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N Krivitski

Publications and source records attributed to N Krivitski.

3 recordsLinked to original sources
PubMed2002

Quantification of lung microvascular injury with ultrasound.

Quantification of water and solute exchange rates across the lung microvascular barrier (LMB) may be an important early-warning indicator of pulmonary microvascular diseases such as acute respiratory distress syndrome. Our objective was to determine the degree to which osmotic water movement across the LMB induced by injection of hypertonic solutions of NaCl and glucose could be detected downstream from the lung with a specialized ultrasonic velocity (USV) transducer manufactured by Transonic Systems. We hypothesized that mathematical modeling of the osmotic transients (OT) would yield estimates of osmotic exchange parameters that were sensitive to microvascular injury. Two groups of six dogs were studied under baseline conditions and after injury with high dose (HD) or low dose (LD) oleic acid. Osmotic conductances (sigmaK(1), sigmaK(2)), and volumes (V(1), V(2)) of two extravascular spaces were estimated by fitting the mathematical model to the OT data. HD results (mean +/- standard error) indicated a significant decrease (by paired t test) in sigmaK(1) from 1.59 +/- 0.09 to 1.04 +/- 0.015 [ml h(-1) (mosm/l)(-1) g(-1) WLW)], an increase in sigmaK(2) from 0.20 +/- 0.08 to 0.32 +/- 0.12 [ml h(-1) (mosm/l)(-1) g(-1)], and a significant increase in V2 from 23.26 +/- 2.51 to 78.0 +/- 15.23 (ml) for NaCl injections. LD V2 estimated from NaCl increased significantly from 21.57 +/- 2.15 to 37.59 +/- 2.36 (ml), sigmaK2 increased from 0.09 +/- 0.03 to 0.17 +/- 0.04 and no significant change in sigmaK(1) was found. Baseline glucose sigmaK(1), sigmaK(2), and V1 in the LD series were 2.08 +/- 0.18, 0.64 +/- 0.19 [ml h(-1) (mosm/l)(-1) g(-1)] and 13.08 +/- 1.89 (ml), respectively, and did not change significantly with injury. We conclude that OT data measured by USV is a sensitive and informative indicator of LMB osmotic properties, and may be useful for quantification of LMB permeability changes due to acute injury. We further conclude that V(1) represents microvascular endothelial volume and V(2) is an estimate of interstitial volume.

Animals↗
PubMedDate not supplied

Use of an extracorporeal arteriovenous tubing loop to measure cardiac output in intensive care unit patients by ultrasound velocity dilution.

Thermodilution cardiac output (CO) measurement requires heart catheterization and is known as a risk factor. The existing cannula in the radial artery in intensive care unit (ICU) patients can be used to measure CO by ultrasound dilution (COus). An arteriovenous shunt between the radial artery and cubital vein was created using a 25 cm tubing loop. An ultrasound flow dilution sensor was clamped on the tubing and connected to a modified HD01 monitor (Transonic Systems, Inc., Ithaca, NY). Calibration injections of 1 ml 0.9% NaCl were injected into the tubing. An intravenous bolus injection consisted of 10-20 ml 0.9% NaCl. Simultaneously, CO was measured by thermal dilution (COth; MI 166A, Hewlett Packard, Andover, MA). Each value for COth or COus was based on the average of three to five injections. Blood flow through the shunt was 10 to 26 ml/min. The comparison was made on 14 patients. In 33 measurements, the regression equation was COth = -0.08 + 1.02 COus (r = 0.97). In 22 cases, the difference between COth and COus was less than 5%, in 9 cases it was in the range of 5-10%, and in 2 cases it was in the range of 10-20%. The presence of arterial and venous lines in an ICU setting obviates the need for cardiac catheterization for the determination of CO.

Cardiac Output↗