The measurement of body temperature is also an important part of the monitoring.Typically, the measurement is made in the nasopharynx or in the esophagus. This is important because the body can cool down quickly during anesthesia, as anesthetics adjust the set point of the body temperature. This also explains the frequently observed cold shivering after an anaesthetic. Children in particular lose heat quickly. It is therefore essential to ensure that heat is retained during the operation.
Neuromuscular monitoring (relaxometry)
Neuromuscular monitoring of the patient is particularly important. To ensure that the muscles are relaxed during the operation and that the doctors can perform the operation without any problems, the patient is usually administered a so-called muscle relaxant. This drug causes the muscles to be temporarily paralyzed.
Relaxometry is now used to monitor the effect and breakdown of these substances. For this purpose, two electrodes are attached to the patient’s forearm at a distance of about 2-4 cm, which are then placed directly above a nerve running there. By connecting the electrodes to a stimulator, electrical pulses can be emitted to stimulate the nerve.
This causes the corresponding muscle to contract (usually the adductor pollicis muscle). As a result, the patient’s thumb bends. On the basis of the stimulus response, the effectiveness of the muscle relaxant used can therefore be assessed.
This is often also done according to certain patterns, e.g. train-of-four stimulation (TOF), in which four electrical stimuli are delivered in succession and the extent of the stimulus response is recorded. Normally, the responses are gradually weaker. If the blockage is very severe, there is no stimulus response at all. Depending on the planned intervention, the achievement of the desired neuromuscular blockade can be checked with this method. Relaxometry is also important when the anesthesia is removed, since the ventilation tubes should not be removed until the relaxation of the muscles has been largely released, so that the patient can breathe independently again.