Monitoring refers to the monitoring of various circulatory parameters and physiological functions of a patient during an operation. Typically, the physician in charge is an anesthesiologist. Depending on the type of surgery, there are different forms of monitoring, which can be extended by certain elements as required. In the following, the basic monitoring, i.e. the standard monitoring during an operation, will be discussed first.

Clinical observation

Nowadays, modern technology has made patient monitoring very electronic. Nevertheless, the anaesthetist should always keep a close eye on the patient. In doing so, he pays particular attention to the smooth movement of the patient’s thorax, which is an indication of adequate ventilation.

The color of the patient’s skin can also provide information about the success of ventilation, since a lack of oxygen can cause the lips to turn blue, for example. Furthermore, the patient’s vegetative functions are observed, such as sweating, watery eyes and dilated pupils. These reactions can occur if the depth of anaesthesia is too shallow.

Electrocardiogram (ECG)

The ECG records the patient’s cardiac current curve. For this purpose electrodes are attached to the patient’s extremities and chest. These then record potential differences that are caused by the electrical excitation line in the heart. The ECG enables the anesthetist to assess the speed of the heartbeat and the heart rhythm.

Blood pressure measurement

During standard monitoring, blood pressure is determined by means of so-called automatic non-invasive blood pressure measurement. For this purpose, the patient is fitted with a blood pressure cuff on one extremity (usually on one arm). The cuff inflates itself every 5 minutes so that the patient’s vessels running underneath are completely compressed.

When the pressure is released, oscillations occur as soon as the blood can flow through the opening vessel again. These oscillations are registered by the cuff. The maximum displacement of the oscillations corresponds to the mean blood pressure.

This method is also called oscillometric blood pressure measurement. It is important that the blood pressure cuff is adapted to the patient. Cuffs that are too small measure incorrectly high blood pressure values, cuffs that are too large measure incorrectly low values. The width of the cuff should be approximately 2/3 of the length of the upper arm.