In this multicenter study the comparison of the mass flow distribution and redistribution versus the relative blood flow per lobe (as a surrogate for Ventilation/ Perfusion (V/Q) matching) with functional respiratory imaging (FRI) and arterial blood gas (ABG) values will be evaluated in hypercapnic Chronic Obstructive Pulmonary Disease (COPD) patients. Therefore a low dose Computed Tomography (CT) scan will be taken in a population of 30 patients with non-invasive ventilation (NIV) and in a control group of 10 patients without NIV. The CT-scan will be used for FRI ...

TY - JOUR. T1 - Prediction of successful ventilator weaning using airway occlusion pressure and hypercapnic challenge. AU - Montgomery, A. B.. AU - Holle, R. H.O.. AU - Neagley, S. R.. AU - Pierson, D. J.. AU - Schoene, Robert Blair. PY - 1987/1/1. Y1 - 1987/1/1. N2 - We studied eleven patients during 14 attempts at weaning from mechanical ventilation to determine whether central ventilatory drive, measured as airway occlusion pressure 0.1 s after onset of inspiration (P0.1), during spontaneous breathing before and during a brief hypercapnic challenge, could accurately predict the success or failure of the attempt. All patients were recovering from acute respiratory failure and could breath spontaneously for 20 minutes on a T-piece but were judged clinically to be marginal weaning candidates. Minute ventilation (V̇I) and P0.1 were measured while breathing spontaneously and were repeated during a hypercapnic challenge that raised end-tidal PCO2 approximately 10 mm Hg. Seven of the 14 weaning ...

Background: Sleep hypoventilation has been proposed as a cause of progressive hypercapnic respiratory failure and death in patients with severe chronic obstructive pulmonary disease (COPD).. Objective: To determine the effects of nocturnal, non-invasive bi-level pressure support ventilation (NIV) on survival, lung function and quality of life in severe hypercapnic COPD.. Design: A multicentre, open-label, randomized controlled trial of NIV plus long term oxygen therapy (LTOT) versus LTOT alone.. Setting: University Hospital sleep/ respiratory medicine departments.. Patients: Severe, stable, smoking-related COPD (FEV1.0 , 1.5 L or ,50% predicted and FEV1.0/FVC ,60% with awake PaCO2 , 46mmHg and on LTOT for at least 3 months) and age less than 80 years. Patients with sleep apnea (Apnea-hypopnea Index , 20/ hr) or morbid obesity (BMI ,40) were excluded.. Intervention: Night-time bilevel pressure support ventilation.. Measurements: Survival, spirometry, arterial blood gases, polysomnography, general ...

TY - JOUR. T1 - Reversal of attenuation of cerebrovascular reactivity to hypercapnia by a nitric oxide donor after controlled cortical impact in a rat model of traumatic brain injury. AU - Zhang, Fangyi. AU - Sprague, Shane M.. AU - Farrokhi, Farrokh. AU - Henry, Matthew N.. AU - Son, Minnette G.. AU - Vollmer, Dennis G.. PY - 2002/10/1. Y1 - 2002/10/1. N2 - Object. Traumatic brain injury (TBI) attenuates the cerebral vasodilation to hypercapnia. Cortical spreading depression (CSD) also transiently reduces hypercapnic vasodilation. The authors sought to determine whether the CSD elicited by a controlled cortical impact (CCI) injury masks the true effect of TBI on hypercapnic vasodilation, and whether a nitric oxide (NO) donor can reverse the attenuation of hypercapnic vasodilation following CCI. Methods. Anesthetized rats underwent moderate CCI. Cerebral blood flow was monitored with laser Doppler flowmetry and the response to hypercapnia was determined for injured and sham-injured animals. The ...

All information about the latest scientific publications of the Clínica Universidad de Navarra. Hyperleptinaemia, respiratory drive and hypercapnic response in obese patients

1. Endogenous opioids have been implicated in the control of breathing in neonates, but their role in ventilatory control in adults remains unclear.. 2. We studied the relationship between circulating immunoreactive β-endorphin and the ventilatory and mouth occlusion pressure responses to hypercapnia in 12 healthy male subjects. In addition, we examined the effect of repetitive hypercapnia on plasma β-endorphin and Cortisol levels.. 3. A weak but significant negative relationship between the ventilatory response to hypercapnia and basal plasma β-endorphin levels was observed (r = −0.35, P , 0.01). A similar negative relationship was noted between mouth occlusion pressure response to hypercapnia and basal plasma β-endorphin levels (r = −0.36, P , 0.01).. 4. Repetitive hypercapnia prevented the fall in plasma Cortisol that occurred under control conditions (P , 0.02) but had no effect on plasma β-endorphin.. 5. We conclude that plasma β-endorphin may play a role in the central chemical ...

The effects of chronic respiratory failure (hypoxia and hypercapnia) on the contractile properties of cardiac muscle are not established. A study was performed of the isometric contractile properties of isolated papillary muscle removed from rats exposed in a normobaric environmental chamber to 28 days of hypoxia (fractional inspired oxygen (FIO2) 10%, fractional inspired carbon dioxide (FICO2) less than 1%), hypercapnia (FIO2 21%, FICO2 5%), and hypoxia with hypercapnia (FIO2 10%, FICO2 5%). Rats exposed to both hypoxia and hypoxia with hypercapnia developed selective right ventricular hypertrophy. Exposure to hypercapnia alone did not alter right ventricular weight. No change in right ventricular papillary muscle contractility per unit muscle mass was observed as measured by maximum active tension, maximum rate of rise or fall of tension, or time to peak tension. Rat cardiac muscle adapts successfully to the altered acid-base environment and increased work load associated with prolonged ...

This study was undertaken to investigate the contribution of carbon dioxide to respiratory control made by the carotid bodies and vagus nerves. Small eupneically breathing dogs, anesthetized with IV ketamine HCL were subjected to inspired CO2 concentrations of 3% while recording simultaneously tidal volume, inspiratory and expiratory airflow rates, and single neuron activity in or near the ventral respiratory group. The burst activity of the ventral respiratory group neuron was considered to be representative of the final integrated motor output of the brain stem respiratory complex. This data provided information concerning: (1) the relationship between group and airflow, (2) the latency response to CO2, (3) the contribution of the carotid body to the hypercapnic response, (4) the vagal contribution to the hypercapnic response. Several specified measures of neuron activity were altered as airflow patterns changed. Subsequent analyses showed correlation between airflow parameters and neuron ...

Putnam, R. W., Ritucci, N. A., & Dean, J. B. (1997). Effect of Hypercapnia on Intracellular pH in Neurons from Chemosensitive and Insensitive Areas of Medullary Brainstem Slices. The FASEB Journal, 11 (3), 3676 ...

We investigated the effect of different levels of hypercapnia on total pulmonary resistance (RL) in 13 subjects ranging from nonsnorers with low RL to snorers with high RL and dynamic narrowing of the upper airway during inspiration. Added CO2 was ad

The authors studied physiologic peculiarities associated with cardiorespiratory response to hypoxia and hypercapnia in various climate and geographic conditions, to combined effects of hypoxia, hypercapnia and physical burden, in artificial atmosphere with various velocity of hypoxia and hypercapnia...

Authors: Kostoglou K, Debert CT, Poulin MJ, Mitsis GD.. We examined the time-varying characteristics of cerebral autoregulation and hemodynamics during a step hypercapnic stimulus by using recursively estimated multivariate (two-input) models which quantify the dynamic effects of mean arterial blood pressure (ABP) and end-tidal CO2 tension ( [Formula: see text] ) on middle cerebral artery blood flow velocity (CBFV). Beat-to-beat values of ABP and CBFV, as well as breath-to-breath values of [Formula: see text] during baseline and sustained euoxic hypercapnia were obtained in 8 female subjects. The multiple-input, single-output models used were based on the Laguerre expansion technique, and their parameters were updated using recursive least squares with multiple forgetting factors. The results reveal the presence of nonstationarities that confirm previously reported effects of hypercapnia on autoregulation, i.e. a decrease in the MABP phase lead, and suggest that the incorporation of [Formula: ...

Nasal high-flow therapy and non-invasive ventilation performed equally well in people with cCOPD with hypercapnia. NHF could therefore be a valuable addition to existing oxygen delivery devices.

Case 1: A seven-year-old lurcher presented after an episode of severe respiratory distress and collapse, which had been treated by the referring veterinary surgeon with a tracheostomy tube placement. Laryngeal paralysis was diagnosed, and the dog was scheduled to undergo left-sided laryngoplasty. During anaesthesia, the dog developed marked hypercapnia and respiratory acidosis during spontaneous ventilation. Initiation of manual ventilation and endotracheal suctioning did not improve the ventilation. On extubation, a blood clot was discovered, occluding approximately two-third of the endotracheal tube (ETT) lumen. Case 2: A two-month-old Jack Russell terrier was presented for ligation of a patent ductus arteriosus. Intraoperatively, the dog developed sudden severe hypercapnia and hypoxaemia. Manual ventilation was initiated, and two attempts of recruiting the lung were made, which initially improved the ventilation. Postoperatively, before extubation, a second episode of severe hypercapnia and ...

TY - JOUR. T1 - Interaction between the ventilatory and cerebrovascular responses to hypo- and hypercapnia at rest and during exercise. AU - Ogoh, Shigehiko. AU - Hayashi, Naoyuki. AU - Inagaki, Masashi. AU - Ainslie, Philip N.. AU - Miyamoto, Tadayoshi. PY - 2008. Y1 - 2008. N2 - Cerebrovascular reactivity to changes in the partial pressure of arterial carbon dioxide (Pa,CO2) via limiting changes in brain [H+] modulates ventilatory control. It remains unclear, however, how exercise-induced alterations in respiratory chemoreflex might influence cerebral blood flow (CBF), in particular the cerebrovascular reactivity to CO2. The respiratory chemoreflex system controlling ventilation consists of two subsystems: the central controller (controlling element), and peripheral plant (controlled element). In order to examine the effect of exercise-induced alterations in ventilatory chemoreflex on cerebrovascular CO2 reactivity, these two subsystems of the respiratory chemoreflex system and cerebral CO2 ...

The ability of brain cells to regulate intracellular pH (pHi) and several phosphate metabolites was evaluated during 1 h of hypercapnia (inspiratory CO2 fraction of 0.10 and 0.05) in anesthetized rats by 31P high-field (145.6 MHz) nuclear magnetic re

Extended hypercapnia exposure led to the restoration of NBC1 mRNA within 2 wk and to a threefold higher expression at the end of the trial, indicating a differentiated response to acute vs. long-term hypercapnic conditions. As with Na+-K+-ATPase and NHE1, the change in message likely results in changing protein levels. In case of the Na+/HCO3− cotransporter, elevated protein contents would support maintenance of elevated bicarbonate levels (Fig. 6B), as described for several fishes (9, 27, 33, 50). The threefold increment of NBC1 mRNA at the end of the trial emphasizes an important role of this transporter in steady-state acid-base regulation under long-term hypercapnia.. Since HCO3− accumulation under hypercapnia is usually accompanied by a decrease of Cl− concentration, a role for gill Cl−/HCO3− exchange has been postulated (see introduction). However, AE1 mRNA expression in Z. viviparus was only slightly affected, with a trend to decrease initially under hypercapnia, reaching a 50% ...

Although the ventilatory and heart rate responses to hypoxia are known to vary widely among subjects, it is not known how exercise or hypercapnia influence the intersubject variability of these responses. If the intersubject variability increases under such conditions, the inherent response of individuals will have more impact on ventilation and heart rate under a variety of hypoxic conditions during exercise or with hypercapnia than at rest or with normocapnia. Seventeen healthy male volunteers underwent tests to measure ventilatory response to isocapnic progressive hypoxia three times respectively: at rest; during CO2 inhalation (end-tidal carbon dioxide tension (PET,CO2) raised by 5 torr from the baseline level); and during mild exercise with a cycle ergometer (12.5 W) in a supine position. The mean (SEM) value of hypoxic ventilatory response (HVR) (delta minute ventilation (VE)/delta arterial oxygen saturation (Sa,O2) was significantly increased both in the exercise and hypercapnic runs ...

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Hypercapnia happens when you have too much carbon dioxide in your bloodstream. It can happen for several reasons, such as hyperventilation. Learn more.

Study Hypercapnia flashcards from Olivier Mba's Augusta University class online, or in Brainscape's iPhone or Android app. ✓ Learn faster with spaced repetition.

A 60-year-old woman presented to our hospital with severe hypercapnic respiratory failure in the absence of a prior smoking history. She reported a 1-day history of increased dyspnoea and a cough productive of green sputum. Her medical history was significant for severe idiopathic scoliosis, cleft p.... ...

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Principal Investigator：MORIMOTO Yuji, Project Period (FY)：2010 - 2012, Research Category：Grant-in-Aid for Scientific Research (C), Section：一般, Research Field：Anesthesiology/Resuscitation studies

A.C. Davidson, I.R. Cameron; Potentiation of the Ventilatory Response to Inhaled CO2 Following Acute Exposure to Hypoxia. Clin Sci (Lond) 1 September 1982; 63 (3): 18P. doi: https://doi.org/10.1042/cs063018Pa. Download citation file:. ...

The successful treatment of hypercapnic respiratory failure with oral modafinil Helen Parnell,1 Ginny Quirke,1 Sally Farmer,1 Sumbo Adeyemo,2 Veronica Varney11Respiratory Department, 2Pharmacy Department, St Helier Hospital, Carshalton, Surrey, UKAbstract: Hypercapnic respiratory failure is common in advanced chronic obstructive pulmonary disease and is usually treated by nasal ventilation. Not all patients requiring such ventilation can tolerate it, with anxiety and phobia influencing their reaction, along with treatment failure. We report the case histories of six patients with hypercapnic respiratory failure who were at risk of death due to refusal of nasal ventilation or its failure despite ongoing treatment. We report their improvement with oral modafinil 200 mg tablets used as a respiratory stimulant, which led to discharge, improved arterial blood gases, and offset further admissions with hypercapnic respiratory failure. This drug is licensed for narcolepsy and is said to stimulate the

TY - JOUR. T1 - Impact of buffering hypercapnic acidosis on cell wounding in ventilator-injured rat lungs. AU - Caples, Sean M.. AU - Rasmussen, Deborah L.. AU - Lee, Won Y.. AU - Wolfert, Marla Z.. AU - Hubmayr, Rolf D.. N1 - Copyright: Copyright 2011 Elsevier B.V., All rights reserved.. PY - 2009/1. Y1 - 2009/1. N2 - We measured the effects of raising perfusate pH on ventilator-induced cell wounding and repair in ex vivo mechanically ventilated hypercapnic rat lungs. Lungs were randomized to one of three perfusate groups: 1) unbuffered hypercapnic acidosis, 2) bicarbonate-buffered hypercapnia, or 3) tris-hydroxy-methyl aminomethane (THAM)-buffered hypercapnia. The membrane-impermeant label propidium iodide was added to the perfusate either during or after injurious ventilation providing a means to subsequently identify transiently wounded and permanently wounded cells in optical sections of subpleural alveoli. Normalizing perfusate pH in hypercapnic preparations attenuated ventilator-induced ...

Davidson, AC, Banham, S, Elliott, M, Kennedy, D, Gelder, C, Glossop, A, Church, AC, Creagh-Brown, B, Dodd, JW, Felton, T et al, Foex, B, Mansfield, L, McDonnell, L, Parker, R, Patterson, CM, Sovani, M and Thomas, L. (2016) BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults ...

Objective: We describe a patient with a prolonged and severe hypercapnia occurring during an episode of status asthmaticus induced by ophthalmic instillation of carteolol. Setting: Prehospital Emergen

Respirology. 2010 Feb;15(2):283-8. doi: 10.1111/j.1440-1843.2009.01665.x. Epub 2009 Nov 23. Multicenter Study; Randomized Controlled Trial; Research Support, Non-U.S. Govt

TY - JOUR. T1 - Management of hypercapnic respiratory failure. T2 - invasive versus non-invasive ventilatory support. AU - Westall, G.. AU - Naughton, M.. PY - 2001/12. Y1 - 2001/12. N2 - Introduction: Recently, non-invasive ventilatory support (NIVS), using a comfortable facial mask, has been used in cooperative patients, and been shown to reduce short and long-term mortality compared with invasive ventilatory support (IVS).2 Aims: We sought to respectively review the management of hypercapnic respiratory failure in patients presenting to the Alfred following the development of a NIVS protocol. Methods: Case records of all patients attending ED with dyspnoea and PaC02 45 mmHg between April and June 1999 were examined. Results: 169 cases were identified (age 60± 23 yrs, 56% female) of whom clinical evidence of COPD (52 %) and congestive heart failure (28%) were identified. As a group, in-hospital mortality was related to presenting PaC02 (9% with PaC02 45-50mmHg; 12% with PaC02 SI60 mmHg and 15 ...

This research examined effects of hypoxic environments on blue crabs, Callinectes sapidus in an estuarine environment. Hypoxic conditions were treated as a multiple stressor involving low dissolved oxygen (D.O.), increased carbon dioxide (hypercapnia), and low pH concurrently. The objectives were to: 1) identify hypoxiahypercapnia by monitoring D.O. and pH as an indicator of hypercapnia in shallow regions of the York River, 2) measure blue crab abundance, and 3) describe blue crab responses to hypoxiahypercapnia via field work at Taskinas Creek and lab measurements of respiration. Ambient D.O. and pH were positively correlated in the Taskinas Creek and York River sites (r= .73). Crab abundance (CPUE) was not significantly different among D.O. and pH ranges. It was concluded that hemolymph blood lactate concentration was not considered a good in situ biomarker for exposure to hypoxickypercapnic conditions. Oxygen uptake was not significantly different between normoxic and hypoxic conditions but was

In the mammalian brain, nitric oxide (NO) is responsible for a vasodilatory tonus as well as the elevation of cerebral blood flow (CBF) induced by hypercapnia. There have been few comparative studies of cerebral vasoregulation in lower vertebrates. Using epi-illumination microscopy in vivo to observe CBF velocity on the brain surface (cerebral cortex), we show that turtles (Trachemys scripta) exposed to hypercapnia (inspired PCO2 = 4.9 kPa) displayed a 62% increase in CBF velocity, while systemic blood pressure remains constant. Exposing turtles to a PCO2 of 14.9 kPa caused an additional increase in CBF velocity, to 104% above control values, as well as a 30% increase in systemic blood pressure. The elevated CBF velocity during hypercapnia could not be blocked by a systemic injection of the NO synthase (NOS) inhibitor NG-nitro-L-arginine (L-NA). However, L-NA injection caused a temporary stop in CBF as well as a persistent increase in systemic blood pressure, suggesting that there is a NO tonus ...

Hypercapnia has been shown in animal experiments to induce pulmonary hypertension. This study measured the sensitivity and time course of the human pulmonary vascular response to sustained (4 h) hypercapnia and hypocapnia. Twelve volunteers undertook three protocols: 1) 4-h euoxic (end-tidal Po(2) = 100 Torr) hypercapnia (end-tidal Pco(2) was 10 Torr above normal), followed by 2 h of recovery with euoxic eucapnia; 2) 4-h euoxic hypocapnia (end-tidal Pco(2) was 10 Torr below normal) followed by 2 h of recovery; and 3) 6-h air breathing (control). Pulmonary vascular resistance was assessed at 0.5- to 1-h intervals by using Doppler echocardiography via the maximum tricuspid pressure gradient during systole. Results show progressive changes in pressure gradient over 1-2 h after the onset or offset of the stimuli, and sensitivities of 0.6 to 1 Torr change in pressure gradient per Torr change in end-tidal Pco(2). The human pulmonary circulatory response to changes in Pco(2) has a slower time course and

BACKGROUND. Noninvasive ventilation (NIV) has a success rate of about 75% during an episode of severe hypercapnic respiratory failure in COPD patients. Recently, a new minimally invasive CO2 extracorporeal removal device (ECCO2-R, Decap; Hemodec, Salerno, Italy) consisting of a pump-driven veno-venous hemofiltration system has been developed. The main features of this system are a low extracorporeal blood flow (,500 ml/min), using a small (14-French) double-lumen catheter, and a relatively small infusion rate of heparin.. METHODS. 15 COPD patients with severe hypercapnic respiratory failure failing NIV after a trial of 2-4 hrs and meeting the criteria for intubation (i.e.pH , 7.30 and hypercapnia (no changes or increased in the PaCO2 baseline values), respiratory rate , 35 b/min, moderate to severe dyspnea) were enrolled.. The average duration of treatment with Decap was 18-24 hours. Intubation was required in 2/15 (13%) patients, and other 2 had procedure related complications (i.e bleeding and ...

100% O2 and CO2 mix (10% CO2 / 90% room air) were delivered in randomised order for 5min, followed by 5 min recovery. Arterial blood gas was taken to verify hyperoxia and hypercapnia. Retinal vessels were imaged every 10 seconds and analysed using ImageJ (percentage relative to baseline). The scotopic threshold response (STR, -5.01 logcd.s/m2) was recorded every minute during the protocol. Results : STZ animals developed hyperglycemia compared to controls (25±0.8 vs 7.7±0.3mmol/L, p,0.05). CO2 produced similar hypercapnia between STZ and control animals (PaCO2 +8.0±2.1mmHg vs +10.4±8.0mmHg, p=0.44), but more vasodilation in STZ animals (arteriole 113±1%, venule 112±1%) compared to controls (arteriole 109±6%, venule 109±2%, p,0.01). Arterioles in STZ animals remained dilated for the duration of hypercapnia, while control arteries reconstricted after 2 minutes. O2 produced hyperoxia similarly between the STZ and control groups (PaO2 +254±34 vs (+263±38mmHg, p=0.85) with no difference in ...

In this study, we prospectively identified adult patients after cardiac arrest and determined the prevalence of hypocapnia exposure and hypercapnia exposure during the first 24 hours after ROSC. Our objective was to test whether post-ROSC exposure to hypocapnia and hypercapnia was associated with poor neurological function at hospital discharge. We found that 36% of patients had any hypocapnia exposure, and 42% had any hypercapnia exposure. By the use of multivariable logistic regression, including multiple sensitivity analyses, we found that both hypocapnia exposure and hypercapnia exposure after ROSC were independent predictors of poor neurological function at hospital discharge. These findings suggest that both hypocapnia and hypercapnia are common during the initial post-ROSC period and are independently associated with poor neurological outcome.. The 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care recommend that ventilation ...

Rationale: Opioids are commonly used to relieve dyspnea, but clinical data are mixed and practice varies widely. Objectives: Evaluate the effect of morphine on dyspnea and ventilatory drive under well-controlled laboratory conditions. Methods: Six healthy volunteers received morphine (0.07 mg/kg) and placebo intravenously on separate days (randomized, blinded). We measured two responses to a CO2 stimulus: (1) perceptual response (breathing discomfort; described by subjects as air hunger) induced by increasing partial pressure of end-tidal carbon dioxide (PetCO2) during restricted ventilation, measured with a visual analog scale (range, neutral to intolerable); and (2) ventilatory response, measured in separate trials during unrestricted breathing. Measurements and Main Results: We determined the PetCO2 that produced a 60% breathing discomfort rating in each subject before morphine (median, 8.5 mm Hg above resting PetCO2). At the same PetCO2 after morphine administration, median breathing ...

Looking for online definition of permissive hypercapnic ventilation in the Medical Dictionary? permissive hypercapnic ventilation explanation free. What is permissive hypercapnic ventilation? Meaning of permissive hypercapnic ventilation medical term. What does permissive hypercapnic ventilation mean?

Gerard J. Criner, MD, FACP, FACCP, Chair and Professor of Thoracic Medicine and Surgery at the Lewis Katz School of Medicine at Temple University and Director of the Temple Lung Center, offered comments to Reuters Health for an article about initiating chronic non-invasive ventilation at home for patients with chronic obstructive pulmonary disease (COPD) and stable hypercapnic respiratory failure. The study, which was conducted by researchers in the Netherlands, was published online in the journal Thorax. Dr. Criner was not involved in the research. MD Alert picked up the Reuters Health report. ...

Carbon dioxide (CO2) is a by-product of aerobic breathing; it is carried and dissolved in blood and bound to haemoglobin and plasma proteins. The arterial carbon dioxide level (pCO2) represents the balance between CO2 production and elimination.1 Avery et al 2 hypothesised that tolerance of pCO2 above the physiological range may … ...

4.4. Ventilatory Responses to Hypoxic Challenges in Morphine-Treated Rats- Episode H1. H1 elicited markedly smaller increases in fr in MOR rats although resting fr was not diminished. As such, morphine elicited latent effects on systems including those within the carotid bodies that drive the hypoxic responses. Our data are consistent with evidence that the negative effects of opioids in humans may be latent since the morphine metabolite, M6G, does not affect resting ventilatory parameters whereas it substantially blunts the ventilatory response to hypercapnic challenge [5]. Since morphine did not markedly blunt the increase in Vt during H1, it is evident that it did not negatively affect neural drive to the chest muscles or diaphragm. This is supported by the finding that Ti in MOR rats (elevated immediately prior to exposure to hypoxia) decreased substantially during H1. Taken together, our data support the concept that morphine affected brainstem centers responsible for generating breathing ...

TY - JOUR. T1 - Hypercapnic blood flow reactivity not increased by α-blockade or cordotomy in piglets. AU - Moore, L. E.. AU - Kirsch, J. R.. AU - Helfaer, M. A.. AU - Greenberg, R. S.. AU - Traystman, R. J.. PY - 1992. Y1 - 1992. N2 - We tested the hypothesis that differential sympathetic innervation explains the attenuated cerebral blood flow (CBF) response to hypercapnia (hyper) in forebrain (fb) compared with brain stem in 1- to 2-wk-old piglets. In pentobarbital sodium-anesthetized piglets, CBF (microspheres) was measured during hypocapnia, normocapnia (normo), and hypercapnia [arterial CO2 partial pressure (Pa(CO)2) of 25, 40, and 65 mmHg, respectively] in random sequence. After pretreatment values were obtained, piglets were randomized to undergo sham treatment (n = 5), high cervical spinal cord transection (n = 6), or pharmacological α-adrenergic blockade (prazosin 1 mg/kg + yohimbine 1 mg/kg, n = 6). After each experimental treatment, CO2 reactivity was again measured. Before ...

Background: The mechanisms underlying cerebral hypercapnic vasodilatation are not fully understood. Objective: To investigate the role of nitric oxide (NO) and ATPsensitive potassium (KATP) channels in basal blood flow regulation and hypercapnia-induced vasodilatation in rabbit cerebral blood ves-

a, b, Representative examples of plethysmographic recordings (breathing frequency) during exposure to hypoxia (10% O2) and hypercapnia (5% CO2) in a wild-type FRA mouse and in a Olfr78−/− FRA mouse. c, Plethysmographic recordings (breathing frequency as a measure of time) of the ventilatory response to hypercapnia (5% CO2) performed on wild-type (n = 10) and Olfr78−/− (n = 10) FRA mice. Each data point represents the mean ± s.e.m. of the values for the group of 10 mice. CO2 (percentage CO2) tensions are indicated at the bottom. d, Breathing frequency during exposure to hypercapnia (5% CO2) in Olfr78−/− FRA mice (n = 10) compared to their wild-type littermates (n = 10). e, Breathing frequency during exposure to hypoxia (10% O2) in Olfr78−/− LEX mice compared to wild-type LEX mice (n = 10 for each genotype, 7 pairs in a C57BL/6 background, 3 pairs in a C57BL/6:129S5 mixed background, 9 out of 10 pairs are sex-matched littermates). f, Breathing frequency during exposure to hypoxia ...

Hypercapnia, elevated partial pressure of CO2 in blood and tissue, develops in many patients with chronic severe obstructive pulmonary disease and other advanced lung disorders. Patients with advanced disease frequently develop bacterial lung infections, and hypercapnia is a risk factor for mortality in such individuals. We previously demonstrated that hypercapnia suppresses induction of NF-κB-regulated innate immune response genes required for host defense in human, mouse, and Drosophila cells, and it increases mortality from bacterial infections in both mice and Drosophila. However, the molecular mediators of hypercapnic immune suppression are undefined. In this study, we report a genome-wide RNA interference screen in Drosophila S2* cells stimulated with bacterial peptidoglycan. The screen identified 16 genes with human orthologs whose knockdown reduced hypercapnic suppression of the gene encoding the antimicrobial peptide Diptericin (Dipt), but did not increase Dipt mRNA levels in air. In ...

1. The effect on respiration of a single dose of propranolol has been studied in normal subjects.. 2. The degree of β-adrenoreceptor blockade was assessed in terms of the impaired heart-rate response to progressive exercise and the plasma propranolol concentration.. 3. No effect of propranolol was demonstrated on either the ventilatory response to rebreathing CO2 in hyperoxia, or the response to progressive isocapnic hypoxia. Simple indices of maximal expiratory flow (FEV1.0% and PEFR) were also unchanged.. 4. The absence of any effect of propranolol on the chemical control of breathing in man is discussed in relation to the conflicting literature.. ...

The human pulmonary vasculature constricts in response to hypercapnia and hypoxia, with important consequences for homeostasis and adaptation. One function of these responses is to direct blood flow away from poorly-ventilated regions of the lung. In humans it is not known whether the stimuli of hypercapnia and hypoxia constrict the pulmonary blood vessels independently of each other or whether they act synergistically, such that the combination of hypercapnia and hypoxia is more effective than the sum of the responses to each stimulus on its own. We independently controlled the alveolar partial pressures of carbon dioxide (Paco 2) and oxygen (Pao 2) to examine their possible interaction on human pulmonary vasoconstriction. Nine volunteers each experienced sixteen possible combinations of four levels of Paco 2 (+6, +1, -4 and -9 mmHg, relative to baseline) with four levels of Pao 2 (175, 100, 75 and 50 mmHg). During each of these sixteen protocols Doppler echocardiography was used to evaluate cardiac

Background: Several factors may affect volume and dimensions of the working space in laparoscopic surgery. The precise impact of these factors has not been well studied. In a porcine model, we used computed tomographic (CT) scanning for measuring working space volume and distances. In a first series of experiments, we studied the relationship between intra-abdominal pressure (IAP) and working space. Methods: Eleven 20 kg pigs were studied under standardized anesthesia and volume-controlled ventilation. Cardiorespiratory parameters were monitored continuously, and blood gas samples were taken at different IAP levels. Respiratory rate was increased when ETCO2 exceeded 7 kPa. Breath-hold CT scans were made at IAP levels of 0, 5, 10, and 15 mmHg. Insufflator volumes were compared to CT-measured volumes. Maximum dimensions of pneumoperitoneum were measured on reconstructed CT images. Results: Respiratory rate had to be increased in three animals. Mild hypercapnia and acidosis occurred at 15 mmHg IAP. ...

From the abstract: Hypercapnia, elevated partial pressure of CO2 in blood and tissue, develops in many patients with chronic severe obstructive pulmonary disease and other advanced lung disorders. Patients with advanced disease frequently develop bacterial lung infections ... We previously demonstrated that hypercapnia suppresses induction of NF-κB-regulated innate immune response genes ... However, the molecular mediators of hypercapnic immune suppression are undefined. In this study, we report a genome-wide RNA interference screen in Drosophila S2* cells stimulated with bacterial peptidoglycan. The screen identified 16 genes with human orthologs whose knockdown reduced hypercapnic suppression of the gene encoding the antimicrobial peptide Diptericin (Dipt), but did not increase Dipt mRNA levels in air. In vivo tests of one of the strongest screen hits, zinc finger homeodomain 2 (Zfh2; mammalian orthologs ZFHX3/ATBF1 and ZFHX4), demonstrate that reducing zfh2 function using a mutation or RNA ...

We investigated whether the involuntary breathing movements (IBM) during the struggle phase of breath holding, together with peripheral vasoconstriction and progressive hypercapnia, have a positive effect in maintaining cerebral blood volume. The central hemodynamics, arterial oxygen saturation, brain regional oxyhemoglobin (bHbO(2)), deoxyhemoglobin, and total hemoglobin changes and IBM were monitored during maximal dry breath holds in eight elite divers. The frequency of IBM increased (by approximately 100%), and their duration decreased ( approximately 30%), toward the end of the struggle phase, whereas the amplitude was unchanged (compared with the beginning of the struggle phase). In all subjects, a consistent increase in brain regional deoxyhemoglobin and total hemoglobin was also found during struggle phase, whereas bHbO(2) changed biphasically: it initially increased until the middle of the struggle phase, with the subsequent relative decline at the end of the breath hold. Mean arterial ...

TY - JOUR. T1 - On the optimization of imaging protocol for the mapping of cerebrovascular reactivity. AU - Ravi, Harshan. AU - Thomas, Binu P.. AU - Peng, Shin Lei. AU - Liu, Hanli. AU - Lu, Hanzhang. PY - 2016/3/1. Y1 - 2016/3/1. N2 - Background To devise an improved blood-oxygen-level-dependent (BOLD) imaging protocol for cerebrovascular reactivity (CVR) measurement that can remove a known artifact of negative values. Methods Theoretical and simulation studies were first performed to understand the biophysical mechanism of the negative CVR signals, through which improved BOLD sequence parameters were proposed. This was achieved by equating signal intensities between cerebrospinal fluid and blood, by means of shortening the echo time (TE) of the BOLD sequence. Then, 10 healthy volunteers were recruited to participate in an experimental study, in which we compared the CVR results of two versions of the optimized (Opt1 and Opt2) protocols with that of the standard protocol at 3 Tesla. Two ...

With weakened respiratory (breathing) muscles, our ability to get rid of carbon dioxide (CO2) is impacted, leading to a retention of it in our blood (called hypercapnia) This hypercapnia is usually more dangerous to us than low oxygen sats (hypoxia) but doctors are conditioned to increasing low sats using oxygen - and the vast majority of doctors seem unaware of our inability to effectively expel CO2 if given O2 ...

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Insufficient ventilation under anesthesia on room air will result in the partial pressure of oxygen in the alveoli becoming insufficient so that unsaturated hemoglobin leaves the lungs (hypoxemia). Also, the elimination of carbon dioxide is decreased hypercapnia and respiratory acidosis Acid base imbalance ...

Nocturnal alterations in gas exchange, such as oxygen desaturation and hypercapnia, are an important clinical problem in patients with chronic obstructive pulmonary disease (COPD). Potential forms of treatment include supplemental oxygen, pharmacolog

OSA leads to increased cardiovascular disease (CVD). The mechanisms underlying vascular dysfunction in OSA include sympathetic activation and oxidative stress (from intermittent hypoxia, hypercapnia, and arousals). These perturbations result in reduced production of endothelium-dependent vasodilators such as nitric oxide (44). Moreover, OSA is associated with a proinflammatory and hypercoagulable state-another pathway that causes vascular injury (45). These mechanisms explain the observation that OSA severity, as indicated by AHI, is significantly associated with risk of stroke (odds ratio 2.5) in patients with type 2 diabetes (46). It should be noted that this study included older and obese populations with a high prevalence of OSA (86%). The independent effects of OSA on CVD should be further examined in lean and younger populations with type 2 diabetes.. There are limited empirical data regarding acceleration of other organ system dysfunction in patients with type 2 diabetes as a result of ...

REPIRATORY FAILURE DEFINITION Failure of the respiratory system to meetthe metabolic demands of the body resulting in hypoxia with or without hypercapnia

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