A Randomized Controlled Trial of the Efficacy and Respiratory Effects of Patient-Controlled Intravenous Remifentanil Analgesia and Patient-Controlled Epidural Analgesia in Laboring Women

Comparative efficacy of opioid and non-opioid analgesics in labor pain management: A network meta-analysis

BACKGROUND

Effective labor pain management is crucial for parturient well-being, as it can improve the delivery experience of pregnant women and reduce anxiety and tension. This systematic review and network meta-analysis compared the efficacy and safety of various analgesics, classified by drug category and individual treatment methods, for labor pain control.

METHODS

A comprehensive literature search was conducted in Pubmed, EMBASE, Cochrane Library, and Web of Science databases. All searches commenced from the database's inception to the date of the literature search (May 31, 2023). The Cochrane Risk of Bias 2 tool assessed study bias risk. Network meta-analyses using a random-effects model and odds ratios (ORs) with 95% confidence intervals (CIs) were performed.

RESULTS

Fifteen randomized controlled trials evaluating analgesic interventions in ASA I or II parturients were included. Combination therapies (OR: 5.81; 95% CI, 3.76-7.84; probability: 60%) and non-opioid analgesics (OR: 5.61; 95% CI, 2.91-8.30; probability: 39.2%) were superior to placebo for labor pain relief. Specifically, dexmedetomidine/ropivacaine/sufentanil (OR: 7.32; 95% CI, 2.73-11.89; probability: 40.6%) and dexmedetomidine/ropivacaine (OR: 6.50; 95% CI, 2.51-10.33; probability: 11.9%) combinations, bupivacaine/fentanyl and ropivacaine/sufentanil combinations, and remifentanil monotherapy showed improved analgesic efficacy versus placebo. Dexmedetomidine/ropivacaine reduced parturient nausea and vomiting versus alternatives.

CONCLUSION

Non-opioids, opioids and combinations thereof effectively relieved labor pain. In addition, dexmedetomidine/ropivacaine combination demonstrated analgesic efficacy and lower nausea and vomiting incidence.

Efficacy and safety of different doses of epidural morphine coadministered with low-concentration ropivacaine after cesarean section: A retrospective cohort study

Objective: The optimal dose of epidural morphine after cesarean section (CS) still remains unknown when combined with low-concentration ropivacaine based on a continuous basal infusion (CBI) mode. The aim of this study was to assess the impact of different dose of epidural morphine plus ropivacaine on maternal outcomes.

Materials and methods: Data of parturients who received epidural analgesia for CS at a teaching hospital from March 2021 to June 2022 were retrospectively collected. Parturients were divided into two groups (RM3 group and RM6 group) according to different medication regimens of morphine. The implementation of epidural analgesia was performed with 3 mg morphine in RM3 group and 6 mg morphine in RM6 group in combination with 0.1% ropivacaine via a CBI pump. The primary outcomes included pain intensity at rest and movement and the incidence of urinary retention and pruritus within postoperative 48 h. The secondary outcomes included the incidence and severity of postoperative nausea and vomiting (PONV) and pruritus, the rate of rescue analgesia and grading of motor Block.

Results: Totally, 531 parturients were eligible for the final analysis, with 428 and 103 parturients in the RM3 group and RM6 group, respectively. There were no statistically significant differences in the visual analogue scores (VAS) at rest and movement within postoperative 48 h between the two groups (all p > 0.05). Compared with the RM6 group, the incidence of urinary retention was lower in the RM3 group within 48 h after CS (4.0% vs. 8.7%, p = 0.044). No significant difference was found in the incidence and severity of PONV and pruritus, the rate of rescue analgesia and grading of motor block between RM3 and RM6 groups.

Conclusion: Epidural 3 mg morphine plus 0.1% ropivacaine in a CBI mode can provide equal efficacy and have lower incidence of urinary retention compared with 6 mg morphine after CS.

Comparison of different delivery modalities of epidural analgesia and intravenous analgesia in labour: a systematic review and network meta-analysis

PURPOSE

In labour, neuraxial analgesia is the standard in the provision of pain relief. However, the optimal mode of delivering epidural solution has not been determined, and some parturients may need an alternative to epidural analgesia. We sought to conduct a systematic review and network meta-analysis to compare continuous epidural infusion (CEI), programmed intermittent epidural bolus (PIEB), computer-integrated CEI, computer-integrated PIEB, patient-controlled epidural bolus (PCEA), fentanyl patient-controlled analgesia (PCA), and remifentanil PCA, either alone or in combination.

METHODS

We searched CENTRAL, CINAHL, Ovid Embase, Ovid Medline, and Web of Science for randomized controlled trials that included nulliparous and/or multiparous parturients in spontaneous or induced labour. The maintenance epidural solution had to include a low concentration local anesthetic and an opioid. Specific subgroups in the obstetric population such as preeclampsia were excluded. Network meta-analysis was performed with a frequentist method, and continuous and dichotomous outcomes are presented as mean differences and odds ratios, respectively, with 95% confidence intervals.

RESULTS

Overall, 73 trials were included. For the first coprimary outcome, the need for rescue analgesia, CEI was inferior to PIEB and PIEB + PCEA was superior to PCEA alone, with a low certainty of evidence given the presence of serious limitations and imprecision. The second coprimary outcome, the maternal satisfaction, was improved by PIEB + PCEA compared with CEI + PCEA and PCEA alone, with a low quality of evidence in view of the presence of serious limitations and imprecision. Fentanyl PCA increased the requirement for rescue analgesia and decreased maternal satisfaction relative to many methods of delivering epidural solution. In terms of secondary outcomes, PIEB increased analgesic efficacy compared with CEI, and PCEA reduced local anesthetic consumption at the expense of inferior analgesia relative to CEI and PIEB. PIEB + PCEA was superior to CEI + PCEA in regard to the pain score at 2 h and 4 h, consumption of local anesthetic, incidence of lower lower limb motor blockade and the rate of spontaneous vaginal delivery. Fentanyl and remifentanil PCA did not provide the same level of analgesia as all epidural methods, resulted in increasing analgesic ineffectiveness with time spent in labour, and predisposed to a higher incidence of side effects such as nausea and/or vomiting and sedation. Remifentanil PCA was superior to fentanyl PCA for analgesia at an early time point, and it increased the incidence of oxygen desaturation relative to other strategies of delivering epidural solution.

CONCLUSIONS

Opioid PCA did not provide the same level of analgesia as epidural methods with a higher incidence of side effects. We interpret the findings of our systematic review and network meta-analysis as suggesting PIEB + PCEA to be the optimal delivery mode of epidural solution. Nevertheless, the potential differing importance of the various maternal, fetal, and neonatal outcomes in determining which is optimal has not, to our knowledge, been elucidated yet.

STUDY REGISTRATION

PROSPERO (CRD42021254978); registered 27 May 2021.

The efficacy and safety of remifentanil patient-controlled versus epidural analgesia in labor: A meta-analysis and systematic review

BACKGROUND

Remifentanil patient-controlled analgesia (rPCA) and epidural analgesia (EA) has been used for pain relief in labor. We aimed to evaluate the efficacy and safety of rPCA versus EA in labor, to provide evidence support for clinical analgesia and pain care.

METHODS

We searched PubMed, EMBASE, ScienceDirect, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang and Weipu databases for RCTs comparing rPCA and EA in labor until February 15, 2022. Two researchers independently screened literature and extracted data. RevMan 5.3 software was used for data analysis.

RESULTS

A total of 10 RCTs involving 3086 parturients were enrolled, 1549 parturients received rPCA and 1537 received EA. Meta-analysis indicated that the incidence of intrapartum maternal fever within 1 hour of labor analgesia (OR = 0.43, 95%CI: 0.30~0.62), after 1 hour of labor analgesia (OR = 0.42, 95%CI: 0.20~0.90) in the rPCA was significantly less than that of EA (all P<0.05). The incidence of respiratory depression (OR = 3.56, 95%CI: 2.45~5.16, P<0.001) in the rPCA was significantly higher than that of EA. There were no significant differences in the incidence of Apgar scores<7 at 5 minutes (OR = 1.18, 95%CI: 0.71~1.96, P = 0.53), the patients' satisfaction of pain relief during labor analgesia (SMD = 0.03, 95%CI: -0.40~0.46, P = 0.90) between rPCA and EA (all P>0.05).

CONCLUSION

rPCA can be an optional alternative to EA with similar pain relief and less risk of intrapartum maternal fever. However, rPCA was associated with increased risk of respiratory depression. Future studies with rigorous design and larger sample size are needed to provide more reliable evidences for clinical rPCA and EA use.

Update on Non-neuraxial Labor Analgesia

Purpose of Review

This review will present recent updates for the use of non-neuraxial analgesia for laboring women.

Recent Findings

Non-neuraxial labor analgesia by nitrous oxide and intravenous opioids are described, and safety concerns with regard to remifentanil administration have been a major focus of recent studies. Fentanyl and nitrous oxide offer some efficacy, albeit less than remifentanil, however with a greater safety margin.

Summary

Women may request or require alternatives to neuraxial labor analgesia, in some cases due to concurrent comorbidities. Remifentanil offers the most efficacious alternative analgesia option; however, safety concerns may preclude widespread use.

Effect and Safety of Remifentanil Patient-Controlled Analgesia Compared with Epidural Analgesia in Labor: An Updated Meta-Analysis of Randomized Controlled Trials

PURPOSE

The study was aimed to systematically assess the effect and safety of remifentanil patient-controlled analgesia (rPCA) versus epidural analgesia (EA) during labor.

METHODS

Eligible trials were retrieved from PubMed, EMBASE, ScienceDirect, and Cochrane Library before April 2020. The primary outcomes were patient satisfaction with pain relief and average visual analog scale (VAS) pain scores during labor; the secondary outcomes were rate of spontaneous delivery, oxygen desaturation, maternal hyperthermia, and neonatal Apgar scores <7 at 1 and 5 min.

RESULTS

Eleven studies involving 3,039 parturients were included. We found that parturients receiving rPCA were similarly satisfied with pain relief compared to those receiving EA (standardized mean difference: -0.19; 95% confidence interval [CI]: -0.57, 0.18), though had significantly higher VAS pain scores during labor (weighted mean difference: 1.41; 95% CI: 0.32, 2.50). The rate of spontaneous delivery was comparable. rPCA increased the risk of maternal oxygen desaturation (risk ratio [RR]:3.23, 95% CI: 1.98, 5.30). There was no statistical significance regarding hyperthermia (RR: 0.49, 95% CI: 0.24, 1.01). No significant difference was found for neonatal Apgar scores <7 at 1 and 5 min.

CONCLUSION

rPCA could be an optional alternative for pain relief to EA without worsening maternal satisfaction with pain relief, delivery modes, or neonatal morbidity. However, rPCA was associated with higher pain intensity during labor and higher incidence of maternal oxygen desaturation. The routine use of rPCA in labor must be armed with close respiratory monitoring. Continued well-designed studies are required to provide more robust evidence.

Peripartum considerations in sickle cell disease

PURPOSE OF REVIEW

Pregnancy exacerbates sickle cell disease (SCD) and is associated with increased frequency and severity of complications resulting in high levels of maternal and fetal morbidity and mortality. We review recent recommendations for managing SCD in pregnancy.

RECENT FINDINGS

An updated pathobiological model of SCD now attributes the clinical picture to a vicious cycle of four major cellular disturbances. Management decisions should be guided by an understanding of this upgraded model. Red cell transfusions are a key therapeutic intervention used in managing several acute and chronic complications. Transfusion however has significant drawbacks. The American Society of Hematology recently published transfusion guidelines to support care providers.

SUMMARY

Patients should be managed by a multidisciplinary and experienced team. The perioperative episode is a recognized period of disease exacerbation and informed anesthetic management can contribute to improved patient outcomes.

Remifentanil patient-controlled versus epidural analgesia on intrapartum maternal fever: a systematic review and meta-analysis

Background

Intravenous remifentanil patient-controlled analgesia (RPCA) is an alternative for epidural analgesia (EA) in labor pain relief. However, it remains unknown whether RPCA is superior to EA in decreasing the risk of intrapartum maternal fever during labor.

Methods

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review and meta-analysis was performed by searching PubMed, EMBASE and the Cochrane Central Register of Controlled Trials from inception to April 2019. All randomized controlled trials (RCTs) investigating the risk of intrapartum maternal fever with RPCA compared with EA alone or EA in combination with spinal analgesia during labor were included.

Results

A total of 825 studies were screened, and 6 RCTs including 3341 patients were identified. Compared with EA, RPCA was associated with a significantly lower incidence of intrapartum maternal fever (risk ratio [RR] 0.48, P = 0.02, I² = 49%) during labor analgesia. After excluding 2 trials via the heterogeneity analysis, there was no difference in the incidence of intrapartum fever between patients receiving RPCA and those receiving EA. Satisfaction with pain relief during labor was lower in the RPCA group than that in the EA group (− 10.6 [13.87, − 7.44], P < 0.00001, I² = 0%). The incidence of respiratory depression was significantly greater in the RPCA group than that in the EA group (risk ratio 2.86 [1.65, 4.96], P = 0.0002, I² = 58%). The incidence of Apgar scores < 7 at 5 min in the RPCA group was equivalent to that in the EA group.

Conclusion

There is no solid evidence to illustrate that the incidence of intrapartum maternal fever is lower in patients receiving intravenous RPCA than in patients receiving EA.

Pain management during labor and vaginal birth

Neuraxial analgesia provides excellent pain relief in labor. Optimizing initiation and maintenance of neuraxial labor analgesia requires different strategies. Combined spinal-epidurals or dural puncture epidurals may offer advantages over traditional epidurals. Ultrasound is useful in certain patients. Maintenance of analgesia is best achieved with a background regimen (either programmed intermittent boluses or a continuous epidural infusion) supplemented with patient-controlled epidural analgesia and using dilute local anesthetics combined with opioids such as fentanyl. Nitrous oxide and systemic opioids are also used for pain relief. Nitrous oxide may improve satisfaction despite variable effects on pain. Systemic opioids can be administered by healthcare providers or using patient-controlled analgesia. Appropriate choice of drug should take into account the stage and progression of labor, local safety protocols, and maternal and fetal/neonatal side effects. Pain in labor is complex, and women should fully participate in the decision-making process before any one modality is selected.

Prospective Observational Investigation of Capnography and Pulse Oximetry Monitoring After Cesarean Delivery With Intrathecal Morphine

BACKGROUND

Intrathecal morphine provides excellent analgesia after cesarean delivery; however, respiratory events such as apnea, bradypnea, and hypoxemia have been reported. The primary study aim was to estimate the number of apneas per subject, termed "apnea alert events" (AAEs) defined by no breath for 30-120 seconds, using continuous capnography in women who underwent cesarean delivery.

METHODS

We performed a prospective, observational study with institutional review board approval of women who underwent cesarean delivery with spinal anesthesia containing 150-µg intrathecal morphine. A STOP-Bang obstructive sleep apnea assessment was administered to all women. Women were requested to use continuous capnography and pulse oximetry for 24 hours after cesarean delivery. Nasal sampling cannula measured end-tidal carbon dioxide (EtCO2) and respiratory rate (RR), and oxygen saturation (SpO2) as measured by pulse oximetry. Capnography data were defined as "valid" when EtCO2 >10 mm Hg, RR >5 breaths per minute (bpm), SpO2 >70%, or during apnea (AAE) defined as "no breath" (EtCO2, <5 mm Hg) for 30-120 seconds. Individual respiratory variable alerts were 10-second means of EtCO2 <10 mm Hg, RR <8 bpm, and SpO2 <94%. Nurse observations of RR (hourly and blinded to capnography) are reported.

RESULTS

We recruited 80 women, mean (standard deviation [SD]) 35 (5) years, 47% body mass index >30 kg/m2/weight >90 kg, and 11% with suspected obstructive sleep apnea (known or STOP-Bang score >3). The duration of normal capnography and pulse oximetry data was mean (SD) (range) 8:28 (7:51) (0:00-22:32) and 15:08 (6:42) (1:31-23:07) hours:minutes, respectively; 6 women did not use the capnography. There were 198 AAEs, mean (SD) duration 57 (27) seconds experienced by 39/74 (53%) women, median (95% confidence interval for median) (range) 1 (0-1) (0-29) per subject. Observation of RR by nurses was ≥14 bpm at all time-points for all women, r = 0.05 between capnography and nurse RR (95% confidence interval, -0.04 to 0.14). There were no clinically relevant adverse events for any woman. Sixty-five women (82%) had complaints with the capnography device, including itchy nose, nausea, interference with nursing baby, and overall inconvenience.

CONCLUSIONS

We report 198 AAEs detected by capnography among women who underwent cesarean delivery after receiving intrathecal morphine. These apneas were not confirmed by the intermittent hourly nursing observations. Absence of observer verification precludes distinction between real, albeit nonclinically significant alerts with capnography versus false apneas. Discomfort with the nasal sampling cannula and frequent alerts may impact capnography application after cesarean delivery. No clinically relevant adverse events occurred.

Side Effects of Intravenous Patient-Controlled Analgesia with Remifentanil Compared with Intermittent Epidural Bolus for Labour Analgesia - A Randomized Controlled Trial

INTRODUCTION

Epidural analgesia is considered a gold standard in obstetric anaesthesia and analgesia. However, in situation when it is contraindicated, unwanted by the patient or simply unavailable, remifentanil can be an excellent alternative. The goal of our study is to analyse the side effects of intravenous patient-controlled analgesia (IV PCA) with remifentanil compared with epidural analgesia during delivery.

MATERIAL AND METHODS

This study included 155 pregnant women in term for birth, divided into 2 groups: a remifentanil group (RG), and an epidural group (EG). Patients in the RG received intravenous PCA with remifentanil, while patients in the ЕG received epidural analgesia with programmed intermittent bolus dosing. Our primary outcome was maternal safety; the secondary outcome was neonatal safety.

RESULTS

The results present a significantly lower SaO2 value of the parturients in the RG (96.95 ± 1.4 vs 98.22 ± 0.6), and a significantly higher respiratory rate per minute in the EG at all time points after the onset of analgesia (20.85 ± 1.4 vs 18.67 ± 0.9). There was more frequent sedation, nausea and vomiting in the RG, while in the EG there was a more elevated temperature, itching and irregularities in the CTG record. Regarding the newborn, there was no significant difference between the two groups in the Apgar scores, pH, pCO2, pO2, and bicarbonate, while there was a significantly lower value of the base excess in the RG group.

CONCLUSION

PCA with remifentanil is safe for the mother, foetus and the newborn, with minimal side effects. Continuous respiratory monitoring, oxygen supply and following of all consensus recommendations are mandatory.

A Retrospective Analysis of the Safety and Efficacy of Opioid-free Anesthesia versus Opioid Anesthesia for General Cesarean Section

Introduction While uncommon for cesarean delivery, general anesthesia may be patient requested or necessary due to maternal contraindication. Traditionally, opioids are used as a part of the general anesthetic. Because of their associated complications, it is standard to limit opioid use and fetal narcotic exposure during cesarean delivery. We conducted a retrospective study to evaluate the feasibility of multi-modal opioid-free general anesthesia for cesarean delivery. Methods Electronic medical records were obtained for patients receiving general anesthesia for cesarean delivery of live pregnancies through 2017 at our tertiary care facility. Post-operative pain was estimated using a 10-cm visual analogue scale and by calculating postoperative narcotic requirements in milligram morphine equivalents (MME) over three-time periods: during post-anesthesia recovery in the post-anesthesia care unit (PACU), the first 24 hrs after PACU discharge, and 24-48 hrs after PACU discharge. Apgar scores were also obtained to quantify neonatal effects of the general anesthetic. Results Eight of 17 patients (47.06%) received opioid-free anesthesia (OFA), and nine of 17 patients (52.94%) received anesthesia with opioids (OA). No significant difference was found between groups in terms of postoperative mean Visual Analog Scale (VAS) pain score over each time period. Similarly, no significant difference was found between groups in terms of postoperative narcotics requirement at all study points. Apgar scores were not significantly different between the two groups. Conclusion The OFA group displayed equivalent analgesia to the OA group in terms of self-reported VAS pain scores and postoperative MME. A larger prospective study is recommended to fully evaluate OFA for cesarean delivery.

Electroacupuncture for pain relief in labour inhibits spinal p38 MAPK-mediated prostaglandin E2 release and uterine prostaglandin E2 receptor expression in rats

BACKGROUND

p38 mitogen-activated protein kinase (p38 MAPK) activation involves the release of prostaglandin E2 (PGE2) and hyperalgesia. We have previously reported that electroacupuncture (EA) relieves labour pain, but the potential mechanisms remain unclear.

OBJECTIVE

To observe the effects of EA on labour pain intensity, serum PGE2 levels and the p38 MAPK signalling pathway in rats during labour.

METHODS

Female rats copulated with male rats to induce pregnancy, and then received castor oil to trigger labour. During labour, rats remained untreated (Control group, n=30) or were treated with remifentanil (n=30) or EA at Jiaji (n=30) or SP6+LI4 (n=30), respectively. The warm water tail-flick test was used to assess labour pain. Serum PGE2 levels were measured by ELISA. Protein expression of prostaglandin E2 receptor (PGER2), p38 MAPK and phospholipase A2 (PLA2) were analysed by Western blotting, and mRNA levels were measured by real-time PCR.

RESULTS

EA treatment at Jiaji or SP6+LI4 significantly relieved labour pain, decreased serum PGE2 levels and inhibited protein and gene expression of PGER2 in the myometrium. Moreover, EA reduced protein expression of PLA2 and p38 MAPK, and inhibited phosphorylation of p38 MAPK in the lumbar spinal cord but not in the cerebral grey matter. Additionally, EA markedly decreased mRNA levels of p38 MAPK in the lumbar spinal cord and significantly reduced PLA2-IV mRNA levels in both the lumbar spinal cord and cerebral grey matter.

CONCLUSIONS

This study indicates that EA relieves labour pain through, at least in part, inhibition of spinal p38 MAPK-mediated PGE2 release and uterine PGER2 expression in rats.

Postoperative Analgesic Effects of Different Doses of Epidural Hydromorphone Coadministered with Ropivacaine after Cesarean Section: A Randomized Controlled Trial

Purpose

Single dose of epidural hydromorphone has been introduced to serve as an alternative method for postcesarean section analgesia. However, optimal dose of epidural hydromorphone remains unknown. Hence, we evaluated and compared the analgesic and adverse effects of postoperative different doses of epidural hydromorphone coadministered with ropivacaine after cesarean section.

Methods

Eighty term parturients with elective cesarean section under epidural anesthesia were allocated into four groups. Epidural analgesia was administered with an epidural bolus of either 0 mg (group H0), or 0.2 mg (group H1), or 0.4 mg (group H2), or 0.6 mg (group H3) hydromorphone coadministered with ropivacaine. The primary outcome was the visual analogue pain scores (VAPSs) and rescue opioid consumption (PCIA with sulfentanil) in 24 hours. Adverse effects such as respiratory depression, pruritus, nausea, and vomiting were recorded.

Results

The VAPSs of group H1 at 2, 4, 6, 12 h and 24 h after surgery was similar to group H0. The VAPSs of group H2 at 4 and 6 h postoperatively were significantly decreased when compared to group H0. But, the VAPSs of group H2 at 2, 12, and 24 h postoperatively were similar to those of group H0. The VAPSs of group H3 at 4, 6, 12 h, and 24 h after surgery were significantly decreased when compared to those of group H0. The total sulfentanil consumption in 24 hours was 90 ± 26 μg in group H0, 75 ± 29 μg in group H1, 54 ± 32 μg in group H2, and 15 ± 16 μg in group H0. Adverse effects were comparable in the four groups.

Conclusions

Epidural administration of 0.6 mg hydromorphone coadministered with ropivacaine after cesarean section provided satisfactory pain relief with less sulfentanil consumption. This trial is registered with ChiCTR-IPR-16010026.

Patient-controlled analgesia with remifentanil vs. alternative parenteral methods for pain management in labour: a Cochrane systematic review

We aimed to assess the effectiveness of remifentanil used as intravenous patient-controlled analgesia for the pain of labour. We performed a systematic literature search in December 2015 (updated in December 2016). We included randomised, controlled and cluster-randomised trials of women in labour with planned vaginal delivery receiving patient-controlled remifentanil compared principally with other parenteral and patient-controlled opioids, epidural analgesia and continuous remifentanil infusion or placebo. The primary outcomes were patient satisfaction with pain relief and the occurrence of adverse events for mothers and newborns. We assessed risk of bias for each included study and applied the GRADE approach for the quality of evidence. We included total zero event trials, using a constant continuity correction of 0.01 and a random-effect meta-analysis. Twenty studies were included in the qualitative analysis; within these, 3713 participants were randomised and 3569 analysed. Most of our pre-specified outcomes were not studied in the included trials. However, we found evidence that women using patient-controlled remifentanil were more satisfied with pain relief than women receiving parenteral opioids (four trials, 216 patients, very low quality evidence) with a standardised mean difference ([SMD] 95%CI) of 2.11 (0.72-3.49), but were less satisfied than women receiving epidural analgesia (seven trials, 2135 patients, very low quality evidence), -0.22 (-0.40 to -0.04). Data on adverse events were sparse. However, the relative risk (95%CI) for maternal respiratory depression for patient-controlled remifentanil compared with epidural analgesia (three trials, 687 patients, low-quality evidence) was 0.91 (0.51-1.62). Compared with continuous intravenous infusion of remifentanil (two trials, 135 patients, low-quality evidence) no conclusion could be reached as all study arms showed zero events. The relative risk (95%CI) of Apgar scores less than 7 at 5 min after birth compared with epidural analgesia (five trials, 1322 participants, low-quality evidence) was 1.26 (0.62-2.57).

A Review of the Impact of Obstetric Anesthesia on Maternal and Neonatal Outcomes

Obstetric anesthesia has evolved over the course of its history to encompass comprehensive aspects of maternal care, ranging from cesarean delivery anesthesia and labor analgesia to maternal resuscitation and patient safety. Anesthesiologists are concerned with maternal and neonatal outcomes, and with preventing and managing complications that may present during childbirth. The current review will focus on recent advances in obstetric anesthesia, including labor anesthesia and analgesia, cesarean delivery anesthesia and analgesia, the effects of maternal anesthesia on breastfeeding and fever, and maternal safety. The impact of these advances on maternal and neonatal outcomes is discussed. Past and future progress in this field will continue to have significant implications on the health of women and children.

Parenteral opioids for maternal pain management in labour

BACKGROUND

Parenteral opioids (intramuscular and intravenous drugs including patient-controlled analgesia) are used for pain relief in labour in many countries throughout the world. This review is an update of a review first published in 2010.

OBJECTIVES

To assess the effectiveness, safety and acceptability to women of different types, doses and modes of administration of parenteral opioid analgesia in labour. A second objective is to assess the effects of opioids in labour on the baby in terms of safety, condition at birth and early feeding.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (11 May 2017) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials examining the use of intramuscular or intravenous opioids (including patient-controlled analgesia) for women in labour. Cluster-randomised trials were also eligible for inclusion, although none were identified. We did not include quasi-randomised trials. We looked at studies comparing an opioid with another opioid, placebo, no treatment, other non-pharmacological interventions (transcutaneous electrical nerve stimulation (TENS)) or inhaled analgesia.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We assessed the quality of each evidence synthesis using the GRADE approach.

MAIN RESULTS

We included 70 studies that compared an opioid with placebo or no treatment, another opioid administered intramuscularly or intravenously or compared with TENS applied to the back. Sixty-one studies involving more than 8000 women contributed data to the review and these studies reported on 34 different comparisons; for many comparisons and outcomes only one study contributed data. All of the studies were conducted in hospital settings, on healthy women with uncomplicated pregnancies at 37 to 42 weeks' gestation. We excluded studies focusing on women with pre-eclampsia or pre-existing conditions or with a compromised fetus. Overall, the evidence was graded as low- or very low-quality regarding the analgesic effect of opioids and satisfaction with analgesia; evidence was downgraded because of study design limitations, and many of the studies were underpowered to detect differences between groups and so effect estimates were imprecise. Due to the large number of different comparisons, it was not possible to present GRADE findings for every comparison.For the comparison of intramuscular pethidine (50 mg/100 mg) versus placebo, no clear differences were found in maternal satisfaction with analgesia measured during labour (number of women satisfied or very satisfied after 30 minutes: 50 women; 1 trial; risk ratio (RR) 7.00, 95% confidence interval (CI) 0.38 to 128.87, very low-quality evidence), or number of women requesting an epidural (50 women; 1 trial; RR 0.50, 95% CI 0.14 to 1.78; very low-quality evidence). Pain scores (reduction in visual analogue scale (VAS) score of at least 40 mm: 50 women; 1 trial; RR 25, 95% CI 1.56 to 400, low-quality evidence) and pain measured in labour (women reporting pain relief to be "good" or "fair" within one hour of administration: 116 women; 1 trial; RR 1.75, 95% CI 1.24 to 2.47, low-quality evidence) were both reduced in the pethidine group, and fewer women requested any additional analgesia (50 women; 1 trial; RR 0.71, 95% CI 0.54 to 0.94, low-quality evidence).There was limited information on adverse effects and harm to women and babies. There were few results that clearly showed that one opioid was more effective than another. Overall, findings indicated that parenteral opioids provided some pain relief and moderate satisfaction with analgesia in labour. Opioid drugs were associated with maternal nausea, vomiting and drowsiness, although different opioid drugs were associated with different adverse effects. There was no clear evidence of adverse effects of opioids on the newborn. We did not have sufficient evidence to assess which opioid drug provided the best pain relief with the least adverse effects.

AUTHORS' CONCLUSIONS

Though most evidence is of low- or very-low quality, for healthy women with an uncomplicated pregnancy who are giving birth at 37 to 42 weeks, parenteral opioids appear to provide some relief from pain in labour but are associated with drowsiness, nausea, and vomiting in the woman. Effects on the newborn are unclear. Maternal satisfaction with opioid analgesia was largely unreported. The review needs to be examined alongside related Cochrane reviews. More research is needed to determine which analgesic intervention is most effective, and provides greatest satisfaction to women with acceptable adverse effects for mothers and their newborn.

Epidural versus non-epidural or no analgesia for pain management in labour

BACKGROUND

Epidural analgesia is a central nerve block technique achieved by injection of a local anaesthetic close to the nerves that transmit pain, and is widely used as a form of pain relief in labour. However, there are concerns about unintended adverse effects on the mother and infant. This is an update of an existing Cochrane Review (Epidural versus non-epidural or no analgesia in labour), last published in 2011.

OBJECTIVES

To assess the effectiveness and safety of all types of epidural analgesia, including combined-spinal-epidural (CSE) on the mother and the baby, when compared with non-epidural or no pain relief during labour.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (ClinicalTrials.gov), the WHO International Clinical Trials Registry Platform (ICTRP) (30 April 2017), and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials comparing all types of epidural with any form of pain relief not involving regional blockade, or no pain relief in labour. We have not included cluster-randomised or quasi-randomised trials in this update.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risks of bias, extracted data and checked them for accuracy. We assessed selected outcomes using the GRADE approach.

MAIN RESULTS

Fifty-two trials met the inclusion criteria and we have included data from 40 trials, involving over 11,000 women. Four trials included more than two arms. Thirty-four trials compared epidural with opioids, seven compared epidural with no analgesia, one trial compared epidural with acu-stimulation, one trial compared epidural with inhaled analgesia, and one trial compared epidural with continuous midwifery support and other analgesia. Risks of bias varied throughout the included studies; six out of 40 studies were at high or unclear risk of bias for every bias domain, while most studies were at high or unclear risk of detection bias. Quality of the evidence assessed using GRADE ranged from moderate to low quality.Pain intensity as measured using pain scores was lower in women with epidural analgesia when compared to women who received opioids (standardised mean difference -2.64, 95% confidence interval (CI) -4.56 to -0.73; 1133 women; studies = 5; I2 = 98%; low-quality evidence) and a higher proportion were satisfied with their pain relief, reporting it to be "excellent or very good" (average risk ratio (RR) 1.47, 95% CI 1.03 to 2.08; 1911 women; studies = 7; I2 = 97%; low-quality evidence). There was substantial statistical heterogeneity in both these outcomes. There was a substantial decrease in the need for additional pain relief in women receiving epidural analgesia compared with opioid analgesia (average RR 0.10, 95% CI 0.04 to 0.25; 5099 women; studies = 16; I2 = 73%; Tau2 = 1.89; Chi2 = 52.07 (P < 0.00001)). More women in the epidural group experienced assisted vaginal birth (RR 1.44, 95% CI 1.29 to 1.60; 9948 women; studies = 30; low-quality evidence). A post hoc subgroup analysis of trials conducted after 2005 showed that this effect is negated when trials before 2005 are excluded from this analysis (RR 1.19, 95% CI 0.97 to 1.46). There was no difference between caesarean section rates (RR 1.07, 95% CI 0.96 to 1.18; 10,350 women; studies = 33; moderate-quality evidence), and maternal long-term backache (RR 1.00, 95% CI 0.89 to 1.12; 814 women; studies = 2; moderate-quality evidence). There were also no clear differences between groups for the neonatal outcomes, admission to neonatal intensive care unit (RR 1.03, 95% CI 0.95 to 1.12; 4488 babies; studies = 8; moderate-quality evidence) and Apgar score less than seven at five minutes (RR 0.73, 95% CI 0.52 to 1.02; 8752 babies; studies = 22; low-quality evidence). We downgraded the evidence for study design limitations, inconsistency, imprecision in effect estimates, and possible publication bias.Side effects were reported in both epidural and opioid groups. Women with epidural experienced more hypotension, motor blockade, fever, and urinary retention. They also had longer first and second stages of labour, and were more likely to have oxytocin augmentation than the women in the opioid group. Women receiving epidurals had less risk of respiratory depression requiring oxygen, and were less likely to experience nausea and vomiting than women receiving opioids. Babies born to women in the epidural group were less likely to have received naloxone. There was no clear difference between groups for postnatal depression, headache, itching, shivering, or drowsiness. Maternal morbidity and long-term neonatal outcomes were not reported.Epidural analgesia resulted in less reported pain when compared with placebo or no treatment, and with acu-stimulation. Pain intensity was not reported in the trials that compared epidural with inhaled analgesia, or continuous support. Few trials reported on serious maternal side effects.

AUTHORS' CONCLUSIONS

Low-quality evidence shows that epidural analgesia may be more effective in reducing pain during labour and increasing maternal satisfaction with pain relief than non-epidural methods. Although overall there appears to be an increase in assisted vaginal birth when women have epidural analgesia, a post hoc subgroup analysis showed this effect is not seen in recent studies (after 2005), suggesting that modern approaches to epidural analgesia in labour do not affect this outcome. Epidural analgesia had no impact on the risk of caesarean section or long-term backache, and did not appear to have an immediate effect on neonatal status as determined by Apgar scores or in admissions to neonatal intensive care. Further research may be helpful to evaluate rare but potentially severe adverse effects of epidural analgesia and non-epidural analgesia on women in labour and long-term neonatal outcomes.

Modern Neuraxial Anesthesia for Labor and Delivery

The availability of safe, effective analgesia during labor has become an expectation for women in most of the developed world over the past two or three decades. More than 60% of women in the United States now receive some kind of neuraxial procedure during labor. This article is a brief review of the advantages and techniques of neuraxial labor analgesia along with the recent advances and controversies in the field of labor analgesia. For the most part, we have aimed the discussion at the non-anesthesiologist to give other practitioners a sense of the state of the art and science of labor analgesia in the second decade of the 21st century.

A Survey of Intravenous Remifentanil Use for Labor Analgesia at Academic Medical Centers in the United States

Remifentanil is most commonly offered when neuraxial labor analgesia is contraindicated. There is no consensus regarding the optimal administration, dosing strategy, or requirements for maternal monitoring, which may pose a patient safety issue. This exploratory survey evaluated the current practices regarding remifentanil use for labor analgesia at academic centers in the United States. Of 126 obstetric anesthesia directors surveyed, 84 (67%) responded. In 2014 to 2015, an estimated 36% (95% confidence interval: 25.7-46.3) of centers used remifentanil, most of which did so less than 5 times. Some serious maternal and neonatal respiratory complications occurred, emphasizing that clinical protocols and adequate monitoring are key to ensure maternal and neonatal safety.

Analysis of Physiological Respiratory Variable Alarm Alerts Among Laboring Women Receiving Remifentanil

BACKGROUND

Remifentanil may be used by laboring women for analgesia, despite controversy because of potential apneas. We evaluated candidate variables as early warning alerts for apnea, based on prevalence, positive predictive rate, sensitivity for apnea event detection, and early warning alert time intervals (lead time) for apnea.

METHODS

We performed a secondary analysis of respiratory physiological data that had been collected during a prospective IRB-approved study of laboring women receiving IV patient-controlled boluses of remifentanil 20 to 60 μg every 1 to 2 minutes. Analyzed data included the respiratory rate (RR), end-tidal CO2 (EtCO2), pulse oximetry (SpO2), heart rate (HR), and the Integrated Pulmonary Index (IPI; Capnostream 20; Medtronic, Boulder, CO) that had been recorded continuously throughout labor. We defined immediate early warning alerts as any drop in a variable value below a prespecified threshold for 15 seconds: RR < 8 breaths per minute (bpm), EtCO2 < 15 mm Hg, and SpO2 < 92%. We defined alerts as "sustained" when the value remained below the threshold for ≥ 10 further seconds. The IPI value (1 to 10; 10 = healthy patient, ≤4 = immediate attention required, 1 = dire condition) was generated from a proprietary algorithm using RR, EtCO2, SpO2, and HR parameters. Apnea was defined as maximal CO2 < 5 mm Hg for at least 30 consecutive seconds.

RESULTS

We counted 62 apneas, among 10 of 19 (52.6%) women who received remifentanil (total dose 1725 ± 1392 μg, administered over 160 ± 132 minutes). We counted 331 immediate early warning alerts for the variables; 271 (82%) alerts were sustained for ≥10 seconds. The positive predictive value of alerts for apnea was 35.8% (99% confidence interval [CI]: 27.1-45.6), 28.9% (99% CI: 20.8-38.7), 4.3% (99% CI: 1.9-9.6), and 24.6% (99% CI: 18.3-32.2) for RR, EtCO2, SpO2, and IPI, respectively. The sensitivity for apnea event detection was 100% (99% CI: 90.3-100) for RR (<8 bpm) and IPI (≤4); 75.8% (99% CI: 59.8-86.9) for EtCO2 <15 mm Hg; and 14.5% (99% CI: 6.5-29.4) for SpO2 <92%. We found a statistically significant difference in the timing of RR, EtCO2, SpO2, and IPI alerts for apnea; Friedman's Q = 33.53; P < .0001. The EtCO2 had a median (interquartile range) lead time of -0.2 (-12.2 to 0.7) seconds, and SpO2 had a median (interquartile range) lead time of 40.0 (40.0 to 40.0) seconds.

CONCLUSIONS

The majority of women receiving IV remifentanil for labor analgesia experienced apneas. Alerts for EtCO2 (<15 mm Hg), RR (<8 bpm), and IPI (≤4) detected most apneas, whereas SpO2 alerts missed the majority of apneas. All variables had a low positive predictive rate, demonstrating the limitations of the respiratory monitors utilized as early warning surveillance for apneas in this setting.

Practice Bulletin No. 177: Obstetric Analgesia and Anesthesia

Labor causes severe pain for many women. There is no other circumstance in which it is considered acceptable for an individual to experience untreated severe pain that is amenable to safe intervention while the individual is under a physician's care. Many women desire pain management during labor and delivery, and there are many medical indications for analgesia and anesthesia during labor and delivery. In the absence of a medical contraindication, maternal request is a sufficient medical indication for pain relief during labor. A woman who requests epidural analgesia during labor should not be deprived of this service based on the status of her health insurance. Third-party payers that provide reimbursement for obstetric services should not deny reimbursement for labor analgesia because of an absence of "other medical indications." Anesthesia services should be available to provide labor analgesia and surgical anesthesia in all hospitals that offer maternal care (levels I-IV) (). Although the availability of different methods of labor analgesia will vary from hospital to hospital, the methods available within an institution should not be based on a patient's ability to pay.The American College of Obstetricians and Gynecologists believes that in order to allow the maximum number of patients to benefit from neuraxial analgesia, labor nurses should not be restricted from participating in the management of pain relief during labor. Under appropriate physician supervision, labor and delivery nursing personnel who have been educated properly and have demonstrated current competence should be able to participate in the management of epidural infusions.The purpose of this document is to review medical options for analgesia during labor and anesthesia for surgical procedures that are common at the time of delivery. Nonpharmacologic options such as massage, immersion in water during the first stage of labor, acupuncture, relaxation, and hypnotherapy are not covered in this document, though they may be useful as adjuncts or alternatives in many cases.

Patient-controlled analgesia with remifentanil versus alternative parenteral methods for pain management in labour

BACKGROUND

Multiple analgesic strategies for pain relief during labour are available. Recently remifentanil, a short-acting opioid, has recently been used as an alternative analgesic due to its unique pharmacological properties.

OBJECTIVES

To systematically assess the effectiveness of remifentanil intravenous patient-controlled analgesia (PCA) for labour pain, along with any potential harms to the mother and the newborn.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (9 December 2015), ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP), handsearched congress abstracts (November 2015), and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and cluster-randomised trials comparing remifentanil (PCA) with another opioid (intravenous (IV)/intramuscular (IM)), or with another opioid (PCA), or with epidural analgesia, or with remifentanil (continuous IV), or with remifentanil (PCA, different regimen), or with inhalational analgesia, or with placebo/no treatment in all women in labour including high-risk groups with planned vaginal delivery.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, extracted data, and appraised study quality.We contacted study authors for additional information other than incomplete outcome data. We performed random-effects meta-analysis.To reduce the risk of random error in meta-analysis we performed trial sequential analysis. We included total zero event trials and used a constant continuity correction of 0.01 (ccc 0.01) for meta-analysis. We applied the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) approach to assess the quality of evidence.

MAIN RESULTS

Twenty RCTs with 3569 women were included. Of those, 10 trials (2983 participants) compared remifentanil (PCA) to an epidural, four trials (216 participants) to another opioid (IV/IM), three trials (215 participants) to another opioid (PCA), two trials (135 participants) to remifentanil (continuous IV), and one trial (20 participants) to remifentanil (PCA, different regimen). No trials were identified for the remaining comparisons.Methodological quality of studies was moderate to poor. We assessed risk of bias as high for blinding issues and incomplete outcome data in 65% and 45% of the included studies, respectively.There is evidence of effect that women in the remifentanil (PCA) group were more satisfied with pain relief than women in the other opioids (IV/IM) group (standardised mean difference (SMD) 2.11, 95% confidence interval (CI) 0.72 to 3.49, four trials, very low-quality evidence), and that women were less satisfied compared to women in the epidural group (SMD -0.22, 95% CI -0.40 to -0.04, seven trials, very low-quality evidence).There is evidence of effect that remifentanil (PCA) provided stronger pain relief at one hour than other opioids administered IV/IM (SMD -1.58, 95% CI -2.69 to -0.48, three trials, very low-quality evidence) or via PCA (SMD -0.51, 95% CI -1.01 to -0.00, three trials, very low-quality evidence). Pain intensity was higher in the remifentanil (PCA) group compared to the epidural group (SMD 0.57, 95% CI 0.31 to 0.84, six trials, low-quality evidence).Data were limited on safety aspects for both the women and the newborns. Only one study analysed maternal apnoea in a comparison of remifentanil (PCA) versus epidural and reported that half of the women in the remifentanil and none in the epidural group had an apnoea (very low-quality evidence). There is no evidence of effect that remifentanil (PCA) was associated with an increased risk for maternal respiratory depression when compared to epidural analgesia (RR 0.91, 95% CI 0.51 to 1.62, ccc 0.01, three trials, low-quality evidence) and no reliable conclusion might be reached compared to remifentanil (continuous IV) (all study arms included zero events, two trials, low-quality evidence). In one trial of remifentanil (PCA) versus another opioid (IM) three out of 18 women in the remifentanil and none out of 18 in the control group had a respiratory depression (very low-quality evidence).There is no evidence of effect that remifentanil (PCA) was associated with an increased risk for newborns with Apgar scores less than seven at five minutes compared to epidural analgesia (RR 1.26, 95% CI 0.62 to 2.57, ccc 0.01, five trials, low-quality evidence) and no reliable conclusion might be reached compared to another opioid (IV) and compared to remifentanil (PCA, different regimen) both with zero events in all study arms (one trial, very-low quality evidence). In one trial of remifentanil (PCA) versus another opioid (PCA) none out of nine newborns in the remifentanil and three out of eight in the opioid (PCA) group had Apgar scores less than seven (very-low quality evidence).There is evidence that remifentanil (PCA) was associated with a lower risk for the requirement of additional analgesia when compared to other opioids (IV/IM) (RR 0.57, 95% CI 0.40 to 0.81, three trials, moderate-quality evidence) and that it was associated with a higher risk compared to epidural analgesia (RR 9.27, 95% CI 3.73 to 23.03, ccc 0.01, six trials, moderate-quality evidence). There is no evidence of effect that remifentanil (PCA) reduced the requirement for additional analgesia compared to other opioids (PCA) (RR 0.76, 95% CI 0.45 to 1.28, three trials, low-quality evidence).There is evidence that there was no difference in the risk for caesarean delivery between remifentanil (PCA) and other opioids (IV/IM) (RR 0.63, 95% CI 0.30 to 1.32, ccc 0.01, four trials, low-quality evidence) and epidural analgesia (RR 1.0, 95% CI 0.82 to 1.22, ccc 0.01, nine trials, moderate-quality evidence), respectively. Pooled meta-analysis revealed an increased risk for caesarean section under remifentanil (PCA) compared to other opioids (PCA) (RR 2.78, 95% CI 0.99 to 7.82, two trials, very low-quality evidence). However, a wide range of clinically relevant and non-relevant treatment effects is compatible with this result.

AUTHORS' CONCLUSIONS

Based on the current systematic review, there is mostly low-quality evidence to inform practice and future research may significantly alter the current situation. The quality of evidence is mainly limited by poor quality of the studies, inconsistency, and imprecision. More research is needed on maternal and neonatal safety outcomes (maternal apnoea and respiratory depression, Apgar score) and on the optimal mode and regimen of remifentanil administration to provide highest efficacy with reasonable adverse effects for mothers and their newborns.

Obstetric analgesia - update 2016

Neuraxial labor analgesia can be initiated via combined spinal-epidural (CSE) or stand-alone epidural. Pros and cons of these techniques are outlined in this review. In recent years computer-integrated patient-controlled epidural analgesia (CI-PCEA) and programed intermittent epidural boluses (PIEB) have been developed, adding to continuous infusion and PCEA for the maintenance of neuraxial analgesia. Postdural puncture headache (PDPH) and fever can occur secondary to labor epidural that both have clinical relevance for the care givers. Insights into the mechanism of epidural fever and treatment strategies for PDPH are outlined. Due to the increase in obesity the specific considerations for this patient group are discussed. New data have been presented for remifentanil, an ultra-shortly acting opioid, that is used in obstetric analgesia. Without breaking new data, the use of nitrous oxide especially by midwives has a kind of renaissance, and this will be discussed, too.

Research: Continuous Surveillance of Sleep Apnea Patients in a Medical-Surgical Unit

This report consists of two separate studies on the use of continuous capnography monitoring conducted in an effort to improve patient safety at Virtua Health System. The desire for improved patient safety is motivating continuous monitoring and improved surveillance in clinical areas not traditionally equipped for such monitoring. We explored the use of remote monitoring of capnography, using enterprise middleware, in patients recovering from surgery in a medical-surgical unit. Continuous monitoring traditionally has been used in higher-acuity settings, such as intensive care units. Patients diagnosed or suspected to have obstructive or central sleep apnea may benefit from the increased surveillance afforded by continuous monitoring. Pain management in this cohort of patients, recovering from bariatric, joint replacement, or other major surgery, often involves administration of opioids (e.g., hydromorphone, morphine sulfate), which are known to increase risk of respiratory depression. Continuous monitoring of these patients increases the likelihood of detecting adverse clinical events. Our goal was to implement continuous monitoring in order to identify alarm conditions caused by adverse clinical events requiring intervention (e.g., opioid-induced respiratory depression) and artifacts related to patient movement, suspect measurements, or other medical device-generated alarm signals.