Mechanisms of gas exchange with different gases during constant-flow ventilation

1990 ◽  
Vol 68 (1) ◽  
pp. 88-93 ◽  
Author(s):  
F. J. Chen ◽  
A. S. Menon ◽  
S. V. Lichtenstein ◽  
N. Zamel ◽  
A. S. Slutsky
Keyword(s):  
Gas Exchange ◽  
Physical Properties ◽  
Flow Rate ◽  
Constant Flow ◽  
Catheter Position ◽  
Arterial Pco2 ◽  
The Mean ◽  
The Difference ◽  
The Individual ◽  
Different Gases

To investigate the mechanisms responsible for the difference in gas exchange during constant-flow ventilation (CFV) when using gases with different physical properties, we used mixtures of 70% N2-30% O2 (N2-O2) and 70% He-30% O2 (He-O2) as the insufflating gases in 12 dogs. All dogs but one had higher arterial PCO2 (PaCO2) with He-O2 compared with N2-O2. At a flow of 0.37 +/- 0.12 l/s, the mean PaCO2's with N2-O2 and He-O2 were 41.3 +/- 13.9 and 53.7 +/- 20.3 Torr, respectively (P less than 0.01); at a flow rate of 0.84 +/- 0.17 l/s, the mean PaCO2's were 29.1 +/- 11.3 and 35.3 +/- 13.6 Torr, respectively (P less than 0.01). The chest was then opened to alter the apposition between heart and the lungs, thereby reducing the extent of cardiogenic oscillations by 58.4 +/- 18.4%. This intervention did not significantly alter the difference in PaCO2 between N2-O2 and He-O2 from that observed in the intact animals, although the individual PaCO2 values for each gas mixture did increase. When the PaCO2 was plotted against stagnation pressure (rho V2), the difference in PaCO2 between N2-O2 and He-O2 was nearly abolished in both the closed- and open-chest animals. These findings suggest that the different PaCO2's obtained by insufflating gases with different physical properties at a fixed flow rate, catheter position, and lung volume result mainly from a difference in the properties of the jet.

Impact of bypass flow rate and catheter position in veno-venous extracorporeal membrane oxygenation on gas exchange in vivo

2014 ◽  
Vol 18 (2) ◽  
pp. 128-135 ◽  
Author(s):  
Konomi Togo ◽  
Yoshiaki Takewa ◽  
Nobumasa Katagiri ◽  
Yutaka Fujii ◽  
Satoru Kishimoto ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Extracorporeal Membrane Oxygenation ◽  
Flow Rate ◽  
Bypass Flow ◽  
Catheter Position ◽  
Membrane Oxygenation

Gas exchange in dogs in the prone and supine positions

1992 ◽  
Vol 72 (6) ◽  
pp. 2292-2297 ◽  
Author(s):  
K. C. Beck ◽  
J. Vettermann ◽  
K. Rehder
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Prone Position ◽  
Pulmonary Blood Flow ◽  
Random Order ◽  
Arterial Pco2 ◽  
Supine Posture ◽  
Pulmonary Shunting ◽  
The Difference ◽  
Arterial Po2

To determine the cause of the difference in gas exchange between the prone and supine postures in dogs, gas exchange was assessed by the multiple inert gas elimination technique (MIGET) and distribution of pulmonary blood flow was determined using radioactively labeled microspheres in seven anesthetized paralyzed dogs. Each animal was studied in the prone and supine positions in random order while tidal volume and respiratory frequency were kept constant with mechanical ventilation. Mean arterial PO2 was significantly lower (P less than 0.01) in the supine [96 +/- 10 (SD) Torr] than in the prone (107 +/- 6 Torr) position, whereas arterial PCO2 was constant (38 Torr). The distribution of blood flow (Q) vs. ventilation-to-perfusion ratio obtained from MIGET was significantly wider (P less than 0.01) in the supine [ln SD(Q) = 0.75 +/- 0.26] than in the prone position [ln SD (Q) = 0.34 +/- 0.05]. Right-to-left pulmonary shunting was not significantly altered. The distribution of microspheres was more heterogeneous in the supine than in the prone position. The larger heterogeneity was due in part to dorsal-to-ventral gradients in Q in the supine position that were not present in the prone position (P less than 0.01). The decreased efficiency of oxygenation in the supine posture is caused by an increased ventilation-to-perfusion mismatch that accompanies an increase in the heterogeneity of Q distribution.

Ventilation-perfusion inequality during constant-flow ventilation

1987 ◽  
Vol 62 (3) ◽  
pp. 1255-1263 ◽  
Author(s):  
P. T. Schumacker ◽  
J. I. Sznajder ◽  
A. Nahum ◽  
L. D. Wood
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Lung Volume ◽  
Intermittent Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Asymmetric Distribution ◽  
Constant Flow ◽  
Arterial Pco2 ◽  
Continuous Stream ◽  
Anesthetized Dogs

Previous work by Lehnert et al. (J. Appl. Physiol. 53:483–489, 1982) has demonstrated that adequate alveolar ventilation can be maintained during apnea in anesthetized dogs by delivering a continuous stream of inspired ventilation through cannulas aimed down the main-stem bronchi. Because an asymmetric distribution of ventilation might introduce ventilation-perfusion (VA/Q) inequality, we compared gas exchange efficiency in nine anesthetized and paralyzed dogs during constant-flow ventilation (CFV) and conventional ventilation (intermittent positive-pressure ventilation, IPPV). Gas exchange was assessed using the multiple inert gas elimination technique. During CFV at 3 l X kg-1 X min-1, lung volume, retention-excretion differences (R-E*) for low- and medium-solubility gases, and the log standard deviation of blood flow (log SD Q) increased, compared with the findings during IPPV. Reducing CFV flow rate to 1 l X kg-1 X min-1 at constant lung volume improved R-E* and log SD Q, but significant VA/Q inequality compared with that at IPPV remained and arterial PCO2 rose. Comparison of IPPV and CFV at the same mean lung volume showed a similar reversible deterioration in gas exchange efficiency during CFV. We conclude that CFV causes significant VA/Q inequality which may be due to nonuniform ventilation distribution and a redistribution of pulmonary blood flow.

scholarly journals Tri-Ponderal Mass Index: A Screening Tool for Risk of Central Fat Accumulation in Brazilian Preschool Children

Medicina ◽  
2019 ◽  
Vol 55 (9) ◽  
pp. 577 ◽  
Author(s):  
Viviane Gabriela Nascimento ◽  
Ciro João Bertoli ◽  
Paulo Rogerio Gallo ◽  
Luiz Carlos de Abreu ◽  
Claudio Leone
Keyword(s):  
Preschool Children ◽  
Roc Curve ◽  
Screening Tool ◽  
The Body ◽  
Fat Accumulation ◽  
Central Fat ◽  
The Mean ◽  
The Difference ◽  
The Individual ◽  
Higher Sensitivity

Background and Objectives: To verify the use of the tri-ponderalmass index (TMI) as a screening tool for risk of central fat accumulation in preschool children. Materials and Methods: An observational, analytical study was carried out on samples from children 2 to 5 years of age. The body mass index (BMI) and the tri-ponderalmass index (TMI: Weight/height3) were calculated. The waist circumference-to-height ratio (WHtR) was used to classify central fat accumulation risk. Preschoolers whose WHtRwas in the upper tertile of the sample were classified as at risk for central fat accumulation. A comparison of the two indicators (BMI and TMI) was made from the area under the receiver operator characteristics (ROC) curve (AUC) in the discrimination of the WHtR. Results: The sample used for analysis was 919 preschoolers. The mean age of the children was 3.9 years (SD = 0.7). The difference in AUC was 5% higher for TMI (p < 0.0001). In the individual analysis of the ROC curve of the TMI, favoring a higher sensitivity, the cutoff point of 14.0 kg/m3 showed a sensitivity of 99.3% (95% CI: 97.6–99.9). Conclusion: Considering WHtR as a marker of possible future metabolic risk among preschool children, TMI proved to be a useful tool, superior to BMI, in screening for risk of central fat accumulation in preschool children.

Catheter position and blood gases during constant-flow ventilation

1987 ◽  
Vol 62 (2) ◽  
pp. 513-519 ◽  
Author(s):  
A. S. Slutsky ◽  
A. S. Menon
Keyword(s):  
Steady State ◽  
Flow Rate ◽  
Blood Gases ◽  
Constant Flow ◽  
Arterial Blood Gases ◽  
Catheter Position ◽  
Flow Rates ◽  
Arterial Blood ◽  
Tracheal Carina ◽  
Co2 Elimination

We studied the effect of catheter position and flow rate on gas exchange during constant-flow ventilation (CFV) in eight anesthetized, paralyzed dogs. The distal tips of the insufflation catheters were positioned 0.5, 2.0, 3.5, and 5.0 cm from the tracheal carina. Flow rates were varied between 10 and 55 l/min and steady-state arterial blood gases were measured. At a given flow rate, arterial CO2 pressure (PaCO2) decreased as CFV was administered further into the lung up to a distance of 3.5 cm from the carina; there were no significant differences in PaCO2 at 3.5 and 5.0 cm. For a given catheter position, PaCO2 decreased with increasing flow rate up to a flow rate of 40 l/min. Further increases in flow rate had no significant effect on PaCO2. Arterial O2 pressure (PaO2) was relatively constant at all flow rates and catheter positions. We conclude that, up to a point, CO2 elimination can be improved by positioning the catheters further into the lung; advancing the catheters further than 3.5 cm from the carina may cause over-ventilation of specific lung regions resulting in a relative plateau in CO2 elimination and relatively constant PaO2's. Positioning the catheters further into the lung permits the use of lower flow rates, thus potentially minimizing the risk of barotrauma.

Inter- and intra-individual variations in the saliva/blood alcohol ratio during ethanol metabolism in man.

1979 ◽  
Vol 25 (8) ◽  
pp. 1394-1398 ◽  
Author(s):  
A W Jones
Keyword(s):  
Coefficient Of Variation ◽  
Ethanol Metabolism ◽  
Single Individual ◽  
Blood Alcohol ◽  
Individual Variations ◽  
Sources Of Variation ◽  
The Mean ◽  
The Difference ◽  
The Individual ◽  
Male Subjects

Abstract The inter- and intra-individual components of variation in the saliva/blood alcohol ratio have been calculated from experiments with 48 male subjects after they drank 0.72 g of ethanol per kilogram of body weight as neat whisky after a short fast. Saliva and blood ethanol profiles were monitored at 30--60 min intervals for up to 7 h after intake. The analytical component of variation inherent in an estimate of the saliva/blood alcohol ratio, expressed as coefficient of variation, was 1.75%. I calculated saliva/blood ethanol ratios for each subject at each sampling time by taking the antilogarithm of the difference (log saliva alcohol--log blood alcohol). The mean ratio between 60 and 360 min after drinking was 1.077 (n = 336) with 95% confidence limits of 1.065 and 1.088. Moreover, the individual ratios showed no systematic variation throughout the absorption, distribution, and elimination phases of ethanol metabolism. Using a two-way analysis of variance and allowing for analytical sources of variation, I determined that the inter- and intra-subject variance components were 53 and 47% of the total biological variation. The saliva/blood alcohol ratio during ethanol metabolism, determined once in a single individual, had a biologically derived coefficient of variation of 10%.

STUDIES ON THE PATTERN OF CIRCULATING STEROIDS IN THE NORMAL MENSTRUAL CYCLE

1977 ◽  
Vol 84 (2) ◽  
pp. 320-332 ◽  
Author(s):  
A. R. Aedo ◽  
M. Nuñez ◽  
B.-M. Landgren ◽  
S. Z. Cekan ◽  
E. Diczfalusy
Keyword(s):  
Circadian Rhythm ◽  
Plasma Levels ◽  
Circadian Variation ◽  
Circadian Variations ◽  
Mean Values ◽  
Normal Menstrual Cycle ◽  
Menstruating Women ◽  
The Mean ◽  
The Difference ◽  
The Individual

ABSTRACT Circadian variations of the plasma levels of dehydroepiandrosterone, 17-hydroxypregnenolone, pregnenolone and testosterone were investigated by radioimmunoassay in 10 normally menstruating women during the periovulatory period. In seven of the subjects it was also possible to estimate androstenedione and dihydrotestosterone levels. Blood was withdrawn continuously over a period of 48 h at a rate of 4 ml/h by means of a non-thrombogenic pump. The circadian rhythm was studied during 13 3-hour sampling periods (39 h) which were identical in all subjects. Dehydroepiandrosterone, 17-hydroxypregnenolone and pregnenolone showed a marked circadian rhythm with highest mean levels in the morning between 06.00 and 09.00 h and lowest mean levels during the night between 21.00 and 24.00 h. The peak levels of individual subjects coincided completely with the highest mean levels in the case of dehydroepiandrosterone, in 9 out of 10 cases with regard to 17-hydroxypregnenolone and in 8 of 10 cases as far as pregnenolone levels were concerned. The lowest individual levels were more dispersed around the means than were the individual peaks. The difference between the highest (morning hours: 06.00–09.00) and lowest (evening hours: 21.00–24.00) geometeric mean values was 404% for 17-hydroxypregnenolone, 163 % for dehydroepiandrosterone and 71 % for pregnenolone. The mean testosterone levels also exhibited an elevation between 06.00 and 09.00 h which was significant (P < 0.05). However, the individual peak values were scattered from 21.00 h of the first day to 18.00 h of the second day. The mean concentrations of androstenedione showed a significant increase between 06.00 and 18.00 h. The individual peaks were widely dispersed. Hence a uniform circadian rhythm correlated to the levels of the Δl5-steroids mentioned above could not be demonstrated in the case of testosterone and androstenedione. An analysis of variance indicated no significant differences between sampling periods as far as dihydrotestosterone levels were concerned. The extent and regularity of the circadian variation in the plasma levels of the Δl5-steroids studied makes it mandatory to standardize very carefully the exact time of blood withdrawal in any longitudinal study. In view of the sharp changes in the plasma levels during the morning hours, it is suggested that sampling during the afternoon period may provide more constant values.

scholarly journals Gender Determination with Ischiopubic Index and Upper Pelvic Index in Iranian Adult Radiographic Stereotypes

2021 ◽  
Vol 19 (2) ◽  
Author(s):  
Hossein Ahmadi Kahjoogh ◽  
Maryam Vasheghani Farahani ◽  
Babak Shekarchi ◽  
Beheshteh Abouhamzeh ◽  
Mahdi Isazadeh
Keyword(s):  
Adult Population ◽  
Male And Female ◽  
Imaging Center ◽  
Study Population ◽  
The Mean ◽  
Spss Software ◽  
The Difference ◽  
The Individual ◽  
Female Subjects

Background: Different parts of the skeletal system have been studied in different studies to determine gender. The pelvis is one of the most important skeletal components for the determination of gender and identification of humans. Objectives: The current study aimed to determine gender using the ischiopubic index and upper pelvic index in the adult population of Iran. Methods: In this study, 140 individuals (70 male and 70 female subjects) referring to Athari Imaging Center in Tehran, Iran, for various medical reasons entered the study by giving written and oral consent using the convenience sampling method. Measurements were performed on digital anteroposterior pelvic radiographs (with standard conditions and radiographic stencil distance from the light source as 100 cm). The obtained data were analyzed using SPSS software (version 22). Results: The mean ischemic index of the whole population was 108.88 ± 13.75. The difference in the ischiopubic index between male and female subjects was significant (P < 0.05). The mean upper pelvic index of the whole study population was 81.70 ± 10.09; however, the difference in the upper pelvic index between the two groups of male and female subjects was not significant (P < 0.05). Conclusions: The pelvic ischemic index in Iranian women is higher than that reported for men. If the ischiopubic index is higher than 103, with 93% sensitivity and 73% specificity, it would be female. According to the study of graphs, if there is a special identity for diagnosis, there will be the possibility to match the graph before the death of the individual with the graph taken from skeletal remains.

Abstract 12662: Differences in Journal Impact Factor(IF) Between Initial and Subsequent Publication of Cardiovascular Clinical Trials-An Analysis From the ClinicalTrials.gov Repository

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Jasjit Bhinder ◽  
Saurav Chatterjee ◽  
Franz H Messerli
Keyword(s):  
Clinical Trial ◽  
Clinical Trials ◽  
Cross Sectional ◽  
Thomson Reuters ◽  
Subsequent Publication ◽  
The Mean ◽  
The Difference ◽  
The Individual ◽  
Sectional Analysis ◽  
Journal Impact

Introduction: After publication of the primary outcome of a clinical trial additional data of interest continue to be published -.To achieve high visibility of their findings most authors tend to select journals with a high IF. The IF is often viewed as a measure of journal quality as a whole. Hypothesis: We compared IF of journals where the primary outcomes from a clinical trial were published to IF of journals where subsequent papers were published. Methods: This was a cross sectional analysis design. We analyzed cardiovascular clinical trials from Clinicaltrials.gov. We did not limit our search by date. We chose clinical trials which had 2 or more published manuscripts in journals with indexed IFs. We queried the Thomson Reuters’ Web of Knowledge to determine the individual IF. Results: Our search returned 72 cardiovascular clinical trials from a query of the Clinicaltrials.gov database. The mean IF of the primary index publication from the trials were 27.01 (95% confidence interval-CI 21.96-32.06); while that from subsequent publications from the same trials were 11.72 (95% CI 8.97-14.47). The mean difference in IF of journals publishing the index and subsequent results was 15.28 (95% 2.11-17.96). There was a strong correlation between the initial publication IF and the IF difference with the subsequent manuscript (p<0.001). Conclusions: The initial publications of cardiovascular trials consistently occur in journals with an IF higher than in subsequent publications. The higher the journal IF of the initial publication the greater the difference in journal IF between initial and subsequent publications.

Effect of withdrawal of respiratory CO2 oscillations on respiratory control at rest

1991 ◽  
Vol 70 (4) ◽  
pp. 1601-1606 ◽  
Author(s):  
E. Takahashi ◽  
I. Tateishi ◽  
K. Yamamoto ◽  
T. Mikami
Keyword(s):  
Resting Metabolic Rate ◽  
Respiratory Control ◽  
Afferent Input ◽  
Respiratory Center ◽  
Arterial Pco2 ◽  
Baseline Drift ◽  
Double Lumen Endotracheal Tube ◽  
Arterial Ph ◽  
The Mean ◽  
The Difference

We examined the effect of sudden withdrawal of respiratory oscillations of arterial PCO2 (CO2 oscillations) at resting metabolic rate on the control of respiration in 11 anesthetized paralyzed vagotomized dogs in normoxic normocapnia. A double-lumen endotracheal tube was inserted so that the left and right lungs were ventilated independently. By alternately ventilating each lung, we could completely abolish CO2 oscillations without affecting the mean blood gas levels (withdrawal of CO2 oscillations). The CO2 oscillation was calculated from arterial pH oscillation measured by a rapidly responding intra-arterial pH electrode. Respiratory center output was monitored by use of a moving time average of the phrenic neurogram. A 3-min period of withdrawal of CO2 oscillations was bracketed by two control periods (simultaneous ventilation of lungs for 3 min) to avoid the confounding effect of the baseline drift in the respiratory center output. The amplitude of the CO2 oscillations in the control was 2.33 +/- 0.89 (SD) Torr. When the difference in the mean level of arterial PCO2 between the control and withdrawal of CO2 oscillations was minimized (-0.09 +/- 0.54 Torr; P greater than 0.25), we found negligible change in the minute phrenic activity during withdrawal of CO2 oscillations (-0.02 +/- 6.11% of the control, P greater than 0.98, n = 49; 99% confidence interval -2.36 to 2.32%). Thus we conclude that the maintenance of normal respiration at rest is not critically dependent on a phasic afferent input to the respiratory center arising from respiratory CO2 oscillations.

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