Evaluation of an on-demand, ex vivo bedside blood gas monitor on pulmonary artery blood gas determinations.

Critically ill patients often have cardiopulmonary perturbations that require rapid and frequent assessment for optimal care, including cardiac output determinations, measurement of cardiac filling pressures, and arterial and mixed venous blood gas determinations. We evaluated the performance of a rapid, on-demand bedside blood gas monitor to determine arterial and mixed venous blood gas values. The blood gas monitor uses fluorescent optode technology to directly measure Po2, Pco2, and pH. This measurement is accomplished by aspirating blood from the artery or vein into a sampling chamber where it interfaces with the fluorescent optode. After approximately 90 s of equilibration, the blood gas values are reported. Since the blood is drawn into the sampling chamber, it can be returned to the patient, thus eliminating the need for phlebotomy. We studied 15 critically ill patients requiring systemic and pulmonary arterial catheterization. Conventional blood gas analysis was performed simultaneously. The results obtained from the blood gas monitor were compared with those obtained via traditional blood gas analysis using Bland-Altman plots and examination of bias and precision. The results were well within the expected clinical variance. During the study period, there was no interference with patient care or adverse events related to the use of the monitoring system. In conclusion, the blood gas monitor can provide rapid, accurate determinations of arterial and mixed venous blood gases allowing optimal therapeutic interventions in critically ill patients.

Identification and characterization of the sulfate precipitate in GI147211C IV formulation.

GI147211, a water soluble analog of camptothecin, is currently being investigated for the treatment of cancer as a topoisomerase I inhibitor. Precipitate was observed in some samples of a stability lot of the IV clinical formulation after being stored at 5 degrees C for one month. The precipitate was identified as the sulfate salt of GI147211 by various techniques including Environmental Scanning Electron Microscope/Energy Dispersive X-ray (ESEM/EDX) and Ion Chromatography (IC). The cause of the precipitation was proven to be from the presence of residual sulfate ions in ammonium sulfate treated glass vials that were suspected to be improperly washed. The solubility product (Ksp) of the sulfate salt was determined in 5% dextrose solution adjusted to pH 3.5 at 5 degrees C to mimic the clinical formulation and refrigerated storage conditions. The Ksp was also determined at 15 and 33 degrees C to determine the temperature effect on the constant. The stoichiometry of the sulfate salt was determined by solubility experiments using HPLC and IC to be 2:1 (base/salt). Based on the stoichiometry, the Ksp was calculated to be 3.04 x 10(-12), 9.27 x 10(-12) and 9.96 x 10(-11) M3 at 5 degrees C, 15 degrees C and 33 degrees C, respectively. Using the Ksp values, the sulfate threshold in GI147211 Injection when GI147211 sulfate precipitates was determined to be 1.3, 3.8 and 41 ppm at 5, 15 and 33 degrees C, respectively. Further experiments demonstrated that using the proper cleaning techniques the sulfate level in the treated vials was reduced to < 1.3 ppm. The washing cycles for the vials used for clinical supplies were thereafter modified so that the sulfate precipitate would no longer be an issue.

Transcutaneous measurement of partial pressure of oxygen and carbon dioxide.

Transcutaneous monitoring is noninvasive and relatively simple to use. In neonates and small infants, this monitoring technique may provide very useful clinical information. Transcutaneous gas monitoring, using conventional electrochemical techniques, provides a means of trending the values of PaO2 and PaCO2 in most patients with relatively normal cardiovascular function. In patients with compromised cardiopulmonary function and in many adults, because of different skin structure, transcutaneous gas monitoring will not accurately reflect arterial blood gas tensions. Because transcutaneous gases depend on skin perfusion, however, it may be useful in monitoring tissue perfusion, especially in patients with peripheral vascular disease and tissue flaps. The heating of the monitoring probe necessitates frequent site changes to avoid thermal injury, which make it more labor intensive than other noninvasive monitoring methods.

Coagulation tests, blood loss, and transfusion requirements in platelet-rich plasmapheresed versus nonpheresed cardiac surgery patients.

The results of several studies suggest that acute platelet-rich plasmapheresis decreases blood loss and allogeneic blood product transfusion requirements in cardiac surgery patients. We designed a randomized, prospective study to determine whether acute platelet-rich plasmapheresis decreases blood loss and allogeneic transfusion requirements in primary cardiac surgery patients. Forty patients were randomized to a control or pheresis group. The pheresis group had platelet-rich plasmapheresis performed before cardiopulmonary bypass (CPB) and the platelet-rich plasma (PRP) was returned after CPB. The control group was managed in the normal fashion without pheresis. All patients had serial coagulation studies, hemoglobin, and platelet counts determined intra- and postoperatively. Chest tube drainage and transfusion requirements were recorded. There were no differences in the coagulation tests, platelet counts, chest tube drainage, or allogeneic blood product transfusion requirements between the two groups at any time. The authors conclude that the use of acute platelet-rich plasmapheresis in primary cardiac surgery patients does not decrease chest tube drainage or the need for allogeneic blood transfusions.

Simple, inexpensive, and rapid way to produce Bacillus subtilis spores for the Guthrie bioassay.

Esculin agar has been found to be a simple, inexpensive, rapid, and reliable means to promote production of spores of inhibitor-sensitive clones of Bacillus subtilis strains ATCC 6051 and 6633 for use in the Guthrie bioassay screening tests for genetic metabolic disorders.

Production of experimental ulcerative colitis in gnotobiotic guinea pigs with simplified microflora.

Conventional guinea pigs provided with a solution of 5% (wt/vol) degraded carrageenan as the sole source of oral fluids developed ulcerations of their ceca and large intestines within 30 days. Similar lesions were not detected in germfree guinea pigs treated in an identical manner, suggesting that an intestinal microflora was necessary for development of intestinal lesions. To simplify the bacterial flora required for production of cecal ulcerations, 10 pools consisting of 10 bacterial strains each were isolated from the cecal microflora of carrageenan-treated animals. Groups of germfree guinea pigs were associated with 2 of the 10 pools by orogastric intubation and observed for development of disease. One-half of each group was treated with carrageenan. The two bacterial pools were characterized by the presence of cytopathic effects for WI-38 and Vero cells, increased chemotactic activity, and increased concentrations of long-chain fatty acids. The results indicated that animals associated with those two pools developed cecal ulcerations during carrageenan treatment. Preliminary results also indicated that cecal ulcerations developed in germfree animals mono-associated with a strain of Bacteroides vulgatus isolated from one of the pools, regardless of whether carrageenan was administered, suggesting a bacterial involvement in disease development in the absence of carrageenan treatment.