A method to test blood flow limitation of peritoneal-blood solute transport.

Current transperitoneal transport models assume that effective blood flow to the microcirculation does not limit solute exchange with dialysate in the cavity. Despite evidence that gas transfer across the peritoneum (assumed to equal the effective blood flow) occurs at rates that exceed maximum urea transfer rates by a factor of two to three, the assumption has been strongly challenged. To address this problem at the tissue level, a technique to determine the effect of local blood flow on small-solute transport was developed in this study. Diffusion chambers were affixed to the serosal side of the anterior abdominal wall of rats, and solutions containing radiolabeled urea or mannitol were placed in the chambers. During each experiment, the local blood flow beneath the chamber was monitored with laser Doppler flowmetry and the disappearance of the tracer versus time was simultaneously measured under three conditions of blood flow: control, 30% of control, and zero blood flow. The results demonstrated no significant differences for either solute between control and the condition in which blood flow was reduced by 70%. However, there was a significant reduction in the rate of mass transfer with no blood flow. It was concluded that blood flow at > or = 30% of control values does not limit solute transfer across the abdominal wall peritoneum during dialysis.

Download Full-text

Blood flow limitations of solute transport across the visceral peritoneum.

Journal of the American Society of Nephrology ◽

10.1681/asn.v8121946 ◽

1997 ◽

Vol 8 (12) ◽

pp. 1946-1950

Author(s):

M Kim ◽

J Lofthouse ◽

M F Flessner

Keyword(s):

Mass Transfer ◽

Blood Flow ◽

Tissue Level ◽

Local Blood Flow ◽

Doppler Flowmetry ◽

Flow Reduction ◽

Visceral Peritoneum ◽

Blood Flow Reduction ◽

Effective Exchange ◽

Liver Surface

In a previous study, no limitations to urea transfer across the parietal peritoneum were demonstrated with decreases in local blood flow of 70%. It was hypothesized that the visceral peritoneum would have similar characteristics. To address this problem at the tissue level, diffusion chambers were affixed to the serosal side of the stomach, cecum, or liver of anesthetized rats (n = 6 each tissue), and solutions containing 14C urea were placed in the chamber. During each experiment, the local chamber blood flow was measured with laser Doppler flowmetry, and, simultaneously, the disappearance of the tracer versus time was determined under three conditions: control, after 60 to 70% blood flow reduction, and postmortem (flow = 0). The results showed no difference in the urea mass transfer coefficient (MTC; mean +/- SEM; cm/min x 10[3]) between control and blood flow reduction for the stomach (4.0 +/- 0.4 versus 3.6 +/- 0.3) or for the cecum (4.6 +/- 0.3 versus 4.0 +/- 0.3). However, the MTC was significantly decreased by local blood flow reduction in the liver (5.4 +/- 0.2 versus 2.6 +/- 0.2). Postmortem data demonstrated significant reductions in the MTC with blood flow equal to zero. It is concluded that a 60 to 70% blood flow reduction from control values does not limit solute transperitoneal transfer in the hollow viscera but causes significant changes in the mass transfer across the liver surface. Because the liver makes up only a small portion of the effective exchange area, overall transperitoneal solute transfer should not be greatly affected by significant decreases in blood flow.

Download Full-text

Assessment of local blood flow with laser Doppler flowmetry in irradiated mandibular and frontal bone, an experiment in Göttingen minipigs

Journal of Cranio-Maxillofacial Surgery ◽

10.1016/j.jcms.2015.10.019 ◽

2015 ◽

Vol 43 (10) ◽

pp. 2071-2077 ◽

Cited By ~ 4

Author(s):

Lucas J. Poort ◽

Monique M.F. Bloebaum ◽

Roland A. Böckmann ◽

Ruud Houben ◽

Marlies E.P.G. Granzier ◽

...

Keyword(s):

Blood Flow ◽

Laser Doppler Flowmetry ◽

Frontal Bone ◽

Laser Doppler ◽

Local Blood Flow ◽

Doppler Flowmetry

Download Full-text

Effects of Blood Flow Pulse Frequency on Mass Transfer Efficiency of a Commercial Hollow Fibre Oxygenator

The International Journal of Artificial Organs ◽

10.1177/039139889802100905 ◽

1998 ◽

Vol 21 (9) ◽

pp. 535-541 ◽

Cited By ~ 8

Author(s):

G.B. Fiore ◽

G. Pennati ◽

F. Inzoli ◽

F. Mastrantonio ◽

D. Galavotti

Keyword(s):

Blood Flow ◽

Blood Perfusion ◽

Blood Flow Rate ◽

Pulse Frequency ◽

Hollow Fibre ◽

Gas Transfer ◽

Transfer Rates ◽

Inlet Conditions ◽

Pulsatile Perfusion

The clinical advantages achievable through pulsatile blood perfusion during cardio-pulmonary bypass have recently suggested the design of new pulsatile systems for extracorporeal circulation. Still it is not clear whether current commercial membrane oxygenators could be adopted with such systems, since their behaviour with pulsatile perfusion has not been satisfactorily documented yet. In a previous paper, we assessed that pulsatile perfusion of a widely used hollow fibre oxygenator (Sorin® Monolyth) at 60 bpm provides more time-consistent oxygen transfer than steady perfusion. The present work is aimed to evaluate how the pulse frequency influences the gas transfer performance of the same device. The oxygenator was subjected to in vitro trials using a roller pump with pulsatile module (Stöckert Instrumente®) to generate pulsed flow. Four different pulse frequencies (45, 60, 75 and 90 bpm) were investigated at a fixed blood flow rate (4.0 l/min). The experiments lasting six hours were carried out using bovine blood with inlet conditions according to AAMI standards requirements. Blood samples were withdrawn every hour and O2 and CO2 transfer rates were evaluated. The experimental findings confirm that with pulsatile blood flow no time decay take place during prolonged perfusion. Moreover, when pulse frequency increases, transition levels occur for both O2 and CO2. Over these thresholds gas transfer rates display significant increases (p < 0.05), though of little magnitude (up to 2.5% for oxygen over 60 bpm; up to 3.7% for carbon dioxide over 75 bpm).

Download Full-text

Newly Developed Pediatric Membrane Oxygenator that Suppresses Excessive Pressure Drop in Cardiopulmonary Bypass and Extracorporeal Membrane Oxygenation (ECMO)

Membranes ◽

10.3390/membranes10110362 ◽

2020 ◽

Vol 10 (11) ◽

pp. 362

Author(s):

Makoto Fukuda ◽

Asako Tokumine ◽

Kyohei Noda ◽

Kiyotaka Sakai

Keyword(s):

Blood Flow ◽

Pressure Drop ◽

Extracorporeal Membrane Oxygenation ◽

High Performance ◽

Flow Channel ◽

Gas Transfer ◽

Membrane Oxygenator ◽

Excessive Pressure ◽

Transfer Rates ◽

Membrane Oxygenation

This article developes a pediatric membrane oxygenator that is compact, high performance, and highly safe. This novel experimental approach, which imaging the inside of a membrane oxygenator during fluid perfusion using high-power X-ray CT, identifies air and blood retention in the local part of a membrane oxygenator. The cause of excessive pressure drop in a membrane oxygenator, which has been the most serious dysfunction in cardiovascular surgery and extracorporeal membrane oxygenation (ECMO), is the local retention of blood and air inside the oxygenator. Our designed blood flow channel for a membrane oxygenator has a circular channel and minimizes the boundary between laminated parts. The pressure drop in the blood flow channel is reduced, and the maximum gas transfer rates are increased by using this pediatric membrane oxygenator, as compared with the conventional oxygenator. Furthermore, it would be possible to reduce the incidents, which have occurred clinically, due to excessive pressure drop in the blood flow channel of the membrane oxygenator. The membrane oxygenator is said to be the “last stronghold” for patients with COVID-19 receiving ECMO treatment. Accordingly, the specification of our prototype is promising for low weight and pediatric patients.

Download Full-text

Blood Flow Does Not Limit Peritoneal Transport

Peritoneal Dialysis International ◽

10.1177/089686089901902s16 ◽

1999 ◽

Vol 19 (2_suppl) ◽

pp. 102-105 ◽

Cited By ~ 4

Author(s):

Michael F. Flessner ◽

Joanne Lofthouse

Keyword(s):

Blood Flow ◽

Water Exchange ◽

Water Transfer ◽

Dialysis Fluid ◽

Local Blood Flow ◽

Transfer Rates ◽

Osmotic Water ◽

Water And Solute Transport ◽

Doppler Flowmeter ◽

Osmotic Water Flow

Objective We investigated the assumption that blood flow to the microvessels underlying the peritoneum does not limit solute or water exchange between the blood and the dialysis fluid. Design Small plastic chambers were affixed to the serosal side of the liver, cecum, stomach, and abdominal wall of anesthetized rats. Solutions that contained labeled solutes or that were made hypertonic were placed into the chambers, which restricted the area of transfer across the tissue to the base of the chamber and which permitted calculation of mass or water transfer rates on the basis of area. The local blood flow was monitored continuously with a laser Doppler flowmeter during three periods of observation: control, after 50% -70% reduction of the blood flow, and postmortem. Results Urea transfer across all serosa, except for the liver, showed no difference in mean mass transfer coefficient (cm/min) between control (0.0038 0.0046) and after 70% flow reduction (0.0037 -0.0040), but demonstrated a significant decrease with blood flow equal to zero (0.0020). These tissues demonstrated small but insignificant decreases in osmotic water flow into the chamber (0.7 -0.9 μL/min/cm2 under control conditions versus 0.4 -0.7 μL/min/cm2 with reduced blood flow). The liver demonstrated limitations in water and solute transport with a 70% decrease in blood flow. Conclusion Because the liver makes up a small part of the peritoneal area, we conclude that large drops in blood flow do not limit overall solute or water transfer across the peritoneum during dialysis, and therefore acute peritoneal dialysis may be an appropriate modality for ICU patients in shock and renal failure.

Download Full-text

Laser Doppler flowmetry in the determination and evaluation of blood flow characteristics during the correction of cosmetic defects of abdominal wall

UMJ Heart & Vessels ◽

10.30978/hv2019-2-27 ◽

2019 ◽

Vol 0 (2) ◽

pp. 27-32

Author(s):

O. V. Panchuk ◽

V. G. Mishalov ◽

I. M. Leschishin ◽

O. I. Ohotska ◽

P. L. Byck ◽

...

Keyword(s):

Blood Flow ◽

Abdominal Wall ◽

Laser Doppler Flowmetry ◽

Flow Characteristics ◽

Laser Doppler ◽

Doppler Flowmetry

Download Full-text

THE ROLE OF LASER AND ULTRASONIC DOPPLER FLOWMETRY IN THE CORRECTION OF COSMETIC DEFECTS OF THE ANTERIOR ABDOMINAL WALL AND PREVENTION OF COMPLICATIONS

Wiadomości Lekarskie ◽

10.36740/wlek202107110 ◽

2021 ◽

Vol 74 (7) ◽

pp. 1605-1611

Author(s):

Orest V. Panchuk ◽

Yaroslav M. Susak ◽

Ievgen G. Donets ◽

Pavlo l. Byck ◽

Olena F. Panchuk ◽

...

Keyword(s):

Blood Flow ◽

Abdominal Wall ◽

Anterior Abdominal Wall ◽

Main Group ◽

Control Group ◽

Entire Study ◽

Doppler Flowmetry ◽

Significant Difference ◽

Simultaneous Operations ◽

Ultrasonic Doppler Flowmetry

The aim: Of work is to determine changes in blood flow in the vessels of the anterior abdominal wall that occur after plastic surgeries in order to improve the results of operations and to develop new methods for the prevention of complications. Materials and methods: The study was conducted in 132 patients. Patients were divided into 2 groups: main group 64 and control group 68 patients. Main group has patients who underwent abdominoplasty in combination with liposuction; control group has patients who underwent abdominoplasty without liposuction. In both groups we make different simultaneous operations. Laser Doppler Flowmetry and Ultrasonic Doppler Flowmetry were performed to determine the blood flow indices in the flaps. Results: Liposuction volumes averaged 3.57 ± 0.74 liters of lipoaspirate. In the main group there were totaly 4 complications, in the control group complications developed in 9 patients. Comparing daily indicators between the two groups, no statistically significant difference in the dynamics of MI changes was found during the entire study period (p = 0.767). Increase in caliber of vessels, on average, from 1.55 ± 0.8 mm in the preoperative period to 1.68 ± 0.75 mm on the 14th day of the postoperative period was statistically significant (p < 0.05). Conclusions: The combination of abdominoplasty with liposuction and simultaneous operations does not lead to greater development of complications and allows to achieve good aesthetic results.

Download Full-text