Oxyhemoglobin saturation following cesarean section in patients receiving epidural morphine, PCA, or im meperidine analgesia

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Increased Susceptibility to Postoperative PCA Morphine-Induced Respiratory Depression in a Patient with an Undiagnosed Traumatic Porencephalic Cyst - A Case Report

Introduction

Patient-controlled analgesia with morphine is routinely used for postoperative pain management. Due to the safety profiles of the technique, which are patient/disease related or technique/equipment related, severe respiratory depression requiring opioid antagonists or airway management are uncommon.

Case presentation

The case of a patient with right colon carcinoma who was operated on for hemicolectomy under general anaesthesia and who presented with apnoea, after postoperatively receiving an initial bolus of 1mg of morphine. A large post-traumatic porencephalic cyst of the left brain hemisphere, previously undiagnosed, was found on the computed tomography scan. We excluded human errors, technique and equipment factors, and the patient did not have any other predisposing conditions like sleep apnoea, obesity, recent head injury or concurrent use of other sedatives. Previously the patient had been entirely asymptomatic, and her increased susceptibility to respiratory depression was the only clinical manifestation of porencephaly.

Conclusion

Adult acquired porencephaly is seldom reported in the literature, clinical manifestations depending on the location and size of the cyst. In the present reported case, increased susceptibility to low-dose opioids might be associated with the structural and functional reorganisation of the brain after head trauma with the occurrence of the porencephalic cyst of the brain.

Management of Pain in the Critically Ill

Analgesia for critically ill patients can be provided most effectively by the use of modern techniques. Under standing of the anatomical pathways for nociceptive sig nal transmission allows the use of techniques that mod ulate or block nociceptive information at several levels (periphery, spinal cord, and systemic). A comprehen sive discussion of analgesic techniques at each level is presented. Formulation of a treatment plan is discussed. Several examples are presented to show the decision- making process for the use of modern analgesic tech niques in critically ill patients.

WITHDRAWN: Patient controlled intravenous opioid analgesia versus continuous epidural analgesia for pain after intra-abdominal surgery

BACKGROUND

There are two common techniques for postoperative pain control after intra-abdominal surgery: patient-controlled analgesia (PCA) with intravenous opioids and continuous epidural analgesia (CEA). It is uncertain which method has better pain control and fewer adverse effects.

OBJECTIVES

The objective of this review was to compare PCA opioid therapy with CEA for pain control after intra-abdominal surgery in terms of analgesic efficacy, side effects, patient satisfaction and surgical outcome by meta-analysis of the relevant trials.

SEARCH METHODS

We searched CENTRAL (The Cochrane Library Issue 4, 2002), MEDLINE (January 1966 to October 2002), EMBASE (January 1988 to October 2002), and reference lists of articles. We also contacted researchers in the field.

SELECTION CRITERIA

Randomized controlled trials of adult patients after intra-abdominal surgery comparing the effect of two pain control regimens in terms of analgesic efficacy and side effects. In the patient-controlled analgesia (PCA) group the patient should be able to operate the device himself. In the continuous epidural analgesia group there was no PCA device.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Study authors were contacted for additional information. Adverse effects information was collected from the trials.

MAIN RESULTS

Nine studies involving 711 participants were included. The PCA group had a higher pain visual analogue scale than the CEA group during 6, 24 and 72 hour periods. The weighted mean difference and 95% confidence interval of resting pain was 1.74 (95% CI 1.30 to 2.19), 0.99 (95% CI 0.65 to 1.33), and 0.63 (95% CI 0.24 to 1.01), respectively. The length of hospital stay and other adverse effects were not statistically different except that the incidence of pruritus was lower in the PCA group, odds ratio of 0.27 (95% CI 0.11 to 0.64).

AUTHORS' CONCLUSIONS

CEA is superior to opioid PCA in relieving postoperative pain for up to 72 hours in patients undergoing intra-abdominal surgery, but it is associated with a higher incidence of pruritus. There is insufficient evidence to draw comparisons about the other advantages and disadvantages of these two methods of pain relief.

Respiratory depression after neuraxial opioids in the obstetric setting

Neuraxial opioids have contributed significantly to improved labor and postcesarean delivery analgesia. In the obstetric population, epidural and intrathecal opioids are associated with a very low risk of clinically significant respiratory depression. Although rare, respiratory depression is a serious risk; patients may die or suffer permanent brain damage as a consequence. This review discusses the mechanism and incidence, as well as the prevention, detection, and management of respiratory depression with morphine, extended-release epidural morphine, and lipophilic opioids in the labor and cesarean delivery setting.

Nocturnal episodic hypoxemia after ambulatory breast cancer surgery: comparison of sevoflurane and propofol-fentanyl anesthesia

PURPOSE

To study the incidence and severity of nocturnal episodic hypoxemia after ambulatory breast cancer surgery and its differences with sevoflurane and propofol anesthesia.

METHODS

Sixty-one adult female patients (ASA PS I-II; age, 32-77 years) without an apparent history of sleep apnea and respiratory disease undergoing major breast cancer surgery on an outpatient basis and with planned overnight admission were randomized to one of two anesthesia maintenance groups: sevoflurane anesthesia (SEV, n = 31) or intravenous propofol, fentanyl, and vecuronium anesthesia (TIVA, n = 30). All patients were administered propofol 2 mg x kg(-1) intravenously for anesthesia induction, had a laryngeal mask airway placed, and received rectal diclofenac and local infiltration anesthesia for pain relief. No opioid analgesic or oxygen was administered after discharge from the postanesthesia care unit (PACU). Oxygen saturation (Sp(O) (2)) was recorded continuously during the first postoperative night. Sp(O) (2) <90% that lasted >10 s was regarded as hypoxemia, and the percentage of effective recording time with Sp(O) (2) <90% (%time with Sp(O) (2) <90) was evaluated.

RESULTS

Six patients (SEV3/TIVA3) had >1% of %time with Sp(O) (2) <90 (S-hypoxemia group), 17 (SEV7/TIVA10) had >0% and <or=1% (M-Hypoxemia group), and 38 (SEV21/TIVA17) had 0% (no-hypoxemia group). There were no statistical differences in age, ASA PS, anesthesia technique, and duration of anesthesia among groups. The S-hypoxemia group had higher body mass index (BMI) and incidence of oxygen supplementation in the PACU than the no-hypoxemia group. No patient had major complications.

CONCLUSION

Nocturnal episodic hypoxemia occurs frequently after ambulatory breast cancer surgery. The incidence was not different between SEV and TIVA. Hypoxic patients had a higher BMI and needed oxygen therapy in PACU more frequently.

Patient-controlled analgesia

One of the most common methods for providing postoperative analgesia is via patient-controlled analgesia (PCA). Although the typical approach is to administer opioids via a programmable infusion pump, other drugs and other modes of administration are available. This article reviews the history and practice of many aspects of PCA and provides extensive guidelines for the practice of PCA-administered opioids. In addition, potential adverse effects and recommendations for their monitoring and treatment are reviewed.

Patient controlled intravenous opioid analgesia versus continuous epidural analgesia for pain after intra-abdominal surgery

BACKGROUND

There are two common techniques for postoperative pain control after intra-abdominal surgery: patient-controlled analgesia (PCA) with intravenous opioids and continuous epidural analgesia (CEA). It is uncertain which method has better pain control and fewer adverse effects.

OBJECTIVES

The objective of this review was to compare PCA opioid therapy with CEA for pain control after intra-abdominal surgery in terms of analgesic efficacy, side effects, patient satisfaction and surgical outcome by meta-analysis of the relevant trials.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library Issue 4, 2002), MEDLINE (January 1966 to October 2002), EMBASE (January 1988 to October 2002), and reference lists of articles. We also contacted researchers in the field.

SELECTION CRITERIA

Randomized controlled trials of adult patients after intra-abdominal surgery comparing the effect of two pain control regimens in terms of analgesic efficacy and side effects. In the patient-controlled analgesia (PCA) group the patient should be able to operate the device himself. In the continuous epidural analgesia group there was no PCA device.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. Adverse effects information was collected from the trials.

MAIN RESULTS

Nine studies involving 711 participants were included. The PCA group had a higher pain visual analogue scale than the CEA group during 6, 24 and 72 hour periods. The weighted mean difference and 95% confidence interval of resting pain was 1.74 (95% CI 1.30 to 2.19), 0.99 (95% CI 0.65 to 1.33), and 0.63 (95% CI 0.24 to 1.01), respectively. The length of hospital stay and other adverse effects were not statistically different except that the incidence of pruritus was lower in the PCA group, odds ratio of 0.27 (95% CI 0.11 to 0.64).

AUTHORS' CONCLUSIONS

CEA is superior to opioid PCA in relieving postoperative pain for up to 72 hours in patients undergoing intra-abdominal surgery, but it is associated with a higher incidence of pruritus. There is insufficient evidence to draw comparisons about the other advantages and disadvantages of these two methods of pain relief.

Nocturnal Arterial Oxygen Desaturation and Episodic Airway Obstruction After Ambulatory Surgery

Some patients experience disordered breathing during sleep and arterial oxygen desaturation after major inpatient surgery. We performed this study to determine whether similar events occur after ambulatory surgery. Forty-five ambulatory surgery patients received an unrestricted anesthetic. Continuous unattended nocturnal recordings of breathing pattern and oxygen saturation were made in the patients' homes before surgery and during the first and second postoperative nights. Nine patients had a respiratory disturbance index >10 and/or >1% of recording time with oxygen saturation <90% on at least one study night. These nine patients had a significantly older median age and a significantly larger median body mass index. Their median respiratory disturbance index and median percentage of time with oxygen saturation <90% were significantly higher on the first postoperative night than on the preoperative night.

Apnea and bradypnea in patients receiving epidural bupivacaine-morphine for postoperative pain relief as assessed by a new monitoring method

STUDY OBJECTIVE

To evaluate postoperative breathing patterns with a new monitoring device in patients given bupivacaine-morphine epidural analgesia.

DESIGN

Open explorative study.

SETTING

Inpatient anesthesia in a university hospital setting.

PATIENTS

15 ASA physical status I and II patients aged 28 to 87 years and scheduled for major abdominal surgery.

INTERVENTIONS

All patients underwent abdominal surgery with epidural anesthesia combined with general anesthesia. Postoperatively, they continued with epidural analgesia consisting of bupivacaine and morphine. On the first postoperative night, the breathing pattern was studied with a new noninvasive monitoring device measuring respiratory frequency and apnea. Arterial blood gas analysis was performed in case of apnea or low respiratory frequency.

MEASUREMENTS AND MAIN RESULTS

A total of 84 alarm events were registered in 11 patients. Twenty-one percent (18/84) of the alarms were associated with arterial carbon dioxide tension (PaCO2) levels greater than 48.8 mmHg. Three of the four patients with PaCO2 levels greater than 48.8 mmHg were older than 80 years of age.

CONCLUSION

The tested noninvasive monitoring device may detect abnormal respiratory breathing patterns in patients at risk for respiratory depression during epidural analgesia with bupivacaine-morphine.

High-dose intrathecal diamorphine for analgesia after Caesarean section

Forty women undergoing elective Caesarean section under spinal anaesthesia using hyperbaric 0.5% bupivacaine were randomly allocated to receive either 0.5 mg or 1 mg intrathecal diamorphine. All women received diclofenac 100 mg at the end of surgery and morphine via a patient-controlled analgesia system. Oral analgesics were not used. Postoperative analgesia was more prolonged and more reliable in the 1-mg group. Mean time to first analgesia was 10.2 h in the 1-mg group and 6.9 h in the 0.5-mg group, and 45% in the 1-mg group used no morphine, compared with 10% in the 0.5-mg group. Mean morphine consumption over 24 h was 5.2 mg in the 1-mg group and 10.6 mg in the 0.5-mg group. Pain scores all tended to be lower in the 1-mg group but this was only significant at 4 h. There were no serious side-effects. Minor side-effects were common but well tolerated, and the incidence did not differ between the groups. If intrathecal diamorphine is used in combination with rectal diclofenac and without oral analgesia, then 1 mg provides superior analgesia to 0.5 mg without any worsening of the side-effects.

Management of pain in intensive care settings

An organized treatment plan for providing analgesia in ICU settings can make a significant difference in patient comfort and outcome. Advanced analgesic techniques are available for use at each level of the "pain pathway." These include agents and methods that act at the periphery, at the spinal cord level, and through a systemic approach. Consultation with specialists in pain management can help achieve optimum therapy for patients in the ICU setting.

[Benefit-risk and monitoring modalities of different techniques and methods of postoperative analgesia]

This review aimed to determine the benefits-risks ratio of postoperative analgesia. The various agents usually used for intravenous postoperative analgesia (paracetamol, NSAID's, opioids), and the techniques for postoperative analgesia (PCA, epidural, perinervous block) are analysed. The rules proposed for the monitoring of postoperative analgesia are considered.

[Patient-controlled analgesia. Benefits, risks, methods of monitoring]

Patient-controlled analgesia refers to a relatively new approach to morphine delivery in which patients are allowed to self-administer small doses of an opioid, to achieve adequate relief of postoperative pain. The main benefit is to reduce fluctuations in opioid plasma concentrations. A matter for worry remains the occurrence of side effects, especially ventilatory depression. In order to guarantee the efficacy and safety of this technique, the education of patients and nurses is essential. Protocols are required, specifying the use of this technique (prescription, patient monitoring, treatment of side effects).

Epidural and intrathecal opioids for postoperative pain management in Europe--a 17-nation questionnaire study of selected hospitals. Euro Pain Study Group on Acute Pain

BACKGROUND

A questionnaire study conducted with the help of selected contact persons in 17 countries in Europe attempted to create a picture of the practice of acute pain management with the use of spinal opioid analgesia (SOA).

METHODS

A questionnaire was mailed to anaesthesiologists in 105 European hospitals. Depending on the population, 5-10 hospitals from each country were selected by a country co-ordinator.

RESULTS

A total of 101 (96.2%) completed questionnaires were returned. During 1 year SOA was used in 55,117 patients (6.6% of all in-patient surgical procedures); of these, 89.2% received epidural opioids and 10.8% intrathecal opioids (ratio 8:1). The most common opioid for SOA was morphine; fentanyl was also used quite frequently; 12 different opioids and 8 non-opioids had been used. ASA 1-2 patients receiving epidural morphine were nursed on surgical wards in 58.4% of the hospitals; in 25.7% of hospitals even ASA 3-4 were nursed on surgical wards. Respiratory depression (requiring naloxone treatment) was noted in 45 of the 49,183 patients who received epidural opioids (0.09%); 33 of these patients had received morphine. In more than 75% of hospitals the monitoring variables were respiratory rate, sedation level and pulse oximetry. There was a great difference between hospitals and countries regarding duration of monitoring.

CONCLUSIONS

This questionnaire study showed that SOA was used in about 7% of 836,000 in-patients undergoing surgery at the 105 selected hospitals. Epidural opioids were used eight times more often than intrathecal opioids. Morphine was the commonest opioid for SOA. The duration of monitoring differed greatly between hospitals and countries; the need for official guidelines is emphasized.

[Evaluation of the activity of a postoperative analgesia department in a Canadian hospital]

OBJECTIVE

To describe the setting up and the activity of an acute pain service (APS).

STUDY DESIGN

Retrospective descriptive study including two surveys among the nursing staff, the first one eight months after the setting up of the APS and the second one ten months later.

RESULTS

In the first 19 months, 3,404 patients were treated in the APS: 1,456 with patient-controlled analgesia (PCA), 1,299 with epidural analgesia, 589 with spinal opioids and 60 with continuous nerve blocks. The resulting overall incidence of respiratory depression was 0.7%. It ranged from 0% with continuous nerve block to 1.2% with PCA. It was at 0.3% with epidural analgesia and 0.5% with spinal opioids. Both surveys confirmed that nurses had a positive attitude toward the APS, mainly because they believed it offered patients significant advantages. Many of them thought that epidural analgesia and PCA were likely to impede patient's ambulation and most of them agreed that these techniques increased their work load.

CONCLUSION

Although the incidence of respiratory depression was low among the APS patients, it can probably still be decreased by a more refined patient selection. Setting up an APS is viewed positively by the nursing staff in spite of some perceived disadvantages.

Oxygen saturation in children in the postoperative period

Some adult patients have periods of significant oxygen desaturation after surgery but, other than for immediately after surgery in the recovery room, few data are available in children. We monitored overnight paired preoperative and postoperative oxygen saturations in 19 children, and overnight postoperative saturations in 50 additional children to determine whether children have periods of desaturation in the postoperative period. The children underwent surgery usually associated with moderate to severe postoperative pain, and were treated with epidural, intravenous, or intramuscular opioids. In the group of 19 children mean (SD) preoperative oxygen saturation was 96.6% +/- 1.3%, and the mean postoperative saturation was 95.7% +/- 1.2%. The average change was 0.88% +/- 1.52%. The 95% confidence interval of the paired difference was 0.13% to 1.6%. There was no significant difference in the percent of monitored time that the patients spent with an oxygen saturation less than 95%, 90%, 85%, or 80%. In the 50 children monitored only in the postoperative period, mean (SD) saturation was 97.8% +/- 1.9%. The data show that, in contrast to some reports in adults, this group of children did not have multiple episodes of clinically significant oxygen desaturation in the postoperative period.

Epidural morphine with butorphanol in pediatric patients

STUDY OBJECTIVE

To determine whether the addition of butorphanol to epidural morphine is effective in reducing the frequency of side effects caused by neuraxial opioids.

DESIGN

Randomized, double-blind study.

SETTING

Large tertiary care pediatric hospital.

PATIENTS

20 children between the ages of 2 and 17 years undergoing spinal, abdominal, or thoracic procedures.

INTERVENTIONS

Patients were divided randomly into one of two groups to receive either 80 micrograms/kg of preservative-free epidural morphine (Group 1) or 80 micrograms/kg of preservative-free epidural morphine with 40 micrograms/kg of butorphanol (Group 2).

MEASUREMENTS AND MAIN RESULTS

Blood pressure, heart rate, respiratory rate, and the first need for additional opioids were monitored in the two groups. In addition, pruritus, nausea and vomiting, and supplemental oxygen (O2) required to maintain oxygen saturation (SpO2) above 90% were monitored. Children who received butorphanol in addition to epidural morphine were much less likely to develop pruritus or nausea and vomiting or to require supplemental O2 to maintain SpO2 above 90%.

CONCLUSION

Butorphanol 40 micrograms/kg added to epidural morphine 80 micrograms/kg is effective in decreasing the occurrence of side effects caused by neuraxial opioids in pediatric patients.

Anesthetic-postoperative morphine regimens for cesarean section and postoperative oxygen saturation monitored by a telemetric pulse oximetry network for 24 continuous hours

STUDY OBJECTIVE

To document the effects of compromised respiratory function on oxygen saturation (SpO2) after cesarean section via the telemetric pulse oximetry network (TPON) for 24 continuous hours.

DESIGN

Prospective study.

SETTING

Postpartum ward of a university hospital.

PATIENTS

ASA physical status I or II parturients undergoing cesarean section.

INTERVENTIONS

Healthy parturients were assigned to 1 of 3 anesthetic-postoperative morphine regimens as follows: general anesthesia-parenteral morphine as needed (GA/PM; n = 11); epidural anesthesia-parenteral morphine as needed (EA/PM; n = 15); epidural anesthesia-epidural morphine 4 to 5 mg (EA/EM; n = 10).

MEASUREMENTS AND MAIN RESULTS

For 24 continuous hours after cesarean section, SpO2, heart rate, and plethysmogram every 10 seconds were recorded by the TPON computer. In addition, pain, somnolence, respiratory rate (RR), and side effects were recorded every 30 minutes to 2 hours. SpO2 less than 94% and less than 92% occurred least with GA/PM. The highest mean cumulative time of SpO2 between 95% and 90% occurred with EA/EM. The longest episode of SpO2 less than 92% and the lowest SpO2 for more than 1 minute also occurred with EA/EM. With all 3 regimens, SpO2 decreased to less than 80% for 20 to 30 seconds at a time, but the lowest SpO2 (less than 85%) for more than 1 minute occurred with EA/EM in 1 patient and was associated with somnolence that required treatment. With all 3 regimens, average RR was within normal limits, but mean RR was significantly lower with EA/EM than with GA/PM or EA/PM from the 8th to the 14th postoperative hours. Somnolence did not differ significantly among the 3 regimens. Pain score was significantly lower with EA/EM than with GA/PM or EA/PM for the first 20 hours.

CONCLUSIONS

All 3 regimens risked low SpO2, with the EA/EM regimen having the highest risk but the best analgesia. Neither general nor epidural anesthesia combined with postoperative parenteral morphine influenced SpO2 postoperatively. In this study, the TPON provided a feasible method of detecting hypoxemia early on in the general ward setting.

A comparison of epidural diamorphine with intravenous patient-controlled analgesia using the Baxter infusor following caesarean section

In a randomised study of analgesia following Caesarean section, we compared the efficacy and side effects of on-demand epidural diamorphine 2.5 mg with intravenous patient-controlled analgesia using diamorphine from the Baxter infusor system. Pain scores fell more rapidly in the epidural group, but by the fourth hour, and thereafter, both techniques had a similar analgesic effect. The patient-controlled analgesia group used significantly more diamorphine (p < 0.001), median 62 mg (range 18-120 mg) compared to the epidural group, median 10 mg (range 2.5-20 mg), over a significantly longer time period (p < 0.001), median 54.25 h (range 38-68 h) compared to the epidural group, median 40.75 h (range 6-70 h). The frequency and severity of nausea, vomiting and pruritus were similar in the two groups, however, the patient-controlled analgesia group were more sedated during the first postoperative day. This reached statistical significance (p < 0.05) between 9-24 h. Overall satisfaction scores (0-100) were high, but the patient-controlled analgesia group scored significantly higher: mean 85.5 (SD 12.2) compared to mean 77.0 (SD 11.7) in the epidural group.

Postoperative pain management and acute pain service activity in Canada

A survey of postoperative pain management practices was mailed to the 56 Canadian university-affiliated teaching hospitals in December 1991. The aims of the survey were (1) to determine the prevalence, structure, and function of Acute Pain Services and (2) to determine the use and management of patient-controlled analgesia (PCA) and epidural opiate analgesia (EOA) in teaching hospitals. Responses were received from 47 hospitals, representing a return rate of 84%. Twenty-five hospitals (53%) operated an Acute Pain Service and an additional 17 (35%) were attempting to organize one. "Time commitment" was given as the primary reason why hospitals were unable to offer an Acute Pain Service. Most commonly used methods of pain relief were EOA and PCA. Most services were multidisciplinary, with 60% having a nurse and 29% a pharmacist. Irrespective of the presence of an Acute Pain Service, PCA was used at 32 (68%) hospitals, and EOA was used at 41 (87%); however, only 15 provided EOA on general wards. Complications have occurred with both PCA and EOA, with 14 of 32 hospitals indicating that they have had a major or serious complication. The data suggest an estimated incidence of severe respiratory depression of 0.03% with PCA and 0.13% with EOA. No deaths were reported at the time of the survey. Epidural opioid-local anaesthetic EOA-LA combinations were used at 26 (63%) hospitals; however, only six administered these combinations on general words. We conclude that a multidisciplinary team approach to manage postoperative pain is viable in university teaching hospitals of all sizes.(ABSTRACT TRUNCATED AT 250 WORDS)

Apnoea and oximetric desaturation in patients receiving epidural morphine after gastrectomy: a comparison of intermittent bolus and patient controlled administration

The number of apnoeic episodes and arterial oxygen desaturations were measured preoperatively and for sixty hours postoperatively in twenty ASA status 1-2 patients scheduled for elective gastrectomy. Monitoring included continuous pulse oximetry, respiratory inductive plethysmography and repeated arterial blood gas analysis. The number and magnitude of apnoeas and desaturation episodes were compared between two postoperative analgesic regimens of epidural morphine; intermittent bolus injection (Group B, n = 10), and patient controlled administration with continuous infusion (Group P, n = 10). Morphine dose, P(a)CO2 and mean SpO2 values were similar between the two groups. Although the number of central apnoeas with SpO2 < 90% was greater in Group B, other episodes of apnoea or desaturation were similarly seen preoperatively. In the postoperative period, central apnoeas with SpO2 < 90% were significantly increased in Group B, while no change was seen in Group P. Apnoeas with SpO2 < 80% were only seen in Group B. We conclude from these results that postoperative apnoeas and episodic desaturations are greatly influenced by the different modes of opioid administration.

Background infusion with patient-controlled analgesia: effect on postoperative oxyhaemoglobin saturation and pain control

The aim of this study was to determine whether the addition of a background infusion (BI) to patient-controlled analgesia (PCA) would lead to significantly improved pain control or poorer oxyhaemoglobin saturation (SpO2) after gynaecological surgery. Sixty-two patients were studied for 24 hours postoperatively; pain scores and morphine dose were recorded hourly, SpO2 was recorded every 10 seconds. Administration of the BI resulted in a significant increase in total morphine dose received although there was no difference in the severity of postoperative desaturation between the therapies. Despite the increased morphine dose pain scores also were similar in the two groups. Addition of a BI at 1 mg/hr did not confer any advantage over PCA alone and is not recommended when PCA is used in this patient group.

The effect of fentanyl administered epidurally by patient-controlled analgesia, continuous infusion, or a combined technique of oxyhaemoglobin saturation after abdominal surgery

The aims of this study were to determine the effect of three different modes of epidural administration of fentanyl on oxyhaemoglobin saturation and pain control. Forty-three patients undergoing elective abdominal surgery were randomly allocated to the following groups: (1) continuous infusion of fentanyl at a rate of 50 micrograms.h-1 with additional epidural boluses (25 micrograms) as required; (2) patient-controlled analgesia using a 25 microgram epidural bolus of fentanyl with a 15 min lock-out period; (3) a combination of patient-controlled analgesia and continuous infusion. Oxyhaemoglobin saturation was measured by continuous computerised pulse oximetry for 48 h after operation together with pain and sedation scores. In the first 24 h after surgery patients in the continuous infusion group spent a significantly greater proportion of time below oxygen saturations of 94% and 85% than those in the other two groups. On day 2 all oxygen saturation measurements were worse than during day 1, but differences between groups were not significant. Those patients receiving patient-controlled analgesia required significantly less fentanyl than patients in either of the other groups (p < 0.05). However, the mean pain and sedation scores did not differ significantly between the three treatment groups. There was no association between total fentanyl dose and oxygen saturation values. Overall, self-administered fentanyl appeared to cause less oxyhaemoglobin desaturation than nurse-administered analgesia without any loss of analgesic effect.

Bupivacaine 0.1% does not improve post-operative epidural fentanyl analgesia after abdominal or thoracic surgery

Epidural infusions of fentanyl, in a 10 micrograms.ml-1 concentration, combined with bupivacaine 0.1% were compared with epidural infusions of fentanyl alone for postoperative analgesia following abdominal or thoracic surgery. There were no detectable differences between the two groups in analgesia (mean visual analogue scale pain scores ranging between 15-35 mm), average infusion rates of 7-9 ml.hr-1, and serum fentanyl concentrations which reached 1-2 ng.ml-1. There was no difference in postoperative pulmonary function (pH, PaCO2, SaO2), or bowel function (time to flatus or po fluids). The incidence of side-effects including somnolence, nausea and vomiting, pruritus and postural hypotension was also similar. Of the patients receiving fentanyl and bupivacaine 0.1%, three developed a transient unilateral sensory loss to pinprick and ice, and two of these patients had unilateral leg weakness equal to a Bromage 1 score. The addition of bupivacaine 0.1% does not improve epidural infusions of fentanyl using a 10 micrograms.ml-1 concentration following abdominal or thoracic surgery.

Oxyhaemoglobin saturation following elective abdominal surgery in patients receiving continuous intravenous infusion or intramuscular morphine analgesia

Oxygen saturation was continuously measured using computerised pulse oximetry for 8 h overnight pre-operatively and for the first 24 h postoperatively in 40 patients receiving intermittent intramuscular morphine or continuous infusion of morphine following elective upper abdominal surgery. The proportion of time with an oxygen saturation less than 94% was used as an index of desaturation. Patients receiving continuous infusion analgesia received a larger morphine dose and achieved better analgesia than the intramuscular group. Postoperatively, the duration of desaturation increased 10-fold over pre-operative values, 'intramuscular' patients spending 39.0% (SD, 37.0%) and 'continuous infusion' patients 40.0% (SD, 37.5%) of the time below 94% saturation. Although newer therapies (e.g. epidural analgesia and patient-controlled analgesia) are currently receiving greater attention, the sequelae of these more traditional analgesic techniques warrant further study.

Patient-controlled analgesia: can it be made safer?

Patient-controlled analgesia (PCA) has been shown to provide superior pain relief when compared with standard therapy options for postoperative analgesia. If PCA is to be implemented widely in teaching, private and country hospitals, its effectiveness needs balanced with a high safety profile. This can be achieved by consideration of patient selection, comprehensive education of patients, medical and nursing staff and equipment familiarisation. Continuous clinical audit allows identification of problem areas along with monitoring analgesic efficacy.

Postoperative pain management and respiratory depression after thoracotomy: a comparison of intramuscular piritramide and intravenous patient-controlled analgesia using fentanyl or buprenorphine

STUDY OBJECTIVE

To compare the analgesic efficacy of fentanyl, buprenorphine, and piritramide and to define the respiratory risk during conventional postoperative pain management and patient-controlled analgesia (PCA).

DESIGN

Randomized, single-blind study.

SETTING

Department of anesthesiology of an urban hospital.

PATIENTS

Sixty patients (ASA) physical status II and III) recovering from unilateral thoracotomy performed under standardized general anesthesia including intercostal blockade.

INTERVENTIONS

Patients were treated with intramuscular (IM) piritramide (7.5 to 15 mg as needed) or intravenous (IV) PCA with fentanyl (demand dose 34 micrograms) or buprenorphine (demand dose 80 micrograms) during the early postoperative period, using the On-Demand Analgesia Computer (ODAC, Janssen Scientific Instruments, Beerse, Belgium).

MEASUREMENTS AND MAIN RESULTS

The mean postoperative observation period was 24 to 25 hours. During this time, patients requested 55.8 +/- 23.2 mg of piritramide, 1.04 +/- 0.54 mg of fentanyl, or 1.81 +/- 0.78 mg of buprenorphine. Analgesia in all groups was judged mostly good to excellent, with a preference for PCA. Side effects were only of minor intensity in all groups; euphoria or dysphoria occurred only with buprenorphine. Two patients using PCA and five patients having IM analgesia developed short periods of respiratory depression (respiratory rate less than or equal to 8 breaths/minute and/or oxygen (O2) desaturation less than or equal to 90%), which promptly responded to commands to breathe deeply. Respiration rates did not differ, and frequent arterial blood sampling showed normal mean partial pressures of oxygen (PO2) and carbon dioxide (PCO2) and arterial oxygen saturation (SaO2) in all subgroups.

CONCLUSIONS

Opioid-induced respiratory depression occurred infrequently during postoperative pain management whether by conventional means or using PCA, even though high doses of opioid analgesics were required intermittently for adequate postoperative pain relief by either technique.

[Use of morphinomimetics in regional anesthesia]

Pain relief is one of medicine's most important challenges and the first aim of anaesthesia. The most common technique of postoperative analgesia remains intramuscular or subcutaneous opiates. There has been a better understanding of the mechanisms of action of opiates over the last decade, and new techniques and methods of administration have been developed especially their regional application. In 1979, two reports acted as catalysts to promote further studies. Wang et al. reported on the efficacy of intrathecal morphine to relieve unbearable malignant pain in 8 patients whereas Behar et al reported on the efficacy of morphine by epidural route. More recently, several studies pointed out the usefulness of the peripheral perineural route for opiates. However, this remains controversial, as some discrepancies persist in the results. The classification of opiate receptors and their relationship to opiate analgesia, as well as the mechanisms of action of regionally administered opiates are analyzed. The dual pre- and postsynaptic actions of spinal opiates are then considered. The parts played by the different neurotransmitters and pathways are set out. The evidence for opiate receptors at peripheral nerve sites and the different hypotheses suggested to explain the effect of opiates given by the perineural route are discussed. The pharmacokinetics and pharmacodynamics of opiates given by the subarachnoid and epidural routes are considered, in particular with respect to the comparative pharmacology of the commonly used opiates. The adverse effects of spinal opiates are reviewed, with their potential risks, and their clinical and therapeutic implications. Opiates and local anaesthetics given by the spinal route are compared. The clinical applications of intrathecal and epidural opiates are discussed, especially in the fields of postoperative analgesia, treatment of chest trauma, and cancer pain. Lastly, the few controlled studies concerning the use of opiates in peripheral nerve blocks, especially brachial plexus blocks, and the prospects of this new technique of giving opiates regionally are discussed.

[Postoperative analgesia after cesarean section: sublingual buprenorphine versus subcutaneous morphine]

This study aimed to compare the efficacy and side-effects of sublingual buprenorphine, a synthetic opioid agonist antagonist, with those of subcutaneous morphine. Fifty ASA class 1 patients were included in the study after having given their informed consent. Caesarean section was carried out under epidural block with 0.5% bupivacaine; no opioids were used during the procedure. The first dose of opioid was given 2 h after the first dose of bupivacaine. Patients were randomly given either 10 mg morphine (n = 25) or 0.4 mg buprenorphine (n = 25), followed by the same dose every 6 h for 36 h. When analgesia was insufficient, tablets containing dextropropoxyphene and paracetamol were given. No attempt was made to blind the study to the patient, but the investigator assessing pain was unaware of the drug given to the patient. Pain intensity was assessed before, and 2 h after each dose of opioid with a 100 mm visual scale, as well as systolic, diastolic and mean arterial blood pressures, heart and breathing rates, and SpO2. Side-effects (pruritus, nausea, vomiting, drowsiness) were also noted. In 2 patients in each group, the protocol was stopped before the 36th h, but after the fourth dose, either because of side-effects, or at the patient's request. Results were similar in both groups of patients, whether for degree of pain relief, or physiological effects. There was no clinically detectable respiratory depression. Duration and intensity of episodes of arterial oxygen desaturation, and the incidence of nausea, were similar in the 2 groups; pruritus was more common in the morphine group.(ABSTRACT TRUNCATED AT 250 WORDS)