Nitrous Oxide Use During Labor: Satisfaction, Adverse Effects, and Predictors of Conversion to Neuraxial Analgesia.

INTRODUCTION: Women desire safe and effective choices for pain management during labor. Currently, neuraxial and opioid analgesia are the most common methods used in the United States. The purpose of this study was to investigate demographic characteristics, safety, and satisfaction in a cohort of parturients who used inhaled nitrous oxide (N2 O) analgesia and to determine predictors of conversion from N2 O to neuraxial analgesia. METHODS: This was a prospective chart review study. Individuals aged at least 18 years who used inhaled N2 O during the first or second stage of labor between March 1, 2016, and July 23, 2017, on the labor and delivery unit of one academic medical center (N = 463) and their neonates were included. Data describing maternal and neonatal factors are reported. Logistic regression and chi-square tests were used to model the effects of oxytocin augmentation, labor induction, parity, prior cesarean birth, pre-N2 O cervical dilatation, and post-N2 O cervical dilatation on the odds of conversion from N2 O to neuraxial analgesia. RESULTS: In this cohort, 31% who chose N2 O for analgesia did not convert to any other analgesic method. Significant positive predictors for conversion from N2 O to neuraxial analgesia included labor induction (odds ratio [OR], 2.9; 95% CI, 1.7-5.0), oxytocin augmentation (OR, 3.1; 95% CI, 1.6-6.0), and labor after cesarean (OR, 6.4; 95% CI, 2.5-16.5). Multiparity (OR, 0.4; 95% CI, 0.2-0.6) and post-N2 O cervical dilatation (OR, 0.8; 95% CI, 0.7-0.9) were negative predictors. Adverse effects related to N2 O use during labor were rare (8%) and were not a significant reason for conversion to neuraxial analgesia. Parturients had moderately high satisfaction with N2 O for pain management (11-point scale, mean [SD], 7.4 [2.9]). Five-minute Apgar scores were 7 or greater in 97.8% of the newborns. DISCUSSION: Understanding predictors of conversion from inhaled N2 O to neuraxial analgesia may assist perinatal care providers in their discussions with women about analgesia options during labor. N2 O is a useful, safe option for labor analgesia in the United States.

Comparison of the effects of sevoflurane and isoflurane anesthesia on the maternal-fetal unit in sheep.

PURPOSE: The aim of this study was to determine the hemodynamic and blood gas effects of inhalational anesthetics on the maternal-fetal sheep unit. The principal hypothesis, tested in chronically instrumented near-term pregnant ewes, was that sevoflurane anesthesia may be safe and useful for the mother and fetus during pregnancy, compared with isoflurane. METHODS: Six chronically instrumented pregnant and 3 nonpregnant ewes were tested repeatedly to establish the minimum alveolar concentration (MAC) for sevoflurane and isoflurane to be used in the hemodynamic and blood gas studies. Progressively increasing concentrations of sevoflurane or isoflurane in oxygen were administered to 12 pregnant ewes. Uterine blood flow, maternal and fetal heart rates, blood pressure, arterial blood gases, and intra-amniotic pressure were subsequently measured. RESULTS: The MAC of sevoflurane was 1.52 +/- 0.1 15% and 1.92 +/- 0.17% in pregnant and nonpregnant ewes, respectively; while the MAC of isoflurane in the pregnant and nonpregnant sheep was 1.02 +/- 0.12% and 1.42 +/- 0.19%, respectively. In both the sevoflurane and isoflurane groups, changes in maternal and fetal blood gases were minimal during exposure to low-dose (0.5-1.0 MAC) inhaled concentrations. Although uterine blood flow was maintained and the fetus remained well oxygenated at higher concentrations of both agents (2.0 MAC of either agent), the agents produced decreases in maternal and fetal arterial pressure. CONCLUSION: A "low-dose" concentration (0.5-1.0 MAC) of sevoflurane may be safe and useful for both mother and fetus during near-term pregnancy. However, a high concentration (1.5-2.0 MAC) of sevoflurane or isoflurane may induce hemodynamic instability in the mother and fetus when administered.

A comparison of Espocan and Tuohy needles for the combined spinal-epidural technique for labor analgesia.

UNLABELLED: When using the needle-through-needle combined spinal-epidural (CSE) technique for labor analgesia, failure to obtain cerebrospinal fluid (CSF), paresthesias, and intrathecal or intravascular migration of the catheter are of concern. Epidural needles with spinal needle apertures, such as the back-hole Espocan (ES) needles, are available and may reduce these risks. We describe the efficacy and adverse events associated with a modified epidural needle (ES) versus a conventional Tuohy needle for CSE. One-hundred parturients requesting labor analgesia (CSE) were randomized into 2 groups: 50-ES 18-gauge modified epidural needle with 27-gauge Pencan atraumatic spinal needle, 50-conventional 18-gauge Tuohy needle with 27-gauge Gertie Marx atraumatic spinal needle. Information on intrathecal or intravascular catheter placement, paresthesia on introduction of spinal needle, failure to obtain CSF through the spinal needle after placement of epidural needle, unintentional dural puncture, and epidural catheter function was obtained. No intrathecal catheter placement occurred in either group. Rates of intravascular catheter placement and unintentional dural puncture were similar between the groups. Significant differences were noted regarding spinal needle-induced paresthesia (14% ES versus 42% Tuohy needles, P = 0.009) and failure to obtain CSF on first attempt (8% ES versus 28% Tuohy needles, P < 0.02). Use of ES needles for CSE significantly reduces paresthesia associated with the insertion of the spinal needle and is associated with more frequent successful spinal needle placement on the first attempt. IMPLICATIONS: The use of modified epidural needles with a back hole for combined spinal-epidural technique significantly reduces paresthesia associated with the insertion of the spinal needle and is associated with more frequent successful spinal needle placement on the first attempt.

Comparison of povidone iodine and DuraPrep, an iodophor-in-isopropyl alcohol solution, for skin disinfection prior to epidural catheter insertion in parturients.

BACKGROUND: Although rare, infectious sequelae of epidural analgesia can occur. A recently marketed antiseptic solution (DuraPrep) which contains an iodophor in isopropyl alcohol, may provide enhanced and longer-lasting antimicrobial activity and thus be useful in the obstetric setting. The purpose of this study was to evaluate the antisepsis achieved with DuraPrep compared with povidone iodine (PI). METHODS: Sixty women in active labor who requested epidural analgesia were randomly assigned to receive skin preparation with either PI or DuraPrep solution. A total of three cultures were obtained from each subject. The first was obtained just prior to skin disinfection, the second was obtained immediately following antisepsis, and the third was obtained just before removal of the catheter. In addition, the distal tip of the catheter was also submitted for culture. RESULTS: The clinical characteristics and the risk factors for infection were similar in the two groups. The proportion of subjects with positive skin cultures immediately after skin disinfection differed significantly between the PI and DuraPrep groups (30 3%, respectively, P = 0.01). The number of subjects with any positive skin cultures at the time of catheter removal was greater in the PI group as compared to the DuraPrep group (97 50%, respectively, P = 0.0001), as was the number of organisms cultured from skin (log CFU 1.93 +/- 0.40 0.90 +/- 0.23, respectively, P = 0.03). Six catheters, all from the PI group, yielded positive cultures by the roll-plate technique. CONCLUSION: As compared to PI, DuraPrep solution was found to provide a greater decrease in the number of positive skin cultures immediately after disinfection, as well as in bacterial regrowth and colonization of the epidural catheters.

The effectiveness of video technology as an adjunct to teach and evaluate epidural anesthesia performance skills.

BACKGROUND: Although video review has been used in teaching, it has not been reported for use as an adjunct to teaching anesthesiology residents. The purpose of the prospective, randomized, blinded study was to determine whether teaching with video review improves epidural anesthesia skills of anesthesiology residents. METHODS: Twenty-two second-year (CA-2) anesthesiology residents beginning their first obstetric anesthesia rotation were assigned to video or non-video groups. All residents were filmed daily as they placed epidural analgesia. Residents assigned to the video group reviewed their tapes twice a week with an attending anesthesiologist, whereas residents assigned to the non-video group never saw their films. Four experienced attending anesthesiologists independently judged videotapes taken on days 1, 15, and 30 and scored the residents for "overall" skill (range of summed overall grades, 0-40), as well as on 13 predetermined criteria. RESULTS: As determined by kappa coefficients, interrater reliability was high among the judges (k = 0.7-0.8). Residents in the video group improved to a greater degree than residents in the non-video group. On day 1, the median overall grades for the video and non-video groups were 21 and 12, respectively. By day 15, the corresponding grades had increased to 32 and 24, respectively (P < 0.01). However, overall median grades continued to improve between days 15 and 30 in the video group only (P < 0.01). CONCLUSIONS: Review of resident videotapes resulted in greater improvement in overall and predetermined performance criteria. In addition, video review was helpful in identifying skills that were inadequately learned, thus allowing for specific teaching in those areas.