Analgesia, pruritus, and ventilation exhibit a dose-response relationship in parturients receiving intrathecal fentanyl during labor

Efficacy of Nalbuphine with Flurbiprofen on Multimodal Analgesia with Transverse Abdominis Plane Block in Elderly Patients Undergoing Open Gastrointestinal Surgery: A Randomized, Controlled, Double-Blinded Trial

Objective

To assess different doses of nalbuphine with flurbiprofen compared to sufentanil with flurbiprofen in multimodal analgesia efficacy for elderly patients undergoing gastrointestinal surgery with a transverse abdominis plane block (TAPB).

Methods

158 elderly patients scheduling for elective open gastrointestinal surgery under general anesthesia and TAPB were randomly assigned to four groups according to different doses of nalbuphine with flurbiprofen in postoperative intravenous analgesia (PCIA). Postoperative pain intensity, effective pressing numbers of PCIA, and adverse effects were recorded at 6, 12, 24, and 48 hours after surgery.

Results

Postoperative pain intensity, effective pressing numbers, and the incidence of postoperative nausea and vomiting (PONV) were similar among the four groups after surgery, while the severity of PONV was decreased in Group L compared with Group S at 6, 12, and 48 h after surgery. No individual experienced pruritus, respiratory depression, or hypotension.

Conclusions

Low dose of nalbuphine (15 μg·kg⁻¹·ml⁻¹) combined with flurbiprofen is superior for elderly patients undergoing elective open gastrointestinal surgery with TAPB in terms of the efficient postoperative analgesia and decreased severity of PONV. This trial is registered with NCT02984865.

Opioid Toxicity

In recent years, there has been a substantial increase in opioid use and abuse, and in opioid-related fatal overdoses. The increase in opioid use has resulted at least in part from individuals transitioning from prescribed opioids to heroin and fentanyl, which can cause significant respiratory depression that can progress to apnea and death. Heroin and fentanyl may be used individually, together, or in combination with other substances such as ethanol, benzodiazepines, or other drugs that can have additional deleterious effects on respiration. Suspicion that a death is drug-related begins with the decedent's medical and social history, and scene investigation, where drugs and drug paraphernalia may be encountered, and examination of the decedent, which may reveal needle punctures and needle track marks. At autopsy, the most significant internal finding that is reflective of opioid toxicity is pulmonary edema and congestion, and frothy watery fluid is often present in the airways. Various medical ailments such as heart and lung disease and obesity may limit an individual's physiologic reserve, rendering them more susceptible to the toxic effects of opioids and other drugs. Although many opioids will be detected on routine toxicology testing, more specialized testing may be warranted for opioid analogs, or other uncommon, synthetic, or semisynthetic drugs.

Understanding Heroin Overdose: A Study of the Acute Respiratory Depressant Effects of Injected Pharmaceutical Heroin

Opioids are respiratory depressants and heroin/opioid overdose is a major contributor to the excess mortality of heroin addicts. The individual and situational variability of respiratory depression caused by intravenous heroin is poorly understood. This study used advanced respiratory monitoring to follow the time course and severity of acute opioid-induced respiratory depression. 10 patients (9/10 with chronic airflow obstruction) undergoing supervised injectable opioid treatment for heroin addiction received their usual prescribed dose of injectable opioid (diamorphine or methadone) (IOT), and their usual prescribed dose of oral opioid (methadone or sustained release oral morphine) after 30 minutes. The main outcome measures were pulse oximetry (SpO2%), end-tidal CO2% (ETCO2%) and neural respiratory drive (NRD) (quantified using parasternal intercostal muscle electromyography). Significant respiratory depression was defined as absence of inspiratory airflow >10s, SpO2% < 90% for >10s and ETCO2% per breath >6.5%. Increases in ETCO2% indicated significant respiratory depression following IOT in 8/10 patients at 30 minutes. In contrast, SpO2% indicated significant respiratory depression in only 4/10 patients, with small absolute changes in SpO2% at 30 minutes. A decline in NRD from baseline to 30 minutes post IOT was also observed, but was not statistically significant. Baseline NRD and opioid-induced drop in SpO2% were inversely related. We conclude that significant acute respiratory depression is commonly induced by opioid drugs prescribed to treat opioid addiction. Hypoventilation is reliably detected by capnography, but not by SpO2% alone. Chronic suppression of NRD in the presence of underlying lung disease may be a risk factor for acute opioid-induced respiratory depression.

Analgesia in Obstetrics

Background: An effective relief of labour pain has become an important part of obstetric medicine. Therefore regional nerve blocks, systemic analgesic and non-pharmacologic techniques are commonly used. This review article gives a summary of pathophysiology and anatomy of labour pain as well as advantages, disadvantages, risks and adverse reactions of analgesic techniques in newborns and parturients. Methods: We performed a selective literature search in Medline via PubMed using the search-terms "Analgesia" and "Obstetrics". We also included the current guidelines of the German Society for Anesthesiology and Intensive Care Medicine. Results: PDA and CSE are safe techniques for the relief of labour pain if contraindications are excluded. The risk for instrumental delivery but not for caesarean section is increased under neuraxial analgesia. PDA and CSE should be performed in an early stage of labour using low doses of local anaesthetics if possible. It is not necessary to wait for a defined cervical dilatation before starting neuraxial analgesia. Anesthesiologists and obstetricians should inform patients as soon as possible before the situation of stress during labour. Systemic opioid analgesia is a possible alternative for neuraxial techniques. Because of possible side effects systemic remifentanil analgesia should only be performed under continuous monitoring. Several nonpharmacologic methods can also relieve labour pain, but results of studies about their effectiveness are inconsistent.

Epidural analgesia for labor: Current techniques

Epidural analgesia is an extremely effective and popular treatment for labor pain. In this review, we trace the history of the use of epidural analgesia and its refinements. We then outline the goals of treatment and methods used to attain those goals. The use of low concentrations of local anesthetics, combined with lipid-soluble opioids, does not impede the progress of labor or depress the newborn. The incidence of side effects is low. Maintenance of analgesia that allows patient control enhances patient satisfaction.

Advances in labor analgesia

The pain of childbirth is arguably the most severe pain most women will endure in their lifetimes. The pain of the early first stage of labor arises from dilation of the lower uterine segment and cervix. Pain from the late first stage and second stage of labor arises from descent of the fetus in the birth canal, resulting in distension and tearing of tissues in the vagina and perineum. An array of regional nerve blocks, systemic analgesic, and nonpharmacologic techniques are currently used for labor analgesia. Nonpharmacologic methods are commonly used, but the effectiveness of these techniques generally lacks rigorous scientific study. Continuous labor support has been shown to decrease the use of pharmacologic analgesia and shorten labor. Intradermal water injections decrease back labor pain. Neuraxial labor analgesia (most commonly epidural or combined spinal-epidural) is the most effective method of pain relief during childbirth, and the only method that provides complete analgesia without maternal or fetal sedation. Current techniques commonly combine a low dose of local anesthetic (bupivacaine or ropivacaine) with a lipid soluble opioid (fentanyl or sufentanil). Neuraxial analgesia does not increase the rate of cesarean delivery compared to systemic opioid analgesia; however, dense neuraxial analgesia may increase the risk of instrumental vaginal delivery.

The effect of celecoxib on intrathecal morphine-induced pruritus in patients undergoing Caesarean section

Pruritus associated with intrathecal opioid administration is particularly common in pregnancy. Nonsteroidal anti-inflammatory drugs (NSAIDs) can reduce the severity of this pruritus but have undesirable side effects. The recent development of drugs that can specifically inhibit the cyclooxygenase 2 isoenzyme have become an attractive alternative. This study was designed to evaluate the efficacy of such a drug (celecoxib) in reducing intrathecal opioid-induced pruritus in a randomised double-blinded study of 60 women undergoing Caesarean section. All of them received spinal anaesthesia with 3 ml of 0.5% hyperbaric bupivacaine and 0.3 mg preservative-free morphine. After delivery of the baby, they received either oral celecoxib 200 mg or placebo. Visual analogue scores for pain and pruritus were measured at 30 min, 2, 4, 8, and 24 h. There was no difference in the severity and onset of pain and pruritus between the two groups. Timing of administration, inadequate dosing and possible altered pharmacokinetics in pregnancy may explain the lack of efficacy.

Intrathecal opioids for combined spinal-epidural analgesia during labour

In <25 years, intrathecal administration of opioids (i.e. spinal analgesia) has evolved from an experimental model into an important therapy for obstetric analgesia and anaesthesia. A small dose of opioid delivered into the CSF provides almost immediate relief from labour pain with minimal risks to the mother and fetus. Careful attention, and prompt treatment when needed, can ameliorate the adverse effects of fetal bradycardia, respiratory depression and pruritus. The major limitation of intrathecal opioids for labour analgesia is the short duration of effect: 90-180 minutes under ideal circumstances. To address this problem, and to increase flexibility for anaesthesia as well as analgesia, the combined spinal-epidural (CSE) technique was developed. The CSE technique involves injection of drugs into the CSF and placement of an epidural catheter. An intrathecally administered opioid provides a rapid onset of labour analgesia without motor block or significant haemodynamic perturbation. The epidural catheter allows ongoing administration of medications to maintain labour analgesia and provides a means of delivering anaesthesia for operative delivery. This review will focus on intrathecally administered opioids as used as part of CSE analgesia. Considerable research has focused on the optimum dose of opioids when delivered intrathecally, with or without adjuncts, in the CSE technique. Fentanyl and sufentanil, two of the lipophilic synthetic opioids, have emerged as the most useful. Bupivacaine, a long-acting local anaesthetic, is often added to prolong the duration of analgesia, although this tends to increase the likelihood of motor blockade of the lower extremities. Comparisons of the CSE technique with standard epidural practices have shown that both are effective means of providing analgesia during labour. Controversy revolves around the incidence of fetal bradycardia following CSE and whether this phenomenon increases the rate of operative deliveries. The rapid onset of analgesia with intrathecally administered opioids must be balanced against the added risks of dural puncture and considered in the context of the whole duration of labour. Ultimately, the decision to choose a CSE technique depends on the experience of the anaesthesia provider and the local availability of drugs, equipment and monitoring capabilities.