[Patient monitoring]

The main problems of monitoring patients on prolonged artificial respiration are discussed. These are: uninterrupted technical control of the respirator and of its clinical effects; continuous observation of the functioning of tubes, vaporizers and nebulizers; adequate tracheobronchial clearance and breathing therapy is absolutely compulsory. Intensive care units are classified into three categories according to their monitoring and surveillance capacities. The minimum, which corresponds to category I, should be performed by every intensive care unit. Category III includes additional computerized intensive care. The most important parameter for monitoring pulmonary function is blood gas analysis, which has been improved by the introduction of continuous arterial pO2 registration. Haemodynamic control serves for detection of arrhythmias and changes in pump function. The determination of pulmonary shunt flow (Qs/Qt) and of the ratio of dead space to tidal volume (VD/VT) impart information on the overall function of both systems (category II). A nomogram to simplify the calculation of pulmonary shunt is proposed which aggregates the factors contributing most to pulmonary shunt in acute respiratory failure. Its results deviate less than 1% from the calculated values if PCO2 ranges between 32 and 52 mm Hg and the error does not exceed 1.5 per cent with a PCO2 up to 82 mm Hg, unless it is combined with a very low Hb and high mixed venous saturation.