Relation between respiratory valve dead space and tidal volume

1980 ◽  
Vol 49 (3) ◽  
pp. 528-532 ◽  
Author(s):  
P. W. Bradley ◽  
M. Younes
Keyword(s):  
Tidal Volume ◽  
Dead Space ◽  
Water Displacement ◽  
Respiratory Valve ◽  
Laboratory Procedures ◽  
The Common ◽  
The Dead ◽  
Marked Tendency

We measured the "effective" dead space of five commonly used respiratory valves: Hans Rudolph valve, two-way J valve, triple-J valve, and modified Otis-McKerrow valves without and with vane. The dead space was measured using a technique that mimicked the operation of valves during ordinary laboratory procedures. The valves were ventilated with tidal volumes ranging from 0.35-3.00 liters and at different frequencies. With all valves, there was a marked tendency for "effective" dead space to be tidal volume dependent. The measured dead space approached the water-displacement volume of the common chamber of the valve only at tidal volumes in excess of 2.0 liters. The relation between valve dead space and tidal volume was independent of frequency.

Effect of common dead space on VA/Q distribution in the dog

1990 ◽  
Vol 68 (6) ◽  
pp. 2488-2493 ◽  
Author(s):  
K. Tsukimoto ◽  
J. P. Arcos ◽  
W. Schaffartzik ◽  
P. D. Wagner ◽  
J. B. West
Keyword(s):  
Blood Flow ◽  
Tidal Volume ◽  
Dead Space ◽  
Volume Ratio ◽  
Inert Gas ◽  
Base Line ◽  
Heavy Exercise ◽  
The Common ◽  
Technique Comparison ◽  
Condition B

Several previous studies have shown worsening ventilation-perfusion (VA/Q) relationships in humans during heavy exercise at sea level. However, the mechanism of this deterioration remains unclear because of the correlation with ventilatory and circulatory variables. Our hypothesis was that the decrease in the series dead space-to-tidal volume ratio during exercise might be partly responsible because mixing in the common dead space can reduce apparent inequality. We tested this notion in 10 resting anesthetized normocapnic dogs passively hyperventilated by increase tidal volume and a) inspired CO2 or b) external dead space. We predicted less apparent VA/Q inequality in condition b because of mixing in the added dead space. After base-line measurements, conditions a and b were randomly assigned, and after a second set of base-line measurements they were repeated in the reverse order in each dog. VA/Q inequality was measured by the multiple inert gas elimination technique. Comparison of conditions a and b demonstrated that additional external dead space improved (P less than 0.001) the blood flow distributions as hypothesized [log standard deviation of perfusion = 0.49 +/- 0.02 (SE) in condition b and 0.61 +/- 0.03 in condition a with respect to 0.52 +/- 0.03 at base line]. This study suggests that the increased tidal volume during exercise could uncover VA/Q inequality not evident at rest because of the higher ratio of common dead space to tidal volume at rest.

Evaluation of the dead space/tidal volume ratio in patients with chronic congestive heart failure

1995 ◽  
Vol 1 (5) ◽  
pp. 401-408 ◽  
Author(s):  
Marco Guazzi ◽  
Giancarlo Marenzi ◽  
Emilio Assanelli ◽  
Giovanni B. Perego ◽  
Gaia Cattadori ◽  
...  
Keyword(s):  
Heart Failure ◽  
Congestive Heart Failure ◽  
Tidal Volume ◽  
Dead Space ◽  
Volume Ratio ◽  
Chronic Congestive Heart Failure ◽  
The Dead

Evaluation of the dead space to tidal volume ratio as a predictor of extubation failure

2006 ◽  
Vol 0 (0) ◽  
Author(s):  
Albert Bousso ◽  
Bernardo Ejzenberg ◽  
Andréa Maria Cordeiro Ventura ◽  
José Carlos Fernandes ◽  
Iracema de Cássia de Oliveira Fernandes ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Dead Space ◽  
Volume Ratio ◽  
Extubation Failure ◽  
The Dead

Time and volume dependence of dead space in healthy and surfactant-depleted rat lungs during spontaneous breathing and mechanical ventilation

2013 ◽  
Vol 115 (9) ◽  
pp. 1268-1274 ◽  
Author(s):  
Constanze Dassow ◽  
David Schwenninger ◽  
Hanna Runck ◽  
Josef Guttmann
Keyword(s):  
Mechanical Ventilation ◽  
Tidal Volume ◽  
Dead Space ◽  
Spontaneous Breathing ◽  
Small Animals ◽  
Single Breath ◽  
Dead Space Volume ◽  
The Dead ◽  
Gas Volume ◽  
Space Volume

Volumetric capnography is a standard method to determine pulmonary dead space. Hereby, measured carbon dioxide (CO2) in exhaled gas volume is analyzed using the single-breath diagram for CO2. Unfortunately, most existing CO2 sensors do not work with the low tidal volumes found in small animals. Therefore, in this study, we developed a new mainstream capnograph designed for the utilization in small animals like rats. The sensor was used for determination of dead space volume in healthy and surfactant-depleted rats ( n = 62) during spontaneous breathing (SB) and mechanical ventilation (MV) at three different tidal volumes: 5, 8, and 11 ml/kg. Absolute dead space and wasted ventilation (dead space volume in relation to tidal volume) were determined over a period of 1 h. Dead space increase and reversibility of the increase was investigated during MV with different tidal volumes and during SB. During SB, the dead space volume was 0.21 ± 0.14 ml and increased significantly at MV to 0.39 ± 0.03 ml at a tidal volume of 5 ml/kg and to 0.6 ± 0.08 ml at a tidal volume of 8 and 11 ml/kg. Dead space and wasted ventilation during MV increased with tidal volume. This increase was mostly reversible by switching back to SB. Surfactant depletion had no further influence on the dead space increase during MV, but impaired the reversibility of the dead space increase.

Effects of Left Atrial Pressure on Pulmonary Shunt and the Dead Space/Tidal Volume Ratio

1978 ◽  
Vol 49 (2) ◽  
pp. 128-135 ◽  
Author(s):  
Theodore H. Stanley ◽  
Judd K. Lunn ◽  
Wen Shin Liu ◽  
Scott Gentry
Keyword(s):  
Tidal Volume ◽  
Dead Space ◽  
Left Atrial ◽  
Volume Ratio ◽  
Atrial Pressure ◽  
Left Atrial Pressure ◽  
Pulmonary Shunt ◽  
The Dead

Unanesthetized dogs with increased respiratory dead space

1960 ◽  
Vol 15 (5) ◽  
pp. 838-842 ◽  
Author(s):  
Thomas B. Barnett ◽  
Richard M. Peters
Keyword(s):  
Tidal Volume ◽  
Respiratory Rate ◽  
Dead Space ◽  
Minute Volume ◽  
Alveolar Ventilation ◽  
Physiologic Dead Space ◽  
Consistent Change ◽  
The Dead ◽  
Animal Preparation ◽  
Respiratory Dead Space

A method is described for maintaining a permanent tracheostomy in dogs. This animal preparation has been used to study the effects of artificially increased respiratory dead space. Trained dogs with tracheostomies have made possible measurements of ventilation without anesthesia. It has been found that additions to the respiratory dead space in the form of tubing of frac34 in. i.d. result in an increase in physiologic dead space of the same magnitude as the volume of tubing added. Increasing the dead space in this manner resulted in an increased minute volume which was accomplished principally by an increase in tidal volume without a significant or consistent change in respiratory rate. Alveolar ventilation remained unchanged even with large additions to the dead space (20–30 cc/kg of animal wt.). Arterial pCO2 was significantly higher in these animals than in the controls. The CO2 tension was similarly elevated when extra dead space of lesser volume (5–20 cc/kg) was allowed to remain on the dogs for more than 48 hours. Submitted on April 13, 1960

Alveolar ventilation during high-frequency oscillation: core dead space concept

1984 ◽  
Vol 56 (3) ◽  
pp. 700-707 ◽  
Author(s):  
D. Isabey ◽  
A. Harf ◽  
H. K. Chang
Keyword(s):  
Tidal Volume ◽  
Dead Space ◽  
High Frequency ◽  
Alveolar Ventilation ◽  
High Frequency Oscillation ◽  
High Frequency Ventilation ◽  
Frequency Oscillation ◽  
Simple Physical Model ◽  
Small Tube ◽  
The Dead

To assess the role of direct alveolar ventilation during high-frequency ventilation, we studied convective gas mixing during high-frequency oscillation with tidal volumes close to the dead space volume in a simple physical model. A main conduit representing a large airway was connected with a rigid sphere (V = 77, 517, and 1,719 cm3) by a small circular tube (d = 0.3 and 0.5 cm; L = 5, 10, and 20 cm). The efficiency of sinusoidal oscillations (f = 5, 20, and 40 Hz) applied at one end of the main conduit was assessed from the washout of a CO2 mixture from the sphere; to flush CO2 from the main fluid line, a constant flow of air was used. The decay in CO2 concentration measured in the sphere was exponential and therefore characterized by a measured time constant (tau m). Taking the small tube volume as the ventilatory dead space (VD), an effective tidal volume (VT*) was computed from tau m and compared with the tidal volume (VT) obtained separately from the pressure variation in the sphere. The discrepancy between these two tidal volumes has been found to be uniquely dependent on the ratio VT/VD within the range of VT/VD studied (0.5–2.2). For VT/VD less than 1.2, VT* was larger than VT, indicating that the conventional concept of alveolar ventilation does not apply. From the partition of the oscillatory flow in the small tube into two regions, the core and the unsteady boundary layer, we theoretically computed the proportions of the sinusoidal flow (or tidal volume) and the dead space for each region.(ABSTRACT TRUNCATED AT 250 WORDS)

A self-retaining nasal flowmeter for preterm infants

1980 ◽  
Vol 48 (3) ◽  
pp. 569-571 ◽  
Author(s):  
R. T. Brouillette ◽  
B. T. Thach
Keyword(s):  
Stainless Steel ◽  
Tidal Volume ◽  
Preterm Infants ◽  
Dead Space ◽  
Nasal Cannula ◽  
Light Weight ◽  
Low Resistance ◽  
Respiratory Airflow ◽  
The Subject ◽  
Compact Design

A nasal flowmeter suitable for preterm infants is described. It is made from a commercially available nasal cannula and 400-mesh stainless steel screen. Low dead space (0.35 ml) and low resistance (1.3 cmH2O . 100 ml-1 . s) are advantages. Light weight and compact design have eliminated the need for extensive restraint of the subject. Also, the investigator need not hold the flowmeter in place. These features make accurate measurement of respiratory airflow and tidal volume possible during polygraphic monitoring studies lasting several hours.

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