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Intrathecal Morphine as an Alternative for Epidural Analgesia for Postoperative Pain in a Resource Constrained Set-up: A Case Series
Correspondence Address :
Dr. Ajay S Shandilya,
Assistant Professor, Department of Anaesthesiology, Chandramma Dayananda Sagar institute of Medical Education and Research, Harohalli,
Kanakapura Taluk, Ramanagar, Karnataka, India.
E-mail: ajay.anaesthesia@gmail.com
Management of postoperative pain is a central piece in the jigsaw of postoperative care. This article reports a series of three patients who were managed with intrathecal morphine to provide postoperative analgesia, for major abdominal surgeries. Morphine was injected intrathecally before the induction of anaesthesia. The patients were pain free postoperatively, required minimal intravenous opioids on the first postoperative day. There was no incidence of postoperative nausea or vomiting, pruritus and respiratory depression. Intrathecal morphine improves the quality of postoperative analgesia, there is a reduction in pain scores in the first 24 hours after surgery and the need for rescue analgesia with intravenous opioids is less. Intrathecal morphine can be used as an alternative to continuous epidural analgesia in early postoperative period.
Enhanced recovery after surgery, Laparotomy, Opioids, Postoperative analgesia, Spinal morphine
Management of postoperative pain is a central piece in the jigsaw of postoperative care. Epidural analgesia is considered the standard of care and is strongly recommended in the Enhanced Recovery After Surgery (ERAS) protocol consensus for gastrointestinal surgeries (1), as a part of multimodal analgesia. Thoracic Epidural Analgesia (TEA) is the gold standard for pain control in patients undergoing open abdominal surgeries (2). Due to logistical issues arising as an effect of the Coronavirus Disease 2019 (COVID-19) pandemic, the epidural catheters at the hospital were exhausted. Hence, other options to supplement the multimodal analgesia had to be explored. Intrathecal opioids have been used as an adjuvant for spinal anaesthesia and in patients undergoing general anaesthesia as an additional mode of analgesia. The technique to deposit intrathecal opioids is fairly simple with a very low risk of failure. Morphine was first used intrathecally in humans in 1979, as a treatment for intractable lower limb and back pain in patients with advanced genitourinary malignancies infiltrating the lumbar plexus (3).
Intrathecal morphine has been used in various surgeries like Caesarian sections (4), lower limb arthroplasties (5). It has also been moderately recommended as a part of ERAS protocols in order to spare systemic opioids (1).
Intrathecal morphine although provides good postoperative analgesia, it’s use has an incidence of increased Postoperative Nausea And Vomiting (PONV), pruritus (6),(7), urinary retention (8) and respiratory depression (7), and hence, necessitates care in the postanaesthesia care unit.
The present case series reports three patients. A 34-year-old male (ASA II, for pancreatico-jejunostomy), a 50-year-old female (American Society of Anaesthesiologists {ASA} I for cholecystectomy and common bile duct exploration), and a 44-year-old female (ASA II for Whipple’s procedure). The patients were given intrathecal morphine 300 μg diluted in 0.9% saline to a total volume of 1 mL, in L3-L4 space before the induction of anaesthesia. Intravenous induction with propofol, fentanyl 100 μg and atracurium was done. Intraoperatively, Electrocardiogram (ECG), SpO2, End tidal carbon dioxide (EtCO2), invasive blood pressure monitoring were done. Dexamethasone 8 mg, ondansetron 8 mg, paracetamol 1 gm and diclofenac 75 mg were given, intraoperatively. All patients were extubated on table and kept in the postoperative Intensive Care Unit (ICU) for observation.
Patients were assessed for pain at various time intervals using the Visual Analogue Scale (VAS) and a rescue analgesia with 4.5 mg morphine was decided to be given, whenever the patient has a VAS of >4. All patients were given paracetamol 1 gm 8th hourly and diclofenac 75 mg 12th hourly, ondansetron 4 mg 8th hourly. The average duration of the surgeries was 6 hours.
The pain scores of all patients were 2 at the 2nd hour, postoperatively. The pain scores of all the patients were similar at 2, 3, 3 at the end of 4 hours, 8 hours and 12 hours of surgery, respectively. At 16 hours postextubation patient 3 had a VAS of 7 needing rescue analgesia with 4.5 mg morphine. Patients 1 and 2 had VAS of 4 at 16 hours and at 24 hours (Table/Fig 1). Postextubation patient 3 had a VAS of 6, rescue analgesia with morphine 4.5 mg was given. Patients 1 and 2 had a score of 5 needing rescue analgesia with morphine 4.5 mg. All patients were instituted with intravenous morphine 4.5 mg 6th hourly from 24 hour onwards, for the next two days.
The patients were started on incentive spirometry from postoperative day 1 and they were comfortable with the exercise. Patients 1 and 2 could be mobilised on to a chair from postoperative day 1. Patient 3 was mobilised on postoperative day 3.
There was no incidence of pruritus, PONV or respiratory depression in any of the patients. Arterial Blood Gas (ABG) was recorded at 6, 12 and 24 hours for all patients with no carbon dioxide retention.
Management of postoperative pain is a very crucial aspect of surgical care and is central to the progress of the patient after surgery. Multimodal analgesia is associated with a reduction in the length of hospital stay (9). Thoracic Epidural Analgesia (TEA) forms a very important part of the multimodal analgesia strategy (1) and has been described as the gold standard for analgesia in upper abdominal surgeries and was regularly being used in the study hospital setting. The coronavirus pandemic created some unexpected logistical issues due to which we had to contend with unavailability of epidural catheters for a while. The number of open abdominal surgeries also increased at the same time due to logistical issues with the laparoscopic equipment. This nudged the decision to use intrathecal morphine as a part of multimodal analgesia.
Intrathecal morphine is known to provide prolonged postoperative analgesia (7), although safety has been a concern as morphine is a hydrophilic opioid having a propensity to stay at higher concentrations in the CSF and reach rostral sites as compared to other opioids causing delayed respiratory depression (10). Other significant side effects of morphine include PONV, pruritus (6),(7) and urinary retention (8).
Wang JK et al., had used a dose of 0.5 mg diluted in physiological saline in eight patients with intractable pain due to genito-urinary malignancies and found that it provided near complete pain relief as compared to placebo. There was no increase in the quality of analgesia when the dose was increased from 0.5 mg to 1 mg (3). Morphine was first used intrathecally in 1979 (3) and has since been used in varying doses ranging from 4 mg (11) to 50 μg (12). A meta-analysis done to find out the analgesic efficacy and side effect profile of intrathecal morphine done by Gonvers E et al., (5) in patients undergoing total knee arthroplasties found that a dose of 100 μg best balanced the analgesia and side effects and that the incidence of postoperative nausea vomiting increased when the dose was more. A meta-analysis by Meylan N et al., showed that intrathecal morphine reduced the need for intravenous fentanyl intraoperatively and also reduced the total does of intravenous morphine needed postoperatively (7). A dose of around 300 μg was used in many studies where the subjects were undergoing major abdominal surgeries (13),(14),(15),(16).
A dose of 300 μg was chosen because the surgeries were major abdominal surgeries with large incisions either subcostally or midline and it was felt that a dose of 100 μg would be too little. A dose of 300 μg of morphine diluted in 1 mL normal saline which was deposited in the subarachnoid space before the induction of general anaesthesia. All patients were given a standard intravenous induction, maintenance of anaesthesia was by inhalational anaesthetics. All patients were given paracetamol. Ondansetron 8 mg and dexamethasone 8 mg were given as preventive measures for pruritus (17) and PONV.
The patients were pain free postoperatively, required minimal intravenous opioid on the 1st postoperative day. There was no incidence of PONV or pruritus. Urinary retention could not be assessed all the patients were catheterised due to the nature of the surgery. There was no incidence of respiratory depression which authors defined as a respiratory rate less than 10/min. There was also no carbon dioxide retention as evidenced in the Arterial Blood Gas test (ABGs).
The administration of intrathecal morphine preoperatively helps in improving the quality of postoperative analgesia and also reduces the need for intravenous opioid administration as rescue analgesia. Intrathecal morphine is as an effective method of pain relief in the early postoperative period and can be used as an alternative to continuous epidural analgesia in major abdominal surgeries.
DOI: 10.7860/JCDR/2022/55916.16867
Date of Submission: Feb 25, 2022
Date of Peer Review: Apr 20, 2022
Date of Acceptance: Jun 23, 2022
Date of Publishing: Oct 01, 2022
AUTHOR DECLARATION:
• Financial or Other Competing Interests: None
• Was informed consent obtained from the subjects involved in the study? Yes
• For any images presented appropriate consent has been obtained from the subjects. Yes
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