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GENERAL ANAESTHESIA WITH INTUBATION
This technique is suitable as a universal method of giving
anaesthesia to an adult for any major surgery, including caesarean
section, or if intubation is specifically indicated: for example,
for protection of the airway.
It
is contraindicated when difficult intubation is anticipated.
See page 14–32.
Normally it is expected that spontaneous breathing will return
after the initial muscle relaxation required for intubation
has worn off, but it cannot be assumed that this will happen
or that breathing will be adequate for every patient. Some
patients will have adequate spontaneous respiration throughout the
procedure; others will not.
The following will make it less likely that a patient will
have adequate spontaneous breathing under anaesthesia:
| :: |
Exaggerated
reflex response from intubation: for example, abdominal straining,
rise in blood pressure |
| :: |
Strong
surgical stimulation |
| :: |
Obesity
or any cause of diminished respiratory function |
| :: |
Head
down position |
| :: |
Unusually
muscular patient |
| :: |
Surgery
around, or movement of, the head, neck or tracheal tube |
| :: |
Upper
abdominal surgery |
| :: |
Use
of halothane without analgesic supplement |
| :: |
Small
size tracheal tube. |
An
open thoracic procedure cannot, of course, be conducted with
spontaneous breathing. See page 14–38 for how to monitor
for adequacy of respiration.
Unless contraindicated, it is important that you give an analgesic supplement
(for example, pethidine 1 mg/kg intravenously at induction) if halothane is to
be the sole agent for maintenance of anaesthesia.
| 1 |
Preoxygenate
the patient by giving:
| • |
High
concentration of oxygen to breathe for at least
3 minutes |
| |
Or |
| • |
10
breaths of pure oxygen at a flow of 10 litres/minute
from a closely
fitting anaesthetic face mask. |
Loading the lungs with oxygen in this way allows the patient to remain well oxygenated
even if tracheal intubation takes several minutes. |
| 2 |
If
there is a risk of regurgitation of stomach contents,
apply cricoid pressure from the time of injection of
anaesthetic until the trachea has been successfully intubated
with a cuffed tracheal tube. |
| 3 |
Induce
anaesthesia with a sleep dose of thiopental, usually
5 mg/kg of body weight for an adult, injected intravenously
over 30–45 seconds. |
| 4 |
Intubate
the trachea after producing muscle relaxation with suxamethonium
(1 mg/kg of body weight). |
| 5 |
Ventilate
either with 10% ether or 1.5% halothane for 3 minutes
to establish inhalational anaesthesia. |
| 6 |
When
the effect of suxamethonium wears off, usually after
3–5 minutes, await the return of spontaneous breathing.
Oxygen supplementation is mandatory if halothane is used
and is strongly advised for ether. Do not
allow surgical diathermy if you are using ether. |
| 7 |
If
spontaneous breathing is inadequate, you must support
the respiration by manual assistance or by mechanical
ventilation. With the latter, you may additionally give
a long acting (non-depolarizing) muscle relaxant.
The detailed description of this technique is beyond the scope of this book. |
| 8 |
At
the end of surgery, turn off the inhalational anaesthetic
agent and give as much oxygen as possible. As the anaesthetic
wears off, respiration will become irregular and breath-holding
will occur. |
| 9 |
Monitor
or continue to assist breathing until the patient breathes
deeply and regularly and the mucous membranes are pink. |
| 10 |
If
there is a regurgitation risk (for example, in caesarean
section) turn the patient into the lateral position and
extubate when he or she is awake, after careful suction
of secretions from the mouth and pharynx. If you cannot
turn the patient, ensure that the stomach is empty before
extubation by, for instance, passing an orogastric tube.
Breath-holding may occur if extubation is carried out
before regular respiration has returned. This is a
critical moment and experience is required to know the right moment at which to
extubate. |
| 11 |
Continue
to give as much oxygen as possible using a tight-fitting
face mask, looking closely for adequate respiration and
pink colour of mucous membranes while maintaining a clear
airway, with jaw thrust if needed. |
Inhalational technique without intubation
Use this technique only if the patient’s stomach is known to be empty.
| 1 |
Induce
anaesthesia by any safe and convenient technique. |
| 2 |
Ensure
that the jaw muscles are relaxed. |
| 3 |
Insert
an oropharyngeal or laryngeal mask airway. |
| 4 |
Connect
the breathing system either to an anaesthetic face mask
or laryngeal mask. |
| 5 |
Beware
of leaks around the cuff of the face mask or laryngeal
mask. |
Remember
that this technique provides no protection against regurgitation
or aspiration of gastric contents. It should not be used
where there is any risk of this occurring and is not therefore
suitable for emergencies or obstetric cases, among others.
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