Respiratory effects of intrathecal morphine after upper abdominal surgery

Comparison of Changes in Chest Wall Mechanics and Respiratory Timing Between Patient-Controlled Epidural Analgesia and Intravenous Patient-Controlled Analgesia After Laparoscopic Gastrectomy: A Randomized Controlled Trial

BACKGROUND

Upper abdominal surgery is associated with postoperative diaphragmatic dysfunction. Whether patient-controlled epidural analgesia (PCEA) is superior to intravenous patient-controlled analgesia (IV-PCA) in preventing postoperative diaphragmatic dysfunction is still unclear in laparoscopic gastric surgery.

METHODS

Sixteen patients undergoing laparoscopic gastrectomy randomly received either PCEA or IV-PCA. The primary outcomes were the change in chest wall mechanics and respiratory timing, measured by respiratory inductive plethysmography (Respitrace; Ambulatory Monitoring Inc., Ardsley, New York, United States) before and after surgery, and analyzed by a data acquisition system (PowerLab; ADInstruments, Dunedin, New Zealand). Inspiratory time (Ti), expiratory time (Te), total respiratory cycle time (Ttot), proportion of inspiratory time over total respiratory cycle time (Ti/Ttot), respiratory rate (RR), and abdominal contribution to tidal volume (AB/V_T [%]) were calculated from the stored data. AB/V_T, relative volume contribution of diaphragm to tidal breathing, represents an index of diaphragmatic function. Because the diaphragm is the main contributor to tidal volume, decreases in AB/V_T indicate diaphragm dysfunction. Changes in outcomes over time between the two groups were analyzed using a linear mixed model, and two-sided p values < 0.05 were considered statistically significant. The secondary outcomes were postoperative pain score (visual analog scale (VAS)), bowel function recovery, and hospital stay duration.

RESULTS

Postoperative AB/V_T in the IV-PCA group was significantly decreased compared to preoperative levels. AB/V_T in the PCEA group was significantly higher than the IV-PCA group on postoperative day (POD) 1. Change in AB/V_T over time between the PCEA group and the IV-PCA group differed significantly (p = 0.01). A decrease of AB/V_T during POD 1 to 3 was observed in the IV-PCA group but not in the PCEA group. As for respiratory timing, there were significant increases in RR with a reduction of Te and Ttot compared to preoperative levels on POD 1 in the PCEA group. There were significant decreases in RR and Ti/Ttot with an increase of Te and Ttot compared to preoperative levels on POD 1 in the IV-PCA group. There was a significant difference in the change of the Ttot over time between the two groups (p = 0.046). There were no significant differences in the changes of Te, Ti/Ttot, Ti, and RR over time between the two groups. There was no significant difference in VAS over time at rest and mobilization, recovery of bowel function, and hospital stay between the two groups.

CONCLUSIONS

Continuous ropivacaine infusion with PCEA partially attenuated diaphragmatic dysfunction after laparoscopic gastrectomy, while pain relief by continuous intravenous administration of fentanyl could not attenuate diaphragmatic dysfunction. This suggests that PCEA might ameliorate postoperative diaphragmatic dysfunction after laparoscopic gastrectomy.

InTrathecal mORphine, traNsversus Abdominis Plane Block, and tramaDOl Infusion for Catheter-Related Bladder Discomfort in Patients Undergoing Robot-Assisted Laparoscopic Prostatectomy (TORNADO): A Pilot Prospective Controlled Study

Catheter-related bladder discomfort (CRBD), affecting surgical patients requiring large catheters, is often intolerable. In this prospective controlled study, we compared the efficacy of three analgesic approaches in the management of CRBD. Here, 33 patients undergoing robot-assisted laparoscopic prostatectomy (RALP) were allocated to the following three groups: intrathecal morphine (IM), transversus abdominis plane block (TAP), and tramadol intravenous infusion (TI). The primary outcome was CRBD assessed at admission in the recovery room (RR) (T0), and 1 h (T1), 12 h (T2), and 24 h (T3) after surgery. The secondary outcomes included the following: Aldrete score; postoperative pain, measured with a numerical rate scale (NRS) at T0, T1, T2, and T3; postoperative opioid consumption; and flatus. The patients of the IM group showed significantly lower CRBD values over time compared to the patients of the TI group (p = 0.006). Similarly, NRS values decreased significantly over time in patients receiving IM compared to patients treated with TI (p < 0.0001). Postoperative nausea and vomiting did not differ among the three groups. Postoperative opioid consumption was significantly lower in the IM group compared to the other two groups. Most patients of the IM group (9 of 11) had flatus on the first postoperative day. In conclusion, IM may prevent CRBD and reduce pain perception and postoperative opioid consumption and expedite bowel function recovery.

Analgesic efficacy of intrathecal morphine and bupivacaine during the early postoperative period in patients who underwent robotic-assisted laparoscopic prostatectomy: a prospective randomized controlled study

Background

The present study was performed to investigate the analgesic efficacy of intrathecal morphine and bupivacaine (ITMB) in terms of treating early postoperative pain in adult patients who underwent robotic-assisted laparoscopic prostatectomy (RALP).

Methods

Fifty patients were prospectively enrolled and randomly classified into the non-ITMB (n = 25) and ITMB (n = 25) groups. The ITMB therapeutic regimen consisted of 0.2 mg morphine and 7.5 mg bupivacaine (total 1.7 mL). All patients were routinely administered the intravenous patient-controlled analgesia and appropriately treated with rescue intravenous (IV) opioid drugs, based on the discretion of the attending physicians who were blinded to the group assignments. Cumulative IV opioid consumption and the numeric rating scale (NRS) score were assessed at 1, 6, and 24 h postoperatively, and opioid-related complications were measured during the day after surgery.

Results

Demographic findings were comparable between patients who did and did not receive ITMB. The intraoperative dose of remifentanil was lower in the ITMB group than in the non-ITMB group. Pain scores (i.e., NRS) at rest and during coughing as well as cumulative IV opioid consumption were significantly lower in patients who received ITMB than in those who did not in the post-anesthesia care unit (PACU; i.e., at 1 h after surgery) and the ward (i.e., at 6 and 24 h after surgery). ITMB was significantly associated with postoperative NRS scores of ≤ 3 at rest and during coughing in the PACU (i.e., at 1 h after surgery) before and after adjusting for cumulative IV opioid consumption. In the ward (i.e., at 6 and 24 h after surgery), ITMB was associated with postoperative NRS scores of ≤ 3 at rest and during coughing before adjusting for cumulative IV opioid consumption but not after. No significant differences in complications were observed, such as post-dural puncture headache, respiratory depression, nausea, vomiting, pruritus, or neurologic sequelae, during or after surgery.

Conclusion

A single spinal injection of morphine and bupivacaine provided proper early postoperative analgesia and decreased additional requirements for IV opioids in patients who underwent RALP.

Trial registration: Clinical Research Information Service, Republic of Korea; approval number: KCT0004350 on October 17, 2019. https://cris.nih.go.kr/cris/en/search/search_result_st01.jsp?seq=15637

The NAPRESSIM trial: the use of low-dose, prophylactic naloxone infusion to prevent respiratory depression with intrathecally administered morphine in elective hepatobiliary surgery: a study protocol and statistical analysis plan for a randomised controlled trial

BACKGROUND

Intrathecally administered morphine is effective as part of a postoperative analgesia regimen following major hepatopancreaticobiliary surgery. However, the potential for postoperative respiratory depression at the doses required for effective analgesia currently limits its clinical use. The use of a low-dose, prophylactic naloxone infusion following intrathecally administered morphine may significantly reduce postoperative respiratory depression. The NAPRESSIM trial aims to answer this question.

METHODS/DESIGN

'The use of low-dose, prophylactic naloxone infusion to prevent respiratory depression with intrathecally administered morphine' trial is an investigator-led, single-centre, randomised, double-blind, placebo-controlled, double-arm comparator study. The trial will recruit 96 patients aged > 18 years, undergoing major open hepatopancreaticobiliary resections, who are receiving intrathecally administered morphine as part of a standard anaesthetic regimen. It aims to investigate whether the prophylactic administration of naloxone via intravenous infusion compared to placebo will reduce the proportion of episodes of respiratory depression in this cohort of patients. Trial patients will receive an infusion of naloxone or placebo, commenced within 1 h of postoperative extubation continued until the first postoperative morning. The primary outcome is the rate of respiratory depression in the intervention group as compared to the placebo group. Secondary outcomes include pain scores, rates of nausea and vomiting, pruritus, sedation scores and adverse outcomes. We will also employ a novel, non-invasive, respiratory minute volume monitor (ExSpiron 1Xi, Respiratory Motion, Inc., 411 Waverley Oaks Road, Building 1, Suite 150, Waltham, MA, USA) to assess the monitor's accuracy for detecting respiratory depression.

DISCUSSION

The trial aims to provide a clear management plan to prevent respiratory depression after the intrathecal administration of morphine, and thereby improve patient safety.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT02885948 . Registered retrospectively on 4 July 2016. Protocol Version 2.0, 3 April 2017. Protocol identification (code or reference number): UCDCRC/15/006 EudraCT registration number: 2015-003504-22. Registered on 5 August 2015.

Efficacy of intrathecal morphine for postoperative pain management following open nephrectomy

Objective

To evaluate the efficacy and safety of intrathecal morphine (ITM) for postoperative pain control in patients with renal cell carcinoma undergoing open nephrectomy.

Methods

Forty-five patients scheduled for open nephrectomy were randomised to receive 300 µg ITM and intravenous patient-controlled analgesia (IV-PCA) (n = 22) or IV-PCA alone (n = 23) for postoperative analgesia. The numeric pain score (NPS), postoperative IV-PCA requirements and opioid-related complications including nausea, vomiting, dizziness, headache, and pruritus were compared between groups.

Results

NPS was significantly lower in the ITM group up to 24 h postoperatively. Upon coughing, NPS at 24 h postoperatively was 50 (interquartile range (IQR) 30–60) in the ITM group and 60 (45–70) in the IV-PCA group. Cumulative morphine consumption at 72 h postoperatively was significantly lower in the ITM group compared with the IV-PCA group (20 (9–33) mg vs. 31 (21–49) mg, respectively). Opioid-related complications were similar in both groups with the exception of pruritus (ITM, 77% vs. IV-PCA, 26%).

Conclusions

ITM was associated with greater analgesia without serious complications in patients undergoing open nephrectomy.

Analgesic Efficacy of Pfannenstiel Incision Infiltration with Ropivacaine 7.5 mg/mL for Caesarean Section

Background. Pain after Caesarean delivery is partly related to Pfannenstiel incision, which can be infiltrated with local anaesthetic solutions. Methods. A double- blind randomized control trial was designed to assess the analgesic efficacy of 7.5 mg/mL ropivacaine solution compared to control group, in two groups of one hundred and forty four parturients for each group, who underwent Caesarean section under spinal anaesthesia: group R (ropivacaine group) and group C (control group). All parturients also received spinal sufentanil (2.5 μg). Results. Ropivacaine infiltration in the Pfannenstiel incision for Caesarean delivery before wound closure leads to a reduction of 30% in the overall consumption of analgesics (348 550 mg for group R versus 504 426 mg for group C with P < .05), especially opioids in the first 24 hours, but also significantly increases the time interval until the first request for an analgesic (4 h 20 min ± 2 h 26 for group R versus 2 h 42 ± 1 h 30 for group C). The P values for the two groups were: P < .0001 for paracetamol, P < .0001 for ketoprofen and P for nalbuphine which was the most significant. There is no significant difference in the threshold of VAS in the two series. Conclusion. This technique can contribute towards a programme of early rehabilitation in sectioned mothers, with earlier discharge from the post-labour suite.

Determination Of The Efficacy And Side-effect Profile Of Lower Doses Of Intrathecal Morphine In Patients Undergoing Total Knee Arthroplasty

BACKGROUND

Intrathecal (IT) morphine provides excellent post-operative analgesia, but causes multiple side effects including nausea and vomiting (PONV), pruritus and respiratory depression, particularly at higher doses. The lowest effective dose of spinal morphine in patients undergoing total knee arthroplasty is not known.

METHODS

We evaluated the analgesic efficacy and side effect profile of 100 - 300 μg IT morphine in patients undergoing elective total knee replacement in this prospective, randomized, controlled, double-blind study. Sixty patients over the age of 60 undergoing elective knee arthroplasty were enrolled. Patients were randomized to receive spinal anaesthesia with 15 mg Bupivacaine and IT morphine in three groups: (i) 100 μg; (ii) 200 μg; and (iii) 300 μg.

RESULTS

Both 200 μg and 300 μg IT morphine provided comparable levels of postoperative analgesia. However, patients that received 100 μg had greater pain postoperatively, with higher pain scores and a greater requirement for supplemental morphine. There were no differences between groups with regard to PONV, pruritus, sedation, respiratory depression or urinary retention.

CONCLUSION

Both 200 μg and 300 μg provided comparable postoperative analgesia, which was superior to that provided by 100 mug IT morphine in patients undergoing total knee arthroplasty. Based on these findings, we recommend that 200 μg IT morphine be used in these patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT00695045.

Spinal analgesia for the postoperative period in renal donors

BACKGROUND

To provide postoperative analgesia by spinal anesthesia, we compared the quality of analgesia and side effects of two doses of morphine added to ropivacaine in kidney donors.

MATERIALS AND METHODS

Thirty renal donors underwent nephrectomy under standard general anesthesia. After the operation, the patients were randomly allocated into two groups of intrathecal doses for spinal anesthesia: the 0.5 group (n = 15) received a total volume of 4 mL including 0.5 mg morphine, 10 mg ropivacaine, and 0.9% NaCl, and the 0.3 group (n = 15), a total volume of 4 mL including 0.3 mg morphine, 10 mg ropivacaine, and 0.9% NaCl. After extubation, an intravenous (IV) morphine protocol was initiated by a patient-controlled analgesia pump to provide sufficient spinal analgesia.

RESULTS

In the 0.3 group, the IV morphine consumption was significantly higher, namely, 14.60 +/- 7.57 times versus 4.60 +/- 10.14 times for the 0.5 group (P = .005). The total amount of morphine was 7.80 +/- 5.40 mg in the 0.5 group and 13.53 +/- 5.30 mg in the 0.3 group (P < .05). Postoperative side effects of nausea and vomiting were higher among the 0.3 group (P < .05).

CONCLUSIONS

In the 0.5 group, the quality of analgesia was better than in the 0.3 group. The need for IV morphine was less in the 0.5 group. Also, side effects like nausea and vomiting were less, so better analgesia in the postoperative period was obtained with the 0.5 mg morphine solution.

Optimizing the dose of intrathecal morphine in older patients undergoing hip arthroplasty

Intrathecal (IT) morphine provides excellent postoperative analgesia but may result in many side effects, including postoperative nausea and vomiting, pruritus, and respiratory depression, particularly at larger doses. Older patients may be at particular risk. The optimal dose of spinal morphine in older patients undergoing hip arthroplasty is not known. We designed this prospective, randomized, controlled, double-blinded study to evaluate the analgesic efficacy and side effect profile of 50-200 microg of IT morphine in older patients undergoing elective hip arthroplasty. Sixty patients older than 65 years undergoing elective hip arthroplasty were enrolled. Patients were randomized to receive spinal anesthesia with 15 mg of bupivacaine and IT morphine in four groups: 1). 0 microg, 2). 50 microg, 3). 100 microg, and 4). 200 microg. IT morphine 100 and 200 microg produced effective pain relief and decreased the postoperative requirement for morphine compared with control. IT morphine 50 microg did not provide effective pain relief. Both 100 and 200 microg of IT morphine provided comparable levels of postoperative analgesia. There were no between-group differences in postoperative nausea and vomiting, sedation, respiratory depression, or urinary retention. Pruritus was significantly more frequent with 200 microg of IT morphine. In conclusion, 100 microg of IT morphine provided the best balance between analgesic efficacy and side effect profile in older patients undergoing hip arthroplasty.

IMPLICATIONS

The dosage of intrathecal morphine that provides the best balance between analgesic efficacy and side effect profile in the older patient undergoing hip arthroplasty is not known. This prospective, randomized, controlled, double-blinded clinical trial demonstrates that a dose of 100 microg of intrathecal morphine provides the best balance between efficacy and side effects, compared with doses of 0, 50, and 200 microg of morphine, in this patient population.

Definitions of "respiratory depression" with intrathecal morphine postoperative analgesia: a review of the literature

PURPOSE

To review the postoperative intrathecal morphine (ITM) analgesia literature for their definitions of "respiratory depression" (RD).

SOURCE

Medline (1966 - June Week 5 2001) and reference lists were searched for original studies involving bolus-dose ITM for postoperative analgesia, which used "respiratory depression" or similar terms.

PRINCIPLE FINDINGS

The search identified 209 studies. These were included if ITM use was appropriate (bolus dose, postoperative analgesia) and the term "respiratory depression" was used, which left 96 studies remaining. Forty-four (46%) did not define "RD" despite using this term. A further 24 (25%) defined RD with respiratory rate (RR) alone. Only 28 (29%) defined RD with more than RR alone. There was no statistically significant association between the presence of a definition for RD with study design, study size or publication period. Also, no significant association existed between rigorousness of RD definitions and the above factors.

CONCLUSION

The term "respiratory depression" has no clear definition from a review of the literature on ITM use for postoperative analgesia. While defining RD with bradypnea is superior to having no definition, this is still inadequate. In future research, the consistent use of terms with specific meanings will facilitate understanding the true incidence of ITM's respiratory effects. If "respiratory depression" is used, then an explicit definition of its meaning should be provided. Future research must also address what is clinically significant respiratory impairment from intrathecal opioids, and how to optimally monitor for this. Further delineating their risks vs benefits will allow for more optimal dosing.

Intrathecal + PCA morphine improves analgesia during the first 24 hr after major abdominal surgery compared to PCA alone

PURPOSE

To compare, over a 48-hr follow-up period, the analgesia and side-effects of patient controlled iv analgesia (PCA) with morphine alone vs combined intrathecal and PCA morphine (IT+PCA) in patients undergoing major abdominal surgery.

METHODS

Sixty adult patients undergoing abdominal surgery for cancer were randomly allocated to receive preoperative IT (0.3 or 0.4 mg) plus postoperative PCA morphine or postoperative PCA morphine alone. Postoperative analgesia was tested at rest and while coughing on a visual analogue pain scale and morphine consumption was recorded. Patients' satisfaction, arterial oxygen saturation, respiratory rate, episodes of nausea, vomiting and pruritus were also noted.

RESULTS

Analgesia at rest and while coughing was significantly better in the IT+PCA morphine group (rest: P = 0.01; coughing: P = 0.005) on the first postoperative day only. IT+PCA morphine constantly provided adequate analgesia during this period. Morphine consumption was lower in the IT+PCA morphine group during this period also (IT+PCA: 9 (17) vs PCA: 40 (26); mg of morphine, mean (SD), P = 0.0001). No difference was found in pain relief and morphine consumption between the groups on the second postoperative day. Nausea and vomiting were more frequent with IT+PCA morphine on the first postoperative day. No respiratory depression occurred in either group. Satisfaction was high in both groups.

CONCLUSIONS

IT+PCA morphine improves patient comfort constantly during the first postoperative day after major abdominal surgery. However, after the first postoperative day, IT+PCA morphine provides no additional benefit.

Intrathecal morphine. Double-blind evaluation of optimal dosage for analgesia after major lumbar spinal surgery

STUDY DESIGN

A prospective, randomized, double-blind study.

OBJECTIVES

To evaluate the efficacy and safety of three different dosages of intrathecal morphine sulfate for postoperative analgesia after lumbar spinal fusion.

SUMMARY OF BACKGROUND DATA

Analgesia and respiratory depression after intrathecal morphine sulfate injection are dose related. The optimal dose to use for major spinal surgery is not known.

METHODS

Sixty patients undergoing posterolateral lumbar fusion with or without decompression were divided randomly into 3 groups of 20 patients each. Anesthesia, monitoring, and surgery were similar for all patients. Just before closing of the wound, morphine sulfate was injected into the dural sack under direct visualization. Patients in groups 1-3 received 0.2 mg, 0.3 mg, and 0.4 mg morphine, respectively. Routine analgesia, consisting of diclofenac, was prescribed to use if necessary. Measurements were made and compared between the groups at zero hours (on admission to the Intensive Care Unit), 6 hours, 12 hours, 18 hours, and 24 hours after surgery.

RESULTS

At zero hours and at 12 hours after surgery, pain levels were similar in groups 2 and 3, but were significantly higher in group 1 (P < 0.05). The respiratory rate was significantly lower in group 3 than in the other two groups (P < 0.05), and the arterial CO2 tension (PaCO2) was consistently higher in group 3. PaCO2 decreased in all three groups over the first 24 hours. Pruritus and nausea did not differ among the three groups.

CONCLUSIONS

For adult patients undergoing posterolateral lumbar fusion, 0.3 mg (0.004 mg/kg) is probably the optimal dose of intrathecal morphine to manage pain.

The safety and efficacy of intrathecal opioid analgesia for acute postoperative pain: seven years' experience with 5969 surgical patients at Indiana University Hospital

To assess the efficacy of the analgesic technique and the incidence of complications, we prospectively evaluated patients who received intrathecal opioid analgesia (ITOA) to manage postsurgical pain. Daily quality assurance data were collected on the first postoperative day and tabulated for 5969 adult patients who had received ITOA for major urologic, orthopedic, general/ vascular, thoracic, and nonobstetrical gynecologic surgery. A scale of 1-10 was used to quantify each patient's satisfaction with analgesia. The incidence of side effects, complications, and naloxone usage was also recorded and tabulated. The mean satisfaction score using a 10-point numeric rating scale was 8.51, with a score of 1 connoting "complete dissatisfaction" and 10 connoting "complete satisfaction." Side effects were minor and easily managed. Pruritus was the most common (37%). Respiratory depression was the least common (3%), easily detected by nursing observation, never life-threatening, and always responsive to treatment with naloxone. There were no deaths, nerve injuries, central nervous system infections, or naloxone-related complications. Postdural puncture headaches were rare (0.54%), as was the need for epidural blood patch (0.37%).

IMPLICATIONS

Over a 7-yr period, intrathecal opioid analgesia was used to control acute postoperative pain on nearly 6000 patients, resulting in a high degree of patient satisfaction and a low incidence of side effects and complications.

[Repercussion of postoperative pain, benefits attending to treatment]

Physiological responses to postoperative acute pain may impede organ functions (cardiovascular, pulmonary, coagulation, endocrine, gastrointestinal, central nervous system, etc). Pain alleviation improves patient's comfort, but also may minimise perioperative stress response, physiological responses and postoperative organ dysfunction, assist postoperative nursing and physiotherapy, enhance clinical outcome, and potentially shorten the hospital stay. Potent postoperative analgesia, especially by epidural route, may be associated with reduction in incidence and severity of many perioperative dysfunctions. Peridural analgesia using local anaesthetics is the best technique for decreasing postoperative stress after lower abdominal or lower limb surgery. Analgesia using either epidural or high doses of morphine may improve some cardiac variables such as tachycardia and ischaemia, but does not change the incidence of severe cardiac complications. For patients undergoing vascular or orthopaedic surgery, epidural analgesia can improve clinical outcome by preventing the development of arterial or venous thromboembolic complications. However, in comparative studies, the control groups did not receive adequate prophylactic treatment for thromboembolic complications. Epidural analgesia can hasten the return of gastrointestinal motility and shorten the hospital stay. Postoperative mental dysfunction is decreased using intravenous PCA morphine in the elderly. Epidural analgesia with local anaesthetics improves postoperative respiratory function but, for unknown reasons, these benefits are not associated with a decrease in respiratory complications. On balance, the mode of acute pain relief decreases adverse physiological responses and many intermediate outcome variables; however, there is inconclusive evidence that it affects clinical outcome. Major advances in postoperative recovery can be achieved by early aggressive perioperative care, including potent analgesia, early mobilisation and oral nutrition. As a result, the hospital stay may be shortened.

[Postoperative locoregional analgesia in the adult: epidural and peripheral techniques. Indications, adverse effects and monitoring]

Regional analgesia is a very effective way to treat postoperative pain. Lumbar and thoracic epidural analgesia are well adapted to major abdominal and thoracic surgery. Nevertheless, respiratory side effects induced by opioids are potentially severe and an adequate monitoring is essential. In orthopaedic surgery, perineural blocks are the best technique to manage postoperative pain and perineural catheters may be used. The importance of intra-articular analgesia, simple and safe, is not fully understood. The association of a local anaesthetic inducing a minor motor block and a strong sensitive block (bupivacaine, ropivacaine), with an opioid seems to be the best pharmacologic choice regarding quality of analgesia and safety. Benefits of postoperative regional analgesia on mortality and morbidity are not demonstrated. Medical and nursing staff and specialized units should improve quality of postoperative regional analgesia as well. General guidelines for the practice of regional anaesthesia must be closely followed.

[A low dose of nalbuphine reverses respiratory depression but not analgesia induced by intraspinal morphine]

Postoperative pain management after scoliosis surgery is based in our institution on intrathecal morphine administration. This case report describes an immediate and major postoperative respiratory depression that occurred in the recovery room, requiring the maintenance of the endotracheal tube. This respiratory depression was reversed by i.v. administration of a low dose of nalbuphine, which allowed tracheal extubation without suppression of morphine-induced analgesia.

[Prevention of respiratory complications after abdominal surgery]

Abdominal surgery, especially upper abdominal surgical procedures are known to adversely affect pulmonary function. Pulmonary complications are the most frequent cause of postoperative morbidity and mortality. This review article aimed to analyse the incidence and risk factors for postoperative pulmonary morbidity and their prevention. The most important means for preoperative assessment is the clinical examination; pulmonary function tests (spirometry) are not reliably predictive for postoperative pulmonary complications. Age, type of surgical procedure, smoking and nutritional state have all been identified as potential predictors for postoperative complications. However, usually there is not enough preoperative time available to obtain beneficial effects of stopping smoking and improvement of nutritional state. In patients with COPD, a preoperative multidisciplinary evaluation including the primary care physician, pulmonologist/intensivist, anesthesiologist and surgeon is required. Consensus as to preoperative physiologic state, therapeutic preparation, and postoperative management is essential. Simple spirometry and arterial blood gas analysis are indicated in patients exhibiting symptoms of obstructive airway disease. There are no values that contra-indicate an essential surgical procedure. Smoking should stop at least 8 weeks preoperatively. Preoperative therapy for elective surgery with antibiotics, beta2-agonist, or anticholinergic bronchodilator aerosols, as well as training in cough and lung expansion techniques should begin at least 24 to 48 hours preoperatively. Postoperative therapy should be continued for 3 to 5 days. Usually, anaesthesia is responsible for early complications, whereas surgical procedures are often associated with delayed morbidity. Laparoscopic procedures are recommended, as postoperative morbidity and hospital stay seem reduced in patients without COPD. Regional anaesthesia is given as having less adverse effects on pulmonary function than general anaesthesia. However, for unknown reasons these benefits are not associated with a decrease in postoperative respiratory complications. Moreover, the quality or the type of postoperative analgesia does not influence postoperative respiratory morbidity. Postoperatively, oxygen administration increases SaO2, but cannot abolish desaturation due to obstructive apnea. The various techniques of physiotherapy (chest physiotherapy, incentive spirometry, continuous positive airway pressure breathing) seem to be equivalent in efficacy; but intermittent positive pressure breathing has no advantages, compared with the other treatments and could even be deleterious. Chest physiotherapy and incentive spirometry are the most practical methods available for decreasing secretion contents of airways, whereas continuous positive airway pressure breathing is efficient on atelectasis. In stage II or III COPD patients, admission in a intensive therapy unit and prolonged mechanical ventilation may be required.

Influence of intrathecal morphine and naloxone intervention on postoperative ventilatory regulation in elderly patients

Thirty elderly patients undergoing major hip surgery under spinal analgesia were randomly allocated in a double-blind manner into three groups. The aim was to evaluate the influence of intrathecal morphine and postoperative naloxone infusion on the regulation of ventilation. The Bupivacaine Group received spinal analgesia with 20 mg bupivacaine intrathecally. The Morphine Group received spinal analgesia with 20 mg bupivacaine + 0.3 mg morphine intrathecally. The Naloxone Group received spinal analgesia with 20 mg bupivacaine + 0.3 mg morphine intrathecally + postoperative naloxone infusion intravenously (1 microgram/kg/h over 12 h, 0.25 micrograms/kg/h over the next 12 h). Evaluation of resting ventilation and the ventilatory responses to hypercarbia and hypoxaemia was made on three occasions: before surgery, and 8, and 24 h after the intrathecal injection. Intrathecal morphine had no significant effect on ventilatory regulation in elderly patients undergoing major hip surgery performed under bupivacaine spinal analgesia. Postoperative administration of opioids or sedatives after intrathecal morphine as well as postoperative blood loss associated with a fall in blood pressure appeared to increase the risk of developing respiratory depression. Naloxone infusion seemed to reduce the risk of developing respiratory depression. Furthermore, one third of the elderly had a poor response to hypoxaemia before surgery.

Is tolerance to intrathecal morphine in intact rats supraspinally mediated?

The effect of repeated intrathecal (IT) injections of 5 micrograms of morphine on the tail flick (TF) was determined in rats that were tested either 0.5 h or 5.0 h after administration on each of five successive days. Tolerance developed rapidly in animals tested 5.0 h after each injection. Animals tested 0.5 h after each injection did not become tolerant. Animals that were tested 5.0 h after an intrathecal saline injection on the first four days were also tolerant to a 5 micrograms dose of morphine on the fifth day. These data are discussed in the context of previous conflicting reports concerning tolerance to intrathecal morphine. It is suggested that, under certain conditions, tolerance to intermittent intrathecal morphine administration may be due to a supraspinal opiate action.

Perioperative functional residual capacity

The literature dealing with the magnitude, mechanism and effects of reduced FRC in the perioperative period is reviewed. During general anaesthesia FRC is reduced by approximately 20%. The reduction is greater in the obese and in patients with COPD. The most likely mechanism is the loss of inspiratory muscle tone of the muscles acting on the rib cage. Gas trapping is an additional mechanism. Lung compliance decreases and airways resistance increases, in large part, due to decreased FRC. The larynx is displaced anteriorly and elongated, making laryngoscopy and intubation more difficult. The change in FRC creates or increases intrapulmonary shunt and areas of low ventilation to perfusion. This is due to the occurrence of compression atelectasis, and to regional changes in mechanics and airway closure which tend to reduce ventilation to dependent lung zones which are still well perfused. Abdominal and thoracic operations tend to increase shunting further. Large tidal volume but not PEEP will improve oxygenation, although both increase FRC. Both FRC and vital capacity are reduced following abdominal and thoracic surgery in a predictable pattern. The mechanism is the combined effect of incisional pain and reflex dysfunction of the diaphragm. Additional effects of thoracic surgery include pleural effusion, cooling of the phrenic nerve and mediastinal widening. Postoperative hypoxaemia is a function of reduced FRC and airway closure. There is no real difference among the various methods of active lung expansion in terms of the speed of restoration of lung function, or in preventing postoperative atelectasis/pneumonia. Epidural analgesia does not influence the rate of recovery of lung function, nor does it prevent atelectasis/pneumonia.

Epidural opioids in children

Experience with spinal opioids in children is limited but is expanding. Anatomy, pharmacology, technique, and results are reviewed. Complications and side effects are described.