Many researchers have pointed out that CO₂ bathing directly effects expanding dermal vessels. To clarify the effect of CO₂ bathing on red blood cell (RBC), the change of RBC viscosity after single bathing(for 10 minutes at 40°C) with artificial CO₂ water made of sodium bicarbonate and citric acid dissolved in plain water was investigated. RBC viscosity was measured at both shear rates of 0.0439 (low) and 94.5 (high) sec^-1 using a viscosimeter (Low Shear 30 made by Contraves). The subjects of this study consisted of three male patients and three female patients with a history of cerebro-vascular disease and ranging from 53 to 80 years old.
The results are presented below.
1) On the twenty-first day of serial CO₂ bathings, a significant decrease in RBC viscosity was found in these patients as compared with that in controls who were subjected to bathing with plain water. However, it was not found on the first day. RBC viscosity of the blood sample that has an elevated PCO₂ due to the CO₂ gas bubbled into it was measured in relation with the PCO₂. RBC viscosity decreased gradually at both shear rates as the PCO₂ was elevated and the MCV increased.
2) MCV increased significantly after single bathing on the twenty-first day of serial CO₂ baths as compared to that of controls who were subjected to bathing with plain water.
3) ATP concentration in RBC decreased significantly after single bathing as compared to that before bathing.
From these results, we can conclude that serial CO₂ baths effectively decrease RBC viscosity due to the increase in MCV, which is attained by CO₂ through “chloride shift.”

Many researchers have pointed out that CO₂ bathing directly effects expanding dermal vessels. The authors have recently reported a decrease in red blood cell after CO₂ bathing. To clarify other effects of CO₂ bathing on RBC, the changes in the hemoglobinoxygen-dissociation curve (P50) were measured after single bathing (for 10 minutes at 40°C) with artificial CO₂ water made of sodium bicarbonate and citric acid dissolved in plain water. P50 was measured with an oxygen-dissociation analyzer (HEMO-O-SCAN^TM made by American Instrument Company) and 2, 3-diphosphoglycerate (2, 3-DPG) in RBC, with enzymatic analysis. The subjects of this study consisted of six male patients and four female patients, ranging from 53 to 80 years old.
The results are presented below.
1) Nine of ten patients showed an increase in P50 after 15 to 30 minutes of CO₂ bathing. The remainder showed a transient increase in P50.
2) No significant increase in 2, 3-DPG concentration in RBC was found in the group subjected to CO₂ bathing as compared to that of the controls who were subjected to plain water bathing. However, seven patients showed an increase in 2, 3-DPG after 15 to 30 minutes of CO₂ bathing, and three patients showed a decrease in 2, 3-DPG.
3) Partial pressures of oxygen (PO₂) and carbon dioxide (PCO₂) in the venous blood were measured. Elevation of PO₂, lowering of PCO₂, and increase in pH were observed in almost all patients after a single CO₂ bath.
From these results, we can conclude that a single CO₂ bath effectively decreases oxygen affinity of hemoglobin, presumably due to a rise in the blood temperature and partially due to an increase in 2, 3-DPG concentration in RBC.

BACKGROUND/AIMS: Endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) has been used to diagnose gastrointestinal submucosal tumors (SMTs). Although rapid on-site evaluation (ROSE) has been reported to improve the diagnostic accuracy of EUS-FNA for pancreatic lesions, on-site cytopathologists are not routinely available. Given this background, the usefulness of ROSE by endosonographers themselves for pancreatic tumors has also been reported. However, ROSE by endosonographers for diagnosis of SMT has not been reported. The aim of this study was to evaluate the diagnostic accuracy of EUS-FNA with ROSE by endosonographers for SMT, focusing on diagnosis of gastrointestinal stromal tumor (GIST), compared with that of EUS-FNA alone. METHODS: Twenty-two consecutive patients who underwent EUS-FNA with ROSE by endosonographers for SMT followed by surgical resection were identified. Ten historical control subjects who underwent EUS-FNA without ROSE were used for comparison. RESULTS: The overall diagnostic accuracy for SMT was significantly higher in cases with than without ROSE (100% vs. 80%, p=0.03). The number of needle passes by FNA with ROSE by endosonographers tended to be fewer, although accuracy was increased (3.3±1.3 vs. 5.9±3.8, p=0.06). CONCLUSIONS: ROSE by endosonographers during EUS-FNA for SMT is useful for definitive diagnosis, particularly for GIST.
Biopsy, Fine-Needle* ; Diagnosis* ; Endoscopic Ultrasound-Guided Fine Needle Aspiration ; Gastrointestinal Stromal Tumors* ; Humans ; Needles