Arterial and Mixed Venous Kinetics of Desflurane and Sevoflurane, Administered Simultaneously, at Three Different Global Ventilation to Perfusion Ratios in Piglets with Normal Lungs

2021 ◽  
Author(s):  
Moritz Kretzschmar ◽  
James E. Baumgardner ◽  
Alf Kozian ◽  
Thomas Hachenberg ◽  
Thomas Schilling ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Minute Ventilation ◽  
Arterial Partial Pressure ◽  
Arterial Blood ◽  
Partial Pressures ◽  
Inhaled Anesthetic ◽  
Kinetics Of ◽  
Normal Lungs ◽  
Mixed Venous

Background Previous studies have established the role of various tissue compartments in the kinetics of inhaled anesthetic uptake and elimination. The role of normal lungs in inhaled anesthetic kinetics is less understood. In juvenile pigs with normal lungs, the authors measured desflurane and sevoflurane washin and washout kinetics at three different ratios of alveolar minute ventilation to cardiac output value. The main hypothesis was that the ventilation/perfusion ratio ( .VA/.Q  ) of normal lungs influences the kinetics of inhaled anesthetics. Methods Seven healthy pigs were anesthetized with intravenous anesthetics and mechanically ventilated. Each animal was studied under three different .VA/.Q conditions: normal, low, and high. For each .VA/.Q condition, desflurane and sevoflurane were administered at a constant, subanesthetic inspired partial pressure (0.15 volume% for sevoflurane and 0.5 volume% for desflurane) for 45 min. Pulmonary arterial and systemic arterial blood samples were collected at eight time points during uptake, and then at these same times during elimination, for measurement of desflurane and sevoflurane partial pressures. The authors also assessed the effect of .VA/.Q on paired differences in arterial and mixed venous partial pressures. Results For desflurane washin, the scaled arterial partial pressure differences between 5 and 0 min were 0.70 ± 0.10, 0.93 ± 0.08, and 0.82 ± 0.07 for the low, normal, and high .VA/.Q conditions (means, 95% CI). Equivalent measurements for sevoflurane were 0.55 ± 0.06, 0.77 ± 0.04, and 0.75 ± 0.08. For desflurane washout, the scaled arterial partial pressure differences between 0 and 5 min were 0.76 ± 0.04, 0.88 ± 0.02, and 0.92 ± 0.01 for the low, normal, and high .VA/.Q conditions. Equivalent measurements for sevoflurane were 0.79 ± 0.05, 0.85 ± 0.03, and 0.90 ± 0.03. Conclusions Kinetics of inhaled anesthetic washin and washout are substantially altered by changes in the global  .VA/.Q   ratio for normal lungs. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

Respiratory changes induced by prolonged laryngeal stimulation in awake piglets

1986 ◽  
Vol 61 (3) ◽  
pp. 1018-1024 ◽  
Author(s):  
D. F. Donnelly ◽  
G. G. Haddad
Keyword(s):  
Blood Pressure ◽  
Partial Pressure ◽  
Minute Ventilation ◽  
Young Animal ◽  
Whole Body ◽  
Electrode Placement ◽  
Base Line ◽  
Stimulus Period ◽  
Arterial Partial Pressure ◽  
Arterial Blood

To examine the role of the laryngeal reflex in modulating cardiorespiratory function, we stimulated the superior laryngeal nerves (SLN) bilaterally in unanesthetized, chronically instrumented piglets (n = 10, age 5–14 days). The SLN were placed in cuff electrodes and wires were exteriorized in the neck for stimulation. A cannula placed in the aorta was used for blood pressure recording and arterial blood sampling. During each experiment, 1–2 days after surgery, ventilation was recorded using whole-body plethysmography, and electroencephalogram and electrocardiogram were recorded after acute subcutaneous electrode placement. After base-line recordings, the SLN were electrically stimulated for 1 h. During this period, mean respiratory frequency decreased by 40–75% and apneas of 10–15 s were regularly interspersed between single breaths or clusters of breaths. Periods of breathing were always associated with opening of the eyes and generally with head and body movements, an awakening that occurred every 10–15 s. At 1 h into the stimulus period, minute ventilation had decreased by 57 +/- 7% (mean +/- SE), arterial partial pressure of O2 (PaO2) by 68 +/- 3 Torr, and arterial partial pressure of CO2 (PaCO2) had increased by 19 +/- 2 Torr. Throughout the entire stimulus period, mean blood pressure and average heart rate were maintained within 12% of base line. We suggest that: low-threshold SLN afferents exert primarily respiratory effects and only minor cardiovascular effects; breathing during laryngeal reflex activation is sustained by an arousal system; and the laryngeal reflex does not pose an imminent threat to the unanesthetized, awake, young animal.

Effects of acetone in heparin on the multiple inert gas elimination technique

1985 ◽  
Vol 58 (4) ◽  
pp. 1143-1147 ◽  
Author(s):  
F. L. Powell ◽  
F. A. Lopez ◽  
P. D. Wagner
Keyword(s):  
Partial Pressure ◽  
Dead Space ◽  
Room Temperature ◽  
Inert Gas ◽  
Published Data ◽  
Physiological Mechanisms ◽  
Heparinized Saline ◽  
Partial Pressures ◽  
Ventilation Perfusion Ratio ◽  
Mixed Venous

We have detected acetone in several brands of heparin. If uncorrected, this leads to errors in measuring acetone in blood collected in heparinized syringes, as in the multiple inert gas elimination technique for measuring ventilation-perfusion ratio (VA/Q) distributions. Error for acetone retention [R = arterial partial pressure-to-mixed venous partial pressure (P-V) ratio] is usually small, because R is normally near 1.0, and the error is similar in arterial and mixed venous samples. However, acetone excretion [E = mixed expired partial pressure (P-E)-to-P-V ratio] will appear erroneously low, because P-E is accurately measured in dry syringes, but P-V is overestimated. A physical model of a homogeneous alveolar lung at room temperature and without dead space shows: the magnitude of acetone E error depends upon the ratio of blood sample to heparinized saline volumes and acetone partial pressures, without correction, acetone E can be less than that of less soluble gases like ether, a situation incompatible with conventional gas exchange theory, and acetone R and E can be correctly calculated using the principle of mass balance if the acetone partial pressure in heparinized saline is known. Published data from multiple inert gas elimination experiments with acetone-free heparin, in our labs and others, are within the limits of experimental error. Thus the hypothesis that acetone E is anomalously low because of physiological mechanisms involving dead space tissue capacitance for acetone remains to be tested.

Role of adrenal catecholamines during forced submergence in ducks

1991 ◽  
Vol 261 (6) ◽  
pp. R1364-R1372 ◽  
Author(s):  
A. M. Lacombe ◽  
D. R. Jones
Keyword(s):  
Blood Pressure ◽  
Partial Pressure ◽  
Heart Rates ◽  
Peripheral Vasoconstriction ◽  
Arterial Partial Pressure ◽  
Arterial Ph ◽  
Venous Infusion ◽  
Lactate Levels

Maximum underwater tolerance (UTmax) of chronically adrenalectomized ducks (ADX, 5.3 +/- 0.3 min) and chronically adrenal-denervated ducks (DNX, 7.2 +/- 0.2 min) was significantly lower than sham-operated controls (SH-ADX, 10 +/- 0.8 min; SH-DNX, 12.2 +/- 0.5 min). After 4 min forced submergence, heart rates of ADX (62 +/- 16 beats/min) and DNX (31 +/- 2 beats/min) ducks were significantly higher than in their respective sham-operated controls (23 +/- 3 and 17 +/- 2 beats/min), although their blood pressure was significantly lower. Arterial partial pressure of O2, arterial O2 content, arterial pH, and lactate levels in DNX ducks (42 +/- 2 mmHg, 4.5 +/- 0.8 ml O2/100 ml blood, 7.233 +/- 0.016, 3.1 +/- 0.3 mM, respectively) were significantly lower than in SH-DNX ducks after 5 min forced submergence (53 +/- 1 mmHg, 6.8 +/- 0.4 ml O2/100 ml blood, 7.301 +/- 0.007, 4.8 +/- 0.4 mM, respectively). Venous infusion of catecholamines in ADX and DNX ducks during forced submergence significantly increased UTmax. It is suggested that adrenal catecholamines increase tolerance to underwater submersion by enhancing peripheral vasoconstriction, thus preserving the O2 stores for the heart and brain. Other adrenal products could also be involved.

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.

Gas Exchange

2017 ◽  
Author(s):  
John W. Kreit
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Capillary Blood ◽  
Pressure Gradients ◽  
Arterial Blood ◽  
Pulmonary Capillary ◽  
Partial Pressures ◽  
Pulmonary Capillary Blood ◽  
And Diffusion

Gas Exchange explains how four processes—delivery of oxygen, excretion of carbon dioxide, matching of ventilation and perfusion, and diffusion—allow the respiratory system to maintain normal partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) in the arterial blood. Partial pressure is important because O2 and CO2 molecules diffuse between alveolar gas and pulmonary capillary blood and between systemic capillary blood and the tissues along their partial pressure gradients, and diffusion continues until the partial pressures are equal. Ventilation is an essential part of gas exchange because it delivers O2, eliminates CO2, and determines ventilation–perfusion ratios. This chapter also explains how and why abnormalities in each of these processes may reduce PaO2, increase PaCO2, or both.

Ventilatory response to moderate and severe hypoxia in adult dogs: role of endorphins

1988 ◽  
Vol 65 (3) ◽  
pp. 1383-1388 ◽  
Author(s):  
J. I. Schaeffer ◽  
G. G. Haddad
Keyword(s):  
Ventilatory Response ◽  
Minute Ventilation ◽  
Severe Hypoxia ◽  
Moderate Hypoxia ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Before And After ◽  
The Relationship ◽  
Arterial Po2

To determine the role of opioids in modulating the ventilatory response to moderate or severe hypoxia, we studied ventilation in six chronically instrumented awake adult dogs during hypoxia before and after naloxone administration. Parenteral naloxone (200 micrograms/kg) significantly increased instantaneous minute ventilation (VT/TT) during severe hypoxia, (inspired O2 fraction = 0.07, arterial PO2 = 28-35 Torr); however, consistent effects during moderate hypoxia (inspired O2 fraction = 0.12, arterial PO2 = 40-47 Torr) could not be demonstrated. Parenteral naloxone increased O2 consumption (VO2) in severe hypoxia as well. Despite significant increases in ventilation post-naloxone during severe hypoxia, arterial blood gas tensions remained the same. Control studies revealed that neither saline nor naloxone produced a respiratory effect during normoxia; also the preservative vehicle of naloxone induced no change in ventilation during severe hypoxia. These data suggest that, in adult dogs, endorphins are released and act to restrain ventilation during severe hypoxia; the relationship between endorphin release and moderate hypoxia is less consistent. The observed increase in ventilation post-naloxone during severe hypoxia is accompanied by an increase in metabolic rate, explaining the isocapnic response.

Role of Oxygen Vacancies on the Ferroelectric Properties of Pzt Thin Films

1991 ◽  
Vol 243 ◽  
Author(s):  
Chi Kong Kwok ◽  
Seshu B. Desu
Keyword(s):  
Thin Films ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Vacancy Concentration ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Low Oxygen ◽  
Partial Pressures ◽  
Pzt Films

AbstractThe properties of ferroelectric thin films can be significantly influenced by the presence of point defects. The concentration of vacancies presented in these thin films is known to be one of the key parameters causing the degradation of these films when these films are subjected to polarization reversals.To study the effects of the vacancy concentration on the ferroelectric properties, sol gel PZT films and powders were annealed in different oxygen partial pressures. For the PZT films, the reduction of oxides to pure metals was not observed even with films annealed at 2×10−5 atmosphere of oxygen partial pressure. Samples annealed at low oxygen partial pressure (for instance, 10−3 and 2×10−5 atmosphere), which has more Pb and O2 depletions and consequently has more Pb and O2 vacancies, cannot be switched easily. The ratios of coercive field after and before fatigue increase as the defect concentrations of the annealed samples increase.

Measurement of arterial blood gases at the transition from exercise to rest

1983 ◽  
Vol 54 (5) ◽  
pp. 1340-1344 ◽  
Author(s):  
B. M. Lewis
Keyword(s):  
Partial Pressure ◽  
Blood Gases ◽  
Normal Subjects ◽  
Forced Expiratory Volume ◽  
Stair Climbing ◽  
Regulation Of Respiration ◽  
Arterial Blood Gas ◽  
Arterial Partial Pressure ◽  
Arterial Blood ◽  
Two Samples

Arterial blood gas samples obtained 5–20 s after stair-climbing exercise were compared with samples taken during the last 30 s of exercise in 137 subjects. Arterial partial pressure of CO2 (PaCO2) did not change significantly, and in 110 subjects the two samples were within the analytical variation (+/- 2 Torr), supporting the cardiodynamic hypothesis of respiratory regulation. Exceptions to this response were 10 subjects who hyperventilated (PaCO2 less than 34) during exercise and 15 with severe obstruction [forced expiratory volume in 1 s (FEV1) less than 70% forced vital capacity (FVC), and FVC less than 70% of predicted] in whom PaCO2 increased significantly. Overall, arterial partial pressure of O2 (PaO2) increased an average of 3.49 Torr (P less than 0.001). In the two groups in which PaCO2 increased, postexercise PaO2 did not rise. In addition, duration of exercise affected PaO2 response. PaO2 increased significantly more after brief (less than 2 min) periods than after longer (4–6 min) exercise, and this difference increased only when subjects with normal or borderline ventilatory function were analyzed. In 13 subjects in whom a second sample was taken 30–45 s after exercise, the increase in PaO2 was progressive and again the difference between short and long exercise was evident. Regulation of respiration to maintain PaCO2 and changes in O2-CO2 kinetics, leading to an increase in the gas exchange ratio at the exercise-rest transition, are the most likely explanations of these data which establish that the usual response to stopping exercise in normal subjects and most patients is an unchanged PaCO2 and a variable increase in PaO2.

Effect of Global Ventilation to Perfusion Ratio, for Normal Lungs, on Desflurane and Sevoflurane Elimination Kinetics

2021 ◽  
Author(s):  
James E. Baumgardner ◽  
Moritz Kretzschmar ◽  
Alf Kozian ◽  
Thomas Hachenberg ◽  
Thomas Schilling ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Time Constant ◽  
Practical Importance ◽  
Elimination Kinetics ◽  
Retention Equation ◽  
Pressure Part ◽  
Inhaled Anesthetic ◽  
The Mathematical Model ◽  
Kinetics Of ◽  
Normal Lungs

Background Kinetics of the uptake of inhaled anesthetics have been well studied, but the kinetics of elimination might be of more practical importance. The objective of the authors’ study was to assess the effect of the overall ventilation/perfusion ratio ( .VA/.Q  ), for normal lungs, on elimination kinetics of desflurane and sevoflurane. Methods The authors developed a mathematical model of inhaled anesthetic elimination that explicitly relates the terminal washout time constant to the global lung  .VA/.Q   ratio. Assumptions and results of the model were tested with experimental data from a recent study, where desflurane and sevoflurane elimination were observed for three different  .VA/.Q   conditions: normal, low, and high. Results The mathematical model predicts that the global  .VA/.Q   ratio, for normal lungs, modifies the time constant for tissue anesthetic washout throughout the entire elimination. For all three  .VA/.Q   conditions, the ratio of arterial to mixed venous anesthetic partial pressure Part/Pmv reached a constant value after 5 min of elimination, as predicted by the retention equation. The time constant corrected for incomplete lung clearance was a better predictor of late-stage kinetics than the intrinsic tissue time constant. Conclusions In addition to the well-known role of the lungs in the early phases of inhaled anesthetic washout, the lungs play a long-overlooked role in modulating the kinetics of tissue washout during the later stages of inhaled anesthetic elimination. The  .VA/.Q  ratio influences the kinetics of desflurane and sevoflurane elimination throughout the entire elimination, with more pronounced slowing of tissue washout at lower  .VA/.Q   ratios. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

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