Postoperative patient-controlled analgesia in the elderly: risks and benefits of epidural versus intravenous administration

Postoperative patient-controlled analgesia provided by the intravenous route using morphine (PCA) or by the epidural route using an opioid in combination with a local anaesthetic (patient-controlled epidural analgesia; PCEA) is not yet routinely used in the elderly. However, this modality theoretically provides adequate control of postoperative pain in such patients. Firstly, an assessment of the level of pain is particularly difficult in the elderly, and patient-controlled techniques that enable the self-administration of analgesic could resolve this problem. Secondly, these techniques provide a fine and controlled titration of analgesic doses. Since analgesic-induced adverse effects increase with age, the risk of overdose is therefore reduced. Thirdly, effective postoperative patient-controlled analgesia may attenuate detrimental physiologic responses, and contribute to improvement in patient outcomes. In the elderly, PCEA provides better pain relief, particularly for dynamic pain, and improves postoperative recovery with a low incidence of adverse effects compared with PCA. PCA and PCEA techniques have a good safety profile in the elderly only when there is careful preoperative patient selection and strict postoperative monitoring. Standard observation of vital signs, sedation and pain scores and assessment of mental status are required. Patient selection is necessary to identify those patients who may be incapable of using the device (e.g. patients with evidence of cognitive dysfunction or physical disabilities). In addition, caution is required among patients with respiratory, renal or hepatic insufficiency. PCA and PCEA are particularly useful for elderly patients undergoing major thoraco-abdominal surgery. However, there is a need for further research in elderly patients. In the future, improvements in the management of postoperative pain in the elderly will lead to a greater expansion of self-controlled techniques.     

Spinal opioid analgesia. A critical update

Small spinal (intrathecal or extrathecal) doses of opioids induce a long-lasting and regional analgesic effect in various experimental animal models. Nowadays extrathecal morphine administration is considered an established method of controlling postoperative and cancer-induced pain conditions. The potency of morphine applied by the spinal route is higher than when the drug is applied by the intravenous (IV) route. Opioids which are more lipophilic than morphine will provide a marginally better analgesic effect when administered by the spinal route as compared with the IV route. Several controlled clinical trials in postoperative patients have demonstrated that a single dose of morphine administered by the spinal route gives a more long-lasting action than a similar IV dose. It is not known whether frequent patient-controlled administration of morphine may provide equally good analgesia without additional side effects. The use of spinal morphine in the treatment of cancer-related pain is based on clinical experience only. There are risks in replacing opioid administration by the oral or IV route with spinal opioids. Morphine should only be used in selected cases until the advantage of spinal opioid analgesia to control postoperative and cancer pain has been clearly defined in well-designed clinical studies. Spinal morphine dosages must be individualised according to the intensity of the nociceptive stimuli and should take into account intra-individual variability in drug responses due to pharmacokinetic and pharmacodynamic factors.     

Efficacy of patient-controlled versus conventional analgesia for postoperative pain

Patient-controlled i.v. administration and intramuscular administration of morphine sulfate were compared in a crossover study to determine their relative effectiveness in relieving postoperative pain. Twenty adult patients scheduled for abdominal surgery were randomly assigned to one of two groups; one group received i.v. morphine sulfate for 24 hours using a patient-controlled analgesia (PCA) device, after which they were given morphine sulfate i.m. for 24 hours. The treatment order was reversed for the other group. Amount of narcotic administered, respiratory rate, and levels of discomfort, activity, and sedation were assessed by the nursing staff every two hours. At the end of each 24-hour treatment phase, patients ranked their level of pain, amount of pain relief, level of sedation, ability to sleep, and ability to perform pulmonary toilet. Patients were also asked whether they preferred PCA or i.m. analgesic therapy for future surgery. Patients reported significantly less discomfort while using PCA than during i.m. morphine administration. No significant differences in amount of narcotic used, respiratory rate, nausea and vomiting, or levels of activity or sedation were noted for the two regimens. Patients' rankings of the two treatment modes did not differ significantly, but a majority of patients indicated a preference for future use of PCA. In these postoperative patients, administration of i.v. morphine sulfate by PCA was as safe as i.m. administration and possibly more effective in relieving pain.     

Morphine at "sub-analgesic" background infusion rate plus low-dose PCA bolus control pain better and is as safe as twice a bolus-only PCA regimen: a randomized, double blind study

Morphine for postoperative pain control is commonly titrated via intravenous patient-controlled analgesia (IV-PCA). An IV morphine background infusion is rarely used. We investigated whether analgesia is effectively attained and morphine consumption is reduced if PCA titration is coadjuvated by a continuous infusion protocol. Following colorectal cancer surgery, consenting patients were randomized to receive a minimal ("sub-analgesic") dose of morphine 0.01 mg/kg/h background infusion plus a 0.01 mg/kg bolus (BI), or a 1.5mg bolus-only morphine (B0) (bolus ratio ～1:2). Bolus lockout time was 7 min in either case. All patients received 0.1mg/kg morphine before protocol initiation, and diclofenac 75 mg intramuscularly b.i.d. during the study period, lasting 48 h. Eighty-six patients (51 males, age 26-95 years) participated in the study. The total mean morphine consumption during the 48 h was 25% lower in the BI than in the B0 group (P<0.05). Although the former applied the PCA device for boluses 19% less than the latter (P<0.05), their pain score was lower (P<0.05) most of the time, and they reported greater satisfaction (P<0.05) on a 10-scale numerical rating score. Pre- and postoperative vital signs were similar for both groups. No patient depicted hypoxemia or lapsed into deep sedation. Four BI and three B0 patients required treatment for postoperative nausea and vomiting. One BI patient had transient pruritus and one B0 69-year individual became disoriented 24h into treatment; either event subsided soon after stopping their respective regimen without the need for treatment. The main conclusions of the results are that very-low-dose background morphine infusion combined with small-dose PCA boluses may provide better pain relief, lower morphine consumption, and minimal complication rate as a 1.5mg PCA bolus-only protocol.     

A computer-based system for controlling plasma opioid concentration according to patient need for analgesia

Microprocessor-controlled infusion pumps, which allow a patient to self-administer bolus doses of an analgesic to relieve pain, are becoming commonplace. While these patient-controlled analgesia (PCA) systems overcome the large interpatient variations in pharmacokinetics, they do not provide steady relief from pain since they rely on delivering a drug in small, incremental doses. To overcome this problem, the authors developed an algorithm and computer-pump system that allows patients to control their own plasma concentration of analgesic. This approach uses individually predetermined pharmacokinetic parameters to provide steady plasma opioid concentrations that can be increased or decreased by the patient in line with the need for more pain relief or fewer side effects. The control software uses a novel, recursive algorithm to compute the pump rates necessary to maintain constant plasma drug (e.g. morphine) concentrations at desired values and to reach a new steady concentration in response to patient requests. This report describes the mathematical approach to the problem of control of plasma opioid concentration, the application of this new drug delivery system to management of persistent pain in cancer patients undergoing bone marrow transplantation, and the magnitude of pharmacokinetic variability with morphine in this patient population. Results are presented from individual patients using this adjustable drug delivery system continuously for up to 2 weeks to control pain from oral mucositis.     

Iontophoretic transdermal fentanyl for the management of acute perioperative pain in hospitalized patients

Introduction: Intravenous (I.V.) morphine administered through a patient-controlled system currently represents the gold standard treatment for moderate to severe acute postoperative pain. To fix the limitations showed by the available I.V. patient-controlled analgesia (PCA) systems that may restrict its use in the clinical practice a needle-free, iontophoretic, fentanyl patient-controlled transdermal system has been developed and recently approved by the United States Food and Drug Administration (FDA) and by the European Medicines Agency (EMA).

Areas covered: This review aims at describing the technology, pharmacology and clinical efficacy of fentanyl iontophoretic transdermal system (ITS) in the treatment of acute pain. A literature search was conducted in the PUBMED database using the term ‘fentanyl iontophoretic transdermal system’ through September 2015 and results from the main clinical trials are discussed.

Expert opinion: In 2015, the appropriate treatment of acute pain after surgery is still a challenge and it represents a primary goal in the care of the surgical patient. When regional analgesia techniques are not applicable and systemic analgesia is required, patient controlled systems represent the standard of care for opioid administration. The fentanyl ITS presents several potential advantages compared to the currently used PCA devices. In particular, it does not require intravenous lines and eliminates the potential for drug administration errors, observed with manually programmed standard PCA devices. Nevertheless, further studies are needed to address eventual inter-individual variability especially for opioid tolerant patients.     

Non-invasive patient-controlled analgesia in the management of acute postoperative pain in the hospital setting

Objective: Acute postoperative pain is experienced by the majority of hospitalized patients undergoing surgical procedures, with many reporting inadequate pain relief and/or high levels of dissatisfaction with their pain management. Patient-controlled analgesia (PCA) ensures patient involvement in acute pain control, a key component for implementing a quality management system. This narrative article overviews the clinical evidence for conventional PCA and briefly discusses new, non-invasive PCA systems, namely the sufentanil sublingual tablet system (SSTS) and the fentanyl iontophoretic transdermal system (FITS).

Methods: A Medline literature search (“patient-controlled analgesia” and “acute postoperative pain”) was conducted to 1 April 2017; results from the main clinical trials are discussed. Additional literature was identified from the reference lists of cited publications.

Results: Moderate to low quality evidence supports opioid-based intravenous PCA as an efficacious alternative to non-patient-controlled systemic analgesia for postoperative pain. However, despite the benefits of PCA, conventional intravenous PCA is limited by system-, drug- and human-related issues. The non-invasive SSTS and FITS have demonstrated good efficacy and safety in placebo- and intravenous morphine PCA-controlled trials, and are associated with high patient/healthcare practitioner satisfaction/ease of care ratings and offer early patient mobilization.

Conclusions: Evidence-based guidelines for acute postoperative pain management support the use of multimodal regimens in many situations. As effective and safe alternatives to conventional PCA, and with the added benefits of being non-invasive, easy to use and allowing early patient mobilization, the newer PCA systems may complement multimodal approaches, or potentially replace certain regimens, in hospitalized patients with acute postoperative pain.     

Sufentanil sublingual tablet system for the management of postoperative pain

Introduction: Intravenous patient-controlled opioid analgesia has been an important improvement in addressing insufficient management of acute postoperative pain for over 40 years. However, there are number of weaknesses for intravenous patient-controlled analgesia, including operator and device error, intravenous line patency issues, and risk of catheter-related infection, all of which contribute to the complications and increase in cost of care. The sublingual sufentanil tablet system is a major evolution in both drug and technological management of postoperative pain.

Areas covered: We reviewed the use of the sublingual sufentanil tablet system in management of moderate to severe postoperative pain in hospitalized patients, with a particular focus on the pharmacological properties of sufentanil and clinical use in different surgical patients.

Expert opinion: The sublingual sufentanil tablet system can decrease intravenous opioid based patient-controlled analgesia related complications and safety issues. Current clinical studies have demonstrated this noninvasive-novel system to be safe and effective in management of acute pain in the postsurgical setting. Researchers should focus on comparing it with other available patient controlled analgesia modalities and evaluating the efficiency and cost effectiveness of the sublingual sufentanil tablet system.     

An iontophoretic, fentanyl HCl patient-controlled transdermal system for acute postoperative pain management

Patient-controlled modalities using intravenous or epidural routes have dramatically improved postoperative pain management. However, acute post-operative pain continues to be undermanaged. Intravenous patient-controlled analgesia (PCA), the current standard of care for acute postoperative pain management, requires the patient to be attached to a staff-programmed pump apparatus via an intravenous catheter and tubing, rendering it invasive and mobility-limiting. An innovative, needle-free, iontophoretic, fentanyl HCl patient-controlled transdermal system (PCTS) is being developed for acute postoperative pain management. Fentanyl HCl PCTS is a compact, self-contained system that is easily applied to the upper outer arm or chest. It provides pain relief therapeutically equivalent to that of a standard regimen of morphine intravenous PCA, with pharmacokinetics similar to those of intravenous fentanyl infusion. Fentanyl HCl PCTS may be an effective, non-invasive alternative to currently available PCA modalities.     

Relationship between plasma morphine concentrations and pharmacologic effects in postoperative patients using patient-controlled analgesia

In postoperative patients using patient-controlled analgesia (PCA) to administer i.v. doses of morphine sulfate, respiratory rates and subjective rankings of pain, sedation, and liking for the drug were correlated with plasma morphine concentrations. In 12 patients selected before surgery, the initial morphine sulfate dose of 0.6 mg/sq m was increased or decreased as needed. Every two hours, cumulative morphine sulfate dose, respiratory rate, and sedation were recorded by the nurse, along with the patient's evaluation of pain and liking for the drug. Plasma was collected in the morning and evening during PCA therapy for morphine analysis. Data were analyzed by analysis of covariance. Dosing rates and rankings of pain, sedation, and liking decreased as a function of time postoperatively, but respiratory rates did not. Sedation and respiratory rates were independent of morphine concentration. Liking of the drug increased directly with plasma morphine concentration but decreased with time. A high level of pain was directly related to morphine use. For all significant relationships, there was high interpatient variability, with the exception of changes in pain rankings induced by morphine. Patients defined a minimum effective plasma morphine concentration of 20-40 ng/mL. The maximum plasma morphine concentration achieved by self-administration was 82 ng/mL. These postoperative patients used patient-controlled analgesia to deliver morphine sulfate i.v. for pain relief, not for euphoria, and did not exhibit sedation or respiratory depression. Morphine was consistently effective at plasma concentrations of 40 ng/mL or greater.     

Patient-controlled analgesia: an appropriate method of pain control in children

Patient-controlled analgesia (PCA) is an analgesic technique originally used in adults but now with an established role in paediatric practice. It is well tolerated in children as young as 5 years and has uses in postoperative pain as well as burns, oncology and palliative care. The use of background infusions is more frequent in children and improves efficacy; however, it may increase the occurrence of adverse effects such as nausea and respiratory depression. Monitoring involves measurement of respiratory rate, level of sedation and oxygen saturation. Efficacy is assessed by self-reporting, visual analogue scales, faces pain scales and usage patterns. This is optimally performed both at rest and on movement. The selection of opioid used in PCA is perhaps less critical than the appropriate selection of parameters such as bolus dose, lockout and background infusion rate. Moreover, opioid choice may be based on adverse effect profile rather than efficacy. The concept of PCA continues to be developed in children, with patient-controlled epidural analgesia, subcutaneous PCA and intranasal PCA being recent extensions of the method. There may also be a role for patient-controlled sedation. PCA, when used with adequate monitoring, is a well tolerated technique with high patient and staff acceptance. It can now be regarded as a standard for the delivery of postoperative analgesia in children aged >5 years.     

An iontophoretic,fentanyl HCl patient-controlled transdermal system for acute postoperative pain management

Patient-controlled modalities using intravenous or epidural routes have dramatically improved postoperative pain management. However, acute post-operative pain continues to be undermanaged. Intravenous patient-controlled analgesia (PCA), the current standard of care for acute postoperative pain management, requires the patient to be attached to a staff-programmed pump apparatus via an intravenous catheter and tubing, rendering it invasive and mobility-limiting. An innovative, needle-free, iontophoretic, fentanyl HCl patient-controlled transdermal system (PCTS) is being developed for acute postoperative pain management. Fentanyl HCl PCTS is a compact, self-contained system that is easily applied to the upper outer arm or chest. It provides pain relief therapeutically equivalent to that of a standard regimen of morphine intravenous PCA, with pharmacokinetics similar to those of intravenous fentanyl infusion. Fentanyl HCl PCTS may be an effective, non-invasive alternative to currently available PCA modalities.     

吗啡及曲马多行术后自控镇痛的临床观察

目的评价吗啡及曲马多用于患者术后自控镇痛(PCA)的安全性及有效性,寻找较好的术后自控镇痛方法,从而减轻术后工作量和提高患者术后的舒适度。方法 50例在全麻下行胆囊切除术的患者,随机分为吗啡组(M组)和曲马多组(T组),每组各25例。镇痛完毕后由患者完成对疼痛的评分,并记录发生的副反应。结果在患者镇痛总体印象评分中,M组镇痛满意的比例略高于T组,但差异无统计学意义。M组副反应明显高于T组(P<0.05)。结论曲马多用于术后PCA的效果与吗啡相近,恶心、呕吐等副反应少,能减少术后护理工作量,更适用于治疗术后急性疼痛。     

Ketamine spares morphine consumption after transthoracic lung and heart surgery without adverse hemodynamic effects.

BACKGROUND: Thoracotomy is associated with severe pain. Large doses of morphine can depress respiratory drive and compromise hemodynamic stability. Ketamine reduces hyperalgesia, prevents opioid tolerance and resistance and lowers morphine consumption. At sub-anesthetic (/=5/10 VAS) and rated pain >/=5/10 on a 0-10 VAS. Rescue intramuscular diclofenac 75mg was available. Follow-up of respiratory, hemodynamic and pain statuses lasted 72h. RESULTS: Fifty-eight patients completed the 6-month study. Heart rate and blood pressures were identically stable in both groups. Respiratory rate and pulse oximetry were higher (P<0.05) in the MK than in the MO group. MO patients (n=28) used twice (2.0+/-2.3mg/patient/h) the amount of morphine compared to MK patients (n=30, 1.0+/-1.4mg/patient/h, P<0.05). Thirty-six hours after starting PCA, 10 MO patients still required IV-PCA compared to 5 MK patients (P<0.05). Diclofenac was used 70% more in MO than in MK patients. MO patients suffered more postoperative nausea and vomiting. No patients had hallucinations. CONCLUSIONS: The concomitant use of sub-anesthetic ketamine plus two-thirds the standard MO dose following thoracotomy, MIDCAB or OPCAB resulted in lower pain scores, reduced MO consumption and shorter postoperative IV-PCA dependence. These advantages were associated with cardiovascular stability and even better respiratory parameters.     

A comparison of patient-controlled and intramuscular morphine in patients after abdominal surgery

This prospective, randomized study compared the effects of two methods of morphine administration after abdominal surgery in 62 adults. All patients were offered intravenous morphine in the Postanesthesia Care Unit. On the ward, one group (PCA-CI) received a continuous infusion of morphine that could be supplemented by a patient-controlled bolus every 10 minutes. The other group (IM) received intramuscular morphine (0.08-0.12 mg/kg) as often as every 3 hours when requested. During three postoperative interviews, patients were questioned about pain relief (visual analogue scale), adverse opioid effects, and satisfaction with the method of analgesia. Total dose of morphine (mg, mg/kg body weight), time to first oral analgesic medication, length of hospital stay, and cost were calculated following discharge. There was a wide interindividual variation in reported pain intensity and morphine usage in both groups. Comparison of both groups demonstrated no significant differences in analgesia, incidence of adverse opioid effects, 24 and 36 hour morphine dose, time to first oral analgesic medication, operating cost, and length of hospital stay. Patients in the PCA-CI group received a slightly greater dose of morphine in relation to body weight (24 hr, P = 0.03; 36 hr, P = 0.05) and reported a greater degree of satisfaction at each assessment (P = 0.005, P = 0.02, P = 0.01). These data support the greater patient satisfaction associated with patient-controlled analgesia but suggest that the wide range of reported pain scores and morphine requirements makes it difficult to demonstrate, in a small population, superior pain relief from patient-controlled analgesia when nurses are encouraged to administer intramuscular pain medication more effectively.     

The effect of duration of dose delivery with patient-controlled analgesia on the incidence of nausea and vomiting after hysterectomy

Aims Postoperative nausea and vomiting (PONV) may be exacerbated by postoperative opioid analgesics and may limit patients' successful use of these medications when used with patient controlled analgesia (PCA). We tested the hypothesis that the rapid change in blood morphine concentration associated with PCA bolus delivery contributed to PONV, and that prolonging its delivery to a brief infusion would result in decreased PONV.
Methods Patients, who were receiving morphine for pain relief via patient-controlled analgesia (PCA) after total abdominal hysterectomy, received 1  mg morphine sulphate incremental doses either over 40  s with a 5  min lockout interval or over 5  min delivery with a 1  min lockout interval. Episodes of nausea, retching and vomiting, along with the use of morphine and the pain relief obtained, were recorded.
Results Data from 20 patients in each group were analysed. Contrary to expectations, most patients in both groups reported nausea postoperatively. Those patients receiving morphine over 5  min experienced more episodes of emesis (36) than those receiving the dose over 40  s (17). Most patients receiving the 40  s doses vomited in the first 12  h (median time 8  h), while those receiving the 5  min doses vomited between 12 and 24  h (median time 19  h) ( P =0.01). There were no differences between groups in the visual analogue pain scores or use of morphine between groups.
Conclusions Reasons for these unexpected findings remain speculative. The high incidence of PONV appears to be inherently high in gynaecological surgery patients and standard antiemetic medication regimens appear to be poorly efficacious. Reasons for the differences in the time-course of emetic episodes between the two groups may be related to differences in the time-course of central opioid receptor occupancy.     

Evaluation of the Safety and Efficacy of Ketorolac versus Morphine by Patient-Controlled Analgesia for Postoperative Pain

Study Objective . To compare ketorolac tromethamine with morphine for pain management after major abdominal surgery. Design . Double-blind, randomized study Setting . Hospital recovery room and postoperative surgical unit. Patients . One hundred ninety-one patients with at least moderate pain after major abdominal surgery. Interventions . Patients received ketorolac by patient-controlled analgesia (PCA) bolus alone (Ket B), ketorolac by bolus plus infusion (Ket I), or morphine by PCA bolus (morphine), with injectable morphine available for supplementation. Measurements and Main Results . Levels of sedation, pain intensity, pain relief, and adverse events were recorded at baseline, at 2, 4, and 6 hours, and at termination. Supplemental morphine was required by 71% of Ket B patients, 67% of Ket I patients, and 38% of morphine patients (p<0.001 for Ket B vs morphine). Although patients receiving ketorolac required more supplemental morphine than the morphine group (6.0 mg Ket I, 6.2 mg Ket B, 4.0 mg morphine), there was a large morphine-sparing effect in both ketorolac groups (total morphine 6.0 mg Ket I, 6.2 mg Ket B, 33.3 mg morphine). Overall pain relief scores were similar for morphine and Ket I groups, and were lower for Ket B than for morphine (p=0.002). There were no differences among groups in numbers of patients with adverse events. Conclusion . Ketorolac may be effective when administered by PCA device, and has a clear morphine-sparing effect. (Pharmacotherapy 1997;17(5):891–899)     

100例术后镇痛药物使用分析

目的：了解我院术后镇痛方法和镇痛药使用情况。方法：抽取2009年3～6月我院普外科、骨科和妇科术后疼痛病例100份,分析镇痛方法、镇痛药物、视觉模拟评分（VAS）及药物不良反应。结果：患者自控镇痛（PCA）泵的使用率为25．0％;术后3d阿片类药物和非甾体镇痛药（NSAIDs）的使用例数分别为20例和44例;两类药物联合用药比例偏低;术后镇痛以哌替啶和双氯芬酸钾为主;术后第1天的VAS为3．43分。结论：我院镇痛药物使用较为积极,但仍存在镇痛不足的现象,且联合用药少,用药品种单一。     

Postoperative pain management with a patient-controlled transdermal delivery system for fentanyl.

PURPOSE: The efficacy and safety of fentanyl hydrochloride patient-controlled trans-dermal system (PCTS) for management of acute postoperative pain are discussed. SUMMARY: Fentanyl hydrochloride PCTS is a self-contained, needle-free, credit-card-sized fentanyl-delivery system that is worn on the patient's arm or chest. The system uses iontophoretic technology to actively deliver preprogrammed doses of fentanyl into the systemic circulation when activated by the patient on demand. PCTS is as safe and effective as i.v. morphine patient-controlled analgesia and superior to placebo for managing acute postoperative pain. Fentanyl absorption from PCTS is clinically insignificant when the device is not activated. This contrasts with the transdermal fentanyl patch, which delivers fentanyl continuously for 72 hours via passive absorption and is indicated only for use in the management of chronic pain. CONCLUSION: Fentanyl hydrochloride PCTS is a self-contained iontophoretic fentanyl-delivery system that provides patients control over pain management and consistent management of pain without analgesic peaks and troughs.     

Decreased pain tolerance before surgery and increased postoperative narcotic requirements in abstinent tobacco smokers

IntroductionThe clinical influence of smoking cessation on pain tolerance before surgery and postoperative pain perception is not fully understood. This clinical study investigated the effect of smoking cessation on pain threshold during the perioperative period in patients undergoing hepatic resection.MethodsWe enrolled 148 male patients (68 non-smokers and 80 abstinent smokers) who underwent hepatic resection and received postoperative patient-controlled intravenous analgesia. Patients were tested for preoperative pain thresholds in response to electrical stimuli. We recorded the cumulative amount of extra morphine equivalent required during the first 48 h after surgery. Pain intensity was evaluated at 1 h, 6 h, 24 h and 48 h after surgery using the visual analogue scale (VAS). Additionally, button-pressing consumption was recorded by a patient-controlled analgesia (PCA) pump.ResultsThe groups did not differ with respect to baseline clinical characteristics. Compared with non-smokers, abstinent smokers exhibited lower pain thresholds before surgery and demanded a larger quantity of extra morphine equivalent during the first 48 h after surgery. Abstinent smokers also exhibited more severe postoperative pain than non-smokers. Postoperative complications, such as nausea, vomiting, dizziness, sedation, and respiratory depression, did not significantly differ between the two groups.ConclusionsIn this study, smokers deprived of cigarettes exhibited decreased pain tolerance before surgery and required a larger quantity of postoperative extra morphine equivalent than non-smokers. Health care providers must be aware of the potential for increased narcotic requirements in smokers.