MECHANISM OF CHANGING INTRAPULMONARY SHUNT WITH VARYING INSPIRED OXYGEN FRACTIONS

1982 ◽  
Vol 10 (3) ◽  
pp. 236
Author(s):  
David H. Skinner ◽  
David M. Rose ◽  
David L. Farber ◽  
I. James Sarfeh
Keyword(s):  
Intrapulmonary Shunt ◽  
Inspired Oxygen

scholarly journals Right-to-left shunt determination in dog lungs under inhalation anesthesia with rebreathing and non-rebreathing system

2006 ◽  
Vol 21 (6) ◽  
pp. 374-379 ◽  
Author(s):  
André Leguthe Rosa ◽  
Patrícia Cristina Azevedo Mota ◽  
Yara Marcondes Machado Castiglia
Keyword(s):  
Partial Pressure ◽  
Carbon Dioxide Partial Pressure ◽  
Partial Pressure Of Oxygen ◽  
Intrapulmonary Shunt ◽  
Inhalation Anesthesia ◽  
Arterial Partial Pressure ◽  
Venous Oxygen Saturation ◽  
Fraction Of Inspired Oxygen ◽  
Inspired Oxygen ◽  
Mixed Venous

PURPOSE: To investigatge right-to-left shunt determination in dog lungs under inhalantion anesthesia with non-rebreathing and rebreathing systems and fraction of inspired oxygen (F I O2) of 0.9 and 0.4, respectively. METHODS: Two groups of 10 dogs each under inhalation anesthesia with sevoflurane: GI in which it was utilized non-rebreathing semiclosed system and F I O2 = 0.9, and GII in which it was utilized rebreathing semiclosed system and F I O2 = 0.4. The study parameters were: heart rate, medium arterial pressure, right-to-left intrapulmonary shunt, hematocrit, hemoglobin, arterial partial pressure of oxygen, mixed venous partial pressure of oxygen, mixed venous oxygen saturation, arterial partial pressure of carbon dioxide, partial pressure of water in the alveoli. RESULTS: Shunt results were significantly different between the two groups - GI data were higher than GII in all the evaluated moments. Hence, the group with nonrebreathing (GI) developed a superior grade of intrapulmonary shunt when compared with the rebreathing group (GII). The partial pressure of water in the alveoli was significantly higher in GII. CONCLUSION: The inhalation anesthesia with non-rebreathing system and F I O2 = 0.9 developed a higher grade of intrapulmonary right-to-left shunt when compared with the rebreathing system and F I O2 = 0.4. The higher humidity in GII contributed to the result.

Use of a Vital Capacity Maneuver to Prevent Atelectasis after Cardiopulmonary Bypass 

1998 ◽  
Vol 88 (1) ◽  
pp. 134-142 ◽  
Author(s):  
Lennart Magnusson ◽  
Vitas Zemgulis ◽  
Arne Tenling ◽  
Johan Wernlund ◽  
Hans Tyden ◽  
...  
Keyword(s):  
Cardiopulmonary Bypass ◽  
Vital Capacity ◽  
Major Complication ◽  
Control Group ◽  
Intrapulmonary Shunt ◽  
Computed Tomographic ◽  
The Third ◽  
Oxygen Fraction ◽  
Lung Area ◽  
Inspired Oxygen

Background Respiratory failure secondary to cardiopulmonary bypass (CPB) remains a major complication after cardiac surgery. The authors previously found that the increase in intrapulmonary shunt was well correlated with the amount of atelectasis. They tested the hypothesis that post-CPB atelectasis can be prevented by a vital capacity maneuver (VCM) performed before termination of the bypass. Methods Eighteen pigs received standard hypothermic CPB (no ventilation during bypass). The VCM was performed in two groups and consisted of inflating the lungs during 15 s to 40 cmH2O at the end of the bypass. In one group, the inspired oxygen fraction (FIO2) was then increased to 1.0. In the second group, the FIO2 was left at 0.4. In the third group, no VCM was performed (control group). Ventilation-perfusion distribution was measured with the inert gas technique and atelectasis by computed tomographic scanning. Results Intrapulmonary shunt increased after bypass in the control group (from 4.9 +/- 4% to 20.8 +/- 11.7%; P < 0.05) and was also increased in the vital capacity group ventilated with 100% oxygen (from 2.2 +/- 1.3% to 6.9 +/- 2.9%; P < 0.01) but was unaffected in the vital capacity group ventilated with 40% oxygen. The control pigs showed extensive atelectasis (21.3 +/- 15.8% of total lung area), which was significantly larger (P < 0.01) than the proportion of atelectasis found in the two vital capacity groups (5.7 +/- 5.7% for the vital capacity group ventilated with 100% oxygen and 2.3 +/- 2.1% for the vital capacity group ventilated with 40% oxygen. Conclusion In this pig model, postcardiopulmonary bypass atelectasis was effectively prevented by a VCM.

Influence of mixed venous PO2 and inspired O2 fraction on intrapulmonary shunt in patients with severe ARDS

1995 ◽  
Vol 78 (4) ◽  
pp. 1531-1536 ◽  
Author(s):  
R. Rossaint ◽  
S. M. Hahn ◽  
D. Pappert ◽  
K. J. Falke ◽  
P. Radermacher
Keyword(s):  
Mechanical Ventilation ◽  
Blood Flow ◽  
Distress Syndrome ◽  
Intrapulmonary Shunt ◽  
Pulmonary Hemodynamics ◽  
Oxygen Fraction ◽  
The Individual ◽  
Inspired Oxygen ◽  
Ventilation And Perfusion ◽  
Mixed Venous

In 12 patients undergoing extracorporeal membrane oxygenation for treatment of severe acute respiratory distress syndrome (ARDS), we examined the effects of independent variations in mixed venous oxygen tension (PvO2) and inspired oxygen fraction (FIO2) on the distribution of ventilation and perfusion as assessed by the multiple inert gas elimination technique. Reducing the oxygen concentration of the constant gas stream through the membrane lungs allowed us to decrease the PvO2 by approximately 20 Torr independently of variations in cardiac output and FIO2 as well as to augment FIO2 without influencing PvO2. The interventions did not induce any change in heart rate or systemic or pulmonary hemodynamics. In general, neither during mechanical ventilation at FIO2 of 0.6 nor during mechanical ventilation at FIO2 of 1.0 did the reduced PvO2 cause variations in the distribution of pulmonary blood flow in our patients with severe ARDS. Nevertheless, in individual patients, decreasing PvO2 or ventilation at FIO2 of 1.0 was associated with changes in intrapulmonary shunt. Therefore, we conclude that it is not possible to predict the influence of such interventions in pulmonary gas exchange in the individual patient suffering from ARDS. Differences in the regulation of the local distribution of blood flow caused by the disease itself might explain this phenomenon.

scholarly journals Effects of inspired oxygen fractions in rabbits anesthetized with isoflurane or sevoflurane, maintained on spontaneous ventilation

2019 ◽  
Vol 71 (3) ◽  
pp. 944-952
Author(s):  
M. Horr ◽  
N. Nunes ◽  
E.G.F. Biteli ◽  
P.C.F. Lopes ◽  
A.P. Gering ◽  
...  
Keyword(s):  
Oxygen Partial Pressure ◽  
Arterial Oxygen ◽  
Intrapulmonary Shunt ◽  
Oxygen Gradient ◽  
Isoflurane Anesthesia ◽  
Partial Pressures ◽  
Respiratory Index ◽  
Alveolar Oxygen ◽  
Spontaneously Breathing ◽  
Inspired Oxygen

ABSTRACT It is important to identify the best inspired fraction of oxygen in a variety of situations, including sevoflurane or isoflurane anesthesia, in spontaneously breathing rabbits. For this, 64 rabbits were assigned to eight groups: GI100 (FiO2= 1,0 + isoflurane), GS100 (FiO2= 1,0 + sevoflurane), GI80 (FiO2= 0,8 + isoflurane), GS80 (FiO2= 0,8 + sevoflurane), GI60 (FiO2= 0,6 + isoflurane), GS60 (FiO2= 0,6 + sevoflurane), GI21 (FiO2= 0,21 + isoflurane), GS21 (FiO2= 0,21 + sevoflurane). The induction was performed with (2.5MAC) of the anesthetic. The vaporizer was setted at 1.5 MAC and FiO2 as attributed for each group. After the induction, the concentration was changed to 1 MAC. Measurements of parameters were performed 30 minutes after induction (T0), and then at 15 minute intervals (from T15 to T60). The arterial partial pressures of oxygen (PaO2), alveolar oxygen partial pressure (PAO2) and alveolar-arterial oxygen gradient [P(A-a)O2] were higher with the use of high FiO2. The GI80 showed higher levels of PaO2 FiO2 ratio and respiratory index (RI). In conclusion, the FiO2 of 0.21 is not indicated, because it causes hypoxemia. The isoflurane determines better ventilation when compared to sevoflurane, but isoflurane associated with 80% of oxygen promotes intrapulmonary shunt increase.

Pronation Technique in ARDS Patients

ABOUTOPEN ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 21-23
Author(s):  
Raffaele Di Fenza ◽  
Hedwige Gay ◽  
Martina Favarato ◽  
Isabella Fontana ◽  
Roberto Fumagalli
Keyword(s):  
Intensive Care ◽  
Intensive Care Units ◽  
Distress Syndrome ◽  
Daily Practice ◽  
Volume Distribution ◽  
Intensive Care Unit Staff ◽  
Safe Technique ◽  
Fraction Of Inspired Oxygen ◽  
And Diffusion ◽  
Inspired Oxygen

In severe acute respiratory distress syndrome (ARDS), characterized by the ratio of arterial partial pressure of oxygen over fraction of inspired oxygen (P/F) less than 150 mm Hg, pronation cycles are the only intervention that showed improved survival, in combination with protective ventilation. The physiological advantages of performing pronation cycles, such as the improvement of oxygenation, better tidal volume distribution with increased involvement of dorsal regions, and easier drainage of secretions, overcome the possible complications, that is, endotracheal tube occlusion or misplacement, pressure ulcers, and brachial plexus injury. However, the incidence of complications is dramatically lower in intensive care units with expertise, adopting prone positioning in daily practice. In this video we are proposing step by step an easy and ergonomic technique to perform pronation maneuvers in patients with severe ARDS. Recent literature suggests that a high percentage of these patients are treated without undergoing pronation cycles. The main purpose of this video is to help increase the number of intensive care units worldwide commonly performing pronation cycles in patients that have indications to be pronated, in order to decrease healthcare burden and costs directly caused by ARDS. Proper intensive care unit staff training is fundamental in minimizing the risks associated with the maneuver for both patients and operators; and diffusion of a safe technique encouraging the operators is the second main purpose of this video.

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