[Transesophageal 2-dimensional echocardiography in hip endoprostheses]

Previous studies indicate that during total hip replacement intraoperative pulmonary embolization of air and medullary bone marrow occurs. This was based on histological examination of lung tissue obtained during animal investigations and postmortem in human tissue. In vivo proof of this embolization has not as yet been found because of the methodological problems involved. Using transoesophageal two-dimensional echocardiography continuously direct imaging of the right atrium and the right ventricle can be carried out and the embolization thus visualized. In a prospective randomized study in 26 patients having to undergo total hip replacement operation the right atrium and right ventricle were continuously scanned. Endexpiratory CO2-partial pressure was simultaneously recorded. A venting hole in the femur is said to prevent the pressure rising in the medullary space and therefore prevents embolization. In 13 patients therefore, a 4.5 mm lateral drill hole 4 cm distal the tip of the prosthesis was made in order to vent the medullary space. Transoesophageal two-dimensional echocardiography revealed air bubbles in 12 of 13 patients in the control group during implantation of the femoral prosthesis. This is significantly different to the group of vented patients where bubbles were only seen in 4 cases (p less than 0.01). Emboli were visible in 8 patients in the control group in contrast to only 2 cases in the vented group (p less than 0.05). The endexpiratory CO2-pressure of the control group fell from 35 mmHg to 33 mm Hg (Median, p less than 0.001). The CO2 of the vented patients remained constant.(ABSTRACT TRUNCATED AT 250 WORDS)