It was quiet in the operating-room. A young anesthetist was bending over a girl patient. Everything was ready for the operation.

The operation to be performed was quite a simple one. Nevertheless, it is still frightening to be on the operating table, so it is not surprising that the patient became particularly frightened when the first drop of ether reached her lunge and she attempted to take off the mask. The nurse had to hold the mask on by force and the young anaesthetist involuntarily gave the anaesthetic at a greater rate, which soon brought about the desired effect.

In a minute or two the patient’s muscles relaxed and she became quiet. But why was she so unnaturally rigid? The patient was not breathing. The next moment the anaesthetist hastily removed the mask and began to give artificial respiration. He asked the nurse in a tremulous voice for lobeline.

In the past, arrest of respiration, a hazardous complica­tion, often occurred at the beginning of anaesthesia. It may develop if the amount of anaesthetic being administered is rapidly increased. Nowadays the technique used in anaesthesia almost completely precludes complications of this type and provides surgeons with reliable methods of combatting its consequences. Nevertheless, it is extremely unpleasant for a student anaesthetist just beginning his career to encounter such a complication, and especially if it is the result of his own carelessness.

This is why the anaesthetist was very energetic in administering artificial respiration. Two or three agonizing minutes had elapsed before the patient made her first inspiration, then the second, the third….

Now the surgeon stepped in and reassured his colleague, telling him that he had merely given the patient too much air. The long wait began once more. Finally the patient took another breath followed by another and yet another. Gradually her breathing became more frequent and regular.

‘Now go on with the anaesthetic before the patient wakes up completely, but do not rush,’ said the surgeon. Before long the people in the operating theatre resumed working at their usual pace. In another half hour the patient was back in the ward.

Why did the patient stop breathing twice during the op­eration? The reason for it the first time is clear: the exces­sive dose of a narcotic substance acted as a depressant on the respiratory centre of the medulla oblongata, and breathing ceased. The reason why breathing stopped the second time was more complicated. To comprehend this, we must first see how breathing is regulated. Three different receptor apparatus participate in controlling respiration. The first are the lung receptors which inform the respiratory centre in the brain of the extent to which they expand or contract. They send the signals to the brain informing it when to stop inhalation or expiration and vice versa.