Influence of Ethanol on Oxycodone-induced Respiratory Depression

Brain oxygen responses induced by opioids: focus on heroin, fentanyl, and their adulterants

Opioids are important tools for pain management, but abuse can result in serious health complications. Of these complications, respiratory depression that leads to brain hypoxia is the most dangerous, resulting in coma and death. Although all opioids at large doses induce brain hypoxia, danger is magnified with synthetic opioids such as fentanyl and structurally similar analogs. These drugs are highly potent, act rapidly, and are often not effectively treated by naloxone, the standard of care for opioid-induced respiratory depression. The goal of this review paper is to present and discuss brain oxygen responses induced by opioids, focusing on heroin and fentanyl. In contrast to studying drug-induced changes in respiratory activity, we used chronically implanted oxygen sensors coupled with high-speed amperometry to directly evaluate physiological and drug-induced fluctuations in brain oxygen levels in awake, freely moving rats. First, we provide an overview of brain oxygen responses to physiological stimuli and discuss the mechanisms regulating oxygen entry into brain tissue. Next, we present data on brain oxygen responses induced by heroin and fentanyl and review underlying mechanisms. These data allowed us to compare the effects of these drugs on brain oxygen in terms of their potency, time-dependent response pattern, and potentially lethal effect at high doses. Then, we present the interactive effects of opioids during polysubstance use (alcohol, ketamine, xylazine) on brain oxygenation. Finally, we consider factors that affect the therapeutic potential of naloxone, focusing on dosage, timing of drug delivery, and contamination of opioids by other neuroactive drugs. The latter issue is considered chiefly with respect to xylazine, which strongly potentiates the hypoxic effects of heroin and fentanyl. Although this work was done in rats, the data are human relevant and will aid in addressing the alarming rise in lethality associated with opioid misuse.

Opioid Overdose: Limitations in Naloxone Reversal of Respiratory Depression and Prevention of Cardiac Arrest

Opioids are effective analgesics, but they can have harmful adverse effects, such as addiction and potentially fatal respiratory depression. Naloxone is currently the only available treatment for reversing the negative effects of opioids, including respiratory depression. However, the effectiveness of naloxone, particularly after an opioid overdose, varies depending on the pharmacokinetics and the pharmacodynamics of the opioid that was overdosed. Long-acting opioids, and those with a high affinity at the µ-opioid receptor and/or slow receptor dissociation kinetics, are particularly resistant to the effects of naloxone. In this review, the authors examine the pharmacology of naloxone and its safety and limitations in reversing opioid-induced respiratory depression under different circumstances, including its ability to prevent cardiac arrest.

Pain management following dental trauma and surgical procedures

Surgical procedures and post-traumatic management of dental patients require effective pain management during treatment, but being considerably more invasive than conservative treatments, pain management is required into the postoperative period. Clinical trials on pain intensity following dental surgical procedures (e.g., 3rd molar extraction, implant placement, periodontal, and endodontic surgery) have shown that pain is most intense approximately 5-6 h after completion of the procedure, reaching its peak levels during the first postoperative day. Greatest consumption of analgesics occurs during the first 48-72 h after 3rd molar extraction. For the management of perioperative pain associated with either conservative or surgical dental treatment, the local anesthetics articaine, lidocaine, mepivacaine, and prilocaine are preferred. These drugs, with a vasoconstrictor, provide a rapid onset and a duration of pulpal anesthesia adequate to complete most dental and surgical procedures painlessly. For management of post-traumatic and postsurgical pain, bupivacaine-administered by an appropriate nerve block-near the conclusion of a surgical procedure, can provide the patient with a pain-free period of up to 12 h. Nonsteroidal anti-inflammatory drugs represent the most effective drugs for the management of dental postsurgical pain. NSAIDs, as a group in therapeutic doses, have numbers needed to treat (NNTs) ranging from 2 to 3, while opioid analgesics do not approach those for NSAIDs. A protocol for management of pain following surgical procedures and traumatic injuries is discussed in this paper and includes preemptive NSAID; perioperative pain management; postoperative pain management-local anesthesia; postoperative pain management-analgesics; postoperative telephone call.

Inhaled Δ9-tetrahydrocannabinol does not enhance oxycodone-induced respiratory depression: randomised controlled trial in healthy volunteers

BACKGROUND

In humans, the effect of cannabis on ventilatory control is poorly studied, and consequently, the effect of Δ⁹-tetrahydrocannabinol (THC) remains unknown, particularly when THC is combined with an opioid. We studied the effect of THC on breathing without and with oxycodone pretreatment. We hypothesised that THC causes respiratory depression, which is amplified when THC and oxycodone are combined.

METHODS

In this randomised controlled crossover trial, healthy volunteers were administered inhaled Bedrocan® 100 mg (Bedrocan International B.V., Veendam, The Netherlands), a pharmaceutical-grade high-THC cannabis variant (21.8% THC; 0.1% cannabidiol), after placebo or oral oxycodone 20 mg pretreatment; THC was inhaled 1.5 and 4.5 h after placebo or oxycodone intake. The primary endpoint was isohypercapnic ventilation at an end-tidal Pco₂ of 55 mm Hg or 7.3 kPa (V_E55), measured at 1-h intervals for 7 h after placebo/oxycodone intake.

RESULTS

In 18 volunteers (age 22 yr [3]; 9 [50%] female), oxycodone produced a 30% decrease in V_E55, whereas placebo was without effect on V_E55. The first cannabis inhalation resulted in V_E55 changing from 20.3 (3.1) to 23.8 (2.4) L min^-1 (P=0.06) after placebo, and from 11.8 (2.8) to 13.0 (3.9) L min^-1 (P=0.83) after oxycodone. The second cannabis inhalation also had no effect on V_E55, but slightly increased sedation.

CONCLUSIONS

In humans, THC has no effect on ventilatory control after placebo or oxycodone pretreatment.

CLINICAL TRIAL REGISTRATION

2021-000083-29 (EU Clinical Trials Register.).

Alcohol and aging - An area of increasing concern

Alcohol use is increasing among adults 65 and older and the size of this population is expanding rapidly. Aging is associated with systemic inflammation, sleep disturbances, cancers, cognitive decline, and increased risk of injury and death from falls and other accidents. Alcohol misuse exacerbates and accelerates these age-related changes. Older drinkers are more sensitive to acute alcohol-induced impairments in memory, coordination, reaction time, and driving performance. Oxidative stress and DNA damage resulting from chronic heavy alcohol consumption contribute to an increased risk of cancer, liver disease, and cardiovascular disease. Medication use increases with age and many medications prescribed to older adults can interact negatively with alcohol. The rapid expansion of the population aged 65 and older, combined with higher levels of alcohol use and AUD in the Baby Boomer cohort than the preceding generation, could significantly increase the burden of alcohol on the healthcare system resulting from AUD and alcohol-related injuries and diseases. Screening and brief intervention for hazardous alcohol use among older patients along with education regarding potential interactions between alcohol and medications could substantially reduce the risk of harms from alcohol but currently is underutilized.

Respiratory Effects of Biased Ligand Oliceridine in Older Volunteers: A Pharmacokinetic-Pharmacodynamic Comparison with Morphine

BACKGROUND

Oliceridine is a G protein-biased µ-opioid, a drug class that is associated with less respiratory depression than nonbiased opioids, such as morphine. The authors quantified the respiratory effects of oliceridine and morphine in elderly volunteers. The authors hypothesized that these opioids differ in their pharmacodynamic behavior, measured as effect on ventilation at an extrapolated end-tidal Pco2 at 55 mmHg, V̇E55.

METHODS

This four-arm double-blind, randomized, crossover study examined the respiratory effects of intravenous 0.5 or 2 mg oliceridine and 2 or 8 mg morphine in 18 healthy male and female volunteers, aged 55 to 89 yr, on four separate occasions. Participants' CYP2D6 genotypes were determined, hypercapnic ventilatory responses were obtained, and arterial blood samples were collected before and for 6 h after treatment. A population pharmacokinetic-pharmacodynamic analysis was performed on V̇E55, the primary endpoint; values reported are median ± standard error of the estimate.

RESULTS

Oliceridine at low dose was devoid of significant respiratory effects. High-dose oliceridine and both morphine doses caused a rapid onset of respiratory depression with peak effects occurring at 0.5 to 1 h after opioid dosing. After peak effect, compared with morphine, respiratory depression induced by oliceridine returned faster to baseline. The effect-site concentrations causing a 50% depression of V̇E55 were 29.9 ± 3.5 ng/ml (oliceridine) and 21.5 ± 4.6 ng/ml (morphine), the blood effect-site equilibration half-lives differed by a factor of 5: oliceridine 44.3 ± 6.1 min and morphine 214 ± 27 min. Three poor CYP2D6 oliceridine metabolizers exhibited a significant difference in oliceridine clearance by about 50%, causing higher oliceridine plasma concentrations after both low- and high-dose oliceridine, compared with the other participants.

CONCLUSIONS

Oliceridine and morphine differ in their respiratory pharmacodynamics with a more rapid onset and offset of respiratory depression for oliceridine and a smaller magnitude of respiratory depression over time.

EDITOR’S PERSPECTIVE

Oral Oxycodone-Induced Respiratory Depression during Normocapnia and Hypercapnia: A Pharmacokinetic-Pharmacodynamic Modeling Study

The widely prescribed opioid oxycodone may cause lethal respiratory depression. We compared the effects of oxycodone on breathing and antinociception in healthy young volunteers. After pharmacokinetic/pharmacodynamic (PK/PD) modeling, we constructed utility functions to combine the wanted and unwanted end points into a single function. We hypothesized that the function would be predominantly negative over the tested oxycodone concentration range. Twenty-four male and female volunteers received 20 (n = 12) or 40 (n = 12) mg oral oxycodone immediate-release tablets. Hypercapnic ventilatory responses (visit 1) or responses to 3 nociceptive assays (pain pressure, electrical, and thermal tests; visit 2) were measured at regular intervals for 7 hours. the PK/PD analyses, that included carbon dioxide kinetics, stood at the basis of the utility function: probability of antinociception minus probability of respiratory depression. Oxycodone had rapid onset/offset times (30-40 minutes) with potency values (effect-site concentration causing 50% of effect) ranging from 0.05 to 0.13 ng/mL for respiratory variables obtained at hypercapnia and antinociceptive responses. Ventilation at an extrapolated end-tidal carbon dioxide partial pressure of 55 mmHg, was used for creation of 3 utility functions, one for each of the nociceptive tests. Contrary to expectation, the utility functions were close to zero or positive over the clinical oxycodone concentration range. The similar or better likelihood for antinociception relative to respiratory depression may be related to oxycodone's receptor activation profile or to is high likeability that possibly alters the modulation of nociceptive input. Oxycodone differs from other μ-opioids, such as fentanyl, that have a consistent negative utility.

Effect of Paroxetine or Quetiapine Combined With Oxycodone vs Oxycodone Alone on Ventilation During Hypercapnia: A Randomized Clinical Trial

IMPORTANCE

Opioids can cause severe respiratory depression by suppressing feedback mechanisms that increase ventilation in response to hypercapnia. Following the addition of boxed warnings to benzodiazepine and opioid products about increased respiratory depression risk with simultaneous use, the US Food and Drug Administration evaluated whether other drugs that might be used in place of benzodiazepines may cause similar effects.

OBJECTIVE

To study whether combining paroxetine or quetiapine with oxycodone, compared with oxycodone alone, decreases the ventilatory response to hypercapnia.

DESIGN, SETTING, AND PARTICIPANTS

Randomized, double-blind, crossover clinical trial at a clinical pharmacology unit (West Bend, Wisconsin) with 25 healthy participants from January 2021 through May 25, 2021.

INTERVENTIONS

Oxycodone 10 mg on days 1 and 5 and the following in a randomized order for 5 days: paroxetine 40 mg daily, quetiapine twice daily (increasing daily doses from 100 mg to 400 mg), or placebo.

MAIN OUTCOMES AND MEASURES

Ventilation at end-tidal carbon dioxide of 55 mm Hg (hypercapnic ventilation) using rebreathing methodology assessed for paroxetine or quetiapine with oxycodone, compared with placebo and oxycodone, on days 1 and 5 (primary) and for paroxetine or quetiapine alone compared with placebo on day 4 (secondary).

RESULTS

Among 25 participants (median age, 35 years [IQR, 30-40 years]; 11 female [44%]), 19 (76%) completed the trial. The mean hypercapnic ventilation was significantly decreased with paroxetine plus oxycodone vs placebo plus oxycodone on day 1 (29.2 vs 34.1 L/min; mean difference [MD], -4.9 L/min [1-sided 97.5% CI, -∞ to -0.6]; P = .01) and day 5 (25.1 vs 35.3 L/min; MD, -10.2 L/min [1-sided 97.5% CI, -∞ to -6.3]; P < .001) but was not significantly decreased with quetiapine plus oxycodone vs placebo plus oxycodone on day 1 (33.0 vs 34.1 L/min; MD, -1.2 L/min [1-sided 97.5% CI, -∞ to 2.8]; P = .28) or on day 5 (34.7 vs 35.3 L/min; MD, -0.6 L/min [1-sided 97.5% CI, -∞ to 3.2]; P = .37). As a secondary outcome, mean hypercapnic ventilation was significantly decreased on day 4 with paroxetine alone vs placebo (32.4 vs 41.7 L/min; MD, -9.3 L/min [1-sided 97.5% CI, -∞ to -3.9]; P < .001), but not with quetiapine alone vs placebo (42.8 vs 41.7 L/min; MD, 1.1 L/min [1-sided 97.5% CI, -∞ to 6.4]; P = .67). No drug-related serious adverse events were reported.

CONCLUSIONS AND RELEVANCE

In this preliminary study involving healthy participants, paroxetine combined with oxycodone, compared with oxycodone alone, significantly decreased the ventilatory response to hypercapnia on days 1 and 5, whereas quetiapine combined with oxycodone did not cause such an effect. Additional investigation is needed to characterize the effects after longer-term treatment and to determine the clinical relevance of these findings.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04310579.

Respiratory effects of the atypical tricyclic antidepressant tianeptine in human models of opioid-induced respiratory depression

BACKGROUND

Animal data suggest that the antidepressant and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor modulator tianeptine is able to prevent opioid-induced respiratory depression. We hypothesize that oral or intravenous tianeptine can effectively prevent or counteract opioid-induced respiratory depression in humans.

METHODS

Healthy male and female volunteers participated in two studies that had a randomized, double blind, placebo-controlled, crossover design. We first tested oral tianeptine (37.5, 50 and 100 mg, 8 subjects/group) pretreatment followed by induction of alfentanil-induced respiratory depression (alfentanil target concentration 100 ng/mL). Primary endpoint was ventilation at an extrapolated end-tidal carbon dioxide concentration of 55 mmHg (V̇E55). We next determined the ability of four subsequent and increasing infusions of intravenous tianeptine (target tianeptine plasma concentrations 400, 1,000, 1,500 and 2,000 ng/mL, each given over 15 min), to counteract remifentanil-induced respiratory depression in 15 volunteers. Ventilation was measured at isohypercpania (baseline ventilation 20 ± 2 L/min). Primary endpoint was minute ventilation during the 60 min of tianeptine versus placebo infusion.

RESULTS

Alfentanil reduced V̇E55 to 13.7 (95% CI 8.6-18.8) L/min following placebo pretreatment and to 17.9 (10.2-25.7) L/min following 50 mg tianeptine pretreatment (mean difference between treatments 4.2 (-11.5-3.0) L/min, p = 0.070). Intravenous tianeptine in the measured concentration range of 500 to 2,000 ng/ml did not stimulate ventilation but instead worsened remifentanil-induced respiratory depression: tianeptine 9.6 ± 0.8 L/min versus placebo 15.0 ± 0.9 L/min, mean difference 5.3 L/min, 95% CI 2.5-8.2 L/min; p = 0.001, after 1 hour of treatment.

CONCLUSIONS

Neither oral nor intravenous tianeptine were respiratory stimulants. Intravenous tianeptine over the concentration range of 500-2000 ng/mL worsened respiratory depression induced by remifentanil.

Are thyrotropin-releasing hormone (TRH) and analog taltirelin viable reversal agents of opioid-induced respiratory depression?

Opioid‐induced respiratory depression (OIRD) is a potentially life‐threatening complication of opioid consumption. Apart from naloxone, an opioid antagonist that has various disadvantages, a possible reversal strategy is treatment of OIRD with the hypothalamic hormone and neuromodulator thyrotropin‐releasing hormone (TRH). In this review, we performed a search in electronic databases and retrieved 52 papers on the effect of TRH and TRH‐analogs on respiration and their efficacy in the reversal of OIRD in awake and anesthetized mammals, including humans. Animal studies show that TRH and its analog taltirelin stimulate breathing via an effect at the preBötzinger complex, an important respiratory rhythm generator within the brainstem respiratory network. An additional respiratory excitatory effect may be related to TRH’s analeptic effect. In awake and anesthetized rodents, TRH and taltirelin improved morphine‐ and sufentanil‐induced respiratory depression, by causing rapid shallow breathing. This pattern of breathing increases the work of breathing, dead space ventilation, atelectasis, and hypoxia. In awake and anesthetized humans, a continuous infusion of intravenous TRH with doses up to 8 mg, did not reverse sufentanil‐ or remifentanil‐induced respiratory depression. This is related to poor penetration of TRH into the brain compartment but also other causes are discussed. No human data on taltirelin are available. In conclusion, data from animals and human indicate that TRH is not a viable reversal agent of OIRD in awake or anesthetized humans. Further human studies on the efficacy and safety of TRH’s more potent and longer lasting analog taltirelin are needed as this agent seems to be a more promising reversal drug.

Risky alcohol use among patients dispensed opioid medications: A clinical community pharmacy study

BACKGROUND

Included among the significant risk factors for opioid overdose is concomitant use of other central nervous system depressants, particularly alcohol. Given the continued expansion of community pharmacy in the continuum of care, it is imperative to characterize alcohol use among pharmacy patients dispensed opioids in order to establish a foundation for identification and intervention in these settings.

METHODS

This secondary analysis utilized data from a one-time, cross-sectional health assessment conducted among patients dispensed opioid medications in 19 community pharmacies in Indiana and Ohio. Adult, English speaking, patients not receiving cancer care who were dispensed opioid medications were asked to self-report alcohol and substance use, behavioral and physical health, and demographic information. Descriptive and logistic regression analyses were employed to characterize alcohol use/risky alcohol use and patient characteristics associated therewith.

RESULTS

The analytical sample included 1494 individuals. Participants were on average 49 years of age (Standard Deviation=14.9)-with 6% being persons of color (n = 89). Weekly drinking was reported by 18.1% (n = 204) and daily drinking was reported by 6.8% (n = 77) of the study sample, with a total of 143 (9.6%) participants reporting moderate/high risk drinking. Males (Adjusted Odds Ratio [AOR]=1.94, 95% CI=1.3,2.9), those with higher pain interference (AOR=1.44, 95% CI=1.0,2.0), overdose history (AOR=1.93, 95% CI=1.1,3.5), sedative use (AOR=2.11, 95% CI=1.3,3.5), and tobacco use (AOR=2.41, 95% CI=1.6,3.7) had increased likelihood of moderate/high risk alcohol use (all p < 0.05).

CONCLUSIONS

Medication labeling and clinical guidelines clearly indicate that patients should abstain from concomitant use of opioids and alcohol. This study has identified rates and associated risk factors of risky alcohol use among a clinical sample of community pharmacy patients dispensed opioid medications. Continuing this line of research and potential clinical service development has the ability to improve patient safety through addressing a significant gap within the current opioid epidemic.

Postmortem Metabolomics Reveal Acylcarnitines as Potential Biomarkers for Fatal Oxycodone-Related Intoxication

Postmortem metabolomics has recently been suggested as a potential tool for discovering new biological markers able to assist in death investigations. Interpretation of oxycodone concentrations in postmortem cases is complicated, as oxycodone tolerance leads to overlapping concentrations for oxycodone intoxications versus non-intoxications. The primary aim of this study was to use postmortem metabolomics to identify potential endogenous biomarkers that discriminate between oxycodone-related intoxications and non-intoxications. Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry data from 934 postmortem femoral blood samples, including oxycodone intoxications and controls positive and negative for oxycodone, were used in this study. Data were processed and evaluated with XCMS and SIMCA. A clear trend in group separation was observed between intoxications and controls, with a model sensitivity and specificity of 80% and 76%. Approximately halved levels of short-, medium-, and long-chain acylcarnitines were observed for oxycodone intoxications in comparison with controls (p < 0.001). These biochemical changes seem to relate to the toxicological effects of oxycodone and potentially acylcarnitines constituting a biologically relevant biomarker for opioid poisonings. More studies are needed in order to elucidate the potential of acylcarnitines as biomarker for oxycodone toxicity and their relation to CNS-depressant effects.

Buprenorphine: a treatment and cause of opioid-induced respiratory depression

Buprenorphine is a partial agonist at the mu opioid receptor. Due to its relatively low maximum effect on respiratory depression it is considered by some to be a safe opioid. But it can produce serious respiratory depression, particularly when combined with sedatives such as benzodiazepines.

Alcohol-involved overdose deaths in US veterans

BACKGROUND

Alcohol-involved overdose deaths are increasing and often occur with other substances but have been minimally studied compared to other causes of overdose.

METHODS

We used national Veterans Health Administration (VHA) records linked to National Death Index data from 2012 to 2018 to examine trends in alcohol-related overdose mortality. Patient characteristics and treatment receipt were compared across categories of alcohol overdose deaths (alcohol-only, alcohol+opioids which may include additional substances, and alcohol+other substances without opioids).

RESULTS

From 2012-2018, 2421 Veterans died from an alcohol-involved overdose (alcohol-only: 868, alcohol+opioids: 1269, alcohol+other substances: 284). The alcohol-involved overdose rate increased 57% during this period. Compared to those who died of an alcohol-only overdose, Veterans who died from alcohol+opioids and alcohol+other substances were more likely Black or Hispanic, and to have an opioid use disorder, but less likely to live in rural areas or to be diagnosed with alcohol use disorder (AUD). Only 32.5% of those who died from alcohol-involved overdose received treatment in a substance use disorder clinic in the year preceding death, compared to 65.1% seen in mental health and 85.7% in primary care. Only 9.5% of Veterans who died from alcohol overdose received medication treatment for AUD and 24.8% received psychotherapy for AUD in the year preceding death.

CONCLUSIONS

Alcohol overdose is increasing primarily related to overdoses involving opioids and other substances. Most patients did not receive any effective medication or psychotherapy treatments for AUD, suggesting further need to identify those at risk and to target treatment for this vulnerable group in healthcare settings.

Ethanol and opioids do not act synergistically to depress excitation in carotid body type I cells

OBJECTIVE

The combination of opioids and ethanol can synergistically depress breathing and the acute ventilatory response to hypoxia. Multiple studies have shown that the underlying mechanisms for this may involve calcium channel inhibition in central neurons. But we have previously identified opioid receptors in the carotid bodies and shown that their activation inhibits calcium influx into the chemosensitive cells. Given that the carotid bodies contribute to the drive to breathe and underpin the acute hypoxic ventilatory response, we hypothesized that ethanol and opioids may act synergistically in these peripheral sensory organs to further inhibit calcium influx and therefore inhibit ventilation.

METHODS

Carotid bodies were removed from 56 Sprague-Dawley rats (1021 days old) and then enzymatically dissociated to allow calcium imaging of isolated chemosensitive type I cells. Cells were stimulated with high K+ in the presence and absence of the µ-opioid agonist [D-Ala2, N-MePhe4, Gly-ol]-enkephalin (DAMGO) (10 µM), a maximal sublethal concentration of ethanol (3 g L-1, 65.1 mM) or a combination of both.

RESULTS

DAMGO alone significantly inhibited Ca2+ influx but this effect was not potentiated by the high concentration of ethanol.

CONCLUSION

These results indicate for the first time that while opioids may suppress breathing via an action at the level of the carotid bodies, ethanol is unlikely to potentiate inhibition via this pathway. Thus, the synergistic effects of ethanol and opioids on ventilatory parameters are likely mediated by central rather than peripheral actions.

Effects of alcohol on brain oxygenation and brain hypoxia induced by intravenous heroin

Alcohol is the most commonly used psychoactive drug, often taken in conjunction with opioid drugs. Since both alcohol and opioids can induce CNS depression, it is often assumed that alcohol potentiates the known hypoxic effects of opioid drugs. To address this supposition, we used oxygen sensors to examine the effects of alcohol on brain oxygenation and hypoxic responses induced by intravenous heroin in awake, freely moving rats. To eliminate robust sensory effects of alcohol following its oral or intraperitoneal delivery, alcohol was administered directly into the stomach via chronically implanted intragastric catheters at human relevant doses. Alcohol delivered at a 0.5 g/kg dose did not affect brain oxygen levels, except for a weak transient increase during drug delivery. This phasic oxygen increase was stronger at a 2.0 g/kg alcohol dose and followed by a weaker tonic increase. Since alcohol absorption from intragastric delivery is much slower and more prolonged than with intraperitoneal or intravenous injections, the rapid rise of brain oxygen levels suggests that alcohol has a direct action on sensory afferents in the stomach well before the drug physically reaches brain tissue via circulation. Despite slow tonic increases in brain oxygen, alcohol at the 2.0 g/kg dose strongly potentiates heroin-induced oxygen responses, increasing both the magnitude and duration of oxygen decrease. Therefore, under the influence of alcohol, the use of opioid drugs becomes much more dangerous, increasing brain hypoxia and enhancing the probability of serious health complications, including coma and death.

Different Doses of Oxycodone for Endoscopic Injection Sclerotherapy of Esophageal Varices

Background

The aim of the present study was to evaluate the effects of different doses of oxycodone during endoscopic injection sclerotherapy (EIS) for esophageal varices with painless sclerosing agents.

Material/Methods

A total of 119 patients were randomly divided into 3 groups: Group A, midazolam and 0.075 mg/kg oxycodone (n=40); Group B, midazolam and 0.1 mg/kg oxycodone (n=40); and Group C, midazolam and 0.125 mg/kg oxycodone (n=39). The main observation index was the incidence of body movement during the perioperative period. The secondary indices were additional propofol usage; postoperative analgesic usage; other adverse effects, such as hypoxia, myoclonus, and cough; and satisfaction scores for surgeons and patients.

Results

The incidence rates for body movement during the perioperative period in groups A, B, and C were 33%, 13%, and 0, respectively (P<0.001). The satisfaction scores for surgeons and patients were highest in Group C (0.125 mg/kg oxycodone). The incidence rates for hypoxia before EIS were 15%, 8%, and 33% (P=0.026) and during EIS were 23%, 3%, and 0% (P<0.001), respectively. There were no significant between-group differences with respect to other adverse effects.

Conclusions

The ideal dose of oxycodone for perioperative analgesia during EIS for esophageal varices is 0.125 mg/kg.

Opioid-Associated Out-of-Hospital Cardiac Arrest: Distinctive Clinical Features and Implications for Health Care and Public Responses: A Scientific Statement From the American Heart Association

Opioid overdose is the leading cause of death for Americans 25 to 64 years of age, and opioid use disorder affects >2 million Americans. The epidemiology of opioid-associated out-of-hospital cardiac arrest in the United States is changing rapidly, with exponential increases in death resulting from synthetic opioids and linear increases in heroin deaths more than offsetting modest reductions in deaths from prescription opioids. The pathophysiology of polysubstance toxidromes involving opioids, asphyxial death, and prolonged hypoxemia leading to global ischemia (cardiac arrest) differs from that of sudden cardiac arrest. People who use opioids may also develop bacteremia, central nervous system vasculitis and leukoencephalopathy, torsades de pointes, pulmonary vasculopathy, and pulmonary edema. Emergency management of opioid poisoning requires recognition by the lay public or emergency dispatchers, prompt emergency response, and effective ventilation coupled to compressions in the setting of opioid-associated out-of-hospital cardiac arrest. Effective ventilation is challenging to teach, whereas naloxone, an opioid antagonist, can be administered by emergency medical personnel, trained laypeople, and the general public with dispatcher instruction to prevent cardiac arrest. Opioid education and naloxone distributions programs have been developed to teach people who are likely to encounter a person with opioid poisoning how to administer naloxone, deliver high-quality compressions, and perform rescue breathing. Current American Heart Association recommendations call for laypeople and others who cannot reliably establish the presence of a pulse to initiate cardiopulmonary resuscitation in any individual who is unconscious and not breathing normally; if opioid overdose is suspected, naloxone should also be administered. Secondary prevention, including counseling, opioid overdose education with take-home naloxone, and medication for opioid use disorder, is important to prevent recurrent opioid overdose.

Tolerance to Opioid-Induced Respiratory Depression in Chronic High-Dose Opioid Users: A Model-Based Comparison With Opioid-Naïve Individuals

Chronic opioid consumption is associated with addiction, physical dependence, and tolerance. Tolerance results in dose escalation to maintain the desired opioid effect. Intake of high-dose or potent opioids may cause life-threatening respiratory depression, an effect that may be reduced by tolerance. We performed a pharmacokinetic-pharmacodynamic analysis of the respiratory effects of fentanyl in chronic opioid users and opioid-naïve subjects to quantify tolerance to respiratory depression. Fourteen opioid-naïve individuals and eight chronic opioid users received escalating doses of intravenous fentanyl (opioid-naïve subjects: 75-350 µg/70 kg; chronic users: 250-700 µg/70 kg). Isohypercapnic ventilation was measured and the fentanyl plasma concentration-ventilation data were analyzed using nonlinear mixed-effects modeling. Apneic events occurred in opioid-naïve subjects after a cumulative fentanyl dose (per 70 kg) of 225 (n = 3) and 475 µg (n = 6), and in 7 chronic opioid users after a cumulative dose of 600 (n = 2), 1,100 (n = 2), and 1,800 µg (n = 3). The time course of fentanyl's respiratory depressant effect was characterized using a biophase equilibration model in combination with an inhibitory maximum effect (Emax ) model. Differences in tolerance between populations were successfully modeled. The effect-site concentration causing 50% ventilatory depression, was 0.42 ± 0.07 ng/mL in opioid-naïve subjects and 1.82 ± 0.39 ng/mL in chronic opioid users, indicative of a 4.3-fold sensitivity difference. Despite higher tolerance to fentanyl-induced respiratory depression, apnea still occurred in the opioid-tolerant population indicative of the potential danger of high-dose opioids in causing life-threatening respiratory depression in all individuals, opioid-naïve and opioid-tolerant.

Ventilatory Response to Hypercapnia as Experimental Model to Study Effects of Oxycodone on Respiratory Depression

BACKGROUND

Opioid analgesics used to treat pain can cause respiratory depression. However, this effect has not been extensively studied, and life- threatening, opioid-induced respiratory depression remains difficult to predict. We tested the ventilatory response to hypercapnia for evaluating the pharmacodynamic effect of a drug on respiratory depression.

METHODS

We conducted a randomized, placebo-controlled, double-blind, crossover, study in 12 healthy adult males. Subjects received 2 treatments (placebo and immediate-release oxycodone 30 mg) separated by a 24-hour washout period. Subjects inhaled a mixture of 7% carbon dioxide, 21% oxygen, and 72% nitrogen for 5 minutes to assess respiratory depression. Minute ventilation, respiratory rate, tidal volume, flow rate, end-tidal CO2, and oxygen saturation were recorded continuously at pre-dose and 30, 60, 120, and 180 minutes post-dose. The primary endpoint was the effect on ventilatory response to hypercapnia at 60 minutes post-dose, as assessed by the slope of the linear relationship between minute ventilation and end-tidal CO2.

RESULTS

At 60 minutes post-dose, subjects had a mean slope of 2.4 in the oxycodone crossover period, compared to 0.1 in the placebo period (mean difference, 2.3; 95%CI: 0.2 to 4.5; p = 0.035). Statistical significance was likewise achieved at the secondary time points (30, 120, and 180 minutes post-dose, p <0.05).

CONCLUSIONS

This model for testing ventilatory response to hypercapnia discriminated the effect of 30 mg of oxycodone vs. placebo for up to 3 hours after a single dose. It may serve as a method to predict the relative effect of a drug on respiratory depression.

Variability in antemortem and postmortem blood alcohol concentration levels among fatally injured adults

Background: Excessive alcohol use is a risk factor for injury-related deaths. Postmortem blood samples are commonly used to approximate antemortem blood alcohol concentration (BAC) levels.Objectives: To assess differences between antemortem and postmortem BACs among fatally injured adults admitted to one shock trauma center (STC).Method: Fifty-two adult decedents (45 male, 7 female) admitted to a STC in Baltimore, Maryland during 2006-2016 were included. STC records were matched with records from Maryland's Office of the Chief Medical Examiner (OCME). The antemortem and postmortem BAC distributions were compared. After stratifying by antemortem BACs <0.10 versus ≥0.10 g/dL, differences in postmortem and antemortem BACs were plotted as a function of length of hospital stay.Results: Among the 52 decedents, 22 died from transportation-related injuries, 20 died by homicide or intentional assault, and 10 died from other injuries. The median BAC antemortem was 0.10 g/dL and postmortem was 0.06 g/dL. Thirty-one (59.6%) decedents had antemortem BACs ≥0.08 g/dL versus 22 (42.3%) decedents using postmortem BACs. Postmortem BACs were lower than the antemortem BACs for 42 decedents, by an average of 0.07 g/dL. Postmortem BACs were higher than the antemortem BACs for 10 decedents, by an average of 0.06 g/dL.Conclusion: Postmortem BACs were generally lower than antemortem BACs for the fatally injured decedents in this study, though not consistently. More routine antemortem BAC testing, when possible, would improve the surveillance of alcohol involvement in injuries. The findings emphasize the usefulness of routine testing and recording of BACs in acute care facilities.

Incidence of Respiratory Depression in a Postanesthesia Care Unit in Patients Undergoing Anesthesia Using Opioids

PURPOSE

To analyze the incidence of respiratory depression (RD) in patients undergoing anesthesia using opioids in a postanesthesia care unit.

DESIGN

Retrospective cohort study.

METHODS

Quantitative approach, performed by documentary analysis of medical records in the postanesthesia care unit.

FINDINGS

A total of 330 patients were included in the study, with a prevalence of female (186; 56.36%) and nonobese patients (295; 89.39%). Five cases of RD in the immediate postoperative period were found, corresponding to an incidence of 1.52%. Each case in this study showed different risk factors related to opioid-induced RD.

CONCLUSIONS

Nursing surveillance is essential in the decision-making process regarding the knowledge of physiological, pharmacologic, and risk factors to detect clinical signs of RD.

The Physiology and Maintenance of Respiration: A Narrative Review

Chronic pain is one of the most common reasons adults seek medical care and is often managed with opioid analgesics; however, opioids may cause respiratory depression by suppressing various components of respiration. Respiration is the physiological process that facilitates gas exchange and is mediated through the proper function of and communication among central neural control (respiratory drive), sensory input systems, the lungs, and the muscles involved in respiration. Normal respiratory function can be dampened with the use of central nervous system (CNS) depressants and/or underlying health conditions. Patients with chronic pain are often exposed to CNS depressants other than opioids, including benzodiazepines, barbiturates, nonbenzodiazepine sedative-hypnotics, and ethanol, which can function synergistically with opioids to increase the risk of respiratory depression. Some patients may also have underlying health issues, such as obstructive sleep apnea, that can be exacerbated with the use of opioids and other CNS depressants and further contribute to respiratory depression. Clinicians should have a thorough understanding of respiration, recognize how various CNS depressants suppress it, and take necessary steps to mitigate the risk of opioid-induced respiratory depression by collaborating with a multidisciplinary team (i.e., sleep and pain specialists), choosing appropriate medications, and educating patients on the proper use and storage of opioids.

Benefit and Risk Evaluation of Biased μ-Receptor Agonist Oliceridine versus Morphine

BACKGROUND

To improve understanding of the respiratory behavior of oliceridine, a μ-opioid receptor agonist that selectively engages the G-protein-coupled signaling pathway with reduced activation of the β-arrestin pathway, the authors compared its utility function with that of morphine. It was hypothesized that at equianalgesia, oliceridine will produce less respiratory depression than morphine and that this is reflected in a superior utility.

METHODS

Data from a previous trial that compared the respiratory and analgesic effects of oliceridine and morphine in healthy male volunteers (n = 30) were reanalyzed. A population pharmacokinetic-pharmacodynamic analysis was performed and served as basis for construction of utility functions, which are objective functions of probability of analgesia, P(analgesia), and probability of respiratory depression, P(respiratory depression). The utility function = P(analgesia ≥ 0.5) - P(respiratory depression ≥ 0.25), where analgesia ≥ 0.5 is the increase in hand withdrawal latency in the cold pressor test by at least 50%, and respiratory depression ≥ 0.25 is the decrease of the hypercapnic ventilatory response by at least 25%. Values are median ± standard error of the estimate.

RESULTS

The two drugs were equianalgesic with similar potency values (oliceridine: 27.9 ± 4.9 ng/ml; morphine 34.3 ± 9.7 ng/ml; potency ratio, 0.81; 95% CI, 0.39 to 1.56). A 50% reduction of the hypercapnic ventilatory response by morphine occurred at an effect-site concentration of 33.7 ± 4.8 ng/ml, while a 25% reduction by oliceridine occurred at 27.4 ± 3.5 ng/ml (potency ratio, 2.48; 95% CI, 1.65 to 3.72; P < 0.01). Over the clinically relevant concentration range of 0 to 35 ng/ml, the oliceridine utility function was positive, indicating that the probability of analgesia exceeds the probability of respiratory depression. In contrast, the morphine function was negative, indicative of a greater probability of respiratory depression than analgesia.

CONCLUSIONS

These data indicate a favorable oliceridine safety profile over morphine when considering analgesia and respiratory depression over the clinical concentration range.

Links between suicidal intent, polysubstance use, and medical treatment after non-fatal opioid overdose

BACKGROUND

Suicidal thinking during non-fatal overdose may elevate risk for future completed suicide or intentional overdose. Long-term outcomes following an intentional non-fatal overdose may be improved through specific intervention and prevention responses beyond those designed for unintentional overdoses, yet little research has assessed suicidal intent during overdoses or defined characteristics that differentiate these events from unintentional overdoses.

METHODS

Patients with a history of opioid overdose (n = 274) receiving residential addiction treatment in the Midwestern United States completed self-report surveys to classify their most recent opioid overdose as unintentional, actively suicidal (wanted to die), or passively suicidal (didn't care about the risks). We characterized correlates of intent using descriptive statistics and prevalence ratios. We also examined how intent related to thoughts of self-harm at the time of addiction treatment.

RESULTS

Of opioid overdoses, 51 % involved suicidal intent (44 % passive and 7 % active). Active suicidal intent was positively associated with hospitalization. Active/passive intent (vs. no intent, aPR: 2.2, 95 % CI: 1.4-3.5) and use of ≥5 substances (vs. 1 substance, aPR: 3.6, 95 % CI: 1.2-10.6) at the last opioid overdose were associated with having thoughts of self-harm or suicide in the 2 weeks before survey completion in adjusted models. Participants who reported active/passive intent more commonly used cocaine or crack (27 %) with opioids during their last overdose relative to unintentional overdoses (16 %).

CONCLUSIONS

Over half of opioid overdoses among individuals in addiction treatment involved some degree of suicidal thinking. Identifying patients most at risk will facilitate better targeting of suicide prevention and monitoring services.

Using Death Certificates to Explore Changes in Alcohol-Related Mortality in the United States, 1999 to 2017

BACKGROUND

Alcohol consumption, alcohol-related emergency department visits, and hospitalizations have all increased in the last 2 decades, particularly among women and people middle-aged and older. The purpose of this study was to explore data from death certificates to assess whether parallel changes in alcohol-related mortality occurred in the United States in recent years.

METHODS

U.S. mortality data from the National Center for Health Statistics were analyzed to estimate the annual number and rate of alcohol-related deaths by age, sex, race, and ethnicity between 1999 and 2017 among people aged 16+. Mortality data contained details from all death certificates filed nationally. For each death, an underlying cause and up to 20 multiple or contributing causes were indicated. Deaths were identified as alcohol-related if an alcohol-induced cause was listed as either an underlying or multiple cause. Joinpoint analyses were performed to assess temporal trends.

RESULTS

The number of alcohol-related deaths per year among people aged 16+ doubled from 35,914 to 72,558, and the rate increased 50.9% from 16.9 to 25.5 per 100,000. Nearly 1 million alcohol-related deaths (944,880) were recorded between 1999 and 2017. In 2017, 2.6% of roughly 2.8 million deaths in the United States involved alcohol. Nearly half of alcohol-related deaths resulted from liver disease (30.7%; 22,245) or overdoses on alcohol alone or with other drugs (17.9%; 12,954). Rates of alcohol-related deaths were highest among males, people in age-groups spanning 45 to 74 years, and among non-Hispanic (NH) American Indians or Alaska Natives. Rates increased for all age-groups except 16 to 20 and 75+ and for all racial and ethnic groups except for initial decreases among Hispanic males and NH Blacks followed by increases. The largest annual increase occurred among NH White females. Rates of acute alcohol-related deaths increased more for people aged 55 to 64, but rates of chronic alcohol-related deaths, which accounted for the majority of alcohol-related deaths, increased more for younger adults aged 25 to 34.

CONCLUSIONS

Death certificates suggest that alcohol-related mortality increased in the United States between 1999 and 2017. Given previous reports that death certificates often fail to indicate the contribution of alcohol, the scope of alcohol-related mortality in the United States is likely higher than suggested from death certificates alone. Findings confirm an increasing burden of alcohol on public health and support the need for improving surveillance of alcohol-involved mortality.

Reversal of Partial Neuromuscular Block and the Ventilatory Response to Hypoxia

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Background

The ventilatory response to hypoxia is a life-saving chemoreflex originating at the carotid bodies that is impaired by nondepolarizing neuromuscular blocking agents. This study evaluated the effect of three strategies for reversal of a partial neuromuscular block on ventilatory control in 34 healthy male volunteers on the chemoreflex. The hypothesis was that the hypoxic ventilatory response is fully restored following the return to a train-of-four ratio of 1.

Methods

In this single-center, experimental, randomized, controlled trial, ventilatory responses to 5-min hypoxia (oxygen saturation, 80 ± 2%) and ventilation at hyperoxic isohypercapnia (end-tidal carbon dioxide concentration, 55 mmHg) were obtained at baseline, during rocuronium-induced partial neuromuscular block (train-of-four ratio of 0.7 measured at the adductor pollicis muscle by electromyography), and following reversal until the train-of-four ratio reached unity with placebo (n = 12), 1 mg neostigmine/0.5 mg atropine (n = 11), or 2 mg/kg sugammadex (n = 11).

Results

This study confirmed that low-dose rocuronium reduced the ventilatory response to hypoxia from 0.55 ± 0.22 (baseline) to 0.31 ± 0.21 l · min−1 · %−1 (train-of-four ratio, 0.7; P &lt; 0.001). Following full reversal as measured at the thumb, there was persistent residual blunting of the hypoxic ventilatory response (0.45 ± 0.16 l · min−1 · %−1; train-of-four ratio, 1.0; P &lt; 0.001). Treatment effect was not significant (analysis of covariance, P = 0.299) with chemoreflex impairment in 5 (45%) subjects following sugammadex reversal, in 7 subjects (64%) following neostigmine reversal, and in 10 subjects (83%) after spontaneous reversal to a train-of-four ratio of 1.

Conclusions

Despite full reversal of partial neuromuscular block at the thumb, impairment of the peripheral chemoreflex may persist at train-of-four ratios greater than 0.9 following reversal with neostigmine and sugammadex or spontaneous recovery of the neuromuscular block.

Averting Opioid-induced Respiratory Depression without Affecting Analgesia

The ventilatory control system is highly vulnerable to exogenous administered opioid analgesics. Particularly respiratory depression is a potentially lethal complication that may occur when opioids are overdosed or consumed in combination with other depressants such as sleep medication or alcohol. Fatalities occur in acute and chronic pain patients on opioid therapy and individuals that abuse prescription or illicit opioids for their hedonistic pleasure. One important strategy to mitigate opioid-induced respiratory depression is cotreatment with nonopioid respiratory stimulants. Effective stimulants prevent respiratory depression without affecting the analgesic opioid response. Several pharmaceutical classes of nonopioid respiratory stimulants are currently under investigation. The majority acts at sites within the brainstem respiratory network including drugs that act at α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (ampakines), 5-hydroxytryptamine receptor agonists, phospodiesterase-4 inhibitors, D1-dopamine receptor agonists, the endogenous peptide glycyl-glutamine, and thyrotropin-releasing hormone. Others act peripherally at potassium channels expressed on oxygen-sensing cells of the carotid bodies, such as doxapram and GAL021 (Galleon Pharmaceuticals Corp., USA). In this review we critically appraise the efficacy of these agents. We conclude that none of the experimental drugs are adequate for therapeutic use in opioid-induced respiratory depression and all need further study of efficacy and toxicity. All discussed drugs, however, do highlight potential mechanisms of action and possible templates for further study and development.

Binge Drinking and Prescription Opioid Misuse in the U.S., 2012-2014

INTRODUCTION

Prescription opioids were responsible for approximately 17,000 deaths in the U.S. in 2016. One in five prescription opioid deaths also involve alcohol. Drinkers who misuse prescription opioids (i.e., use without a prescription or use only for the experience or feeling it causes) are at a heightened risk of overdose. However, little is known about the relationship between drinking patterns and prescription opioid misuse.

METHODS

Data were analyzed from 160,812 individuals (aged ≥12 years) who responded to questions about prescription opioid misuse and alcohol consumption in the 2012, 2013, or 2014 National Survey on Drug Use and Health (analyzed in 2017-2018). The prevalence of self-reported past-30-days prescription opioid misuse was assessed by sociodemographic characteristics, other substance use (i.e., cigarettes, marijuana), and drinking patterns. Multiple logistic regression analyses were used to calculate AORs.

RESULTS

From 2012 to 2014, 1.6% (95% CI=1.5, 1.7) of all individuals aged ≥12 years (estimated 4.2 million) and 3.5% (95% CI=3.3, 3.8) of binge drinkers (estimated 2.2 million) reported prescription opioid misuse. Prescription opioid misuse was more common among binge drinkers than among nondrinkers (AOR=1.7, 95% CI=1.5, 1.9). Overall, the prevalence of prescription opioid misuse increased significantly with binge drinking frequency (p-value<0.001).

CONCLUSIONS

More than half of the 4.2 million people who misused prescription opioids during 2012-2014 were binge drinkers, and binge drinkers had nearly twice the odds of misusing prescription opioids, compared with nondrinkers. Widespread use of evidence-based strategies for preventing binge drinking might reduce opioid misuse and overdoses involving alcohol.

Benefit versus Severe Side Effects of Opioid Analgesia

Background

Previous studies integrated opioid benefit and harm into one single function—the utility function—to determine the drug toxicity (respiratory depression) in light of its wanted effect (analgesia). This study further refined the concept of the utility function using the respiratory and analgesic effects of the opioid analgesic alfentanil as example.

Methods

Data from three previous studies in 48 healthy volunteers were combined and reanalyzed using a population pharmacokinetic–pharmacodynamic analysis to create utility probability functions. Four specific conditions were defined: probability of adequate analgesia without severe respiratory depression, probability of adequate analgesia with severe respiratory depression, probability of inadequate analgesia without severe respiratory depression, and probability of inadequate analgesia with severe respiratory depression.

Results

The four conditions were successfully identified with probabilities varying depending on the opioid effect-site concentration. The optimum analgesia probability without serious respiratory depression is reached at an alfentanil effect-site concentration of 68 ng/ml, and exceeds the probability of the most unwanted effect, inadequate analgesia with severe respiratory depression (odds ratio, 4.0). At higher effect-site concentrations the probability of analgesia is reduced and exceeded by the probability of serious respiratory depression.

Conclusions

The utility function was successfully further developed, allowing assessment of specific conditions in terms of wanted and unwanted effects. This approach can be used to compare the toxic effects of drugs relative to their intended effect and may be a useful tool in the development of new compounds to assess their advantage over existing drugs.

Frequent respiratory events in postoperative patients aged 60 years and above

There is limited information on the occurrence of respiratory events in postoperative patients after discharge from the postanesthesia care unit. We studied the respiratory rate (RR) of 68 patients aged 60 years and above during the first 6 hours following elective surgery under general anesthesia to assess the frequency of respiratory events in the care unit and on the ward. RR was derived from the continuous RR counter RespiR8, measuring RR by quantifying the humidity of exhaled air. One-minute-averaged RRs were collected and analyzed to assess the frequency of postoperative bradypnea (RR 1–6 breaths/minute) and apnea (cessation of inspiratory flow ≥60 seconds). Values were median (interquartile range) or mean (SD). The median RR was 13 (10–15) breaths/minute. In the 6-hour postoperative period, 78% and 57% of patients experienced at least one bradypnea or apnea event, respectively. A median of ten (3.5–24) bradypnea and three (1–11) apnea events were detected per patient. The occurrence of respiratory events in the postanesthesia care unit (PACU) was a predictor of events on the ward (bradypnea, r²=0.4, P<0.001; apnea, r²=0.2, P<0.001). Morphine consumption correlated weakly with respiratory events in the PACU, but not on the ward. Patients with apnea had significantly larger neck circumference than patients without (39.6 [0.7] versus 37.4 [0.8] cm, P<0.05). Bradypneic or apneic respiratory events are frequent in postoperative elderly patients and even occur relatively late after surgery. Continuous respiratory monitoring on the ward, especially in patients with risk factors, such as early occurrence of events, opioid use, and larger neck circumference, is likely warranted.

The analgesic efficacy of oxycodone hydrochloride versus fentanyl during outpatient artificial abortion operation: A randomized trial

BACKGROUND

Problems like body movement, respiratory depression, and complained of pain are still common phenomenon in outpatient artificial abortion general anesthesia. Oxycodone hydrochloride is a semisynthetic opioid and has a good therapeutic effect on visceral pain. We hypothesize that oxycodone hydrochloride would be superior to fentanyl in outpatient artificial abortion surgery.

METHODS

In this clinical trial 149 American Society of Anesthesiologists (ASA) I or II female outpatients scheduled for elective artificial abortion surgeries under general anesthesia were randomly divided into 3 groups: oxycodone hydrochloride 0.06 mg/kg group (group A), oxycodone hydrochloride 0.08 mg/kg group (group B), and control group fentanyl 2 ug/kg (group C). The primary outcome was level body movement and respiratory depression during the surgery, the second outcome included the visual analogue scale (VAS) score 30 minutes after waking.

RESULTS

A total of 120 participants completed the study, n = 40 in each group. There was no significant difference in patients' age, body mass index (BMI), preoperative heart rate, mean arterial blood pressure, consumption dose of propofol, intraoperative body movement type and times, and duration of surgery among the 3 groups (P > .05). Comparing the incidence of intraoperative respiratory depression and SPO2 < 90% among the 3 groups, group C's was significantly higher than those of groups A and B, and the difference was statistically significant (P < .05). Group A had no difference compared with group B. In VAS score 30minutes after waking, group C was the highest, followed by group A, with group B as the lowest. The difference among the 3 groups was statistically significant (P < .05), but a difference delta less than 1 on the VAS scale is not clinically significant.

CONCLUSION

The analgesic effect of oxycodone hydrochloride at 0.06 mg/kg applied to painless artificial abortion surgery is not superior than that of fentanyl, but the incidence of intraoperative respiratory depression and hypoxemia is significantly lower than fentanyl.