Search

Clinically notable pericardial effusions developed in three patients with renal failure. Pericardiocentesis showed hemorrhagic fluid, the source of which was not apparent. Simultaneous determinations of Pco 2 , Po 2 , and pH values showed a substantial increase in Pco 2 levels and decrease in Po 2 , pH, and bicarbonate levels in the pericardial compared with the intracardial aspirates. This was true when pericardial fluid Pco 2 , Po 2 , and pH values were compared with mixed venous samples. Determination of Po 2 , Pco 2 , pH, and bicarbonate values in pericardial aspirates may determine the source of the fluid. ( JAMA 239:2151-2152, 1978)

To the Editor.— In the development of catheters for continuous measurement of blood gases by mass spectrometry ( J Appl Physiol 28:375-377, 1970; 32:276-282, 1972), it has been necessary to compare data with results of analyses by ordinary instruments that do not provide an absolute standard. In order to assess the accuracy of clinical blood gas measurements, a study was done in dogs in which split samples of arterial blood were analyzed on four separate instruments of three independent institutions. A dog weighing 20 kg (44 lb) was anesthetized with pentobarbital sodium (25 mg/kg) and placed on a respirator. Thefemoral artery was cannulated percutaneously and a Teflon catheter inserted for continuous measurement of blood gases by mass spectrometry. A Y-piece allowed withdrawal of arterial blood samples through the same puncture site. When the spectrometer indicated stable blood gas levels, split samples of arterial blood were obtained in heparinized glass syringes

With the ready availability of reliable blood gas measurements from the well equipped hospital laboratory, the need for elementary orientation of nurses, technicians, and junior house staff has become a recurring educational task. Even the mature clinician may have found that his understanding of the blood gases and their relationship to acid-base balance and to the manifestations of clinical disease has grown a bit rusty from disuse. For all these people, Ayers has provided a relatively painless way to review fundamentals by means of 42 slides illustrating partial pressure of gases, oxygen saturation, the oxygen paradox, alveolar ventilation, arterial and venous PCO 2 , acidosis, alkalosis, mixed syndromes or respiratory and metabolic acid-base disturbance, and the potassium balance. These slides do not provide enough detail to guide clinical practice, but they will serve to rekindle the learning process of physicians and to orient nurses, technicians, and medical students so that they

of respiratory failure and should be made when giving oxygen to patients with carbon dioxide retention or when assisting ventilation. There ate other situations where blood gas measurements are needed to monitor the progress of a disease which affects pulmonary gas exchange, and these measurements may influence the management of that disease. This need to measure blood gases must be seen in the light of the problems of organization that occur in providing a blood gas service. This problem is compounded by machine unreliability and a reluctance to measure the mixed venous Pco,.

The present study documents by serial blood gas measurements that temporary support of the arrested circulation is more likely to be effective when prompt ventilation and endotracheal intu...