| 1. |
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| 2. |
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| 3. |
- Alm, Ann-Sophie, et al.
(author)
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Variation of lipopolysaccharide-induced acute lung injury in eight strains of mice.
- 2010
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1878-1519 .- 1569-9048. ; 171, s. 157-164
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Journal article (peer-reviewed)abstract
- Clinical and experimental evidence suggests that genetic variations may play an important role in the development of acute lung injury (ALI). Lipopolysaccharide (LPS)-induced ALI models has been widely applied for pathophysiological and pharmacological research. In order to understand the variation of acute pulmonary reactions between mouse strains and find the optimal strain for target-oriented study, the present study investigated the alterations of acute lung hyperinflation, inflammation and injury in C57BL/6J, Balb/cJ, DBA/1J, CD-1, NMRI, DBA/2J, A/J and C3H/HeN mice after the intra-tracheal challenge with LPS. We found that LPS-induced ALI varied between measured variables, durations and strains. General score of LPS-induced acute lung hyperinflation, inflammation and edema followed the order CD-1, A/J, Balb/c, DBA/2J, C57BL/6J, DBA/1J, NMRI, C3H/HeN mice at 4h, and CD-1, C57BL/6J, Balb/c, C3H/HeN, NMRI, A/J, DBA/2J, DBA/1 mice at 24h. Thus, these data provide useful information to select sensitive or resistant strain mouse for understanding genetic variation of pathogenesis and screening of target-oriented drugs.
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| 4. |
- Andersson, Johan, et al.
(author)
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Pulmonary gas exchange is reduced by the cardiovascular diving response in resting humans
- 2008
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 160:3, s. 320-324
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Journal article (peer-reviewed)abstract
- The diving response reduces the pulmonary O2 uptake in exercising humans, but it has been debated whether this effect is present at rest. Therefore, respiratory and cardiovascular responses were recorded in 16 resting subjects, performing apnea in air and apnea with face immersion in cold water (10 ◦C). Duration of apneas were predetermined to be identical in both conditions (average: 145 s) and based on individual maximal capacity (average: 184 s). Compared to apnea in air, an augmented diving response was elicited by apnea with face immersion. The O2 uptake from the lungs was reduced compared to the resting eupneic control (4.6 ml min−1 kg−1), during apnea in air (3.6 ml min−1 kg−1) and even more so during apnea with face immersion (3.4 ml min−1 kg -1). We conclude that the cardiovascular djustments of the diving response reduces pulmonary gas exchange in resting humans, allowing longer apneas by preserving the lungs’ O2 store for use by vital organs.
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| 5. |
- Aucoin, Rachelle, et al.
(author)
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Impact of trigeminal and/or olfactory nerve stimulation on measures of inspiratory neural drive : Implications for breathlessness
- 2023
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In: Respiratory Physiology and Neurobiology. - : Elsevier BV. - 1569-9048. ; 311
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Research review (peer-reviewed)abstract
- The perception of breathlessness is mechanistically linked to the awareness of increased inspiratory neural drive (IND). Stimulation of upper airway cold receptors on the trigeminal nerve (TGN) with TGN agonists such as menthol or cool air to the face/nose has been hypothesized to reduce breathlessness by decreasing IND. The aim of this systematic scoping review was to identify and summarize the results of studies in animals and humans reporting on the impact of TGN stimulation or blockade on measures of IND. Thirty-one studies were identified, including 19 in laboratory animals and 12 in human participants. Studies in laboratory animals consistently reported that as TGN activity increased, measures of IND decreased (e.g., phrenic nerve activity). In humans, stimulation of the TGN with a stream of cool air to the face/nose decreased the sensitivity of the ventilatory chemoreflex response to hypercapnia. Otherwise, TGN stimulation with menthol or cool air to the face/note had no effect on measures of IND in humans. This review provides new insight into a potential neural mechanism of breathlessness relief with selected TGN agonists.
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| 6. |
- Aucoin, Rachelle, et al.
(author)
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Impact of trigeminal nerve and/or olfactory nerve stimulation on activity of human brain regions involved in the perception of breathlessness
- 2023
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In: Respiratory Physiology and Neurobiology. - : Elsevier BV. - 1569-9048. ; 311
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Research review (peer-reviewed)abstract
- Breathlessness is a centrally processed symptom, as evidenced by activation of distinct brain regions such as the insular cortex and amygdala, during the anticipation and/or perception of breathlessness. Inhaled L-menthol or blowing cool air to the face/nose, both selective trigeminal nerve (TGN) stimulants, relieve breathlessness without concurrent improvements in physiological outcomes (e.g., breathing pattern), suggesting a possible but hitherto unexplored central mechanism of action. Four databases were searched to identify published reports supporting a link between TGN stimulation and activation of brain regions involved in the anticipation and/or perception of breathlessness. The collective results of the 29 studies demonstrated that TGN stimulation activated 12 brain regions widely implicated in the anticipation and/or perception of breathlessness, including the insular cortex and amygdala. Inhaled L-menthol or cool air to the face activated 75% and 33% of these 12 brain regions, respectively. Our findings support the hypothesis that TGN stimulation contributes to breathlessness relief by altering the activity of brain regions involved in its central neural processing.
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| 7. |
- Ax, M., et al.
(author)
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Regional lung ventilation in humans during hypergravity studied with quantitative SPECT
- 2013
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 189:3, s. 558-564
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Journal article (peer-reviewed)abstract
- Recently we challenged the view that arterial desaturation during hypergravity is caused by redistribution of blood flow to dependent lung regions by demonstrating a paradoxical redistribution of blood flow towards non-dependent regions. We have now quantified regional ventilation in 10 healthy supine volunteers at normal and three times normal gravity (1G and 3G). Regional ventilation was measured with Technegas (Tc-99m) and quantitative single photon emission computed tomography (SPECT). Hypergravity caused arterial desaturation, mean decrease 8%, p<0.05 vs. 1G. The ratio for mean ventilation per voxel for non-dependent and dependent lung regions was 0.81+/-0.12 during 1G and 1.63+/-0.35 during 3G (mean+/-SD), p<0.0001. Thus, regional ventilation was shifted from dependent to non-dependent regions. We suggest that arterial desaturation during hypergravity is caused by quantitatively different redistributions of blood flow and ventilation. To our knowledge, this is the first study presenting high-resolution measurements of regional ventilation in humans breathing normally during hypergravity.
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| 8. |
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| 9. |
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| 10. |
- Bergmann, Astrid, et al.
(author)
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Early and late effects of remote ischemic preconditioning on spirometry and gas exchange in healthy volunteers
- 2020
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 271
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Journal article (peer-reviewed)abstract
- Purpose: Remote ischemic preconditioning (RIP) may protect remote organs from ischemia-reperfusion-injury (IRI) in surgical and non-surgical patients. There are few data available on RIP and lung function, especially not in healthy volunteers. The null-hypothesis was tested that RIP does not have an effect on pulmonary function when applied on healthy volunteers that were breathing spontaneously and did not experience any intervention. After approval of the Ethics Committee and informed consent of the study subjects, 28 healthy non-smoking volunteers were included and randomized in either the RIP group (n = 13) or the control group (n = 15). In the RIP group, lower limb ischemia was induced by inflation of a blood pressure cuff to a pressure 20 mmHg above the systolic blood pressure. After five minutes the blood pressure cuff was released for five minutes rest. The procedure was repeated three times resulting in 40 min ischemia and reperfusion. Capillary blood samples were taken, and lung function tests were performed at baseline (T1) and 60 min (T2) and 24 h (T3) after RIP. The control group was treated in the same fashion, but the RIP procedure was replaced by a sham protocol.Results: 60 min after RIP capillary pO(2) decreased significantly and returned to baseline level after 24 h in the RIP group. This did not occur in the control group. Capillary pCO(2), variables of lung function tests and pulmonary capillary blood volume remained unchanged throughout the experiment in both groups.Conclusion: Oxygenation is impaired early after RIP which is possibly induced by transient ventilation-perfusion inequality. No late effects of RIP were observed. The null hypothesis has to be rejected that RIP has no effect on respiratory variables in healthy volunteers.
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| 11. |
- Bergmann, Astrid, et al.
(author)
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Effect of remote ischemic preconditioning on exhaled nitric oxide concentration in piglets during and after one-lung ventilation
- 2020
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 276
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Journal article (peer-reviewed)abstract
- BACKGROUND: Remote ischemic preconditioning (RIP) may protect target organs from ischemia - reperfusion injury, however, little is known on pulmonary effects of RIP prior to, immediately after and several hours after one-lung ventilation (OLV). The present randomized, controlled, animal experiment was undertaken to analyze these issues.METHODS: After animal ethics committee approval, twelve piglets (26 ± 2 kg) were anesthetized and randomly assigned to a control (n = 6) or to a RIP group (n = 6). For RIP, arterial perfusion of a hind limb was suspended by an inflated blood pressure cuff (200 mmHg for 5 min) and deflated for another 5 min, this was repeated four times. After intubation, mechanical ventilation (MV) was kept constant with tidal volume 10 ml/kg, inspired oxygen fraction (FIO2) 0.40, and positive end-expiratory pressure (PEEP) 5cmH2O. FIO2 was increased to 1 after RIP in the RIP group and after the sham procedure in the control group, respectively, for the time of OLV. OLV was established by left-sided bronchial blockade. After OLV, TLV was re-established until the end of the protocol. Exhaled nitric oxide (NO) was measured by ozon chemiluminiscense and ventilatory and hemodynamic variables were assessed according to the protocol.RESULTS: Hemodynamic and respiratory data were similar in both groups. Arterial pO2 was higher in the RIP group after two hours of OLV. In the control group, exhaled NO decreased during OLV and remained at low levels for the rest of the protocol. In the RIP group, exhaled NO decreased as well during OLV but returned to baseline levels when TLV was re-established.CONCLUSIONS: RIP has no effects on hemodynamic and respiratory variables in juvenile, healthy piglets. RIP improves the oxygenation after OLV and prevents the decline of exhaled NO after OLV.
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| 12. |
- Bergmann, Astrid, et al.
(author)
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Pulmonary effects of remote ischemic preconditioning in a porcine model of ventilation-induced lung injury
- 2019
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In: Respiratory Physiology & Neurobiology. - : Elsevier. - 1569-9048 .- 1878-1519. ; 259, s. 111-118
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Journal article (peer-reviewed)abstract
- BACKGROUND: One-lung ventilation (OLV) may result in lung injury due to increased mechanical stress and tidal recruitment. As a result, a pulmonary inflammatory response is induced. The present randomized, controlled, animal experiment was undertaken to assess the effects of remote ischemic preconditioning (RIP) on diffuse alveolar damage and immune response after OLV.METHODS: Fourteen piglets (26 ± 2 kg) were randomized to control (n = 7) and RIP group (n = 7). For RIP, a blood pressure cuff at hind limb was inflated up to 200 mmHg for 5 min and deflated for another 5 min, this being done four times before OLV. Mechanical ventilation settings were constant throughout the experiment: VT = 10 ml/kg, FIO2 = 0.40, PEEP = 5cmH2O. OLV was performed by left-sided bronchial blockade. Number of cells was counted from BAL fluid; cytokines were assessed by immunoassays in lung tissue and serum samples. Lung tissue samples were obtained for histological analysis and assessment of diffuse alveolar damage (DAD) score.RESULTS: Hemodynamic and respiratory data were similar in both groups. Likewise, no differences in pulmonary tissue TNF-α and protein content were found, but fewer leukocytes were counted in the ventilated lung after RIP. DAD scores were high without any differences between controls and RIP. On the other hand, alveolar edema and microhemorrhage were significantly increased after RIP.CONCLUSIONS: OLV results in alveolar injury, possibly enhanced by RIP. On the other hand, RIP attenuates the immunological response and decreased alveolar leukocyte recruitment in a porcine model of OLV.
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| 13. |
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| 14. |
- Brander, Lukas, et al.
(author)
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Neural control of ventilation prevents both over-distension and de-recruitment of experimentally injured lungs
- 2017
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 237, s. 57-67
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Journal article (peer-reviewed)abstract
- Background: Endogenous pulmonary reflexes may protect the lungs during mechanical ventilation. We aimed to assess integration of continuous neurally adjusted ventilatory assist (cNAVA), delivering assist in proportion to diaphragm's electrical activity during inspiration and expiration, and Hering-Breuer inflation and deflation reflexes on lung recruitment, distension, and aeration before and after acute lung injury (ALI).Methods: In 7 anesthetised rabbits with bilateral pneumothoraces, we identified adequate cNAVA level (cNAVA(AL)) at the plateau in peak ventilator pressure during titration procedures before (healthy lungs with endotracheal tube, [HLETT]) and after ALI (endotracheal tube [ALI(ETT)] and during non-invasive ventilation [ALI(NIV)]). Following titration, cNAVA(AL) was maintained for 5 min. In 2 rabbits, procedures were repeated after vagotomy (ALI(ETT+VAG)). In 3 rabbits delivery of assist was temporarily modulated to provide assist on inspiration only. Computed tomography was performed before intubation, before ALI, during cNAVA titration, and after maintenance at cNAVA(AL).Results: During ALI(ETT) and ALI(NIV), normally aerated lung-regions doubled and poorly aerated lung-regions decreased to less than a third (p < 0.05) compared to HLETT; no over-distension was observed. Tidal volumes were <5 ml/kg throughout. Removing assist during expiration resulted in lung de-recruitment during ALI(ETT) but not during ALI(NIV). During ALI(ETT+VAG) the expiratory portion of EAdi disappeared, resulting in cyclic lung collapse and recruitment.Conclusions: When using cNAVA in ALI, vagally mediated reflexes regulated lung recruitment preventing both lung over-distension and atelectasis. During non-invasive cNAVA the upper airway muscles play a role in preventing atelectasis. Future studies should be performed to compare these findings with conventional lung-protective approaches.
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| 15. |
- Bratel, Tomas, et al.
(author)
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Ventilation-perfusion relationships in pulmonary arterial hypertension : Effect of intravenous and inhaled prostacyclin treatment
- 2007
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 158:1, s. 59-69
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Journal article (peer-reviewed)abstract
- In seven patients with idiopathic or secondary pulmonary arterial hypertension (PAH), ventilation-perfusion (V-A/Q) relationships were measured during a right heart catheterization using the multiple inert-gas elimination technique before and during intravenous infusion with epoprostenol (EPO), and following 5 months of 20 mu g inhaled iloprost taken three times daily (ILO). Pre-treatment pulmonary vascular resistance (PVR) was 9.3 +/- 5.0 mmHg/l/min and the dispersion of perfusion and ventilation for V-A/Q-ratios was increased. EPO reduced PVR by 20%, and increased cardiac output, shunt, and mixed venous oxygenation (Sv(O2)) The arterial oxygen tension (Pa-O2) remained unchanged. Basal central haemodynamics did not change after 5 months of ILO. Fifteen minutes after ILO, PVR decreased by 20%, and the shunt, Sv(O2), and Pa-O2 remained unaltered. Conclusions: In secondary PAH with normal lung volumes, significant V-A/Q mismatching occurred. The PVR was reduced to a similar degree during EPO and after ILO, but only EPO increased the shunt and Sv(O2). EPO and ILO did not significantly affect the Pa-O2.
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| 16. |
- Buehler, Sarah, et al.
(author)
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Simultaneous monitoring of intratidal compliance and resistance in mechanically ventilated piglets : A feasibility study in two different study groups
- 2015
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 219, s. 36-42
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Journal article (peer-reviewed)abstract
- Compliance measures the force counteracting parenchymal lung distension. In mechanical ventilation, intratidal compliance-volume (C(V))-profiles therefore change depending on PEEP, tidal volume (V-T), and underlying mechanical lung properties. Resistance counteracts gas flow through the airways. Due to anatomical linking between parenchyma and airways, intratidal resistance-volume (R(V))-profiles are hypothesised to change in a non-linear way as well. We analysed respiratory system mechanics in fifteen piglets with lavage-induced lung injury and nine healthy piglets ventilated at different PEEP/V-T-settings. In healthy lungs, R(V)-profiles remained mostly constant and linear at all PEEP-settings whereas the shape of the C(V)-profiles showed an increase toward a maximum followed by a decrease (small PEEP) or volume-dependent decrease (large PEEP). In the lavage group, a large drop in resistance at small volumes and slow decrease toward larger volumes was found for small PEEP/V-T-settings where C(V)-profiles revealed a volume-dependent increase (small PEEP) or a decrease (large PEEP and large VT). R(V)-profiles depend characteristically on PEEP, V-T, and possibly whether lungs are healthy or not. Curved R(V)-profiles might indicate pathological changes in the underlying mechanical lung properties and/or might be a sign of derecruitment.
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| 17. |
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| 18. |
- Christensson, Eva, et al.
(author)
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Whole blood gene expression signature in patients with obstructive sleep apnea and effect of continuous positive airway pressure treatment
- 2021
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In: Respiratory Physiology & Neurobiology. - : Elsevier. - 1569-9048 .- 1878-1519. ; 294
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Journal article (peer-reviewed)abstract
- The molecular mechanisms of obstructive sleep apnea (OSA), in particular the gene expression patterns in whole blood of patients with OSA, can shed more light on the underlying pathophysiology of OSA and suggest potential biomarkers. In the current study, we have enrolled thirty patients with untreated moderate-severe OSA together with 20 BMI, age, and sex-matched controls and 15 normal-weight controls. RNA-sequencing of whole blood and home sleep apnea testing were performed in the untreated state and after three and twelve months of continuous positive airway pressure (CPAP) treatment. Analysis of the whole blood transcriptome of the patients with OSA revealed a unique pattern of differential expression with a significant number of downregulated immune-related genes including many heavy and light chain immunoglobulins and interferon-inducible genes. This was confirmed by the gene ontology analysis demonstrating enrichment with the biological processes associated with various immune functions. Expression of these genes was recovered after three months of CPAP treatment. After 12 months of CPAP treatment, the overall gene expression profile returns to the initial, untreated level. In addition, we have confirmed the importance of choosing BMI-matched controls as a reference group as opposed to normal-weight healthy individuals based on the significantly different gene expression signatures between these two groups.
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| 19. |
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| 20. |
- Elfwing, Magnus, et al.
(author)
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Fetal development of baroreflex sensitivity: The chicken embryo as a case model
- 2011
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In: Respiratory Physiology & Neurobiology. - : Elsevier B.V.. - 1569-9048 .- 1878-1519. ; 178:1, s. 75-83
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Research review (peer-reviewed)abstract
- The baroreflex is the main short term compensatory mechanism to buffer blood pressure changes and maintain circulatory homeostasis. Its ontogeny and importance during prenatal life is not fully understood so we used broiler chickens to investigate the maturation of the baroreflex in late incubation using a novel method that measured changes in heart rate during spontaneous fluctuations in blood pressure. Our results suggest that a baroreflex is already functional at d17 with no indication of further maturation in terms of sensitivity (gain at 17 d was 52.9 ± 8.3 and at 20 d 69.5 ± 16.2 ms kPa−1). The physiological relevance of these values is shown using data surrogation methods. Although the results contrast with the progressive baroreflex maturation indicated by the pharmacological method, we sustain that both methods provide information on baroreflex regulation. While the spontaneous method evaluates truly physiological (but small) pressure changes, the pharmacological method provides a more consistent and repetitive challenge for the reflex that requires a different recruitment of baroreflex effectors.
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| 21. |
- Elia, Antonis, Dr, et al.
(author)
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Stress biomarker changes following a series of repeated static and dynamic apneas in non-divers
- 2024
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 323
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Journal article (peer-reviewed)abstract
- Purpose: This study examined the magnitude of physiological strain imposed by repeated maximal static and dynamic apneas through assessing a panel of stress-related biomarkers. Methods: Eleven healthy men performed on three separate occasions (≥72-h apart): a series of five repeated maximal (i) static (STA) or (ii) dynamic apneas (DYN) or (iii) a static eupneic protocol (CTL). Venous blood samples were drawn at 30, 90, and 180-min after each protocol to determine ischaemia modified albumin (IMA), neuron-specific enolase (NSE), myoglobin, and high sensitivity cardiac troponin T (hscTnT) concentrations. Results: IMA was elevated after the apnoeic interventions (STA,+86%;DYN,+332%,p ≤ 0.047) but not CTL (p = 0.385). Myoglobin was higher than baseline (23.6 ± 3.9 ng/mL) 30-min post DYN (+70%,38.8 ± 13.3 ng/mL,p = 0.030). A greater myoglobin release was recorded in DYN compared with STA and CTL (p ≤ 0.035). No changes were observed in NSE (p = 0.207) or hscTnT (p = 0.274). Conclusions: Five repeated maximal DYN led to a greater muscle injury compared with STA but neither elicited myocardial injury or neuronal-parenchymal damage.
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| 22. |
- Engan, Harald K., et al.
(author)
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Acute dietary nitrate supplementation improves dry static apnea performance
- 2012
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 182:2-3, s. 53-59
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Journal article (peer-reviewed)abstract
- Acute dietary nitrate (NO3-) supplementation has been reported to lower resting blood pressure, reduce the oxygen (O-2) cost of sub-maximal exercise, and improve exercise tolerance. Given the proposed effects of NO3- on tissue oxygenation and metabolic rate, it is possible that NO3- supplementation might enhance the duration of resting apnea. If so, this might have important applications both in medicine and sport. We investigated the effects of acute NO3- supplementation on pre-apnea blood pressure, apneic duration, and the heart rate (HR) and arterial O-2 saturation (SaO(2)) responses to sub-maximal and maximal apneas in twelve well-trained apnea divers. Subjects were assigned in a randomized, double blind, crossover design to receive 70 ml of beetroot juice (BR; containing similar to 5.0 mmol of nitrate) and placebo juice (PL; similar to 0.003 mmol of nitrate) treatments. At 2.5 h post-ingestion, the subjects completed a series of two 2-min (sub-maximal) static apneas separated by 3 min of rest, followed by a maximal effort apnea. Relative to PL, BR reduced resting mean arterial pressure by 2% (PL: 86 +/- 7 vs. BR: 84 +/- 6 mmHg; P = 0.04). The mean nadir for SaO(2) after the two sub-maximal apneas was 97.2 +/- 1.6% in PL and 98.5 +/- 0.9% in BR (P = 0.03) while the reduction in HR from baseline was not significantly different between PL and BR. Importantly, BR increased maximal apneic duration by 11% (PL: 250 +/- 58 vs. BR: 278 +/- 64 s; P = 0.04). In the longer maximal apneas in BR, the magnitude of the reductions in HR and SaO(2) were greater than in PL (P <= 0.05). The results suggest that acute dietary NO3- supplementation may increase apneic duration by reducing metabolic costs. (c) 2012 Elsevier B.V. All rights reserved.
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| 23. |
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| 24. |
- Grönkvist, Mikael J, et al.
(author)
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Contributions of lower limb and abdominal compression to ventilation inhomogeneity in hypergravity
- 2005
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In: Respir Physiol Neurobiol. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 148:1-2, s. 113-23
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Journal article (peer-reviewed)abstract
- Gravito-inertial load in the head-to-foot direction (Gz) and compression of the lower body half by an anti-G suit (AGS) are both known to influence ventilation distribution in the lungs. To study the interaction of Gz and AGS and to asses the separate contributions from lower limbs and abdominal compressions to large and small-scale ventilation inhomogeneities nine males performed SF6/He vital capacity (VC) single-breath washouts at 1, 2, and 3 Gz in a centrifuge, with abdominal and/or lower limbs compressions. SF6/He and (SF6-He) phase III slopes were used for determination of overall and small-scale ventilation inhomogeneity. Closing volume and phase IV height were used as measures of large-scale inhomogeneity. VC decreased marginally with G-load but markedly with lower limbs compression. Small-scale ventilation inhomogeneity increased slightly with G-load, but substantially with AGS pressurization. Small-scale ventilation inhomogeneity increased with AGS pressurization. Large-scale inhomogeneity increased markedly with G-load. Translocation of blood to the lungs might be the key determinant for changes in small-scale ventilation inhomogeneity when pressurizing an AGS.
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| 25. |
- Hafström, Ola, 1960, et al.
(author)
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Cardiorespiratory effects of nicotine exposure during development
- 2005
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In: Respir Physiol Neurobiol. - 1569-9048. ; 149:1-3, s. 325-41
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Journal article (peer-reviewed)abstract
- Exposure to tobacco smoke is a major risk factor for the sudden infant death syndrome. Nicotine is thought to be the ingredient in tobacco smoke that is responsible for a multitude of cardiorespiratory effects during development, and pre- rather than postnatal exposure is considered to be most detrimental. Nicotine interacts with endogenous acetylcholine receptors in the brain and lung, and developmental exposure produces structural changes as well as alterations in neuroregulation. Abnormalities have been described in sympathicovagal balance, arousal threshold and latency, breathing pattern at rest and apnea frequency, ventilatory response to hyperoxia or hypoxia, heart rate regulation and ability to autoresuscitate during severe hypoxia. This review discusses studies performed on infants of smoking mothers and nicotine-exposed animals yielding varying and sometimes inconsistent results that may be due to differences in experimental design, species and the dose of exposure. Taken together however, developmental nicotine exposure appears to induce vulnerability during hypoxia and a potential inability to survive severe asphyxia.
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| 26. |
- Hazeri, Mohammad, et al.
(author)
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Details of the physiology of the aerodynamic and heat and moisture transfer in the normal nasal cavity
- 2020
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In: Respiratory Physiology & Neurobiology. - : Elsevier. - 1569-9048 .- 1878-1519. ; 280
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Journal article (peer-reviewed)abstract
- Anatomically accurate 3D models of 10 healthy nasal cavities are developed from computerized tomography (CT) scan images. Considering anatomical and physiological importance of different parts of the nasal cavity, the surface of each nasal passage is divided to eleven anatomical surfaces. Also the coronal cross sections in the nasal passage are divided to six sub-sections that share the total nasal passage airflow. The details of the flow field, heat transfer and water-vapor transport are numerically investigated for resting and low activity conditions. The mean and standard deviation of the different anatomical and air conditioning parameters such as: surface area, wall shear stress, heat and moisture transfer on different parts of the nasal passage surfaces and volume flow rates through different sections are presented. Results show that the percentages of airflow for inferior, middle and superior meatuses are 11.3 +/- 6.4, 36.5 +/- 9.5, 1.9 +/- 0.81 % respectively and 4.1 +/- 2.1 % of air passes through olfactory area. The inhaled air passing from the remaining surface (main passage) is 46.2 +/- 10 %. Heat and moisture fluxes are highest in the anterior part of the nasal cavity, turbinates and lower part of the septum respectively. The percentage of the heat transfer from turbinates is 25.7 +/- 3.9 % of total nasal heat transfer.
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| 27. |
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| 28. |
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Holmberg, Hans-Christer, et al.
(author)
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Insufficient ventilation as a cause of impaired pulmonary gas exchange during submaximal exercise
- 2007
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 157:2-3, s. 348-59
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Journal article (peer-reviewed)abstract
- Pulmonary ventilation and gas exchange were determined during prolonged skiing (approximately 76% of V(O2, max); cardiac output=26-27 L min(-1)) using diagonal technique (DIA) for 40 min followed by 10 min of double poling (DPOL) and 10 min of leg skiing (LEG). Exercise caused approximately 2-5% reduction of arterial oxygen saturation Sa(O2). For a given cardiac output and V(O2), DPOL presented higher V(E), lower Pa(CO2) and a more efficient pulmonary gas exchange, revealed by higher PA(O2) and Pa(O2) and lower A-aD(O2). The A-aD(O2) widened 2 mmHg L(-1) of cardiac output increase. However, for a given cardiac output and V(O2), exercise mode had an important influence on pulmonary ventilation and gas exchange. Highly trained cross-country skiers' present about 2 units reduction in Sa(O2) from resting values during submaximal exercise at 76% of V(O2, max). Half of the reduction in saturation is accounted for by the rightward-shift of the oxygen dissociation curve of the haemoglobin. The exercise duration has almost no repercussion on pulmonary gas exchange in these athletes, with the small effect on Sa(O2) associated to the increase in body core temperature.
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| 34. |
- Holmgren, Helene, 1981, et al.
(author)
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Effects of breath holding at low and high lung volumes on amount of exhaled particles
- 2013
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 185:2, s. 228-234
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Journal article (peer-reviewed)abstract
- Exhaled breath contains particles originating from the respiratory tract lining fluid. The particles are thought to be generated during inhalation, by reopening of airways closed in the preceding expiration. The aim here was to explore processes that control exhaled particle concentrations. The results show that 5 and 10 s breath holding at residual volume increased the median concentration of particles in exhaled air by 63% and 110%, respectively, averaged over 10 subjects. An increasing number of closed airways, developing on a timescale of seconds explains this behaviour. Breath holds of 5, 10 and 20 s at total lung capacity decreased the concentration to 63%, 45% and 28% respectively, of the directly exhaled concentration. The decrease in particle concentration after breath holding at total lung capacity is caused by gravitational settling in the alveoli and associated bronchioles. The geometry employed here when modelling the deposition is however not satisfactory and ways of improving the description are discussed.
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| 35. |
- Horsley, Alex R, et al.
(author)
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Effects of cystic fibrosis lung disease on gas mixing indices derived from alveolar slope analysis.
- 2008
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In: Respiratory physiology & neurobiology. - : Elsevier BV. - 1569-9048. ; 162:3, s. 197-203
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Journal article (peer-reviewed)abstract
- S(cond) and S(acin) are derived from analysis of concentration-normalized phase III slopes (Sn(III)) of a multiple breath inert gas washout. Studies in healthy and COPD subjects suggest these reflect ventilation heterogeneity in conducting and acinar airway zones respectively, but similar studies in cystic fibrosis (CF) are lacking. S(cond), S(acin) and lung clearance index (LCI, a measure of overall gas mixing efficiency) were measured in 22 adults and 18 children with CF and 17 adult and 29 child controls. Plethysmography and gas transfer measurements were performed in adults, and spirometry in all subjects. S(cond) was elevated in almost all CF patients, including children with mild disease and normal LCI. However, S(cond) did not correlate with other measurements and appeared to reach a maximum; further increase in ventilation heterogeneity being restricted to S(acin). The nature and/or severity of CF lung disease may invalidate assumptions underlying the ability to separate phase III slope analysis of ventilation heterogeneity into proximal and peripheral components, and LCI may be a better indicator of gas mixing in this population.
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| 36. |
- Jonasson, Sofia, 1980-, et al.
(author)
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Comparisons of effects of intravenous and inhaled methacholine on airway physiology in a murine asthma model
- 2009
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 165:2-3, s. 229-236
-
Journal article (peer-reviewed)abstract
- Airway responses to intravenous (i.v.) and inhaled (i.h.) delivery of methacholine (MCh) in BALB/c and C57BL/6 mouse strains have been compared with and without ovalbumin (OVA)-induced airway inflammation. Bronchial reactivity to MCh was assessed in anaesthetised and tracheostomised animals by using an animal ventilator (flexiVent). We partitioned the response of the lungs into airway and parenchymal components in order to compare the contributions of the airways with those of the lung parenchyma to the pulmonary mechanical responses resulting from different routes of MCh administration. Our results indicate disparate physiological responses. Intravenous MCh delivery induced a higher maximum lung resistance than i.h. MCh in OVA-treated BALB/c mice but not in C57BL/6 mice. Inhaled MCh delivery led to a significantly larger fall in lung compliance and a greater impact on peripheral airways than i.v. MCh in both strains. In conclusion, i.v. and i.h. MCh produced disparate effects in different murine strains and variant responses in inflamed airways and healthy controls. The two methods of MCh delivery have important advantages but also certain limitations with regard to measuring airway reactivity in a murine model of allergic asthma.
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| 37. |
- Jones, Andrew M., et al.
(author)
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‘Priming’ exercise and O2 uptake kinetics during treadmill running
- 2008
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 161:2, s. 182-188
-
Journal article (peer-reviewed)abstract
- We tested the hypothesis that priming exercise would speed V˙O2 kinetics during treadmill running. Eight subjects completed a square-wave protocol, involving two bouts of treadmill running at 70% of the difference between the running speeds at lactate threshold (LT) and V˙O2 max, separated by 6-min of walking at 4 km h−1, on two occasions. Oxygen uptake was measured breath-by-breath and subsequently modelled using non-linear regression techniques. Heart rate and blood lactate concentration were significantly elevated prior to the second exercise bout compared to the first. However, V˙O2 kinetics was not significantly different between the first and second exercise bouts (mean ± S.D., phase II time constant, Bout 1: 16 ± 3 s vs. Bout 2: 16 ± 4 s; V˙O2 slow component amplitude, Bout 1: 0.24 ± 0.10 L min−1 vs. Bout 2: 0.20 ± 0.12 L min−1; mean response time, Bout 1: 34 ± 4 s vs. Bout 2: 34 ± 6 s; P > 0.05 for all comparisons). These results indicate that, contrary to previous findings with other exercise modalities, priming exercise does not alter V˙O2 kinetics during high-intensity treadmill running, at least in physically active young subjects. We speculate that the relatively fast V˙O2 kinetics and the relatively small V˙O2 slow component in the control (‘un-primed’) condition negated any enhancement of V˙O2 kinetics by priming exercise in this exercise modality.
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| 38. |
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| 39. |
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| 40. |
- Karlsson, Lars L., et al.
(author)
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Venous gas emboli and exhaled nitric oxide with simulated and actual extravehicular activity
- 2009
-
In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 169, s. S59-S62
-
Journal article (peer-reviewed)abstract
- The decompression experienced due to the change in pressure from a space vehicle (1013hPa) to that in a suit for extravehicular activity (EVA) (386hPa) was simulated using a hypobaric chamber. Previous ground-based research has indicated around a 50% occurrence of both venous gas emboli (VGE) and symptoms of decompression illness (DCI) after similar decompressions. In contrast, no DCI symptoms have been reported from past or current space activities. Twenty subjects were studied using Doppler ultrasound to detect any VGE during decompression to 386hPa, where they remained for up to 6h. Subjects were supine to simulate weightlessness. A large number of VGE were found in one subject at rest, who had a recent arm fracture; a small number of VGE were found in another subject during provocation with calf contractions. No changes in exhaled nitric oxide were found that can be related to either simulated EVA or actual EVA (studied in a parallel study on four cosmonauts). We conclude that weightlessness appears to be protective against DCI and that exhaled NO is not likely to be useful to monitor VGE.
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| 41. |
- Keramidas, Michail E., et al.
(author)
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Muscle and cerebral oxygenation during exercise performance after short-term respiratory work
- 2011
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In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 175:2, s. 247-254
-
Journal article (peer-reviewed)abstract
- The purpose of the study was to investigate the effect of 30-min voluntary hyperpnoea on cerebral, respiratory and leg muscle balance between 02 delivery and utilization during a subsequent constant-power test. Eight males performed a VO2max test, and two exercise tests at 85% of peak power output: (a) a control constant-power test (CPT), and (b) a constant-power test after a respiratory maneuver (CPTRM). Oxygenated (Delta[O(2)Hb]), deoxygenated (Delta[HHb]) and total (Delta[tHb]) hemoglobin in cerebral, intercostal and vastus lateralis were monitored with near-infrared spectroscopy. The performance time dropped similar to 15% in CPTRM (6:55 +/- 2:52 min) compared to CPT (8:03 +/- 2:33 min), but the difference was not statistically significant. The vastus lateral's and intercostal Delta[tHb] and Delta[HHb] were lower in CPTRM than in CPT (P <= 0.05). There were no differences in cerebral oxygenation between the trials. Thus, respiratory work prior to an exercise test influences the oxygenation during exercise in the leg and respiratory muscles, but not in the frontal cortex. (C) 2010 Elsevier B.V. All rights reserved.
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| 42. |
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| 43. |
- Koca Akdeva, Hatice, et al.
(author)
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Surfactant protein A in particles in exhaled air and plasma
- 2022
-
In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 301
-
Journal article (peer-reviewed)abstract
- Respiratory tract lining fluid (RTLF) is an important component of the lung epithelial barrier. Pathological changes in RTLF may cause increased permeability of the epithelial barrier, but changes within RTLF are difficult to assess non-invasively. The aim of this study was to explore if the use of the non-invasive measurement technique, Particles in Exhaled Air (PEx) and blood test were useful in assessing epithelial barrier, and if cigarette smoking affects the relationship. In a general population subcohort from the European Community Respiratory Health Survey III in Iceland (n = 112), we collected RTLF droplets using the PEx technique, in conjunction with blood samples and questionnaire data. We measured surfactant protein A (SP-A) in the collected plasma and PEx samples. Participants were defined as healthy if they did not currently have asthma, were non-smokers and had forced expiratory volume in one second & GE; 80% of predicted value. Of the 112 participants, 97 were healthy and 15 were current smokers. There was no correlation between plasma and PEx SP-A levels. However, the ratio of plasma to PEx SP-A was significantly higher in smokers compared to healthy subjects. The lack of correlation between PEx and plasma SP-A in healthy participants, indicates that SP-A in plasma does not diffuse freely over the lung epithelial barrier. However, the lung epithelial barrier may be injured by smoking, leading to diffusion of SP-A across the barrier into the bloodstream, causing an increased ratio of plasma to PEx SP-A.
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| 44. |
- Kretzschmar, Moritz, et al.
(author)
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Bronchoconstriction induced by inhaled methacholine delays desflurane uptake and elimination in a piglet model
- 2016
-
In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 220, s. 88-94
-
Journal article (peer-reviewed)abstract
- Bronchoconstriction is a hallmark of asthma and impairs gas exchange. We hypothesized that pharmacokinetics of volatile anesthetics would be affected by bronchoconstriction. Ventilation/perfusion (V̇A/Q̇) ratios and pharmacokinetics of desflurane in both healthy state and during inhalational administration of methacholine (MCh) to double peak airway pressure were studied in a piglet model. In piglets, MCh administration by inhalation (100μg/ml, n=6) increased respiratory resistance, impaired V̇A/Q̇ distribution, increased shunt, and decreased paO2 in all animals. The uptake and elimination of desflurane in arterial blood was delayed by nebulization of MCh, as determined by Micropore Membrane Inlet Mass Spectrometry (wash-in time to P50, healthy vs. inhalation: 0.5min vs. 1.1min, to P90: 4.0min vs. 14.8min). Volatile elimination was accordingly delayed. Inhaled methacholine induced severe bronchoconstriction and marked inhomogeneous V̇A/Q̇ distribution in pigs, which is similar to findings in human asthma exacerbation. Furthermore, MCh-induced bronchoconstriction delayed both uptake and elimination of desflurane. These findings might be considered when administering inhalational anesthesia to asthmatic patients.
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| 45. |
- Larsson, Per, et al.
(author)
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The effect of exhalation flow on endogenous particle emission and phospholipid composition
- 2017
-
In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048. ; 243, s. 39-46
-
Journal article (peer-reviewed)abstract
- Exhaled particles constitute a micro-sample of respiratory tract lining fluid. Inhalations from low lung volumes generate particles in small airways by the airway re-opening mechanism. Forced exhalations are assumed to generate particles in central airways by mechanisms associated with high air velocities. To increase knowledge on how and where particles are formed, different breathing manoeuvres were compared in 11 healthy volunteers. Particles in the 0.41-4.55 mu m diameter range were characterised and sampled. The surfactant lipid dipalmitoylphosphatidylcholine (DPPC) was quantified by mass spectrometry. The mass of exhaled particles increased by 150% (95% CI 10-470) for the forced exhalation and by 470% (95% CI 150-1190) for the airway re-opening manoeuvre, compared to slow exhalations. DPPC weight percent concentration (wt%) in particles was 2.8 wt% (95%CI 1.4-4.2) and 9.4 wt% (95%CI 8.0-10.8) for the forced and the airway re-opening manoeuvres, respectively. In conclusion, forced exhalation and airway re-opening manoeuvres generate particles from different airway regions having different DPPC concentration.
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| 46. |
- Laveneziana, Pierantonio, et al.
(author)
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Does expiratory muscle activity influence dynamic hyperinflation and exertional dyspnea in COPD?
- 2014
-
In: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 199, s. 24-33
-
Journal article (peer-reviewed)abstract
- Increased expiratory muscle activity is common during exercise in patients with COPD but its role in modulating operating lung volumes and dyspnea during incremental cycle ergometry is currently unknown. We compared gastric (Pga) and esophageal (Pes) pressures, operating lung volumes and qualitative descriptors of dyspnea during exercise in 12 COPD patients and 12 age- and sex-matched healthy controls. Pes- and Pga-derived measures of expiratory muscle activity were significantly (p<0.05) greater in COPD than in health during exercise. End-expiratory lung volume (EELV) increased by 0.8L, independent of increased expiratory muscle activity in COPD. Dynamic function of the diaphragm was not different in health and COPD throughout exercise. In both groups, dyspnea descriptors alluding to increased work and inspiratory difficulty predominated whereas expiratory difficulty was rarely reported, even at the limits of tolerance. In conclusion, increased expiratory muscle activity did not mitigate the rise in EELV, the relatively early respiratory mechanical constraints or the attendant perceived inspiratory difficulty during exercise in COPD.
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| 47. |
- Lee, Juyoung, et al.
(author)
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NIV-NAVA versus NCPAP immediately after birth in premature infants : A randomized controlled trial
- 2022
-
In: Respiratory Physiology & Neurobiology. - : Elsevier. - 1569-9048 .- 1878-1519. ; 302
-
Journal article (peer-reviewed)abstract
- Objective: To evaluate whether noninvasive-neurally adjusted ventilatory assist (NIV-NAVA) decrease respiratory efforts compared to nasal continuous positive airway pressure (NCPAP) during the first hours of life.Methods: Twenty infants born between 28+0 and 31+6 weeks were randomized to NIV-NAVA or NCPAP. Positive end-expiratory pressure was constantly kept at 6 cmH(2)O for both groups and the NAVA level was 1.0 cmH(2)O/mu V for NIV-NAVA group. The electrical activity of diaphragm (Edi) were recorded for the first two hours.Results: Peak and minimum Edi decreased similarly in both groups (P = 0.98 and P = 0.59, respectively). Leakages were higher in the NIV-NAVA group than in the NCPAP group (P < 0.001). The neural apnea defined as a flat Edi for >= 5 s were less frequent in NIV-NAVA group than in NCPAP group (P = 0.046).Conclusions: Immediately applied NIV-NAVA in premature infants did not reduce breathing effort, measured as peak Edi. However, NIV-NAVA decreased neural apneic episodes compared to NCPAP.
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| 48. |
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| 49. |
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| 50. |
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