O2 and CO2 transport in relation to ventilation in the Atlantic mackerel, Scomber scombrus

1984 ◽  
Vol 62 (4) ◽  
pp. 546-554 ◽  
Author(s):  
R. G. Boutilier ◽  
P. Aughton ◽  
G. Shelton
Keyword(s):  
Major Change ◽  
Blood Oxygenation ◽  
Dominant Negative ◽  
Positive Pressure ◽  
Forward Movement ◽  
Atlantic Mackerel ◽  
Arterial Blood ◽  
Ram Ventilation ◽  
Pressure Phase ◽  
Regular Alternation

Adult mackerel actively ventilate their gills whilst swimming at low speeds (20–60 cm∙s−1; ca. 0.6–2.0 body lengths∙s−1) in a swim tunnel at 15 °C. There was a regular alternation of a buccal pump, with dominant positive pressure phase, and an opercular pump, with dominant negative pressure phase. The two pumps cooperated to produce a maintained differential pressure across the gills (buccal to opercular cavities) so that water would flow in this direction for most, if not all, of the respiratory cycle. At swimming velocities between 60 and 80 cm∙s−1 (2.0–2.6 body lengths∙s−1), mackerel were found to suspend their cyclic buccal–opercular pump and rely instead on ventilation of the gills by forward movement through the water column (ram ventilation). The transition from one type of ventilation to the other caused no major change in the oxygenation of arterial blood, though CO2 was eliminated readily at the higher swimming speeds despite its being produced in larger quantities. Variations in arterial acid–base relationships were largely due to the mackerel's response to capture and subsequent experimental procedures, and not to the change from cyclic to ram ventilation. It is concluded that arterial blood oxygenation and CO2 output are regulated within limits that suggest the gills are adequately ventilated at all swimming speeds.

scholarly journals Sustained Inflation Reduces Pulmonary Blood Flow during Resuscitation with an Intact Cord

Children ◽  
2021 ◽  
Vol 8 (5) ◽  
pp. 353
Author(s):  
Jayasree Nair ◽  
Lauren Davidson ◽  
Sylvia Gugino ◽  
Carmon Koenigsknecht ◽  
Justin Helman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Perinatal Asphyxia ◽  
Arterial Blood Flow ◽  
Positive Pressure ◽  
Optimal Timing ◽  
Delayed Cord Clamping ◽  
Arterial Blood ◽  
Cord Clamping ◽  
Sustained Inflation ◽  
Near Term

The optimal timing of cord clamping in asphyxia is not known. Our aims were to determine the effect of ventilation (sustained inflation–SI vs. positive pressure ventilation–V) with early (ECC) or delayed cord clamping (DCC) in asphyxiated near-term lambs. We hypothesized that SI with DCC improves gas exchange and hemodynamics in near-term lambs with asphyxial bradycardia. A total of 28 lambs were asphyxiated to a mean blood pressure of 22 mmHg. Lambs were randomized based on the timing of cord clamping (ECC—immediate, DCC—60 s) and mode of initial ventilation into five groups: ECC + V, ECC + SI, DCC, DCC + V and DCC + SI. The magnitude of placental transfusion was assessed using biotinylated RBC. Though an asphyxial bradycardia model, 2–3 lambs in each group were arrested. There was no difference in primary outcomes, the time to reach baseline carotid blood flow (CBF), HR ≥ 100 bpm or MBP ≥ 40 mmHg. SI reduced pulmonary (PBF) and umbilical venous (UV) blood flow without affecting CBF or umbilical arterial blood flow. A significant reduction in PBF with SI persisted for a few minutes after birth. In our model of perinatal asphyxia, an initial SI breath increased airway pressure, and reduced PBF and UV return with an intact cord. Further clinical studies evaluating the timing of cord clamping and ventilation strategy in asphyxiated infants are warranted.

scholarly journals Effect of mechanical pressure-controlled ventilation in patients with disturbed respiratory function during laparoscopic cholecystectomy

2013 ◽  
Vol 70 (1) ◽  
pp. 9-15
Author(s):  
Maja Surbatovic ◽  
Zoran Vesic ◽  
Dragan Djordjevic ◽  
Sonja Radakovic ◽  
Snjezana Zeba ◽  
...  
Keyword(s):  
Laparoscopic Cholecystectomy ◽  
Respiratory Function ◽  
Respiratory Diseases ◽  
Positive Pressure ◽  
Time Interval ◽  
Time Intervals ◽  
Controlled Ventilation ◽  
Arterial Blood ◽  
Pressure Controlled Ventilation ◽  
Pressure Controlled

Background/Aim: Laparoscopic cholecystectomy is considered to be the gold standard for laparoscopic surgical procedures. In ASA III patients with concomitant respiratory diseases, however, creation of pneumoperitoneum and the position of patients during surgery exert additional negative effect on intraoperative respiratory function, thus making a higher challenge for the anesthesiologist than for the surgeon. The aim of this study was to compare the effect of intermittent positive pressure ventilation (IPPV) and pressure controlled ventilation (PCV) during general anesthesia on respiratory function in ASA III patients submitted to laparoscopic cholecystectomy. Methods. The study included 60 patients randomized into two groups depending on the mode of ventilation: IPPV or PCV. Respiratory volume (VT), peak inspiratory pressure (PIP), compliance (C), end-tidal CO2 pressure (PETCO2), oxygen saturation (SpO2), partial pressures of O2, CO2 (PaO2 and PaCO2) and pH of arterial blood were recorded within four time intervals. Results. There were no statistically significant differences in VT, SpO2, PaO2, PaCO2 and pH values neither within nor between the two groups. In time interval t1 there were no statistically significant differences in PIP, C, PETCO2 values between the IPPV and the PCV group. But, in the next three time intervals there was a difference in PIP, C, and PETCO2 values between the two groups which ranged from statistically significant to highly significant; PIP was lower, C and PETCO2 were higher in the PCV group. Conclusion. Pressure controlled ventilation better maintains stability regarding intraoperative ventilatory parameters in ASA III patients with concomitant respiratory diseases during laparoscopic cholecystectomy.

scholarly journals Non-invasive positive pressure ventilation in acute hypercapnic respiratory failure: clinical experience of a respiratory ward

2004 ◽  
Vol 61 (2) ◽  
Author(s):  
R. Scala ◽  
M. Naldi ◽  
I. Archinucci ◽  
G. Coniglio
Keyword(s):  
Clinical Practice ◽  
Respiratory Failure ◽  
Standard Therapy ◽  
Positive Pressure Ventilation ◽  
Controlled Trial ◽  
Positive Pressure ◽  
Hypercapnic Respiratory Failure ◽  
Non Invasive ◽  
Arterial Blood ◽  
Acute Hypercapnic Respiratory Failure

Background: Although a controlled trial demonstrated that non-invasive positive pressure ventilation (NIV) can be successfully applied to a respiratory ward (RW) for selected cases of acute hypercapnic respiratory failure (AHRF), clinical practice data about NIV use in this setting are limited. The aim of this observational study is to assess the feasibility and efficacy of NIV applied to AHRF in a RW in everyday practice. Methods: Twenty-two percent (216/984) of patients consecutively admitted for AHRF to our RW in Arezzo (years: 1996-2003) received NIV in addition to standard therapy, according to pre-defined routinely used criteria. Tolerance, effects upon arterial blood gases (ABG), success rate (avoidance a priori criteria for intubation) and predictors of failure of NIV were analysed. Results: Nine patients (4.2%) were found to be intolerant to NIV, while the remaining 207 (M: 157, F: 50; mean (SD) age: 73.2 (8.9) yrs; COPD: 71.5%) were ventilated for >1 hour. ABG significantly improved after two hours of NIV (pH: 7.32 (0.06) versus median (Interquartiles) 7.28 (7.24-7.31), p<0.0001; PaCO2: 71.9 (13.5) mmHg versus 80.0 (15.2) mmHg, p<0.0001; PaO2/FiO2: 212 (66) versus 184 (150-221), p<0.0001). NIV succeeded in avoiding intubation in 169/207 patients (81.6%) with hospital mortality of 15.5%. NIV failure was independently predicted by Activity of Daily Living score, pneumonia as cause of AHRF and Acute Physiology and Chronic Health Evaluation III score. Conclusions: In clinical practice NIV is feasible, effective in improving ABG and useful in avoiding intubation in most AHRF episodes that do not respond to the standard therapy managed in an RW adequately trained in NIV.

Increases in intramuscular pressure raise arterial blood pressure during dynamic exercise

2001 ◽  
Vol 91 (5) ◽  
pp. 2351-2358 ◽  
Author(s):  
K. M. Gallagher ◽  
P. J. Fadel ◽  
S. A. Smith ◽  
K. H. Norton ◽  
R. G. Querry ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Arterial Blood Pressure ◽  
Dynamic Exercise ◽  
Positive Pressure ◽  
Intramuscular Pressure ◽  
Arterial Blood ◽  
Exercise In Humans ◽  
Cuff Occlusion

This investigation was designed to determine the role of intramuscular pressure-sensitive mechanoreceptors and chemically sensitive metaboreceptors in affecting the blood pressure response to dynamic exercise in humans. Sixteen subjects performed incremental (20 W/min) cycle exercise to fatigue under four conditions: control, exercise with thigh cuff occlusion of 90 Torr (Cuff occlusion), exercise with lower body positive pressure (LBPP) of 45 Torr, and a combination of thigh cuff occlusion and LBPP (combination). Indexes of central command (heart rate, oxygen uptake, ratings of perceived exertion, and electromyographic activity), cardiac output, stroke volume, and total peripheral resistance were not significantly different between the four conditions. Mechanical stimulation during LBPP and combination conditions resulted in significant elevations in intramuscular pressure and mean arterial pressure from control at rest and throughout the incremental exercise protocol ( P < 0.05). Conversely, there existed no significant changes in mean arterial pressure when the metaboreflex was stimulated by cuff occlusion. These findings suggest that under normal conditions the mechanoreflex is tonically active and is the primary mediator of exercise pressor reflex-induced alterations in arterial blood pressure during submaximal dynamic exercise in humans.

scholarly journals Is the resting rate of oxygen consumption of locomotor muscles in crustaceans limited by the low blood oxygenation strategy?

2001 ◽  
Vol 204 (5) ◽  
pp. 933-940 ◽  
Author(s):  
J. Forgue ◽  
A. Legeay ◽  
J.C. Massabuau
Keyword(s):  
Blood Oxygenation ◽  
Whole Body ◽  
Blood Gas ◽  
Astacus Leptodactylus ◽  
Night Time ◽  
Arterial Blood ◽  
Rate Of Oxygen Consumption ◽  
Locomotor Muscles

Numerous water-breathers exhibit a gas-exchange regulation strategy that maintains O(2) partial pressure, P(O2), in the arterial blood within the range 1–3 kPa at rest during the daytime. In a night-active crustacean, we examined whether this could limit the rate of O(2)consumption (M(O2)) of locomotor muscles and/or the whole body as part of a coordinated response to energy conservation. In the crayfish Astacus leptodactylus, we compared the in vitro relationship between the M(O2) of locomotor muscles as a function of the extracellular P(O2) and P(CO2) and in vivo circadian changes in blood gas tensions at various values of water P(O2). In vitro, the M(O2) of locomotor muscle, either at rest or when stimulated with CCCP, was O(2)-dependent up to an extracellular P(O2) of 8–10 kPa. In vivo, the existence of a night-time increase in arterial P(O2) of up to 4 kPa at water P(O2) values of 20 and 40 kPa was demonstrated, but an experimental increase in arterial P(O2) during the day did not lead to any rise in whole-body M(O2). This suggested that the low blood P(O2) in normoxia has no global limiting effect on daytime whole-body M(O2). The participation of blood O(2) status in shaping the circadian behaviour of crayfish is discussed.

Continuous Airway Pressure Breathing With the Head-Box in the Newborn Lamb: Effects on Regional Blood Flows

PEDIATRICS ◽  
1977 ◽  
Vol 59 (6) ◽  
pp. 858-864
Author(s):  
G. Gabriele ◽  
C. R. Rosenfeld ◽  
D. E. Fixler ◽  
J. M. Wheeler
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Airway Pressure ◽  
Left Ventricular Pressure ◽  
Blood Gases ◽  
Ocular Blood Flow ◽  
Left Ventricular ◽  
Positive Pressure ◽  
Blood Flows ◽  
Arterial Blood

Continuous airway pressure delivered by a head-box is an accepted means of treating clinical hyaline membrane disease. To investigate hemodynamic alterations resulting from its use, eight newborn lambs, 1 to 6 days of age, were studied at 6 and 11 mm Hg of positive pressure, while spontaneously breathing room air. Organ blood flows and cardiac output were measured with 25 µ-diameter radioactive microspheres. Heart rate, left ventricular pressure, and arterial blood gases did not change during the study. Jugular venous pressures increased from 6.4 mm Hg to 18.6 and 24.2 mm Hg at 6 and 11 mm Hg, respectively (P &lt; .005). Cardiac output decreased approximately 20% at either intrachamber pressure setting. Renal blood flow fell 21% at 11 mm Hg. No significant changes in blood flow were found in the brain, gastrointestinal tract, spleen, heart, or liver when compared to control flows. Of particular interest was the finding of a 28% reduction in ocular blood flow at 6 mm Hg and 52% at 11 mm Hg. From these results, we conclude that substantial cardiovascular alterations may occur during the application of head-box continuous airway pressure breathing, including a significant reduction in ocular blood flow.

scholarly journals Connexin26 mediates CO2-dependent regulation of breathing via glial cells of the medulla oblongata

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Joseph van de Wiel ◽  
Louise Meigh ◽  
Amol Bhandare ◽  
Jonathan Cook ◽  
Sarbjit Nijjar ◽  
...  
Keyword(s):  
Glial Cells ◽  
Minute Ventilation ◽  
Dominant Negative ◽  
Structural Motif ◽  
Wild Type ◽  
Arterial Blood ◽  
Highly Sensitive ◽  
Fundamental Process ◽  
Regulation Of Breathing ◽  
Direct Sensing

AbstractBreathing is highly sensitive to the PCO2 of arterial blood. Although CO2 is detected via the proxy of pH, CO2 acting directly via Cx26 may also contribute to the regulation of breathing. Here we exploit our knowledge of the structural motif of CO2-binding to Cx26 to devise a dominant negative subunit (Cx26DN) that removes the CO2-sensitivity from endogenously expressed wild type Cx26. Expression of Cx26DN in glial cells of a circumscribed region of the mouse medulla - the caudal parapyramidal area – reduced the adaptive change in tidal volume and minute ventilation by approximately 30% at 6% inspired CO2. As central chemosensors mediate about 70% of the total response to hypercapnia, CO2-sensing via Cx26 in the caudal parapyramidal area contributed about 45% of the centrally-mediated ventilatory response to CO2. Our data unequivocally link the direct sensing of CO2 to the chemosensory control of breathing and demonstrates that CO2-binding to Cx26 is a key transduction step in this fundamental process.

Catecholamines inhibit growth in fetal sheep in the absence of hypoxemia

1998 ◽  
Vol 274 (6) ◽  
pp. R1536-R1545 ◽  
Author(s):  
John M. Bassett ◽  
Clifford Hanson
Keyword(s):  
Growth Hormone ◽  
Weight Gain ◽  
Plasma Glucose ◽  
Fetal Development ◽  
Plasma Insulin ◽  
Blood Oxygenation ◽  
Fetal Sheep ◽  
Inhibition Of Growth ◽  
Arterial Blood ◽  
Chronic Hypoxemia

To evaluate contributions of catecholamines to inhibition of growth during chronic hypoxemia or severe undernutrition, epinephrine (Epi; 0.25–0.35 μg ⋅ kg−1 ⋅ min−1) or norepinephrine (NE; 0.5–0.7 μg ⋅ kg−1 ⋅ min−1) was administered to normoxemic fetuses in twin-pregnant ewes for 8–12 days, from 125 to 127 days of gestation. Both had similar effects and decreased fetal weight by ∼20% relative to control twins ( P < 0.01). Weight gain ceased during infusion of Epi or NE (−21 ± 14.8 or 14 ± 20.9 g/day), whereas controls gained 93 ± 13.2 g/day ( P < 0.01). Effects on tissues and organs varied, spleen and thymus being most retarded, whereas brain weight and skeletal measures were affected little. Selected muscles from infused fetuses weighed 72% of those in controls. Growth ceased during infusion ( P < 0.001). Weight gain of hindlimb bones was negligible, but length increased at 56% of control rates. Arterial blood CO2and plasma insulin were decreased ( P< 0.001), but plasma glucose, growth hormone, and blood oxygenation increased ( P < 0.001). Actions of Epi and NE could underlie asymmetrical growth retardation occurring in many adverse physiological situations during fetal development.

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