anesthesia general

hai ... here i am .. back with a lot of notes ... hihi , so .. for this section ~ i would like to share few words "perhaps" hihi ... regarding postoperative pain management ... take your time to read those articles . Thank You ^_^ MUAAHHH :)

Intrathecal morphine

February 10th, 2011 | Add a Comment

The intrathecal administration of opioids especially intrathecal morphine has emerged as a popular and effective form of postoperative pain control.

Intrathecal opioids are able to provide long-lasting analgesia after a single injection. They work by binding to the µ opioid receptors, which are located in the substantia gelatinosa of the dorsal horn of the spinal cord.

These receptors are concentration dependent and are typically not activated by systemic doses of opioids. Unlike intrathecal local anesthetics, intrathecal opioids provide analgesia without disrupting sensory, motor, or sympathetic functions.

Because of its hydrophilic properties and potent receptor affinity, preservative-free morphine (i.e., Duramorph or Astramorph) is the ideal opioid for intrathecal use.

The onset of analgesic effects is directly proportional to the lipid solubility of the opioid. Preservative-free morphine (along with hydromorphone and meperidine) has a relatively low lipid solubility and its onset of action is delayed for typically 20 to 40 minutes after administration.

The hydrophilic nature of the opioid also determines its duration of action. Preservative-free morphine is very hydrophilic and poorly lipid soluble, which extends its duration of analgesic effect up to 12 to 24 hours.

Because of its poor lipid solubility, intrathecal morphine remains in the cerebrospinal fluid (CSF) for a prolonged period of time. It is circulated through cerebral spinal bulk flow and eventually rises rostrally to supraspinal levels.

Intrathecal morphine, therefore, has bimodal analgesic effects. The first peak is soon after administration and is due to spinal opiate receptor binding. The second peak occurs 12 to 24 hours later and is due to supraspinal binding as the drug is circulated.

Compared with systemic dosing of morphine, intrathecal administration is effective in providing analgesia at a fraction of the systemic dose (0.25–0.5 mg) and thus has a much lower side-effect profile.

The side effects, however, are important to recognize and treat. Respiratory depression can be delayed up to 24 hours after administration and is due to the cephalad spread of intrathecal morphine to the opioid receptors in the medullary centers of the brain stem.

Thus, patients receiving intrathecal morphine must be closely monitored for up to 24 hours afterward for signs of respiratory depression.

Patients with postoperative pain despite having received intrathecal morphine present a management dilemma. Giving the patient additional systemic opioids must be done cautiously, as it may increase and potentiate the risk of respiratory depression.

Generally, patients who have received intrathecal morphine should not be placed on a patient-controlled analgesia machine and should be given only intermittent doses of short-acting narcotics until theintrathecal morphine analgesic effect occurs. Nonopioid analgesics can also be considered if not contraindicated after surgery.

Other intrathecal morphine side effects are similar to side effects of systemic morphine and include pruritus, nausea, vomiting, and urine retention. These effects are dose related and may be reversed with naloxone.

References

Raj PP, ed. Practical Management of Pain. 3rd Ed. St Louis: Mosby; 2000:180.

Rathmell JP, Lair TR, Nauman B. The role of intrathecal drugs in the treatment of acute pain. Anesth Analg 2005

Waldman SD, ed. Interventional Pain Management. 2nd Ed. Philadelphia: WB Saunders; 2001: 621 and 622

HERE... 

Pain Physician. 2007 Mar;10(2):357-66.

Drug-related side effects of long-term intrathecal morphine therapy.

Ruan X.

Source

Physician's Pain Specialists of Alabama, Mobile, AL, USA. xiuluruan@yahoo.com

Abstract

BACKGROUND:

The introduction of intrathecal opioid administration for intractable chronic non-malignant pain and cancer pain is considered as one of the most important breakthroughs in pain management. Morphine, the only opioid approved by FDA for intrathecal administration, has been increasingly utilized for this purpose. For over 3 decades, there have been numerous reports on the non-nociceptive side effects associated with ever increasing long-term intrathecal morphine usage.

OBJECTIVES:

To review the literature on side effects due to long-term intrathecal morphine therapy with discussions of alternate treatment options.

DESIGN:

English-language publications were identified through MEDLINE search and the bibliographies of identified articles were reviewed.

RESULTS:

Most side effects of intrathecal morphine therapy are dose dependent and mediated by opioid receptors. Common ones include nausea, vomiting, pruritus, urinary retention, constipation, sexual dysfunction, and edema. Less common ones include respiratory depression, and hyperalgesia. Catheter tip inflammatory mass formation is a less common complication that may not be mediated by opioid receptors.

CONCLUSION:

The utilization of intrathecal morphine administration for cancer and intractable non-malignant chronic pain represents an important leap forward in pain management. Yet, a wide variety of non-nociceptive side effects may also occur in susceptible patients. The side effects due to intrathecal morphine administration are mostly mediated by opioid receptors. Treatment usually involves the utilization of opioid receptor antagonist, such as naloxone. Patients considering intrathecal opioid pump therapy should be informed and advised about the possible side effects associated with long-term intrathecal morphine administration prior to placement of a permanent morphine infusion pump.


However ... in malaysia specifically our federal territory , we have provided pain management involving intrathecal morphine prior to obstetric patient in which only certain of the patient will having minor side effect ( should not be said side effect exactly) such as nauseated , vomiting , mild pruritus , or giddiness .By the way,  it will resolve in between 24 hours that we suggested the patient to drink a lot of water and encouraged early ambulation.   OH... oh... correct me if  i make some mistake... hihihi


Patient Controlled Analgesia 

Indications

• PCA is used for the management of moderate to severe pain when inadequate analgesia would result from oral analgesia or intermittent IV morphine boluses.

• The child must have the cognitive ability to understand the concept PCA and is willing to self-manage analgesia.

• Lack of normal hand function does not prevent patients from using PCA. A number of alternate handsets and a breath-triggered switch are available.

Contraindications to PCA

• If the child is unable to understand the concept of PCA or they do not wish to control their own analgesia, a nurse controlled opioid infusion would be more suitable.

Click to download PDF version (110 KB)

Prescription and program of PCA

• PCA is a specialised analgesia technique and is managed by CPMS. 
• Most patients are commenced on PCA in the recovery room. For other patients requiring PCA a referral needs to be made to CPMS by paging 5773(24 hours) and completing an inpatient consultation report sheet (MR2). The referrer needs to ensure that the patient's primary consultant has approved of CPMS involvement. 
• ONLY CPMS and Anaesthesia staff may prescribe PCA. For safety reasonsONLY Recovery or CPMS staff may program the PCA infusion pumps. 
• Morphine is the preferred opioid in most circumstances. Fentanyl or hydromorphone are alternative choices. Pethidine is NOT routinely used due to the concern for nor-pethidine toxicity. In some circumstances patients may have pethidine prescribed but this should only be for a short duration (generally less than 48 hours). 
• The PCA infusion is prescribed according to the guidelines on the Patient Controlled Analgesia attachment. This attachment is only valid if attached to a current medication chart (MR52). 
• If the prescription differs from the guidelines the designated box must be ticked.

PCA set up

• The PCA syringe must be prepared in accordance with RCH medication policy and labelled clearly with an intravenous additives label.

• PCA infusion pumps (Alaris P5000 PCA) must be used for all PCA infusions.

• The PCA infusion line should be clearly labelled with a blue IV opioid label at the 3-way-tap where the PCA line meets the maintenance line.

• 50 mL Braun Omnifix syringes are used for PCA, together with 180 cm minimum volume extension tubing.

• A 3-way-tap at the syringe end of the opioid infusion line is not required.

• The two authorised persons who make up each PCA syringe must sign the record of infusion on the Patient Controlled Analgesia attachment.

• Syringe and lines should be changed every 72 hours or more often depending on individual unit policy or the patient's medical condition.

• Keys for the PCA infusion pumps are kept with the ward drug keys on every ward. The operating theatre recovery room also has a set of PCA keys.

PCA delivery

• To avoid the IV occluding between PCA tries, the patient should have maintenance IV fluids (with a minimum infusion rate of 5 mL/hr) running through an infusion pump (IVAC or similar). No anti-reflux valves are required if an infusion pump is used. 
• The volume infused should be checked every hour and documented on the fluid balance chart. 
• The treatment for opioid overdose is the opioid antagonist naloxone (Narcan). Naloxone is available in the ward/unit drug cupboard and on the ward/unit resuscitation trolley. 
• The naloxone dose is available in 3 dose ranges: 1 microgram/kg for opioid induced pruritus and urinary retention 2 microgram/kg for excess sedation and 10 microgram/kg for resuscitation.

Concurrent drugs

• When opioid infusions are used, NO ORAL/ RECTAL/ INTRAVENOUS OR INTRAMUSCULAR opioids or sedative agents should be given without prior consultation with CPMS or an anaesthetist.

• Paracetamol, ketamine, local anaesthetics, tramadol and NSAIDs may be used concurrently with PCA infusions and may help to reduce opioid consumption and associated side effects.

Precautions

• If the patient is receiving other medication that may cause sedation (e.g. antihistamines, benzodiazepines or anticonvulsants), the patient may be at increased risk of sedation and respiratory depression. 
• Prolonged administration of opioid infusions and impaired liver and/or renal function may alter drug elimination with ALL opioids and possibly result in drug accumulation and toxicity.  
   
  • The morphine metabolite M3G causes CNS disturbances (including myoclonus and tremor) and the morphine metabolite M6G is a potent analgesic. Both these metabolites may accumulate in patients receiving long-term morphine infusions or patients with renal impairment. 
  • The hydromorphone metabolite H3G may accumulatein patients receiving long-term hydromorphone infusions orpatients with renal impairment. H3G can cause CNS disturbances (including confusion, tremor and agitation). 
  • Pethidine infusions may result in accumulation of the toxic metabolite
    nor-pethidine, which can cause CNS disturbances (including confusion, tremor and convulsions).
      
  • Prolonged fentanyl infusion may result in drug accumulation and potential increase in opioid related side effects. 
• Development of opioid tolerance with long-term administration of opioids may require the opioid dose to be increased. 
• Careful tapering of doses is important when weaning long-term opioids to avoid opioid withdrawal.

Parents and PCA

• It is important that the child's parents understand the concept of PCA, so they can support their child in its use.

• The child's parents must NOT push the PCA button for their child, but may encourage their child to use it as required.

Patient review

• CPMS reviews patients twice daily on week days and once daily on weekends and public holidays.

• If analgesia is inadequate or the patient is experiencing side-effects, CPMS must be called to review the patient.

• CPMS can be contacted at all times on pager 5773.

Observations

The following observations should be recorded on the general observation chart:

• Sedation score, respiratory rate and heart rate: 1 hourly until the PCA is ceased. [The need for less frequent observations for patients receiving long-term PCA should be discussed with CPMS.] It is important to accurately assess sedation during wake and sleep periods
• Pain score: 1 hourly while awake (using developmentally appropriate scale e.g. Wong-Baker Faces scale, Numeric scale, FLACC scale or PAT score).
    
• Vomiting score: 1 hourly  for the first 12 hours, then 4 hourly as indicated.
• Pulse oximetry: if indicated 

Indications for pulse oximetry: Pulse oximetry MUST BE implemented and used continuously in high-risk patients with: University of Michigan Sedation Scale (UMSS)  0 Awake and alert  1 Minimally sedated: may appear tired/sleepy, responds to verbal conversation and/or sound   2 Moderately sedated: somnolent/sleeping, easily aroused with light tactile stimulation or simple verbal command  3 Deep sedation: deep sleep, arousable only with deep or significant physical simulation  4 Unarousable  S Patient is sleeping  UMSS sedation score > 2 Significant cardiorespiratory impairment Sleep apnoea, snoring or airway obstruction Spot oximetry less than 94% SaO2 or patients receiving: Supplementary oxygen Concurrent sedative agents Clinical indicators for 'spot' pulse oximetry are: Tachypnoea or bradypnoea Respiratory distress Pallor or cyanosis or impaired oxygenation Confusion or agitation Hypotension Nurse concern

• PCA use: good and bad tries and total mg, recorded hourly. 
• The effectiveness of the analgesia should be recorded in the Nursing Progress notes or in the appropriate clinical pathway.

CPMS should be called if pain relief is inadequate after more than 5 good tries per hour for three hours.

Any observations outside normal values for age should be reported to CPMS +/- the primary treating team.

Complications

IF RESPIRATORY DEPRESSION OR OVERSEDATION IS SUSPECTED:

• CEASE the PCA
• CEASE all other infusions that could be contributing to sedation
• Attempt to rouse the patient
• Call 777 [MET team] if appropriate
• If apnoeic: administer bag & mask ventilation with 100% oxygen
• If breathing: maintain airway, monitor oxygen saturations and administer oxygen
  via face mask at 8 L/min
• Check circulation. If pulseless: commence chest compressions
• Administer naloxone per instructions on the attachment chart if opioid toxicity is suspected
• Call CPMS for urgent review

Ceasing the PCA

• The decision to cease the PCA should ideally be made in consultation with CPMS.

• Most patients self-wean off PCA, using it less as their pain decreases.

• Oral/rectal opioids may be administered immediately after the PCA is ceased.

• The date and time of ceasing the PCA must be recorded on the Patient Controlled Analgesia attachment chart.

• Any remaining opioid must be disposed of according to the RCH Drugs of Addiction policy.

• The PCA infusion pump must be returned to Recovery when it is no longer required.