| |
PAIN MANAGEMENT AND TECHNIQUES
Effective analgesia is an essential part of postoperative management.
The important injectable drugs for pain are the opiate analgesics.
Nonsteroidal anti-inflammatory drugs (NSAIDs), such as diclofenac
(1 mg/kg) and ibuprofen can also be given orally and rectally,
as can paracetamol (15 mg/kg).
There are three situations where an opiate might be given:
| :: |
Preoperatively |
| :: |
Intraoperatively |
| :: |
Postoperatively. |
Opiate premedication is rarely indicated, although an injured patient in pain
may have been given an opiate before coming to the operating room. Opiates given
pre- or intraoperatively have important effects in the postoperative period since
there may be delayed recovery and respiratory depression, even necessitating
mechanical ventilation. The short acting opiate fentanyl is used intra-operatively
to avoid this prolonged effect.
Naloxone antagonizes (reverses) all opiates, but its effect quickly wears off.
The commonly available inexpensive opiates are pethidine and morphine. Morphine
has about ten times the potency and a longer duration of action than pethidine.
The ideal way to give analgesia postoperatively is to:
| :: |
Give
a small intravenous bolus of about a quarter or a third
of the maximum dose (e.g. 25 mg pethidine or 2.5 mg morphine
for an average
adult) |
| :: |
Wait
for 5–10 minutes to observe the effect: the desired
effect is analgesia, but retained consciousness |
| :: |
Estimate
the correct total dose (e.g. 75 mg pethidine or 7.5 mg morphine)
and give the balance intramuscularly. |
With this method, the patient receives analgesia quickly and the correct dose is
given.
If opiate analgesia is needed on the ward, it is most usual to give an intramuscular
regimen:
| :: |
Morphine:
– Age 1 year to adult: 0.1–0.2 mg/kg
– Age 3 months to 1 year: 0.05–0.1 mg/kg |
| :: |
Pethidine:
give 7–10 times the above doses if using pethidine. |
Opiate analgesics should be given cautiously if the age is less than 1 year.
They are not recommended for babies aged less than 3 months unless very close
monitoring in a neonatal intensive care unit is available.
If a good level of monitoring by ward nurses exists, a system of regular pain
scoring (assessment) combined with intramuscular opiates can be effective for
controlling severe pain.
The use of regular oral or rectal paracetamol as a routine
for postoperative patients improves pain control and reduces the need for opiates.
NSAIDS
can be used with paracetamol, or as an alternative.
Because of individual patient (and sociocultural) variations, the dose needed
to achieve the right effect is often not precisely known. Excessive sedation
or respiratory depression may result. Morphine and pethidine are legally controlled
because of their addiction potential. However, addiction following the medical
use of opiates is very rare and fear of it should not prevent the use
of these effective drugs to treat severe pain.
Opiates are generally cardiostable; if the blood pressure is low, it is more
logical to increase the intravenous fluids and give the analgesic if the patient is
in pain.
A common misconception is that sedatives and analgesics are the same thing: they
are not. Diazepam is not an analgesic.
The condition of the patient will largely determine the need for analgesia: you
must judge what is required. In general, the severely ill or debilitated
patient with sepsis, bowel obstruction or other metabolic derangement should
not receive opiate analgesia in the immediate postoperative period. On the
other hand, an otherwise fit trauma patient will need postoperative analgesia.
Children after orthopaedic procedures are usually in particular need. Thoracotomy,
chest trauma and chest drains can be very painful: the pain restricts breathing
and causes hypoxia and postoperative chest problems.
Patients with head injury and those after intracranial surgery traditionally
receive codeine phosphate 30–60 mg because of the sedating and respiratory
depressant effects of morphine. Hypercarbia from respiratory depression is particularly
dangerous in a spontaneously breathing patient with brain trauma.
Postoperative pain usually increases the blood pressure and this can be harmful, especially
if the patient was hypertensive preoperatively.
You may have used a volatile agent, such as halothane, as the sole method of
maintaining anaesthesia for an operation. When this has worn off at the end
of the operation, you must check if the patient is suffering pain and give appropriate
analgesia.
When using halothane as the sole anaesthetic in a fit patient, give an opiate
analgesic with the induction agent.
It is widespread and very bad practice among inexperienced anaesthetists to
withhold analgesia in order to have a robustly screaming patient going along the
theatre corridor back to the ward.
Good practice is to balance the amount of analgesia given, so that adequate pain
relief is provided while respiratory depression is avoided.
Prescribe regular analgesia. In practice, “On demand” often means “Not given”.
|
|
|
