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Model-Base Estimation of Non-Invasive Ventilation Weaning of Preterm Infants Exposed to Osteopathic Manipulative Treatment: A Propensity-Score-Matched Cohort Study. Healthcare (Basel) 2022; 10:healthcare10122379. [PMID: 36553903 PMCID: PMC9777985 DOI: 10.3390/healthcare10122379] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/23/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022] Open
Abstract
Ventilation weaning is a key intensive care event influencing preterm infants’ discharge from a neonatal intensive care unit (NICU). Osteopathic manipulative treatment (OMT) has been recently introduced in some Italian NICUs. This retrospective cohort study tested if OMT is associated with faster non-invasive ventilation (NIV) weaning. The time to NIV weaning was assessed in very preterm and very low birth weight infants who either received or did not receive OMT. The propensity score model included gender, antenatal steroids, gestational age (GA), birth weight (BW), and Apgar score 5′. Out of 93 infants, 40 were included in the multilevel survival analysis, showing a reduction of time to NIV weaning for GA (HR: 2.58, 95%CI: 3.91 to 1.71, p < 0.001) and OMT (HR: 3.62, 95%CI: 8.13 to 1.61, p = 0.002). Time to independent ventilation (TIV) was modeled with GA and BW as dependent variables and OMT as the factor. A negative linear effect of GA and BW on TIV was shown. OMT exposure studied as the factor of GA had effects on TIV in infants born up to the 32nd gestational week. Preterm infants exposed to OMT were associated with earlier achievement of NIV weaning. This result, together with the demonstrated OMT safety, suggests the conduct of clinical trials in preterm infants younger than 32 weeks of GA.
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Whitaker-Fornek JR, Nelson JK, Lybbert CW, Pilarski JQ. Development and regulation of breathing rhythms in embryonic and hatchling birds. Respir Physiol Neurobiol 2019; 269:103246. [DOI: 10.1016/j.resp.2019.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 05/19/2019] [Accepted: 06/23/2019] [Indexed: 11/28/2022]
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Ellwein Fix L, Khoury J, Moores RR, Linkous L, Brandes M, Rozycki HJ. Theoretical open-loop model of respiratory mechanics in the extremely preterm infant. PLoS One 2018; 13:e0198425. [PMID: 29902195 PMCID: PMC6002107 DOI: 10.1371/journal.pone.0198425] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 05/20/2018] [Indexed: 11/18/2022] Open
Abstract
Non-invasive ventilation is increasingly used for respiratory support in preterm infants, and is associated with a lower risk of chronic lung disease. However, this mode is often not successful in the extremely preterm infant in part due to their markedly increased chest wall compliance that does not provide enough structure against which the forces of inhalation can generate sufficient pressure. To address the continued challenge of studying treatments in this fragile population, we developed a nonlinear lumped-parameter respiratory system mechanics model of the extremely preterm infant that incorporates nonlinear lung and chest wall compliances and lung volume parameters tuned to this population. In particular we developed a novel empirical representation of progressive volume loss based on compensatory alveolar pressure increase resulting from collapsed alveoli. The model demonstrates increased rate of volume loss related to high chest wall compliance, and simulates laryngeal braking for elevation of end-expiratory lung volume and constant positive airway pressure (CPAP). The model predicts that low chest wall compliance (chest stiffening) in addition to laryngeal braking and CPAP enhance breathing and delay lung volume loss. These results motivate future data collection strategies and investigation into treatments for chest wall stiffening.
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Affiliation(s)
- Laura Ellwein Fix
- Department of Mathematics and Applied Mathematics, Virginia Commonwealth University, Richmond, Virginia, United States of America
- * E-mail:
| | - Joseph Khoury
- Division of Neonatal Medicine, Children’s Hospital of Richmond, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Russell R. Moores
- Division of Neonatal Medicine, Children’s Hospital of Richmond, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Lauren Linkous
- Department of Mathematics and Applied Mathematics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Matthew Brandes
- VCU School of Medicine, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Henry J. Rozycki
- Division of Neonatal Medicine, Children’s Hospital of Richmond, Virginia Commonwealth University, Richmond, Virginia, United States of America
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Torres‐Tamayo N, García‐Martínez D, Lois Zlolniski S, Torres‐Sánchez I, García‐Río F, Bastir M. 3D analysis of sexual dimorphism in size, shape and breathing kinematics of human lungs. J Anat 2018; 232:227-237. [PMID: 29148039 PMCID: PMC5770305 DOI: 10.1111/joa.12743] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2017] [Indexed: 11/30/2022] Open
Abstract
Sexual dimorphism in the human respiratory system has been previously reported at the skeletal (cranial and thoracic) level, but also at the pulmonary level. Regarding lungs, foregoing studies have yielded sex-related differences in pulmonary size as well as lung shape details, but different methodological approaches have led to discrepant results on differences in respiratory patterns between males and females. The purpose of this study is to analyse sexual dimorphism in human lungs during forced respiration using 3D geometric morphometrics. Eighty computed tomographies (19 males and 21 females) were taken in maximal forced inspiration (FI) and expiration (FE), and 415 (semi)landmarks were digitized on 80 virtual lung models for the 3D quantification of pulmonary size, shape and kinematic differences. We found that males showed larger lungs than females (P < 0.05), and significantly greater size and shape differences between FI and FE. Morphologically, males have pyramidal lung geometry, with greater lower lung width when comparing with the apices, in contrast to the prismatic lung shape and similar widths at upper and lower lungs of females. Multivariate regression analyses confirmed the effect of sex on lung size (36.26%; P < 0.05) and on lung shape (7.23%; P < 0.05), and yielded two kinematic vectors with a small but statistically significant angle between them (13.22°; P < 0.05) that confirms sex-related differences in the respiratory patterns. Our 3D approach shows sexual dimorphism in human lungs likely due to a greater diaphragmatic action in males and a predominant intercostal muscle action in females during breathing. These size and shape differences would lead to different respiratory patterns between sexes, whose physiological implications need to be studied in future research.
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Affiliation(s)
- Nicole Torres‐Tamayo
- Paleoanthropology GroupMuseo Nacional de Ciencias Naturales (CSIC)MadridSpain
- Biology DepartmentFaculty of SciencesAutonoma University of MadridMadridSpain
| | - Daniel García‐Martínez
- Paleoanthropology GroupMuseo Nacional de Ciencias Naturales (CSIC)MadridSpain
- Biology DepartmentFaculty of SciencesAutonoma University of MadridMadridSpain
| | | | | | - Francisco García‐Río
- Hospital Universitario La PazInstitute of Biomedical Research (Idipaz)MadridSpain
| | - Markus Bastir
- Paleoanthropology GroupMuseo Nacional de Ciencias Naturales (CSIC)MadridSpain
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Bifurcation of the respiratory response to lung inflation in anesthetized dogs. Respir Physiol Neurobiol 2017; 244:26-31. [PMID: 28698025 DOI: 10.1016/j.resp.2017.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 06/26/2017] [Accepted: 06/28/2017] [Indexed: 11/23/2022]
Abstract
Numerous studies have demonstrated the effect of lung volume on prolongation of duration of expiration (TE) with limited understanding of the TE shortening and termination of expiration as observed in newborn. In 14 dogs, the effects of varied onset of lung inflation during expiration on the TE were evaluated. When lung inflation was applied in the first part of expiration (20-60% of TE) TE was lengthened. However, in the second portion (60-80% of TE) of expiration, lung inflation either terminated or prolonged TE; whereas in the last portion of expiration (80-90% of TE), lung inflation tended to terminate expiration prematurely. The effects were abolished after bilateral vagotomy. We postulate that prolongation of TE relates to the Breuer-Hering inflation reflex, which increases the time needed for a passive expiration; whereas the ability to shorten TE could relate to Head's paradoxical reflex acting to initiate inspiration or to activate inspiratory motor activity to brake expiratory flow as occurs in the newborn.
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Siew ML, van Vonderen JJ, Hooper SB, te Pas AB. Very Preterm Infants Failing CPAP Show Signs of Fatigue Immediately after Birth. PLoS One 2015; 10:e0129592. [PMID: 26052947 PMCID: PMC4460041 DOI: 10.1371/journal.pone.0129592] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 05/10/2015] [Indexed: 11/30/2022] Open
Abstract
Objective To investigate the differences in breathing pattern and effort in infants at birth who failed or succeeded on continuous positive airway pressure (CPAP) during the first 48 hours after birth. Methods Respiratory function recordings of 32 preterm infants were reviewed of which 15 infants with a gestational age of 28.6 (0.7) weeks failed CPAP and 17 infants with a GA of 30.1 (0.4) weeks did not fail CPAP. Frequency, duration and tidal volumes (VT) of expiratory holds (EHs), peak inspiratory flows, CPAP-level and FiO2-levels were analysed. Results EH incidence increased <6 minutes after birth and remained stable thereafter. EH peak inspiratory flows and VT were similar between CPAP-fail and CPAP-success infants. At 9-12 minutes, CPAP-fail infants more frequently used smaller VTs, 0-9 ml/kg and required higher peak inspiratory flows. However, CPAP-success infants often used large VTs (>9 ml/kg) with higher peak inspiratory flows than CPAP-fail infants (71.8 ± 15.8 vs. 15.5 ± 5.2 ml/kg.s, p <0.05). CPAP-fail infants required higher FiO2 (0.31 ± 0.03 vs. 0.21 ± 0.01), higher CPAP pressures (6.62 ± 0.3 vs. 5.67 ± 0.26 cmH2O) and more positive pressure-delivered breaths (45 ± 12 vs. 19 ± 9%) (p <0.05) Conclusion At 9-12 minutes after birth, CPAP-fail infants more commonly used lower VTs and required higher peak inspiratory flow rates while receiving greater respiratory support. VT was less variable and larger VT was infrequently used reflecting early signs of fatigue.
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Affiliation(s)
- Melissa L. Siew
- The Ritchie Centre, MIMR-PHI, Monash University, Clayton, Australia
- * E-mail:
| | - Jeroen J. van Vonderen
- Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, the Netherlands
| | - Stuart B. Hooper
- The Ritchie Centre, MIMR-PHI, Monash University, Clayton, Australia
| | - Arjan B. te Pas
- Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, the Netherlands
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Le Rolle V, Samson N, Praud JP, Hernández AI. Mathematical modeling of respiratory system mechanics in the newborn lamb. Acta Biotheor 2013; 61:91-107. [PMID: 23381500 DOI: 10.1007/s10441-013-9175-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 01/07/2013] [Indexed: 11/27/2022]
Abstract
In this paper, a mathematical model of the respiratory mechanics is used to reproduce experimental signal waveforms acquired from three newborn lambs. As the main challenge is to determine specific lamb parameters, a sensitivity analysis has been realized to find the most influent parameters, which are identified using an evolutionary algorithm. Results show a close match between experimental and simulated pressure and flow waveforms obtained during spontaneous ventilation and pleural pressure variations acquired during the application of positive pressure, since root mean square errors equal to 0.0119, 0.0052 and 0.0094. The identified parameters were discussed in light of previous knowledge of respiratory mechanics in the newborn.
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Shiraishi M, Hirasawa K, Shimizu S, Nishida H, Osawa M. Effect of sitting position on respiratory status in preterm infants. J Perinat Med 2009; 37:407-12. [PMID: 19309252 DOI: 10.1515/jpm.2009.059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To evaluate whether using a sitting-type car safety seats for preterm infants is advisable. PATIENTS AND METHODS A total of 65 preterm infants underwent polysomnography in the supine and sitting positions. The infants with <95% of SpO(2) were assigned to the desaturation (DS) group. Their backgrounds, breathing patterns, and breathing types were analyzed. RESULTS Of the 65 cases, 18 were assigned to the DS group. No significant differences were observed between the DS and non-DS groups in their background characteristics. Of the 18 DS cases, 15 were included in the non-obstructive group (8, periodic breathing; 6, tachypnea; 1, irregular breathing). CONCLUSIONS Immaturity of the respiratory center and decompensation for the respiratory changes caused by the sitting position were suspected to cause DS in infants. Sitting-type car safety seats should be used with caution for preterm infants, and all preterm infants need to be screened by polysomnographic examination in the sitting position.
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Affiliation(s)
- Mika Shiraishi
- Department of Pediatrics, Tokyo Women's Medical University, Tokyo, Japan.
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Trias EL, Hassantoufighi A, Prince GA, Eichelberger MC. Comparison of airway measurements during influenza-induced tachypnea in infant and adult cotton rats. BMC Pulm Med 2009; 9:28. [PMID: 19515232 PMCID: PMC2706213 DOI: 10.1186/1471-2466-9-28] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Accepted: 06/10/2009] [Indexed: 11/16/2022] Open
Abstract
Background Increased respiratory rate (tachypnea) is frequently observed as a clinical sign of influenza pneumonia in pediatric patients admitted to the hospital. We previously demonstrated that influenza infection of adult cotton rats (Sigmodon hispidus) also results in tachypnea and wanted to establish whether this clinical sign was observed in infected infant cotton rats. We hypothesized that age-dependent differences in lung mechanics result in differences in ventilatory characteristics following influenza infection. Methods Lung tidal volume, dynamic elastance, resistance, and pleural pressure were measured in a resistance and compliance system on mechanically-ventilated anesthestized young (14–28 day old) and adult (6–12 week old) cotton rats. Animals at the same age were infected with influenza virus, and breathing rates and other respiratory measurements were recorded using a whole body flow plethysmograph. Results Adult cotton rats had significantly greater tidal volume (TV), and lower resistance and elastance than young animals. To evaluate the impact of this increased lung capacity and stiffening on respiratory disease, young and adult animals were infected intra-nasally with influenza A/Wuhan/359/95. Both age groups had increased respiratory rate and enhanced pause (Penh) during infection, suggesting lower airway obstruction. However, in spite of significant tachypnea, the infant (unlike the adult) cotton rats maintained the same tidal volume, resulting in an increased minute volume. In addition, the parameters that contribute to Penh were different: while relaxation time between breaths and time of expiration was decreased in both age groups, a disproportionate increase in peak inspiratory and expiratory flow contributed to the increase in Penh in infant animals. Conclusion While respiratory rate is increased in both adult and infant influenza-infected cotton rats, the volume of air exchanged per minute (minute volume) is increased in the infant animals only. This is likely to be a consequence of greater lung elastance in the very young animals. This model replicates many respiratory features of humans and consequently may be a useful tool to investigate new strategies to treat respiratory disease in influenza-infected infants.
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Affiliation(s)
- Elman L Trias
- Children's National Medical Center, Washington, DC 20010, USA.
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Siew ML, Wallace MJ, Kitchen MJ, Lewis RA, Fouras A, Te Pas AB, Yagi N, Uesugi K, Siu KKW, Hooper SB. Inspiration regulates the rate and temporal pattern of lung liquid clearance and lung aeration at birth. J Appl Physiol (1985) 2009; 106:1888-95. [PMID: 19342434 DOI: 10.1152/japplphysiol.91526.2008] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
At birth, the initiation of pulmonary gas exchange is dependent on air entry into the lungs, and recent evidence indicates that pressures generated by inspiration may be involved. We have used simultaneous plethysmography and phase-contrast X-ray imaging to investigate the contribution of inspiration and expiratory braking maneuvers (EBMs) to lung aeration and the formation of a functional residual capacity (FRC) after birth. Near-term rabbit pups (n = 26) were delivered by cesarean section, placed in a water plethysmograph, and imaged during the initiation of spontaneous breathing. Breath-by-breath changes in lung gas volumes were measured using plethysmography and visualized using phase-contrast X-ray imaging. Pups rapidly (1-5 breaths) generate a FRC (16.2 +/- 1.2 ml/kg) by inhaling a greater volume than they expire (by 2.9 +/- 0.4 ml.kg(-1).breath(-1) over the first 5 breaths). As a result, 94.8 +/- 1.4% of lung aeration occurred during inspiration over multiple breaths. The incidence of EBMs was rare early during lung aeration, with most (>80%) occurring after >80% of max FRC was achieved. Although EBMs were associated with an overall increase in FRC, 34.8 +/- 5.3% of EBMs were associated with a decrease in FRC. We conclude that lung aeration is predominantly achieved by inspiratory efforts and that EBMs help to maintain FRC following its formation.
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Affiliation(s)
- Melissa L Siew
- Department of Physiology, Monash University, Melbourne, Victoria 3800, Australia
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te Pas AB, Wong C, Kamlin COF, Dawson JA, Morley CJ, Davis PG. Breathing patterns in preterm and term infants immediately after birth. Pediatr Res 2009; 65:352-6. [PMID: 19391251 DOI: 10.1203/pdr.0b013e318193f117] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
There is limited data describing how preterm and term infants breathe spontaneously immediately after birth. We studied spontaneously breathing infants >or=29 wk immediately after birth. Airway flow and tidal volume were measured for 90 s using a hot wire anemometer attached to a facemask. Twelve preterm and 13 term infants had recordings suitable for analysis. The median (interquartile range) proportion of expiratory braking was very high in both groups (preterm 90 [74-99] vs. term 87 [74-94]%; NS). Crying pattern was the predominant breathing pattern for both groups (62 [36-77]% vs. 64 [46-79]%; NS). Preterm infants showed a higher incidence of expiratory hold pattern (9 [4-17]% vs. 2 [0-6]%; p = 0.02). Both groups had large tidal volumes (6.7 [3.9] vs. 6.5 [4.1] mL/kg), high peak inspiratory flows (5.7 [3.8] vs. 8.0 [5] L/min), lower peak expiratory flow (3.6 [2.4] vs. 4.8 [3.2] L/min), short inspiration time (0.31 [0.13] vs. 0.32 [0.16] s) and long expiration time (0.93 [0.64] vs. 1.14 [0.86] s). Directly after birth, both preterm and term infants frequently brake their expiration, mostly by crying. Preterm infants use significantly more expiratory breath holds to defend their lung volume.
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Affiliation(s)
- Arjan B te Pas
- Division of Newborn Services, Royal Women's Hospital, Carlton, Victoria 3053, Australia.
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Le Rolle V, Hernandez AI, Carrault G, Samson N, Praud JP. A model of ventilation used to interpret newborn lamb respiratory signals. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2008:4945-8. [PMID: 19163826 DOI: 10.1109/iembs.2008.4650323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This paper presents a model-based method for the analysis of respiratory signals specifically adapted to newborns. The model includes a description of upper airways, distensible and lower airways, lungs, chest wall, alveoli, pleura and respiratory muscle activity. The model was used in stationary and non-stationary conditions to simulate respiratory signals obtained in one newborn lamb in various physiological conditions. An identification algorithm was used to adapt the model parameters to lamb data. Finally, the identified parameters were compared to values previously reported in adult humans.
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te Pas AB, Davis PG, Hooper SB, Morley CJ. From liquid to air: breathing after birth. J Pediatr 2008; 152:607-11. [PMID: 18410760 DOI: 10.1016/j.jpeds.2007.10.041] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 09/19/2007] [Accepted: 10/24/2007] [Indexed: 11/30/2022]
Affiliation(s)
- Arjan B te Pas
- Division of Newborn Services, Royal Women's Hospital, Carlton, Victoria, Australia
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Pilarski JQ, Hempleman SC. Development of avian intrapulmonary chemoreceptors. Respir Physiol Neurobiol 2007; 157:393-402. [PMID: 17331814 DOI: 10.1016/j.resp.2007.01.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2006] [Revised: 01/23/2007] [Accepted: 01/23/2007] [Indexed: 10/23/2022]
Abstract
Although avian intrapulmonary chemoreceptors (IPC) have been studied extensively in adults, the maturation of IPC CO(2) sensitivity during development is completely unknown. To begin investigating IPC development we asked two fundamental questions: (1) Are IPC capable of sensing CO(2) during early development, and, if so, how early? And, (2) does IPC CO(2) sensitivity during early development exhibit postnatal maturation compared to IPC discharge characteristics in adult ducks? We addressed these questions by recording from single IPC Anas platyrhynchos ducklings beginning approximately 6 h prior to internal pipping through 4 days of postnatal development. We then compared mean IPC discharge characteristics during early development with mean IPC activity from adult ducks greater than 12 weeks old. In total, we recorded 28 individual IPC from 5 ducklings and 12 adult ducks. Results show that IPC were capable of responding to rapid step changes in CO(2) before hatching occurred, during the paranatal developmental period. We also found that mean IPC activity during early development had increased peak discharge frequencies, greater spike frequency adaptation, and less tonic CO(2) sensitivity when compared to adults (P< or =0.05). These results suggest that during early development phasic IPC CO(2) sensitivity is fully developed, yet tonic IPC CO(2) sensitivity exhibits postnatal maturation possibly associated with hatching. These results also suggest that the mechanisms that underlie phasic and tonic IPC action potential discharge, and therefore the degree of partial spike frequency adaptation, may be independent processes with different developmental trajectories.
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Affiliation(s)
- Jason Q Pilarski
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona 86011-5640, USA.
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Romaniuk JR, Dick TE, Kowalski KE, Dimarco AF. Effects of pulse lung inflation on chest wall expiratory motor activity. J Appl Physiol (1985) 2006; 102:485-91. [PMID: 16959914 DOI: 10.1152/japplphysiol.00130.2006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effects of pulse lung inflation (LI) on expiratory muscle activity and phase duration (Te) were determined in anesthetized, spontaneously breathing dogs (n = 20). A volume syringe was used to inflate the lungs at various times during the expiratory phase. The magnitude of lung volume was assessed by the corresponding change in airway pressure (Paw; range 2-20 cmH(2)O). Electromyographic (EMG) activities were recorded from both thoracic and abdominal muscles. Parasternal muscle EMG was used to record inspiratory activity. Expiratory activity was assessed from the triangularis sterni (TS), internal intercostal (IIC), and transversus abdominis (TA) muscles. Lung inflations <7 cmH(2)O consistently inhibited TS activity but had variable effects on TA and IIC activity and expiratory duration. Lung inflations resulting in Paw values >7 cmH(2)O, however, inhibited expiratory EMG activity of each of the expiratory muscles and lengthened Te in all animals. The responses of expiratory EMG and Te were directly related to the magnitude of the lung inflation. The inhibition of expiratory motor activity was independent of the timing of pulse lung inflation during the expiratory phase. The inhibitory effects of lung inflation were eliminated by bilateral vagotomy and could be reproduced by electrical stimulation of the vagus nerve. We conclude that pulse lung inflation resulting in Paw between 7 and 20 cmH(2)O produces a vagally mediated inhibition of expiratory muscle activity that is directly related to the magnitude of the inflation. Lower inflation pressures produce variable effects that are muscle specific.
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Affiliation(s)
- Jaroslaw R Romaniuk
- Department of Physiology, Case Western Reserve University, MetroHealth Medical Center, Cleveland, USA
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Frappell PB, MacFarlane PM. Development of the respiratory system in marsupials. Respir Physiol Neurobiol 2006; 154:252-67. [PMID: 16781204 DOI: 10.1016/j.resp.2006.05.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2005] [Revised: 04/30/2006] [Accepted: 05/01/2006] [Indexed: 10/24/2022]
Abstract
Marsupials at birth are small and relatively undeveloped. At birth, the lung in some species is at the canalicular stage of development and though lung diffusion and metabolic rate are strongly correlated, the allometric exponent suggests that smaller newborns have relatively smaller diffusing capacity with respect to their demand for oxygen. Without improvement in functional or structural parameters newborn marsupials are reliant to varying degrees on skin gas exchange to compensate for the immaturity of the lung. Indeed, in some species there is complete reliance on the skin for gas exchange at birth. Nevertheless, with an early dependence on ventilation, the CNS would appear already to contain neurons with properties and connections that permit rhythmic motor output at birth and pulmonary reflexes mature soon after. Despite appropriate neural control and the presence of surfactant, the highly compliant nature of the newborn chest wall results in substantial chest wall distortion during inspiratory effort which reduce the efficacy of the lung for ventilation. This review explores the morpho-functional development of the respiratory system, including oxygen transport and cardiac shunts, and the establishment of convective requirement in marsupials, a group that places emphasis on extended postnatal development.
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Affiliation(s)
- P B Frappell
- Adaptational and Evolutionary Respiratory Physiology Laboratory, Department of Zoology, La Trobe University, Melbourne 3086, Vic., Australia.
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