Paracetamol
In normal doses paracetamol is a safe and effective analgesic. It has a different and central mode of action to NSAIDs. It is best used by administering regularly and can be used in combination with
NSAIDs.
NSAIDs
NSAIDs administered appropriately can be useful adjuncts in the management of acute postoperative pain. They are usually administered in addition to opioids and, only occasionally, are used as the sole analgesic after major surgery. NSAIDs are most effective when administered regularly. Before prescribing an NSAID you should satisfy yourself that there are no contraindications to its use. Read the section on NSAIDS in the BNF. Common problems with
[non-selective] NSAIDS are:
Gastro-intestinal: Peptic ulceration. The risk is independent of the route of administration and it may occur without a previous history. It is a greater problem in fasting patients (eg postoperatively).
.Renal: NSAIDS may cause renal failure. This is of particular significance in patients with impaired hepatic or renal function, and in the elderly. However, in the presence of significant hypovolaemia, even patients with normal renal function may suffer acute renal failure.
Bleeding: NSAIDs inhibit normal platelet action and therefore can contribute to intra and post operative bleeding.
Allergic reactions to NSAIDs are relatively common, and should they occur with one drug you should avoid all NSAIDs.
Respiratory: NSAIDs cause bronchospasm in a minority of asthmatic patients. Patients affected tend to be adult onset asthmatics, with nasal polyps–ask the patient if they have previously taken these drugs and of any problems encountered
Be aware of problems of concomitant use with anticoagulants.
[Appendix 1: interactions, NSAIDS, BNF]
Avoid with certain types of surgery
NSAIDs should always be used with care in the post-operative period, particularly after major surgery. They should not be prescribed for more than 48 hours without enquiry re side effects and efficacy.
Selective Cyclo-oxygenase -2 inhibitors are not recommended at present by the Acute Pain Teams in
NHS Tayside.
Use of intermittent IM injection of opioids
The use of IM opioids has been the mainstay of traditional postoperative analgesia for many years.
There are several reasons why this method of opioid delivery has yielded poor results in the past:
 In the absence of systematic assessment, pain will be significantly under-estimated by most medical and nursing staff.
 Because traditional teaching under emphasises the benefits of good analgesia and overemphasises the risks of opioids, these drugs tend to be under prescribed by doctors, and under administered by nurses.
 For many reasons patients tend not to demand sufficient analgesia, especially when drugs are prescribed on a "prn" basis.
Tayside Pain Management Guidelines contain a flow chart for the administration of IM/SC opioids which should be followed.

Patient Controlled Analgesia (PCA)
PCA is a method of administering IV opioid via an infusion pump which allows the patient to titrate
(within pre-set limits) the dose of opioid according to personal need by pressing a hand held button.
The machine is set with a "lock-out" time during which no drug will be delivered, even if the button is pressed. PCA has been shown to be a safe and effective method of analgesia when used by clinical staff who understand the technique, and who have immediate back-up advice available. Patients on
PCA require regular observation of pain, sickness and sedation scores by the nursing staff in addition to conventional postoperative recordings. PCA should be continued (usually 2-3 days) until the patient no longer requires parenteral opioids. Another method should be started before PCA is discontinued.
. Initial setting of PCA pumps (or subsequent adjustments) should only be carried out after discussion with a member of the Acute Pain Team. If in doubt ask.
Morphine is the most frequently used opioid, although others may be used. Always check the patient’s drug chart. Morphine is available in a ready made solution of 50mg in 50ml of saline which is then drawn into a standard 60 ml syringe and used to prime the delivery tubing. The full syringe and primed line are loaded into the pump. Before programming the PCA pump it must be reset to ensure that the previous details are deleted, and that it starts from “zero” for the new patient.
 The following are standard settings for a normal sized adult:
 Loading dose: zero
 Duration: Stat
Bolus dose: 1mg/ml
Lockout: 5 minutes
 Concentration: 1mg/ml Background: zero.
 After setting, the pump is locked, and the key kept with the ward control drug keys.
If the PCA is connected to the patient's "drip" cannula, a dedicated PCA set with a nonreturn valve must be used to prevent back flow of morphine into the infusion tubing.
Alternatively, PCA may be delivered via a separate IV cannula.
Inadequate analgesia
You should be able to deal with the initial management of inadequate analgesia and to diagnose and deal with any complications. Such problems can occur relatively frequently in the early period after surgery and inadequate pain relief should be managed as follows:
 Assess the patient to exclude changing or new pathology (eg blocked vascular graft; abdominal catastrophe; myocardial infarction; etc) as the cause of the increased pain.
Check receiving adjuvants.
Check pump functioning correctly and venflon patent.
Check that the patient understands the concept of PCA and is pressing button.
 Treat the pain by careful IV titration of dilute opioid, eg morphine 1mg/ml. This is injected at the rate of 1mg of morphine (1ml) every minute until the pain is controlled, or the respiratory rate is less than 12 breaths per minute, or the patient starts to become drowsy. Any severe pain may be treated in this way.
 Do not give oral or IM opioids to patients receiving PCA. The time course of their

effect may complicate the issue and lead to respiratory depression.
 If analgesia remains inadequate, or becomes inadequate again within a short time of your initial morphine titration (<2hours), do not change the settings on the PCA pump. Titrate IV morphine again or contact the Acute Pain Team if you are concerned.
Decision to stop PCA
PCA is stopped when the patient is able to tolerate adequate analgesia orally.
Complications of Opioids
Complications of opioids in the peri-operative period can occur with any mode of administration be it oral, IM, IV (PCA or infusion) intra thecal or epidural. They must be recognised and dealt with immediately. A problem may occur if a PCA or epidural pump is wrongly programmed, or malfunctions and it is important to check the pump settings.
 Nausea and vomiting: Anti-emetic treatment should be given early. Consult the
Tayside Guidelines for the treatment of PONV.
 Over sedation: This is not usually a problem with appropriate doses of opioids, but it may be associated with someone other than the patient activating a PCA demand button.
 Hypotension: Hypotension is not usually due to opioids, but to some other pathology.
 Respiratory depression: If the respiratory rate is <10/min, give oxygen 6 L/min. If the respiratory rate is <8/min, give oxygen 6 L/min, stop opioid administration and consult Acute Pain Team. If the patient is very drowsy, and help is not immediately available, give naloxone as follows: dilute  g naloxone in 10ml of water or saline and give a 1ml dose IV every minute, titrating the effect until the respiratory rate is
10/min. Do not give a whole pre-filled syringe of naloxone except in the most dire circumstances. You will reverse all the analgesia as well as the respiratory depression and cause serious patient distress. Naloxone has a short duration of effect and may need to be repeated.
 Spinal/Epidural opioids may cause late respiratory depression. This is rare but dangerous and can happen up to 24 hours after administration because of recirculation of CSF. It is important to be aware of the possibility of late respiratory depression, and such opioid administration needs to be clearly documented, and communicated to ward staff. Patients should be monitored on the ward, and administration of additional opioids via other routes should be according to anaesthetist instructions (generally after a delay, a PCA pump with IV morphine is started – oral and IM opioid should be avoided).
Spinal and epidural opioids can also cause pruritis (itch; see below) and nausea.
Peripheral nerve blockade (PNB)
Peripheral nerves can be blocked with local anaesthetic. This can provide excellent anaesthesia and analgesia for peripheral surgery, particularly orthopaedic procedures. Typically blocks last for up to
12 or even 24 hours. Peripheral nerve catheters are used to administer local anaesthetic, and continue a peripheral nerve block for longer periods. There are very few side effects, and the catheters can and should be used in conjunction with the ‘pain ladder’ drugs. Problems should be reported to the Acute
Pain Team or the ‘on call’ Anaesthetist.

Epidural Infusion Analgesia (EIA)
This is used after major surgery, or in patient’s with cardiorespiratory disease, and in those who are unable to use PCA effectively e.g. because of confusion. A small catheter is introduced into the epidural space and used for the infusion of a local anaesthetic, often supplemented by an opioid.
While it is a very effective method, there are a number of potential problems and the local guidelines must be followed to the letter. Problems should be reported to the Acute Pain Team or the ‘on call’
Anaesthetist. Protocols for dealing with problems encountered with epidurals are available on all wards where epidurals are run.
Problems are relatively infrequent, particularly after the first few hours, but there are a few possible complications:
Abscess or haematoma: Rare. May present with unexplained motor block , back pain, fever, odd feelings in legs, loss of sphincter control. This is an emergency-an anaesthetist or Acute
Pain Team must be informed immediately
 Hypotension: Sympathetic nerve block may cause this. Other causes should be excluded eg dehydration, blood loss, myocardial ischemia, dysrythmias. This is true of patients who have had spinal anaesthesia also. Management comprises:
 Elevating legs.
 Ensuring that the patient is receiving oxygen.
 Considering the cause, and treating appropriately.
 Remembering that hypovolaemia is common after major surgery: Try giving
250-500ml IV fluid as a stat bolus.
 If hypotension is severe give IV ephedrine (3-6mg) if the pulse rate is slow, or metaraminol 0.5 mgs if it is fast, to maintain BP while establishing what is wrong with the patient.
 Seeking senior help sooner rather than later.
 Respiratory depression: Epidural opioids may cause respiratory depression up to
24h after the infusion has been discontinued. Marked sedation will often precede respiratory depression. If the infusion is still running, stop the pump, and contact the Acute Pain Team. Use naloxone as indicated earlier in this guide to maintain respiratory rate.
 Pruritis: This is usually due to the opioid in an infusion and usually responds to low dose naloxone or chlorpheniramine. Topical treatment (eg calamine lotion) is not effective.
 Urinary retention: If this occurs a urinary catheter will be required.
 Motor block: The aim of epidural analgesia is to provide pain relief without lower limb motor nerve block. Too much drug will lead to immobility and pressure sores, and paralysis in the legs is also an indicator of rare, but serious complications such as epidural haematoma. Any leg weakness (especially increasing weakness) must be reported to the Acute Pain Team.
 Inadequate analgesia: This may be due to technical problems or an inadequate infusion rate. The adequacy of the block is checked regularly by the nursing staff and any hint of a reduced effect should be reported to the Acute Pain Team so that an anaesthetist can be called to identify and rectify the problem. If the patient has
severe pain treat it with IV morphine as noted earlier, but keep the patient under direct observation until the anaesthetist arrives.