Surgical Care at the District Hospital
Part 1 2 3 4 5 6 Primary Trauma Care Manual
Resusciation and Anaesthesia
Resuscitation and Preparation for Anaesthesia and Surgery
Management of emergencies and cardiopulmonary resuscitation
Other conditions requiring urgent attention
Intravenous access
Fluids and drugs
Drugs and resuscitation
Preoperative assessment and investigations
Anaesthetic issues in the emergency situation
Important medical conditions for the anaesthetist
Practical Anaesthesia
General anaesthesia
Anaesthesia during pregnancy and for operative  delivery
Pediatric anaesthesia
Conduction anaesthesia
Specimen anaesthetic techniques
Monitoring the anaesthetized patient
Postoperative management
Anaesthetic infrastructure and supplies
Equipment and supplies for different level hospitals
Anaesthesia and oxygen
Fires, explosions and other risks
Care and maintenance of equipment
Hypertension
 


> PREPARATION FOR GENERAL ANAESTHESIA
> INTRAVENOUS INDUCTION
> INTRAMUSCULAR INDUCTION
> INHALATIONAL INDUCTION
> MAINTENANCE OF ANESTHESIA
> FAILED INTUBATION



INHALATIONAL INDUCTION

Inhalational anaesthesia forms the basis of most general anaesthetic techniques in common use, although intravenous techniques are an alternative. There are two different systems available for delivering anaesthetic gases and vapours to the patient:

:: Draw-over system: uses air as the carrier gas with added volatile agents or compressed medical gases
:: Continuous-flow system: compressed medical gases (which must have a minimum of 30% oxygen) pass through flow meters and vaporizers to supply anaesthetic to the patient.

Draw-over systems can be used with either cylinders or oxygen concentrators as their oxygen source; Boyle’s machines function only if cylinders are available. The draw-over system is capable of producing first-class anaesthetic and surgical conditions. Modern draw-over apparatus has proved extremely reliable, easy to understand and maintain and economical in use. However, some small hospitals, and many larger ones, are equipped with continuous-flow machines. Detailed descriptions of both systems are found in Anaesthesia at the District Hospital (WHO, 2001).

Inhalation (gas) induction is the technique of choice for inducing anaesthesia when the patient’s airway is difficult to manage. If you use an intravenous induction for such a patient and “lose” the airway, the patient may die of hypoxia if you are unable to ventilate the lungs. In contrast, inhalational induction can proceed only if the patient has a clear airway down which the anaesthetic can pass. If the airway becomes obstructed, the patient will stop taking up further anaesthetic and redistribution of the drug in the body will lighten the anaesthesia. As this happens, the patient will clear the obstruction.

Inhalational induction is also preferred by some children who may object to needles. Inhalational induction is an important technique. Practise regularly; it is simple and requires only patience, care and observation. Either draw-over or continuous-flow apparatus can be used for inhalational induction (Figure 14.2) but slightly differing techniques are needed.

Figure 14.2
Figure 14.2


Using draw-over apparatus

The best agents to use are ether (for example from the EMO or PAC vaporizer) and halothane (for example from the PAC or Oxford Miniature Vaporizer (OMV)). If oxygen is available (1 litre/minute), it should be added with a Tpiece.

For a smooth induction:

1 Gently apply a well fitting face mask and begin induction with halothane. Halothane is preferable because, unlike ether, it is not an irritant. Gradually increase the concentration until the patient is asleep (maximum 2–3% halothane).
2 Then, slowly turn on the supply of ether and increase the concentration by 1% every five breaths. If the patient coughs or holds his or her breath, reduce the ether concentration immediately by a third of its setting and try again.
3 When you reach 8% ether, turn off the halothane. You may then proceed to laryngoscopy and intubation after further deepening the anaesthesia by increasing the ether concentration to about 15%.

Watch for the onset of paralysis of the lower intercostal muscles to show that the anaesthesia is deep enough. The addition of oxygen is desirable at least until after intubation. At high altitude, you will need more oxygen supplement.
4 If your attempt at intubation does not succeed, reapply the face mask and deepen the anaesthesia again for a second attempt:
If intubation is still impossible, but you can maintain a clear airway
using a face mask, you may proceed to give anaesthetic with the face
mask, using ether at 7–10% to provide relaxation if required
If relaxation is not required, reduce the ether concentration to 6%.
With ether at this concentration your patient can, if necessary, manage
without oxygen supplementation, provided that he or she is not very
young, old, ill or anaemic.



Take special care if halothane is used as an alternative to ether; it depresses the heart and respiration. Give additional oxygen if at all possible and use a tracheal tube and controlled ventilation for all but brief operations.

Using a compressed gas machine

1 Check your machine, making sure that you have adequate supplies of gas for the duration of anaesthesia:

If intubation is still impossible, but you can maintain a clear airway using a face mask, you may proceed to give anaesthetic with the face mask, using ether at 7–10% to provide relaxation if required
Use an oxygen analyser at the gas outlet, if possible
If you are using a one-way breathing valve at the patient end of the circuit, set the total gas flow (oxygen or oxygen plus nitrous oxide) higher than the patient’s minute volume.
 
2 If you are using halothane as your main anaesthetic agent, place the face mask on the patient’s face and gradually increase the halothane concentration up to a maximum of 3%, reducing it to 1.5% after the patient has settled or after intubation.
3 If you are using ether (without halothane) as your volatile agent:


Turn on the supply of ether from the Boyle’s bottle with the face mask
held about 30 cm above the patient’s face
Gradually lower the mask over the next minute to slowly increase the ether concentration in the inspired gas; this is usually well tolerated
Once the mask is in contact with the face, slowly increase the ether concentration over a few minutes
The patient will be ready for intubation when you can see paradoxical (inward) movement of the lower ribs during inspiration.
 


1
2
3

> PREPARATION FOR GENERAL ANAESTHESIA
> INTRAVENOUS INDUCTION
> INTRAMUSCULAR INDUCTION
> INHALATIONAL INDUCTION
> MAINTENANCE OF ANESTHESIA
> FAILED INTUBATION



Top of Page