur during pregnancy. This edition features two new chapters and rewritten versions of key chapters such as Epidural and Spinal Analgesia and Anesthesia. And, Expert Consult functionality allows you to access the entire contents of the book online.

David H. Chestnut

Papers

Obstetric Anesthesia: Principles and Practice

Analysis of statistical tests to compare visual analog scale measurements among groups.

Continuous Infusion Epidural Analgesia during Labor: A Randomized, Double-blind Comparison of 0.0625% Bupivacaine / 0.0002% Fentanyl Versus 0.125% Bupivacaine

Does early administration of epidural analgesia affect obstetric outcome in nulliparous women who are in spontaneous labor

Chestnut's obstetric anesthesia : principles and practice