INFLUENCE OF SIMULTANEOUS AND EQUAL INCREASE IN EXTERNAL DEAD SPACE AND TIDAL VOLUME ON ARTERIAL BLOOD GASES IN ARTIFICIALLY VENTILATED PATIENTS

1975 ◽  
Vol 19 (6) ◽  
pp. 501
Author(s):  
I. MOLNAR ◽  
H. E. REFSUM ◽  
D. L. Coppel
Keyword(s):  
Tidal Volume ◽  
Dead Space ◽  
Blood Gases ◽  
Arterial Blood Gases ◽  
Arterial Blood ◽  
Ventilated Patients

scholarly journals Tidal Volume, Lung Hyperinflation and Arterial Oxygenation during General Anaesthesia

1993 ◽  
Vol 21 (6) ◽  
pp. 806-810 ◽  
Author(s):  
W. A. Tweed ◽  
W. T. Phua ◽  
K. Y. Chong ◽  
E. Lim ◽  
T. L. Lee
Keyword(s):  
Gas Exchange ◽  
Tidal Volume ◽  
General Anaesthesia ◽  
Blood Gases ◽  
Arterial Oxygenation ◽  
Arterial Blood Gases ◽  
Controlled Ventilation ◽  
Arterial Blood ◽  
Patients At Risk ◽  
Induction Of Anaesthesia

Impaired pulmonary oxygen (O2) exchange is common during general anaesthesia but there is no clinical unanimity as to methods of prevention or treatment. We studied 14 patients at risk for pulmonary dysfunction because of increased age, obesity, cigarette smoking, or chronic lung disease. Pulmonary O2 exchange was measured during four conditions of ventilation: awake spontaneous, conventional tidal volume (CVT, 7 ml.kg-1) or high tidal volume (HVT, 12 ml.kg-1) controlled ventilation, and five min after manual hyperinflation (H1) of the lungs. The F1O2 was controlled at 0.5, and FETCO2 was kept constant by adding dead space during HVT. Eight patients were ventilated with N2O/O2 and six with air/O2. Arterial blood gases were used to calculate the (A-a)DO2. In seven patients (A-a)DO2 worsened after induction of anaesthesia, while in seven there was no change or an improvement. Manual HI significantly reduced (A-a)DO2, but changing tidal volume (VT) had no effect. Using a multivariate model to predict O2 exchange, obesity and type of surgery were significantly associated with worsening, while level of VT and inspiratory gas (N2O or N2) were not significant predictors. Thus patient and surgical factors were more important determinants of pulmonary gas exchange during anaesthesia than were tidal volume or inspiratory gas. Manual HI is a simple and effective manoeuvre to improve gas exchange.

scholarly journals Acute Effect of Chest Physical Therapy on Arterial Blood Gases for Mechanical Ventilated Patients

2020 ◽  
Vol 88 (12) ◽  
pp. 1469-1475
Author(s):  
HEBA A. ABDEEN, Ph.D.; SAAD M. ELGENDY, M.Sc. ◽  
NAGY L. NASSEF, Ph.D.; YOUSSEF M.A. SOLIMAN, M.D.
Keyword(s):  
Physical Therapy ◽  
Blood Gases ◽  
Acute Effect ◽  
Arterial Blood Gases ◽  
Arterial Blood ◽  
Ventilated Patients ◽  
Chest Physical Therapy

Inspiratory airway CO2 loading in the pony

1984 ◽  
Vol 57 (4) ◽  
pp. 1097-1103 ◽  
Author(s):  
H. W. Shirer ◽  
J. A. Orr ◽  
J. L. Loker
Keyword(s):  
Tidal Volume ◽  
Dead Space ◽  
Blood Gases ◽  
Minute Volume ◽  
Arterial Pco2 ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Airway Dead Space ◽  
Arterial Po2 ◽  
Stimulation Of

To determine if CO2-sensitive airway receptors are important in the control of breathing, CO2 was preferentially loaded into the respiratory airways in conscious ponies. The technique involved adding small amounts of 100% CO2 to either the latter one-third or latter two-thirds of the inspiratory air in an attempt to raise CO2 concentrations in the airway dead space independent of the arterial blood. Arterial blood gas tensions (PCO2 and PO2) and pH, as well as respiratory output (minute volume, tidal volume, and respiratory rate), were measured in a series of 20 experiments on 5 awake ponies. Elevation of airway CO2 to approximately 12% by addition of CO2 to the latter portion of the inspiratory tidal volume did not alter either ventilation or arterial blood gases. When CO2 was added earlier in the inspiratory phase to fill more of the airway dead space, a small but significant increase in minute volume (2.1 l X min-1 X m-2) and tidal volume (0.1 l X m-2) was accompanied by an increase in arterial PCO2, arterial PO2, and a fall in pH (0.96 Torr, 10.5 Torr, 0.007 units, respectively). A second series of 12 experiments on 6 awake ponies using radiolabeled 14CO2 determined that the increases in breathing were minimal when compared with the large increase that occurred when these animals inhaled 6% 14CO2 (12.7 l X min-1 X m-2). Also, stimulation of systemic arterial or central nervous system chemoreceptors cannot be eliminated from the response since significant amounts of 14CO2 were present in the arterial blood when this marker gas was added to the latter two-thirds of the inspiratory tidal volume. The results, therefore, provide no evidence for CO2-sensitive airway receptors that can increase breathing when stimulated during the latter part of the inspiratory cycle.

Ventilation and respiratory pattern and timing in resting awake cats

1985 ◽  
Vol 63 (2) ◽  
pp. 148-154 ◽  
Author(s):  
D. B. Jennings ◽  
P. C. Szlyk
Keyword(s):  
Tidal Volume ◽  
Normal Control ◽  
Blood Gases ◽  
Bimodal Distribution ◽  
Inspiratory Flow ◽  
Respiratory Pattern ◽  
Respiratory Drive ◽  
Arterial Blood Gases ◽  
Arterial Blood ◽  
Awake Cats

The purpose of this study was to characterize the variability and patterns of spontaneous respiratory behaviour in awake cats. Respiration was measured in six cats over 80 or 90 min by the plethysmographic technique. In three cats, arterial blood gases were measured. Breath frequency (f) and tidal volume (VT) varied considerably breath-to-breath, although on average, these measurements as well as average ventilation remained relatively constant. The incidence of breath ventilation (VT × 60/TTOT) and VT were distributed unimodally but the incidence of breath f had a bimodal distribution. In the low f range, average f was 22.5 breaths/min, and in the high f range, average f was 41.6 breaths/min. The latter range appeared to be associated with purring. Inspiratory duration (TI) was less than expiratory duration (TE) at low f but exceeded TE at high f. For a given breath ventilation there was a predictable f and VT. At shorter TI (higher f) mean inspiratory flow, an index of central respiratory drive, increased but VT decreased. This study indicates that "normal" control respiratory behaviour in awake cats is better described by the range and pattern of breathing than by average values.

scholarly journals Assessment of Non-linear Imputation of PaO2/FiO2 from SpO2/FiO2 Among Patients Receiving Mechanical Ventilation in China

2021 ◽  
Author(s):  
Shan Wang ◽  
Liga Yusvirazi ◽  
Haiyan Yin ◽  
Hongjun Kang ◽  
Yan Zhao ◽  
...  
Keyword(s):  
Distress Syndrome ◽  
Blood Gases ◽  
Arterial Blood Gases ◽  
Arterial Blood Gas ◽  
Mechanically Ventilated ◽  
Mechanically Ventilated Patients ◽  
Arterial Blood ◽  
Non Linear ◽  
Log Linear ◽  
Ventilated Patients

Abstract Objectives: Arterial blood gas measurements are not always immediately available despite their potential relevance to management of mechanically ventilated patients. Retrospective and prospective studies have validated the non-linear imputation of PaO2/FIO2 from SpO2/FIO2, predominantly in USA. In this study, the objective was to validate the non-linear imputation algorithm among mechanically ventilated patients in the Chinese population. Method: Mechanically ventilated patients admitted to the emergency departments or ICUs at two participating hospitals in China were enrolled prospectively. At the time of a clinical arterial blood gas being drawn, SpO2, oximeter waveform characteristics, receipt of vasopressor, and skin pigmentation were simultaneously recorded. For the various imputation methods, we calculated both imputation error and the area under the curve for patients meeting criteria for acute respiratory distress syndrome (PaO2/FIO2 ≤ 300) and moderate-severe acute respiratory distress syndrome (PaO2/FIO2 ≤ 150). Result: We studied 663 arterial blood gases from 646 patients; 177 (26%) arterial blood gases were associated with SpO2 less than or equal to 96%. Non-linear imputation had lower mean absolute error than linear imputation method when SpO2 was less than or equal to 96% (p<0.001). At the PaO2/FiO2 threshold of 300 or less, non-linear imputation AUC (0.90 95% CI 0.85-0/95) was not significantly higher than the AUCs of linear and log-linear imputation methods (0.88 95% CI 0.82-0.94). The same result was shown at the PaO2 /FiO2 threshold of 150 or less. For patients with a threshold SpO2 of 96% or less, AUC analysis yielded similar results between non-linear vs. linear and log-linear imputations. Conclusions: In this cohort of mechanically ventilated patients, non-linear imputation was not superior to linear and log-linear imputations for patients with SpO2 of 96% or less. All strategies performed similarly in estimating PaO2/FIO2 from SpO2/FIO2.

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