Surgery
-
A method for determining the optimal level of positive end-expiratory pressure (PEEP) by means of noninvasive conjunctival oxygen (PcjO2) monitoring and arterial blood gas analysis was developed from the pattern of changes in PcjO2 tension, invasive hemodynamic parameters, and oxygen transport variables during PEEP titration in a series of patients with adult respiratory distress syndrome. All patients had radial and pulmonary artery (PA) catheters inserted and blood volume was measured with 125I serum albumin before each study. During progressive increases in the level of PEEP, PcjO2 tensions reflected changes in both PaO2 and cardiac index (CI), depending on whether PEEP produced a significant decrease in CI. ⋯ In patients whose CjI significantly decreases because of PEEP, PA catheterization and measurement of cardiac output are indicated because of the likelihood of a significant (greater than 15%) decrease in CI. In the absence of a significant decrease in the CjI, optimum PEEP occurs at the level producing maximum PcjO2. It is hoped that by following the described algorithm, many patients will be spared the cost and morbidity of unnecessary PA catheterization.
-
We investigated the cuff-occluded rate of rise of peripheral venous pressure (CORRP)--a new, nearly noninvasive peripheral hemodynamic monitoring parameter--in dogs subjected to hemorrhage and resuscitation. Twelve adult mongrel dogs under general anesthesia were subjected to hemorrhage of 30% of their estimated total blood volume (TBV) for 30 minutes; after this time the extracted blood was reinfused. Arterial pressure (AP), central venous pressure (CVP), pulmonary arterial pressure (PAP), cardiac output (CO), pulmonary venous pressure (PWP), heart rate, and CORRP were continuously monitored. ⋯ These average blood losses are all significantly different from the average blood loss required to effect a CSC in CORRP. The blood loss required to effect a CSC in CO averaged 9.7% +/- 6%. We conclude that in these anesthetized dogs, CORRP detected blood loss earlier than other commonly used hemodynamic parameters, including several invasive parameters such as CVP, PAP, and PWP; CORRP and CO were equivalent in their ability to detect early stages of blood loss.