Chronic Refractory Angina

Nursing Guidance for
Intrathecal Pump Drug Administration SynchroMed� EL

These Guidance recommendations have been produced in accordance with the NHS Executive publication "Clinical Guidelines" (May 1996) and incorporate those standards produce by the King's Fund for evidence based clinical practice.

Produced for the National Refractory Angina Centre
E-mail Dave.Trenbath@ccl-tr.nwest.nhs.uk

Introduction (see clinical section)

IIntrathecal pumps are used in the suppression of pain by the infusion of a prescribed medication such as morphine directly into the intrathecal space. Opioids being very effective in the relief of chronic pain and recommended in-patients with chronic refractory angina. However dose related side effects are common and many patients find this intolerable. Epidural or intrathecal opioid administration enables much smaller doses of opioids to be delivered and thereby allows for a more accurate assessment of dose related side effect.

Within the algorithm of treatments some patients will have effectively been managed by repeated epidurals infusions. Epidural infusions however are only used in the sort term and to assess the effectiveness of opioids in controlling the patients pain. In the long-term the administration of intrathecal opioids via a totally implantable device is safer.

In this section we describe our nursing guidance for intrathecal opioids. The availability of fully implantable systems for the relief of pain, such as neuroaxial opiate infusion(1) offers an opportunity to resolve the problem of refractory anginal pain that has not been successfully treated by less invasive therapies within the clinical guideline algorithm.

Treatment contract

It is essential that from the very beginning there is complete agreement made about the aims of treatment, between the patient their carers and the treatment team. The actual aim being to improve the patient and carers quality of life by reducing the effect of angina but it should be emphasised that as with all treatments for chronic refractory angina pectoris intrathecal opioid administration cannot cure the problem. At all stages of the treatment, expectations must be discussed to ensure that the patient and carers expectations on pain relief are not unrealistic and unachievable

Criteria for Intrathecal Pump

We only consider opioid administration by this route if the patient continues to have unacceptable levels of pain and alternative routes of administration are unacceptable.

Safety

Clinicians are naturally concerned about the potential risks of masking myocardial ischaemic pain, which because of the negative feedback of chest pain theoretically may increase the risk of myocardial infarction. However it has been suggested that through the relief of pain myocardial oxygen demand is reduced without altering coronary perfusion pressure(3.4.5). In addition studies have demonstrated that totally implanted programmable device for infusion decreases the risk of infection(6) and as shown by Pasqualucci et al small amounts of intrathecal morphine provides excellent pain relief but without circulatory or respiratory side effects(7).

Synchromed� Infusion System (MEDTRONIC)

The implantation of Synchromed infusion system is a surgical procedure requiring complete aseptic technique and prophylactic antibiotics.

There are two parts that make up the system both fully implantable. The catheter, which is small of bore and made of soft plastic, one end of which is connected to the pump which is implanted under the abdominal wall close to the surface, and the other end placed into the intrathecal space. The pump is round in shape, stores and releases the prescribed amounts of medication directly into the intrathecal space. The pump dimensions are 2.5cm thick, 8.5cm in diameter, and weighs about 205g. It is made of titanium a lightweight medical grade metal.

The pump consists of a side access injection port, which allows direct access of medication into the catheter and bypasses the pump. A filler port that allows access to the reservoir that holds the medication.

The pump is designed to deliver a controlled amount of medication through the catheter into the intrathecal space, where it most effective. The exact dose, rate and timing are entered into your pump through a programmer, an external computer that controls the pumps memory and that can be used to review and if need be, reprogram the medication delivery. The system allows for up to 10 different settings within any 24-hour period the program can therefore be customised to suite the pain requirements of the individual.

The system with its own battery will in time require replacement due to battery failure, and the more settings to the system the higher the battery will drain.

The greatest risk to patients is one of infection, which can result in the system having to be removed. The implant can be carried out over two stages but this does carry a higher risk of infection it is therefore more desirable to carry out the entire procedure at one sitting.

1. To prevent improper injection through the side arm catheter access port, always use the appropriate refill kit for refill procedures.

2. Always use the template and instructions provided in the refill kit or catheter access port kit.

3. If local or systemic infection is suspected, use extreme caution when emptying or refilling the pump reservoir.

4. Do not refill the pump reservoir until the pump has been completely emptied.

5. The refill volume must not exceed 10 or 18mls, which is dependent on the reservoir volume of the pump.

6. Do not exert extreme pressure as this may activate the reservoir valve.

7. Do not inject at a rate that exceeds more than 1ml per 3seconds.

8. Do not allow air into the pump's reservoir whilst refilling.

9. Always use a filter when injecting into the side access port.

Injecting into Side Catheter Access Port Injection

1. Identify pump model.

2. Put sterile gloves on.

3. Prepare injection site with appropriate skin cleansing agent i.e. povidone iodine.

4. Use sterile procedure to assemble refill kit.

5. Place template over site.

6. Insert needle through the skin and into the side catheter access port.

7. Open clamp remove 1-2 mls from the side access port to ensure removal of drug from catheter.

8. Close clamp discard syringe with aspirate

9. Attach filter and inject at a rate not to exceed 15mls per minute. Observe needle site during this procedure for swelling.

10. Close clamp and remove needle apply pressure to injection site.

Refilling the implanted pump

1. Identify pump model.

2. Confirm volume required does not exceed the reservoir size.

3. Program the appropriate new parameters.

4. Put sterile gloves on.

5. Prepare injection site with appropriate skin cleansing agent i.e. povidone iodine.

6. Use sterile procedure to assemble refill kit.

7. Place template over site.

8. Insert needle through Template Centre Hole and into the pump.

Caution must be taken following drug dose alteration, as there will be a residue of the original strength remaining within the catheter this will still continue to be delivered following reprogramming and this should be taken into account when resetting drug delivery. Pump tubing volume without a side port 0.23mls, with side port 0.26mls.

All patients prior to entering the program for SCS implant and then subsequently Intrathecal pump implantation are seen by a psychologist to ensure suitability for inclusion in to the program.

Adverse effects with the use of Intrathecal Opioid Infusion

Medical (surgical) Complications 

1. Bleeding.

2. Infection.

3. Neurological deficits related to tissue damage.

4. Cerebrospinal fluid leaks.

Technical (delivery problems) complications.

1. Catheter fracture

2. Kinking.

3. DisconnectionÌs

4. Tip obstruction

5. Dislodgment

6. Accidental withdrawal

7. Pump overfilling

8. Battery failure

9. Pump failure-irregular flow rate.

10. Pump torsion

11. Programming error.

12. Wrong refill (subcutaneous-side port)

The pharmacological short term side effects of intrathecal morphine when compared with systemic administration are similar ⁸ differing only on the degree of drowsiness which is more acute in the systemic delivery.

Pruritus is a common side effect associated with intrathecal opioid delivery 9 the effect of which may precede pain relief but antihistamine should be prescribed to control the "itch reflex".

Nausea will usually occur within four hours of morphine delivery and can be controlled by an anti emetic and or by reducing drug delivery and gradually increasing it over the next few days.

Urinary retention following the administration of intrathecal opioids is more common than intravenous or intramuscular administration and is not dose related¹⁰ treatment with cholinomimetic drugs or intermittent catheterisation can be useful in its treatment.

Constipation commonly occurs with the use of opioids mild laxatives and stool softeners should be used.

Respiratory depression following intrathecal opioid delivery is more likely to occur in opioid-naŒve patients¹¹ but is not usually a major problem in those patients who have gone through screening test prior to pump implantation.

Weight gain/oedema in opioid delivery is thought to be related to hormonal changes ¹² and cannot be controlled by diet and is not dose dependent but are commonly observed in long term patient. ¹²

MEDICAL (surgical) Complications

Implantation of a pump for intrathecal opioid delivery must be done with the highest level of care to minimise surgical complications, which may include bleeding, infection, tissue damage, and CSF leaks.

Bleeding excessively post surgery can be minimised by carefully screen the patient pre surgery for coagulopathies and for those patients on NSAIDs check platelet count.

Necrosis, Seromas, Skin perforations, at the pump pocket site may be caused by improper positioning of the pump or reaction to the size/or construction of the pump. ¹³

Infection may occur along the superficial or deep catheter track, the pump insertion site, or within the epidural or intrathecal space. ¹³ Meningitis while rare requires immediate explantation of all foreign body materials and the start of intravenous antibiotics therapy ^15.

Neurological deficits related to tissue damage following implantation of the catheter into the spinal canal can lead to damage of the nerve roots or the spinal cord. Damage to these tissues can lead to radiculitis, myelitis, paralysis, paresis, loss of bowel and bladder control, and or myelopathic pain. ¹⁴

Cerebrospinal fluid (CSF) leaks into the epidural space are inevitable due to the nature of the procedure, due to the Tuohy needle being of a larger size to that of the catheter. This leak usually will stop within several days, but may on occasions persist. Other reasons for CSF leaks are incomplete tissue sealing around the catheter at the site of insertion, multiple subarachniod punctures during insertion of the catheter, dislodgement, disconnection, break, puncture, or migration of the catheter. Leaks of CSF around the incision site will always require resuturing.

Postural puncture headaches can occur as a result of CSF leakage in the majority of patient this will disappears within a few days. However in a few patients this can last for months. ¹⁵

Catheter complications can include dislodgement, kinks, breakage, occlusion, migration which may result in drug under infusion leading to lose of analgesia, inconsistent analgesia, or drug withdrawal symptoms.

Pump complications associated with programmable pumps include overfilling of the pump, pump torsion, and pump failure.

Post procedure observation of the patient.

1. Hypotension - check blood pressure regularly for one hour post procedure.

2. Bradycardia - record pulse for one hour post procedure.

3. Respiratory depression - record respiratory rate depth and pattern of breathing.

4. Nausea or vomiting.

5. Observe infiltration site for haematoma - Recent anticoagulant therapy can predispose to haemorrhage into the epidural space.

6. Headache - May be caused by accidental puncture of the dura.

7. Urinary retention - due to parasympathetic block of the sacral level of the spinal cord.

8. Observe effective of pain relief following the procedure.

Nursing Guidelines

Admission assessment procedure

Review history Clinical Assessment e.g. Physiological - psychological - social history.

Commence Pain assessment chart.

Introduction of the patients named nurse.

Referral to physiotherapist for explanation of postoperative exercises.

Baseline observations.

Refractory angina patients will be on drug therapies that may cause hypotension and bradycardia in their mode of action. It is important to observe and record the patients blood pressure pulse and respiratory rate prior to the procedure to establish a base line.

Investigations to be requested by the doctor

Electrocardiogram (ECG), Chest X-ray, (CXR), Full blood count (FBC), Urea and electrolytes (U+E's), International Normalised Ratio (INR) if required.

Anticoagulation therapy:

Pre Intrathecal Pump Implant

1. Discuss - goals, benefits, and risks.

2. Document patient's response to intrathecal implant pre surgery.

3. Assess their level of pain using an analogue chart.

4. Discuss what functional changes may be required of the patient during the initially few weeks following the operation e.g. Excessive body movement can dislodge the catheter and or accidentally pull it out

5. Information re intrathecal implant.

6. Develop realistic expectations about pain relief with patient.

7. Explain procedure

8. Review medical history and ensure completion of prescription sheet and signed consent for surgery obtained.

9. Reinforce explanation of procedures.

10. Commence pain analogue assessment chart.

11. Identify patients or careers anxieties and address them.

12. Commence discharge planning.

13. Orientate patient to the ward and if possible give approximate time for surgery along with date.

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