Der Anaesthesist
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The term blood volume (BV) measurement can be understood as the exact volumetric definition of both components of blood, the red cell volume (RCV) and the plasma volume (PV) using tracer dilution methods. The tracer used to measure the RCV must be bound to the erythrocytes and for the PV to plasma proteins, in order to label the distribution space of each carrier (i.e. erythrocytes and albumin molecules). To differentiate this there are indirect methods to estimate the BV, such as measurement of the diastolic pressure or transoesophageal echocardiography, which will not be discussed here. ⋯ However, the results of the RCV measurement can only be delivered after 1 h which makes it more suitable for clinically stable situations. In contrast the PV estimation is based on the measurement of the ICG concentration in the arterial bloodstream after a bolus injection of the dye in the central veins and is used more in intensive care because of the invasivity. The results can be obtained 5 min after injection of the dye and therefore even rapid changes in the PV can be monitored.
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Myasthenia gravis is a chronic autoimmune disease characterised by progressive weakness and easy fatigability of voluntary skeletal muscles. These symptoms are related to a decrease in the number of functional acetylcholine receptors, impaired neuromuscular transmission, and a broadened neuromuscular cleft. Symptomatic treatment is based on anticholinesterases in order to increase the synaptic dwell of acetylcholine. ⋯ Although sensitivity to non-depolarising neuromuscular blocking agents is increased, muscle relaxants can be administered during general anaesthesia as long as neuromuscular monitoring assesses their individual effect. Due to the individual variability in the response to muscle relaxants, accurate titration in combination with pre- and intraoperative neuromuscular monitoring is essential for myasthenic patients. Postoperatively, intensive care observation is mandatory including neuromuscular monitoring.