1
|
Marinho CDL, Maioli MCP, do Amaral JLM, Lopes AJ, de Melo PL. Respiratory resistance and reactance in adults with sickle cell anemia: Correlation with functional exercise capacity and diagnostic use. PLoS One 2017; 12:e0187833. [PMID: 29220407 PMCID: PMC5722327 DOI: 10.1371/journal.pone.0187833] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 10/26/2017] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND The improvement in sickle cell anemia (SCA) care resulted in the emergence of a large population of adults living with this disease. The mechanisms of lung injury in this new population are largely unknown. The forced oscillation technique (FOT) represents the current state-of-the-art in the assessment of lung function. The present work uses the FOT to improve our knowledge about the respiratory abnormalities in SCA, evaluates the associations of FOT with the functional exercise capacity and investigates the early detection of respiratory abnormalities. METHODOLOGY/PRINCIPAL FINDINGS Spirometric classification of restrictive abnormalities resulted in three categories: controls (n = 23), patients with a normal exam (n = 21) and presenting pulmonary restriction (n = 24). FOT analysis showed that, besides restrictive changes (reduced compliance; p<0.001), there is also an increase in respiratory resistance (p<0.001) and ventilation heterogeneity (p<0.01). FOT parameters are associated with functional exercise capacity (R = -0.38), pulmonary diffusion (R = 0.66), respiratory muscle performance (R = 0.41), pulmonary volumes (R = 0.56) and airway obstruction (R = 0.54). The diagnostic accuracy was evaluated by investigating the area under the receiver operating characteristic curve (AUC). A combination of FOT and machine learning (ML) classifiers showed adequate diagnostic accuracy in the detection of early respiratory abnormalities (AUC = 0.82). CONCLUSIONS In this study, the use of FOT showed that adults with SCA develop a mixed pattern of respiratory disease. Changes in FOT parameters are associated with functional exercise capacity decline, abnormal pulmonary mechanics and diffusion. FOT associated with ML methods accurately diagnosed early respiratory abnormalities. This suggested the potential utility of the FOT and ML clinical decision support systems in the identification of respiratory abnormalities in patients with SCA.
Collapse
Affiliation(s)
- Cirlene de Lima Marinho
- Biomedical Instrumentation Laboratory—Institute of Biology and Faculty of Engineering, and BioVasc Research Laboratory—Institute of Biology, State University of Rio de Janeiro, Rio de Janeiro—Brazil
| | | | - Jorge Luis Machado do Amaral
- Department of Electronics and Telecommunications Engineering, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Agnaldo José Lopes
- School of Medical Sciences, Pulmonary Function Testing Laboratory, Rio de Janeiro/RJ, State University of Rio de Janeiro, Rio de Janeiro–Brazil
- Rehabilitation Sciences Post-Graduation Program, Augusto Motta University Centre, Rio de Janeiro, Brazil
| | - Pedro Lopes de Melo
- Biomedical Instrumentation Laboratory—Institute of Biology and Faculty of Engineering, and BioVasc Research Laboratory—Institute of Biology, State University of Rio de Janeiro, Rio de Janeiro—Brazil
| |
Collapse
|
2
|
Lee GD, Kim HC, Yoo JW, Lee SJ, Cho YJ, Bae K, Lee JD. Computed tomography confirms a reduction in diaphragm thickness in mechanically ventilated patients. J Crit Care 2016; 33:47-50. [PMID: 26979912 DOI: 10.1016/j.jcrc.2016.02.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 02/12/2016] [Accepted: 02/14/2016] [Indexed: 11/16/2022]
Abstract
PURPOSE Patients who require mechanical ventilation (MV) may experience diaphragm atrophy, which may delay the discontinuation of MV. Here, we used computed tomographic (CT) scans to confirm this phenomenon. METHOD AND MATERIALS Patients who underwent two chest CT scans while on MV were retrospectively evaluated. Diaphragm thickness was measured using a three-dimensional CT image processing program. RESULTS Thirteen patients, including 8 men, who underwent 26 CT scans were assessed. The mean age was 67.8 ± 7.5 years. The interval between CT scans was 18.4 ± 14.9 days. The first CT scans revealed that the mean thicknesses of the left and right sides of the diaphragm were 3.8 ± 0.6 and 3.9 ± 0.8 mm, respectively (total: 7.7 ± 1.4 mm). These values were significantly reduced to 3.4 ± 0.6 and 3.5 ± 0.9 mm, respectively, (total: 6.9 ± 1.5 mm) after the second scan (P < .01). No significant change in body weight (57.3 ± 12.6 vs. 56.7 ± 11.6 kg) or body mass index (21.8 ± 5.1 vs. 21.6 ± 4.8 kg/m(2)) was observed. CONCLUSION Computed tomography confirmed that diaphragm thickness was reduced in critically ill patients who underwent MV.
Collapse
Affiliation(s)
- Gi Dong Lee
- Department of Internal Medicine, Gyeongsang National University School of Medicine, Jinju, Republic of Korea.; Gyeongsang Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea
| | - Ho Cheol Kim
- Department of Internal Medicine, Gyeongsang National University School of Medicine, Jinju, Republic of Korea.; Gyeongsang Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea..
| | - Jung-Wan Yoo
- Department of Internal Medicine, Gyeongsang National University School of Medicine, Jinju, Republic of Korea.; Gyeongsang Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea
| | - Seung Jun Lee
- Department of Internal Medicine, Gyeongsang National University School of Medicine, Jinju, Republic of Korea.; Gyeongsang Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea
| | - Yu Ji Cho
- Department of Internal Medicine, Gyeongsang National University School of Medicine, Jinju, Republic of Korea.; Gyeongsang Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea
| | - Kyungsoo Bae
- Gyeongsang Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea.; Department of Diagnostic Radiology, Gyeongsang National University School of Medicine, Jinju, Republic of Korea
| | - Jong Deog Lee
- Department of Internal Medicine, Gyeongsang National University School of Medicine, Jinju, Republic of Korea.; Gyeongsang Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea
| |
Collapse
|
3
|
Basoudan N, Shadgan B, Guenette JA, Road J, Reid WD. Effect of acute hypoxia on inspiratory muscle oxygenation during incremental inspiratory loading in healthy adults. Eur J Appl Physiol 2016; 116:841-50. [PMID: 26892509 DOI: 10.1007/s00421-016-3334-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 01/22/2016] [Indexed: 11/25/2022]
Abstract
PURPOSE To non-invasively examine the effect of acute hypoxia and inspiratory threshold loading (ITL) on inspiratory muscles [sternocleidomastoid (SCM), scalene (SA) and parasternal (PS)] oxygenation in healthy adults using near-infrared spectroscopy (NIRS). METHODS Twenty healthy adults (12 M/8 F) were randomly assigned to perform two ITL tests while breathing a normoxic or hypoxic (FIO2 = 15 %) gas mixture. NIRS devices were placed over the SCM, PS, SA, and a control muscle, tibialis anterior (TA), to monitor oxygenated (O2Hb), deoxygenated (HHb), total hemoglobin (tHb) and tissue saturation index (TSI). With the nose occluded, subjects breathed normally for 4 min through a mouthpiece that was connected to a weighted threshold loading device. ITL began by adding a 100-g weight to the ITL device. Then, every 2 min 50-g was added until task failure. Vital signs, ECG and ventilatory measures were monitored throughout the protocol. RESULT Participants were 31 ± 12 year and had normal spirometry. At task failure, the maximum load and ventilatory parameters did not differ between the hypoxic and normoxic ITL. At hypoxic ITL task failure, SpO2 was significantly lower, and ∆HHb increased more so in SA, SCM and PS than normoxic values. SCM ∆TSI decreased more so during hypoxic compared to normoxic ITL. ∆tHb in the inspiratory muscles (SCM, PS and SA) increased significantly compared to the decrease in TA during both hypoxic and normoxic ITL. CONCLUSION The SCM, an accessory inspiratory muscle was the most vulnerable to deoxygenation during incremental loading and this response was accentuated by acute hypoxia.
Collapse
Affiliation(s)
- Nada Basoudan
- Department of Physical Therapy, University of British Columbia (UBC), Vancouver, Canada.
- College of Health and Rehabilitation Sciences, Princess Nora Bint Abdul Rahman University, Riyadh, Saudi Arabia.
| | - Babak Shadgan
- International Collaboration on Repair Discoveries, Vancouver, Canada
| | - Jordan A Guenette
- Department of Physical Therapy, University of British Columbia (UBC), Vancouver, Canada
- Centre for Heart Lung Innovation, UBC and St. Paul's Hospital, Vancouver, Canada
| | - Jeremy Road
- Division of Respiratory Medicine, Department of Medicine, UBC, Vancouver, Canada
| | - W Darlene Reid
- Physical Therapy Department, University of Toronto, Toronto, Canada
| |
Collapse
|
4
|
de Bisschop C, Montaudon M, Glénet S, Guénard H. Feasibility of intercostal blood flow measurement by echo-Doppler technique in healthy subjects. Clin Physiol Funct Imaging 2015; 37:282-287. [DOI: 10.1111/cpf.12298] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 08/03/2015] [Indexed: 11/26/2022]
Affiliation(s)
| | - Michel Montaudon
- Unité d'imagerie thoracique et cardiovasculaire (Pr Laurent); Hôpital du Haut-Lévêque; CHU de Bordeaux; France
| | - Stéphane Glénet
- Laboratoire de physiologie; Université de Bordeaux; Bordeaux Cedex France
| | - Hervé Guénard
- Laboratoire de physiologie; Université de Bordeaux; Bordeaux Cedex France
| |
Collapse
|
5
|
Kallio M, Peltoniemi O, Anttila E, Jounio U, Pokka T, Kontiokari T. Electrical activity of the diaphragm during neurally adjusted ventilatory assist in pediatric patients. Pediatr Pulmonol 2015; 50:925-31. [PMID: 25103680 DOI: 10.1002/ppul.23084] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 05/15/2014] [Accepted: 05/22/2014] [Indexed: 11/05/2022]
Abstract
BACKGROUND Neurally adjusted ventilatory assist (NAVA) is a ventilation mode which provides respiratory support proportional to the electrical activity of the diaphragm (Edi). The aims of this trial were to assess the feasibility of aiming at peak Edi between 5 and 15 µV during NAVA in clinical practice, to study the effect of age, sedation level and ventilatory settings on the Edi signal and to give some reference values for Edi in a pediatric population. METHODS As a part of a larger randomized controlled trial, 81 patients received Edi catheter for monitoring Edi and guiding NAVA ventilation. The goal for peak Edi during invasive ventilation was 5-15 µV. Edi activity and NAVA levels were observed during invasive ventilation and an hour after extubation. RESULTS Sixty-six patients with healthy lungs (81.5%) were ventilated, mostly as part of postoperative care, while respiratory distress was the indication for invasive ventilation in the remaining 15 patients (18.5%). NAVA levels varied from 0.2 to 2.0 cmH2O/µV in the patients with healthy lungs, but were higher, from 0.7 to 4.0 cmH2O/µV, in the respiratory distress patients (P < 0.001). The latter had higher peak Edi values in all phases of treatment. The effect of age and level of sedation on Edi was statistically significant, but carried only limited clinical relevance. The peak post-extubation Edi levels of the patients with healthy lungs and respiratory distress, respectively, were 9 ± 7 and 20 ± 14 µV. Two out of the three patients for whom extubation failed had an atypical Edi pattern prior to extubation. CONCLUSIONS Optimizing the level of support during NAVA by aiming at a peak Edi between 5 and 15 µV was an applicable strategy in our pediatric population. Relatively high post-extubation Edi signal levels were seen in patients recovering from respiratory distress. Information revealed by the Edi signal could be used to find patients with a potential risk of extubation failure.
Collapse
Affiliation(s)
- Merja Kallio
- Department of Pediatrics, Oulu University Hospital, Oulu, Finland
| | - Outi Peltoniemi
- Department of Pediatrics, Oulu University Hospital, Oulu, Finland
| | - Eija Anttila
- Department of Pediatrics, Oulu University Hospital, Oulu, Finland
| | - Ulla Jounio
- Department of Pediatrics, Oulu University Hospital, Oulu, Finland
| | - Tytti Pokka
- Department of Pediatrics, Oulu University Hospital, Oulu, Finland
| | | |
Collapse
|
6
|
Simpson JA, Iscoe S. Hypoxia, not hypercapnia, induces cardiorespiratory failure in rats. Respir Physiol Neurobiol 2014; 196:56-62. [PMID: 24566393 DOI: 10.1016/j.resp.2014.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 02/06/2014] [Accepted: 02/16/2014] [Indexed: 12/29/2022]
Abstract
Mechanical respiratory loads induce cardiorespiratory failure, presumably by increasing O2 demand concurrently with decreases in O2 availability (decreased PaO2). We tested the hypothesis that asphyxia alone can cause cardiorespiratory failure ("failure") in pentobarbital-anesthetized rats. We also tested the hypothesis that hypoxia, not hypercapnia, is responsible by supplying supplemental O2 during mechanical loading in a separate group of rats. Asphyxia (mean PaO2 and PaCO2 of 43 and 69mmHg, respectively) resulted in failure, evident as a slowing of mean respiratory frequency (133-83breaths/min) and a sudden and large drop in mean arterial pressure (71-47mmHg), after 214±66min (n=16; range 117-355min). Neither respiratory drive nor heart rate decreased, indicating that failure was peripheral, not central. Of 8 rats tested after 3h of asphyxia for the presence in blood of cardiac troponin T, all were positive. In an additional 6 rats, normocapnic hypoxia (mean PaCO2 and PaO2 were 39±2.2 and 41±3.1mmHg, respectively) caused failure after an average 205min (range 181-275min), no different from that of asphyxic rats. In the 6 rats that breathed O2 during an initially moderate inspiratory resistive load, endurances exceeded 7h (failure occurring only because we increased the load after 6h) and tracheal pressure and left ventricular dP/dt were maintained despite supercarbia (PaCO2>150mmHg). Thus, asphyxia alone can induce failure, the failure is due to hypoxia, not hypercapnia, and hypercapnia has minimal effects on cardiac and respiratory muscle function in the presence of hyperoxia.
Collapse
Affiliation(s)
- J A Simpson
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6.
| | - S Iscoe
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6
| |
Collapse
|
7
|
Ong BA, Caboot J, Jawad A, McDonough J, Jackson T, Arens R, Marcus CL, Smith-Whitley K, Mason TBA, Ohene-Frempong K, Allen JL. Respiratory muscle force and lung volume changes in a population of children with sickle cell disease. Br J Haematol 2013; 163:112-7. [PMID: 23869561 PMCID: PMC3776481 DOI: 10.1111/bjh.12481] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 06/19/2013] [Indexed: 11/29/2022]
Abstract
Sickle cell disease (SCD) is a disorder known to impact the respiratory system. We sought to identify respiratory muscle force and lung volume relationships in a paediatric SCD population. Thirty-four SCD-SS subjects underwent pulmonary function testing. Height, weight, age, and gender-adjusted percent predicted maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) values were compared to spirometry and lung volumes. Statistical analyses were performed using Pearson's correlation coefficient and paired two-tailed t-test. The mean ± standard deviation (SD) MIP and MEP was 69·6 ± 31·6 cm H2 O and 66·9 ± 22·9 cm H2 O, respectively, and mean ± SD percent predicted MIP (101·3 ± 45·9) exceeded MEP (72·1 ± 26·0) (P = 0·002). MIP correlated with forced vital capacity (FVC; r = 0·51, P = 0·001) and TLC (r = 0·54, P < 0·0001). MEP also correlated with FVC (r = 0·43, P = 0·011) and total lung capacity (TLC; r = 0·42, P = 0·013). Pearson's correlation coefficient testing yielded relationships between MIP and MEP (r = 0·64, P < 0·0001). SCD-SS patients showed correlations between respiratory muscle force and lung volume, and reduced percent predicted expiratory muscle force compared to inspiratory muscle force. Respiratory muscle strength may affect lung volumes in these patients, and expiratory muscles may be more susceptible than the diaphragm to SCD-induced vaso-occlusive damage.
Collapse
Affiliation(s)
- Bruce A Ong
- Division of Pediatric Pulmonology, Tripler Army Medical Center, Honolulu, HI, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Interest of monitoring diaphragmatic electrical activity in the pediatric intensive care unit. Crit Care Res Pract 2013; 2013:384210. [PMID: 23509617 PMCID: PMC3594948 DOI: 10.1155/2013/384210] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 01/15/2013] [Accepted: 01/21/2013] [Indexed: 01/03/2023] Open
Abstract
The monitoring of electrical activity of the diaphragm (EAdi) is a new minimally invasive bedside technology that was developed for the neurally adjusted ventilatory assist (NAVA) mode of ventilation. In addition to its role in NAVA ventilation, this technology provides the clinician with previously unavailable and essential information on diaphragm activity. In this paper, we review the clinical interests of EAdi in the pediatric intensive care setting. Firstly, the monitoring of EAdi allows the clinician to tailor the ventilatory settings on an individual basis, avoiding frequent overassistance leading potentially to diaphragmatic atrophy. Increased inspiratory EAdi levels can also suggest insufficient support, while a strong tonic activity may reflect the patient efforts to increase its lung volume. EAdi monitoring also allows detection of patient-ventilator asynchrony. It can play a role in evaluation of extubation readiness. Finally, EAdi monitoring provides the clinician with better understanding of the ventilatory capacity of patients with acute neuromuscular disease. Further studies are warranted to evaluate the clinical impact of these potential benefits.
Collapse
|
9
|
Abstract
OBJECTIVE Regional blood flow to the diaphragm muscle varies with the workload of inspiration. To provide anatomical insight into coupling between muscle fiber recruitment and oxygen supply, we tested whether arterioles are physically associated with motor nerve branches of the diaphragm. METHODS Following vascular casting, intact diaphragm muscles of C57BL/6 and CD-1 mice were stained for motor innervation. Arteriolar networks and nerve networks were mapped (~2 μm resolution) to evaluate their physical proximity. RESULTS Neurovascular proximity was similar between muscle regions and mouse strains. Of total mapped nerve lengths (C57BL/6, 70 ± 15 mm; CD-1, 87 ± 13 mm), 80 ± 14% and 67 ± 10% were ≤250 μm from the nearest arteriole and associated predominantly with arterioles ≤45 μm in diameter. Distances to the nearest arteriole encompassing 50% of total nerve length (D(50)) were consistently within 200 μm. With nerve networks repositioned randomly within muscle borders, D(50) values nearly doubled (p < 0.05). Reference lines within anatomical boundaries reduced proximity to arterioles (p < 0.05) as they deviated from the original location of motor nerves. CONCLUSION Across two strains of mice, motor nerves and arterioles of the diaphragm muscle are more closely associated than can be explained by chance. We hypothesize that neurovascular proximity facilitates local perfusion upon muscle fiber recruitment.
Collapse
Affiliation(s)
- Diego Correa
- The John B. Pierce Laboratory, New Haven, Connecticut, USA.
| | | |
Collapse
|
10
|
Vogiatzis I, Athanasopoulos D, Habazettl H, Kuebler WM, Wagner H, Roussos C, Wagner PD, Zakynthinos S. Intercostal muscle blood flow limitation in athletes during maximal exercise. J Physiol 2009; 587:3665-77. [PMID: 19451206 PMCID: PMC2742289 DOI: 10.1113/jphysiol.2009.171694] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 05/13/2009] [Indexed: 11/08/2022] Open
Abstract
We investigated whether, during maximal exercise, intercostal muscle blood flow is as high as during resting hyperpnoea at the same work of breathing. We hypothesized that during exercise, intercostal muscle blood flow would be limited by competition from the locomotor muscles. Intercostal (probe over the 7th intercostal space) and vastus lateralis muscle perfusion were measured simultaneously in ten trained cyclists by near-infrared spectroscopy using indocyanine green dye. Measurements were made at several exercise intensities up to maximal (WRmax) and subsequently during resting isocapnic hyperpnoea at minute ventilation levels up to those at WRmax. During resting hyperpnoea, intercostal muscle blood flow increased linearly with the work of breathing (R2 = 0.94) to 73.0 +/- 8.8 ml min-1 (100 g)-1 at the ventilation seen at WRmax (work of breathing approximately 550-600 J min-1), but during exercise it peaked at 80% WRmax (53.4 +/- 10.3 ml min-1 (100 g)-1), significantly falling to 24.7 +/- 5.3 ml min-1 (100 g)-1 at WRmax. At maximal ventilation intercostal muscle vascular conductance was significantly lower during exercise (0.22 +/- 0.05 ml min-1 (100 g)-1 mmHg-1) compared to isocapnic hyperpnoea (0.77 +/- 0.13 ml min-1 (100 g)-1 mmHg-1). During exercise, both cardiac output and vastus lateralis muscle blood flow also plateaued at about 80% WRmax (the latter at 95.4 +/- 11.8 ml min-1 (100 g)-1). In conclusion, during exercise above 80% WRmax in trained subjects, intercostal muscle blood flow and vascular conductance are less than during resting hyperpnoea at the same minute ventilation. This suggests that the circulatory system is unable to meet the demands of both locomotor and intercostal muscles during heavy exercise, requiring greater O2 extraction and likely contributing to respiratory muscle fatigue.
Collapse
Affiliation(s)
- Ioannis Vogiatzis
- Department of Critical Care Medicine and Pulmonary Services, Evangelismos Hospital, M. Simou, G. P. Livanos Laboratories, National and Kapodistrian University of Athens, Athens, Greece.
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Abstract
In septic patients increased central drive and increased metabolic demands combine to increase energy demands on the ventilatory muscles. This occurs at a time when energy supplies are limited and energy production hindered, and it leads to an energy supply-demand imbalance and often ventilatory failure. Problems related to contractile function of the ventilatory muscles also contribute, especially when the clinical course is prolonged. The increased ventilatory activity increases interactions between the ventilatory and cardiovascular systems, and when ventilatory muscles fail and mechanical ventilatory support is required a new set of problems emerges. In this review I discuss factors related to ventilatory muscle failure, giving emphasis to mechanical and supply demand aspects. I also review the implications of changes in ventilatory patterns for heart-lung interactions.
Collapse
Affiliation(s)
- Sheldon Magder
- Department of Medicine, Division of Critical Care, McGill University Health Centre, Montreal, Quebec, Canada.
| |
Collapse
|
12
|
Emeriaud G, Beck J, Tucci M, Lacroix J, Sinderby C. Diaphragm electrical activity during expiration in mechanically ventilated infants. Pediatr Res 2006; 59:705-10. [PMID: 16627886 DOI: 10.1203/01.pdr.0000214986.82862.57] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The presence of diaphragm electrical activity (EAdi) during expiration is believed to be involved in the maintenance of end-expiratory lung volume (EELV) and has never been studied in intubated and mechanically ventilated infants. The aim of this study was to quantify the amplitude of diaphragm electrical activity present during expiration in mechanically ventilated infants and to measure the impact of removing positive end-expiratory pressure (PEEP) on this activity. We studied the EAdi in 16 ready-to-be weaned intubated infants who were breathing on their prescribed ventilator and PEEP settings. In all 16 patients, 5 min of data were collected on the prescribed ventilator settings. In a subset of eight patients, the PEEP was briefly reduced to zero PEEP (ZEEP). EAdi was recorded with miniaturized sensors placed on a conventional nasogastric feeding tube. Airway pressure (Paw) was also measured. For each spontaneous breath, we identified the neural inspiration and neural expiration. Neural expiration was divided into quartiles (Q1, Q2, Q3, and Q4), and the amplitude of EAdi calculated for each Q1-Q4 represented 95 +/- 29%, 31 +/- 15%, 15 +/- 8%, and 12 +/- 7%, respectively, of the inspiratory EAdi amplitude. EAdi for Q3-Q4 significantly increased during ZEEP, and decreased after reapplication of PEEP. These findings confirm that the diaphragm remains partially active during expiration in intubated and mechanically ventilated infants and that removal of PEEP affects this tonic activity. This could have potential implications on the management of PEEP in intubated infants.
Collapse
Affiliation(s)
- Guillaume Emeriaud
- Department of Pediatrics, Hôpital Sainte-Justine, Quebec, Canada, H3T 1C5
| | | | | | | | | |
Collapse
|
13
|
Spahija J, Beck J, Lindström L, Bégin P, de Marchie M, Sinderby C. Effect of increased diaphragm activation on diaphragm power spectrum center frequency. Respir Physiol Neurobiol 2005; 146:67-76. [PMID: 15733780 DOI: 10.1016/j.resp.2004.11.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2004] [Indexed: 11/17/2022]
Abstract
Increased transdiaphragmatic pressure, reduced muscle blood flow, and increased duty cycle have all been associated with a reduction in the center frequency (CFdi) of the diaphragm's electrical activity (EAdi). However, the specific influence of diaphragm activation on CFdi is unknown. We evaluated whether increased diaphragm activation would result in a greater decline in the CFdi when pressure-time product (PTPdi) was kept constant. Five healthy subjects performed periods of intermittent quasi-static diaphragmatic contractions with a fixed duty cycle. In separate runs, subjects targeted transdiaphragmatic pressures (Pdi) by performing end-inspiratory holds with the glottis open and expulsive maneuvers at end-expiratory lung volume (EELV). Diaphragm activation and pressures were measured with an electrode array and balloons mounted on an esophago-gastric catheter, respectively. The EAdi, which was 25+/-8%(S.D.) of maximum at EELV, increased to 61+/-8% (P<0.001) when an identical Pdi (averaging 31+/-13 cmH2O) was generated at a higher lung volume (77% of inspiratory capacity). The latter was associated with a 17% greater decline in CFdi (P=0.012). In order to reproduce at EELV, the decrease in CFdi observed at the increased lung volume, a two-fold increase in PTPdi was required. We conclude that CFdi responds specifically to increased diaphragm activation when pressure-time product remains constant.
Collapse
Affiliation(s)
- Jadranka Spahija
- Research Center, Respiratory Health Research Unit, Sacré-Coeur Hospital of Montréal, Montreal, Que., Canada H4J 1C5.
| | | | | | | | | | | |
Collapse
|
14
|
Abstract
Relaxation is the process by which, after contraction, the muscle actively returns to its initial conditions of length and load. In rhythmically active muscles such as diaphragm, relaxation is of physiological importance because diaphragm must return to a relatively constant resting position at the end of each contraction-relaxation cycle. Rapid and complete relaxation of the diaphragm is likely to play an important role in adaptation to changes in respiratory load and breathing frequency. Regulation of diaphragm relaxation at the molecular and cellular levels involves Ca(2+) removal from the myofilaments, active Ca(2+) pumping by the sarcoplasmic reticulum (SR), and decrease in the number of working cross bridges. The relative contribution of these mechanisms mainly depends on sarcomere length, muscle tension, and the intrinsic contractile function. Increased capacity of SR to take up Ca(2+) can arise from increased density of active SR pumping sites or in slow-twitch fibers from phosphorylation of phospholamban, whereas impaired coupling between ATP hydrolysis and Ca(2+) transport into the SR or intracellular acidosis reduces SR Ca(2+) pump activity. In experimental conditions of decreased contractile performance, slowed, enhanced, or unchanged relaxation rates have been reported in vitro. In vivo, a slowing in the rate of decline of the respiratory pressure is generally considered an early reliable index of respiratory muscle fatigue. Impaired relaxation rate may, in turn, favor mismatch between blood flow and metabolic demand, especially at high breathing frequencies.
Collapse
Affiliation(s)
- C Coirault
- Laboratoire d'Optique Appliquée, Ecole Nationale Supérieure des Techniques Avancées, Ecole Polytechnique, Institut National de la Santé et de la Recherche Médicale U 451, Batterie de l'Yvette, 91761 Palaiseau Cedex, France
| | | | | |
Collapse
|
15
|
Danialou G, Vicaut E, Sambe A, Aubier M, Boczkowski J. Predominant role of A1 adenosine receptors in mediating adenosine induced vasodilatation of rat diaphragmatic arterioles: involvement of nitric oxide and the ATP-dependent K+ channels. Br J Pharmacol 1997; 121:1355-63. [PMID: 9257914 PMCID: PMC1564813 DOI: 10.1038/sj.bjp.0701247] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
1. We investigated, by intravital microscopy in rats, the role of the subtypes of adenosine receptors A1 (A1/AR) and A2 (A2AR) in mediating adenosine-induced vasodilatation of second and third order arterioles of the diaphragm. 2. Adenosine, and the A1AR selective agonists R(-)-N6-(2-phenylisopropyl)-adenosine (R-PIA) and N6-cyclo-pentyl-adenosine (CPA) induced a similar concentration-dependent dilatation of diaphragmatic arterioles. The non selective A2AR subtype agonist N6-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl) ethyl]adenosine (DPMA) also dilated diaphragmatic arterioles but induced a significantly smaller dilatation than adenosine. By contrast the selective A(2a)AR subtype agonist 2-[p-(2-carboxyethyl)phenyl amino]-5'-N-ethyl carboxamido adenosine (CGS 21680) did not modify diaphragmatic arteriolar diameter. 3. The non selective adenosine receptor antagonist 1,3-dipropyl-8-p-sulphophenylxanthine (SPX, 100 microM) and the selective A1AR antagonist 8-cyclopentyl-1,3-dipropylxanthine (CPX, 50 nM) significantly attenuated adenosine-induced dilatation of diaphragmatic arterioles. By contrast, adenosine significantly dilated diaphragmatic arterioles in the presence of A2AR antagonist 3,7-dimethyl-1-propargylxanthine (DMPX, 10 microM). 4. The dilatation induced by adenosine was unchanged by the mast cell stabilizing agent sodium cromoglycate (cromolyn, 10 microM). 5. The nitric oxide (NO) synthase inhibitor N omega-nitro-L-arginine (L-NOARG, 300 microM) attenuated the dilatation induced by adenosine, and by the A1AR and A2AR agonists. 6. The ATP-dependent K+ channel blocker glibenclamide (3 microM) significantly attenuated diaphragmatic arteriolar dilatation induced by adenosine and by the A1AR agonists R-PIA and CPA. By contrast, glibenclamide did not significantly modify arteriolar dilatation induced by the A2AR agonist DPMA. 7. These findings suggest that adenosine-induced dilatation of diaphragmatic arterioles in the rat is predominantly mediated by the A1AR, via the release of NO and activation of the ATP-dependent K+ channels.
Collapse
Affiliation(s)
- G Danialou
- INSERM U408, Faculté Xavier Bichat, Paris, France
| | | | | | | | | |
Collapse
|