British journal of anaesthesia
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We have compared the value of different variables used in the assessment of blood loss during progressive hypovolaemia and resuscitation under general anaesthesia in anaesthetized pigs. We measured mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP), the negative component of the systolic arterial pressure variation (delta Down) and left ventricular end-diastolic area (LVEDa) using echocardiography. Blood was progressively withdrawn (up to 35 ml kg-1 in seven steps) and then reinfused after the same pattern. ⋯ The highest r values were obtained with MAP and LVEDa, and the highest nS value with delta Down. The least difference between withdrawal and reinfusion was with LVEDa, the lowest values of minWBV were with PCWP and LVEDa, and the highest value of maxRBV was obtained with PCWP. During progressive haemorrhage under general anaesthesia, LVEDa was an accurate variable for assessment of blood volume loss, delta Down contributed no further information compared with MAP, and PCWP was the most reliable variable for assessing return to baseline blood volume.