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Grifoni G, Haissaguerre M, Bongiorni MG, Benali K, Soldati E, Zucchelli G. Short-coupled Purkinje ectopy inducible by pharmacological and hyperventilation tests. HeartRhythm Case Rep 2024; 10:68-71. [PMID: 38264118 PMCID: PMC10801065 DOI: 10.1016/j.hrcr.2023.10.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024] Open
Affiliation(s)
- Gino Grifoni
- Second Division of Cardiology, Cardio-Thoracic and Vascular Department, Pisa University Hospital, Pisa, Italy
| | - Michel Haissaguerre
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, and Bordeaux University Hospital, Bordeaux, France
| | - Maria Grazia Bongiorni
- Second Division of Cardiology, Cardio-Thoracic and Vascular Department, Pisa University Hospital, Pisa, Italy
| | - Karim Benali
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, and Bordeaux University Hospital, Bordeaux, France
- CHU Saint Etienne, University of Rennes, Rennes, France
| | - Ezio Soldati
- Second Division of Cardiology, Cardio-Thoracic and Vascular Department, Pisa University Hospital, Pisa, Italy
| | - Giulio Zucchelli
- Second Division of Cardiology, Cardio-Thoracic and Vascular Department, Pisa University Hospital, Pisa, Italy
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Shaw DM, Harrell JW. Integrating physiological monitoring systems in military aviation: a brief narrative review of its importance, opportunities, and risks. ERGONOMICS 2023; 66:2242-2254. [PMID: 36946542 DOI: 10.1080/00140139.2023.2194592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 03/18/2023] [Indexed: 06/18/2023]
Abstract
Military pilots risk their lives during training and operations. Advancements in aerospace engineering, flight profiles, and mission demands may require the pilot to test the safe limits of their physiology. Monitoring pilot physiology (e.g. heart rate, oximetry, and respiration) inflight is in consideration by several nations to inform pilots of reduced performance capacity and guide future developments in aircraft and life-support system design. Numerous challenges, however, prevent the immediate operationalisation of physiological monitoring sensors, particularly their unreliability in the aerospace environment and incompatibility with pilot clothing and protective equipment. Human performance and behaviour are also highly variable and measuring these in controlled laboratory settings do not mirror the real-world conditions pilots must endure. Misleading or erroneous predictive models are unacceptable as these could compromise mission success and lose operator trust. This narrative review provides an overview of considerations for integrating physiological monitoring systems within the military aviation environment.Practitioner summary: Advancements in military technology can conflictingly enhance and compromise pilot safety and performance. We summarise some of the opportunities, limitations, and risks of integrating physiological monitoring systems within military aviation. Our intent is to catalyse further research and technological development.Abbreviations: AGS: anti-gravity suit; AGSM: anti-gravity straining manoeuvre; A-LOC: almost loss of consciousness; CBF: cerebral blood flow; ECG: electrocardiogram; EEG: electroencephalogram; fNIRS: functional near-infrared spectroscopy; G-forces: gravitational forces; G-LOC: gravity-induced loss of consciousness; HR: heart rate; HRV: heart rate variability; LSS: life-support system; NATO: North Atlantic Treaty Organisation; PE: Physiological Episode; PCO2: partial pressure of carbon dioxide; PO2: partial pressure of oxygen; OBOGS: on board oxygen generating systems; SpO2: peripheral blood haemoglobin-oxygen saturation; STANAG: North Atlantic Treaty Organisation Standardisation Agreement; UPE: Unexplained Physiological Episode; WBV: whole body vibration.
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Affiliation(s)
- David M Shaw
- Aviation Medicine Unit, Royal New Zealand Air Force Base Auckland, Auckland, New Zealand
- School of Sport, Exercise and Nutrition, Massey University, Auckland, New Zealand
| | - John W Harrell
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH, USA
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Sedentary behaviour, but not moderate-to-vigorous physical activity, is associated with respiratory responses to acute psychological stress. Biol Psychol 2023; 177:108510. [PMID: 36716988 DOI: 10.1016/j.biopsycho.2023.108510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 01/25/2023] [Accepted: 01/26/2023] [Indexed: 01/28/2023]
Abstract
BACKGROUND Acute psychological stress induces respiratory responses, and stress-induced respiratory changes can be used to non-invasively reflect metabolic regulation. Respiratory and cardiovascular responses to stress are both driven by sympathetic mechanisms. Higher volumes of sedentary behaviour and lower volumes of physical activity are associated with elevated sympathetic tone and larger cardiovascular responses to stress. The aim of this study was to test whether these associations translate to measures of respiratory stress reactivity. METHODS Daily hours of sedentary behaviour (thigh-mounted activPAL) and moderate-to-vigorous physical activity (MVPA; wrist-mounted ActiGraph) were assessed across seven days. Breath-by-breath respiratory (e.g., breathing frequency [BF], end-tidal carbon dioxide partial pressure [PetCO2], carbon dioxide output [V̇CO2] and respiratory exchange ratio [RER]) responses to an 8-min Paced Auditory Serial Addition Test were then measured using a Cortex MetaLyzer3B. RESULTS Healthy participants (N = 61, mean age ± SD = 25.7 ± 8.9 years) recorded high volumes of sedentary behaviour (9.96 ± 1.48 h/day) and MVPA (1.70 ± 0.71 h/day). In adjusted models (with the inclusion of sedentary behaviour, MVPA, and other a priori selected covariates) hours of daily sedentary behaviour were associated with baseline to stress changes in BF (Β = 0.695, 95% CI = 0.281 - 1.109, p = .014), VT (Β = -0.042, 95% CI = -0.058 - -0.026, p = .014), PetCO2 (Β = -0.537, 95% CI = -0.829 - -0.245, p = .014), V̇CO2 (Β = -0.008, 95% CI = -0.014 - -0.003, p = .030), and RER (Β = -0.013, 95% CI = -0.021 - -0.005, p = .022). Daily hours of MVPA were not linked with respiratory responses to stress. DISCUSSION Sedentary behaviour, but not MVPA, is associated with respiratory stress reactivity. Future work should untangle the underlying mechanisms of these findings and explore the consequences for cardiometabolic disease.
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Sedentary Behaviour, Physical Activity and Psychobiological Stress Reactivity: A Systematic Review. Biol Psychol 2022; 172:108374. [DOI: 10.1016/j.biopsycho.2022.108374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 05/27/2022] [Accepted: 05/31/2022] [Indexed: 11/18/2022]
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Parkes MJ, Green S, Cashmore J, Ghafoor Q, Clutton-Brock T. Shortening the preparation time of the single prolonged breath-hold for radiotherapy sessions. Br J Radiol 2021; 95:20210408. [PMID: 34930022 PMCID: PMC8822572 DOI: 10.1259/bjr.20210408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Objective: Single prolonged breath-holds of >5 min can be obtained in cancer patients. Currently, however, the preparation time in each radiotherapy session is a practical limitation for clinical adoption of this new technique. Here, we show by how much our original preparation time can be shortened without unduly compromising breath-hold duration. Methods: 44 healthy subjects performed single prolonged breath-holds from 60% O2 and mechanically induced hypocapnia. We tested the effect on breath-hold duration of shortening preparation time (the durations of acclimatization, hyperventilation and hypocapnia) by changing these durations and or ventilator settings. Results: Mean original breath-hold duration was 6.5 ± 0.2 (standard error) min. The total original preparation time (from connecting the facemask to the start of the breath-hold) was 26 ± 1 min. After shortening the hypocapnia duration from 16 to 5 min, mean breath-hold duration was still 6.1 ± 0.2 min (ns vs the original). After abolishing the acclimatization and shortening the hypocapnia to 1 min (a total preparation time now of 9 ± 1 min), a mean breath-hold duration of >5 min was still possible (now significantly shortened to 5.2 ± 0.6 min, p < 0.001). After shorter and more vigorous hyperventilation (lasting 2.7 ± 0.3 min) and shorter hypocapnia (lasting 43 ± 4 s), a mean breath-hold duration of >5 min (5.3 ± 0.2 min, p < 0.05) was still possible. Here, the final total preparation time was 3.5 ± 0.3 min. Conclusions: These improvements may facilitate adoption of the single prolonged breath-hold for a range of thoracic and abdominal radiotherapies especially involving hypofractionation. Advances in knowledge: Multiple short breath-holds improve radiotherapy for thoracic and abdominal cancers. Further improvement may occur by adopting the single prolonged breath-hold of >5 min. One limitation to clinical adoption is its long preparation time. We show here how to reduce the mean preparation time from 26 to 3.5 min without compromising breath-hold duration
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Affiliation(s)
- Michael John Parkes
- School of Sport, Exercise & Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom.,National Institute for Health Research (NIHR)/Wellcome Trust Birmingham Clinical Research Facility, Birmingham, United Kingdom.,Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom.,Marie Sklodowska-Curie Fellow, Department of Radiation Oncology, University Medical Centre, Amsterdam, Netherlands
| | - Stuart Green
- Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom
| | - Jason Cashmore
- Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom
| | - Qamar Ghafoor
- Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom
| | - Thomas Clutton-Brock
- National Institute for Health Research (NIHR)/Wellcome Trust Birmingham Clinical Research Facility, Birmingham, United Kingdom.,Department of Anaesthesia and Intensive Care Medicine, University of Birmingham and University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom
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Dash S, Kumar A. Hyperventilation Leading to Transient T-wave Inversion Mimicking Unstable Angina. Cureus 2021; 13:e12980. [PMID: 33659120 PMCID: PMC7920229 DOI: 10.7759/cureus.12980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
T-wave inversion in ECG is very frequent and concerning finding as it is often associated with life-threatening conditions. There are numerous conditions mentioned in the literature for transient T-wave inversion such as acute coronary syndrome, cardiac memory T-wave, subarachnoid hemorrhage, electroconvulsive therapy, hyperventilation and indeterminate origin. Hyperventilation is already known as a cause of transient T-wave inversion; however, it is often forgotten in modern clinical settings. A 33-year-old doctor working in the same hospital reported to the emergency department during working hours with a history of acute onset breathing difficulties and atypical chest pain involving the retrosternal region. Arterial blood gas analysis (ABG) findings of respiratory alkalosis with transient T-wave inversion, which normalized soon after normal breathing and reassurance along with normal cardiac workup helped us to reach the correct diagnosis of hyperventilation syndrome.
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Affiliation(s)
- Snehangsh Dash
- Internal Medicine, 12 Air Force Hospital, Gorakhpur, IND
| | - Anil Kumar
- Cardiology, 7 Air Force Hospital, Kanpur, IND
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7
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Parkes MJ, Sheppard JP, Barker T, Ranasinghe AM, Senanayake E, Clutton-Brock TH, Frenneaux MP. Hypocapnia Alone Fails to Provoke Important Electrocardiogram Changes in Coronary Artery Diseased Patients. Front Physiol 2020; 10:1515. [PMID: 32038268 PMCID: PMC6983462 DOI: 10.3389/fphys.2019.01515] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 12/02/2019] [Indexed: 11/13/2022] Open
Abstract
Background There is still an urgent clinical need to develop non-invasive diagnostic tests for early ischemic heart disease because, once angina occurs, it is too late. Hypocapnia has long been known to cause coronary artery vasoconstriction. Some new cardiology tests are accompanied by the claim that they must have potential diagnostic value if hypocapnia enhances their cardiac effects in healthy subjects. But no previous study has tested whether hypocapnia produces bigger cardiac effects in patients with angina than in healthy subjects. Methods Severe hypocapnia (a PetCO2 level of 20 mmHg) lasting >15 min was mechanically induced by facemask, while conscious and unmedicated, in 18 healthy subjects and in 10 patients with angina and angiographically confirmed coronary artery disease, awaiting by-pass surgery. Each participant was their own control in normocapnia (where CO2 was added to the inspirate) and the order of normocapnia and hypocapnia was randomized. Twelve lead electrocardiograms (ECG) were recorded and automated measurements were made on all ECG waveforms averaged over >120 beats. 2D echocardiography was also performed on healthy subjects. Results In the 18 healthy subjects, we confirm that severe hypocapnia (a mean PetCO2 of 20 ± 0 mmHg, P < 0.0001) consistently increased the mean T wave amplitude in leads V1–V3, but by only 31% (P < 0.01), 15% (P < 0.001) and 11% (P < 0.05), respectively. Hypocapnia produced no other significant effects (p > 0.05) on their electro- or echocardiogram. All 10 angina patients tolerated the mechanical hyperventilation well, with minimal discomfort. Hypocpania caused a similar increase in V1 (by 39%, P < 0.05 vs. baseline, but P > 0.05 vs. healthy controls) and did not induce angina. Its effects were no greater in patients who did not take β-blockers, or did not take organic nitrates, or had the worst Canadian Cardiovascular Society scores. Conclusion Non-invasive mechanical hyperventilation while awake and unmedicated is safe and acceptable, even to patients with angina. Using it to produce severe and prolonged hypocapnia alone does produce significant ECG changes in angina patients. But its potential diagnostic value for identifying patients with coronary stenosis requires further evaluation.
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Affiliation(s)
- Michael J Parkes
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom.,National Institute for Health Research/Wellcome Trust Birmingham Clinical Research Facility, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom
| | - James P Sheppard
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom.,National Institute for Health Research/Wellcome Trust Birmingham Clinical Research Facility, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom
| | - Thomas Barker
- Department of Cardiovascular Medicine, University of Birmingham, Birmingham, United Kingdom
| | - Aaron M Ranasinghe
- Department of Cardiovascular Medicine, University of Birmingham, Birmingham, United Kingdom
| | - Eshan Senanayake
- Department of Cardiovascular Medicine, University of Birmingham, Birmingham, United Kingdom
| | - Thomas H Clutton-Brock
- National Institute for Health Research/Wellcome Trust Birmingham Clinical Research Facility, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom.,Department of Anaesthesia and Intensive Care Medicine, University of Birmingham, Birmingham, United Kingdom
| | - Michael P Frenneaux
- National Institute for Health Research/Wellcome Trust Birmingham Clinical Research Facility, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom.,Department of Cardiovascular Medicine, University of Birmingham, Birmingham, United Kingdom
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Abstract
A 19-year-old patient presented with severe chest pain, which is not typical for cardiac angina. However, his smoking history and the strong family history of ischaemic heart disease coupled with evidence of progressive T-wave changes on his electrocardiogram (ECG) caused dilemma in deciding further management. His blood tests were normal apart from hypophosphataemia, and he had two negative troponin results. His arterial blood gases showed respiratory alkalosis. He was given analgesia for a diagnosis of musculoskeletal chest pain and the next morning his ECG, arterial blood gases and phosphate levels all normalised. He had a normal echocardiogram and was reviewed by the cardiologist who diagnosed musculoskeletal chest pain which led to distress and hyperventilation causing hypophosphataemia and transient T-wave inversion. This case is a reminder of an under-recognised physiological phenomenon involving the cardiac conduction during hyperventilation.
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Affiliation(s)
- Hala Alsafadi
- Royal Hampshire County Hospital, Winchester, UK and Southern Health NHS Foundation Trust, UK
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West NS, Parkes MJ, Snowden C, Prentis J, McKenna J, Iqbal MS, Cashmore J, Walker C. Mitigating Respiratory Motion in Radiation Therapy: Rapid, Shallow, Non-invasive Mechanical Ventilation for Internal Thoracic Targets. Int J Radiat Oncol Biol Phys 2018; 103:1004-1010. [PMID: 30496883 DOI: 10.1016/j.ijrobp.2018.11.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 11/06/2018] [Accepted: 11/19/2018] [Indexed: 12/25/2022]
Abstract
PURPOSE Reducing respiratory motion during the delivery of radiation therapy reduces the volume of healthy tissues irradiated and may decrease radiation-induced toxicity. The purpose of this study was to assess the potential for rapid shallow non-invasive mechanical ventilation to reduce internal anatomy motion for radiation therapy purposes. METHODS AND MATERIALS Ten healthy volunteers (mean age, 38 years; range, 22-54 years; 6 female and 4 male) were scanned using magnetic resonance imaging during normal breathing and at 2 ventilator-induced frequencies: 20 and 25 breaths per minute for 3 minutes. Sagittal and coronal cinematic data sets, centered over the right diaphragm, were used to measure internal motions across the lung-diaphragm interface. Repeated scans assessed reproducibility. Physiologic parameters and participant experiences were recorded to quantify tolerability and comfort. RESULTS Physiologic observations and experience questionnaires demonstrated that rapid shallow non-invasive ventilation technique was tolerable and comfortable. Motion analysis of the lung-diaphragm interface demonstrated respiratory amplitudes and variations reduced in all subjects using rapid shallow non-invasive ventilation compared with spontaneous breathing: mean amplitude reductions of 56% and 62% for 20 and 25 breaths per minute, respectively. The largest mean amplitude reductions were found in the posterior of the right lung; 40.0 mm during normal breathing to 15.5 mm (P < .005) and 15.2 mm (P < .005) when ventilated with 20 and 25 breaths per minute, respectively. Motion variations also reduced with ventilation; standard deviations in the posterior lung reduced from 14.8 mm during normal respiration to 4.6 mm and 3.5 mm at 20 and 25 breaths per minute, respectively. CONCLUSIONS To our knowledge, this study is the first to measure internal anatomic motion using rapid shallow mechanical ventilation to regularize and minimize respiratory motion over a period long enough to image and to deliver radiation therapy. Rapid frequency and shallow, non-invasive ventilation both generate large reductions in internal thoracic and abdominal motions, the clinical application of which could be profound-enabling dose escalation (increasing treatment efficacy) or high-dose ablative radiation therapy.
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Affiliation(s)
- Nicholas S West
- Department of Radiotherapy Physics, Northern Centre for Cancer Care, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom.
| | - Michael J Parkes
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Christopher Snowden
- Departments of Perioperative and Critical Care Medicine, Freeman Hospital, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - James Prentis
- Departments of Perioperative and Critical Care Medicine, Freeman Hospital, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Jill McKenna
- Department of Therapeutic Radiography, Northern Centre for Cancer Care, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Muhammad Shahid Iqbal
- Department of Clinical Oncology, Northern Centre for Cancer Care, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Jason Cashmore
- Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom
| | - Christopher Walker
- Department of Radiotherapy Physics, Northern Centre for Cancer Care, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
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Parkes MJ, Green S, Stevens AM, Parveen S, Stephens R, Clutton-Brock TH. Safely prolonging single breath-holds to >5 min in patients with cancer; feasibility and applications for radiotherapy. Br J Radiol 2017; 89:20160194. [PMID: 27168468 PMCID: PMC5257330 DOI: 10.1259/bjr.20160194] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVE Multiple, short and deep inspiratory breath-holds with air of approximately 20 s are now used in radiotherapy to reduce the influence of ventilatory motion and damage to healthy tissue. There may be further clinical advantages in delivering each treatment session in only one single, prolonged breath-hold. We have previously developed techniques enabling healthy subjects to breath-hold for 7 min. Here, we demonstrate their successful application in patients with cancer. METHODS 15 patients aged 37-74 years undergoing radiotherapy for breast cancer were trained to breath-hold safely with pre-oxygenation and mechanically induced hypocapnia under simulated radiotherapy treatment conditions. RESULTS The mean breath-hold duration was 5.3 ± 0.2 min. At breakpoint, all patients were normocapnic and normoxic [mean end-tidal partial pressure of carbon dioxide was 36 ± 1 standard error millimetre of mercury, (mmHg) and mean oxygen saturation was 100 ± 0 standard error %]. None were distressed, nor had gasping, dizziness or disturbed breathing in the post-breath-hold period. Mean blood pressure had risen significantly from 125 ± 3 to 166 ± 4 mmHg at breakpoint (without heart rate falling), but normalized within approximately 20 s of the breakpoint. During breath-holding, the mean linear anteroposterior displacement slope of the L breast marker was <2 mm min(-1). CONCLUSION Patients with cancer can be trained to breath-hold safely and under simulated radiotherapy treatment conditions for longer than the typical beam-on time of a single fraction. We discuss the important applications of this technique for radiotherapy. ADVANCES IN KNOWLEDGE We demonstrate for the first time a technique enabling patients with cancer to deliver safely a single prolonged breath-hold of >5 min (10 times longer than currently used in radiotherapy practice), under simulated radiotherapy treatment conditions.
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Affiliation(s)
- Michael J Parkes
- 1 School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK.,2 National Institute for Health Research (NIHR)/Wellcome Trust Birmingham Clinical Research Facility, Queen Elizabeth Hospital, Birmingham, UK
| | - Stuart Green
- 3 Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Birmingham, UK
| | - Andrea M Stevens
- 3 Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Birmingham, UK
| | - Sophia Parveen
- 3 Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Birmingham, UK
| | - Rebecca Stephens
- 3 Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Birmingham, UK
| | - Thomas H Clutton-Brock
- 2 National Institute for Health Research (NIHR)/Wellcome Trust Birmingham Clinical Research Facility, Queen Elizabeth Hospital, Birmingham, UK.,4 Department Anaesthesia and Intensive Care Medicine, University of Birmingham and University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Birmingham, UK
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Parkes MJ, Green S, Stevens AM, Parveen S, Stephens R, Clutton-Brock TH. Reducing the within-patient variability of breathing for radiotherapy delivery in conscious, unsedated cancer patients using a mechanical ventilator. Br J Radiol 2016; 89:20150741. [PMID: 26959610 PMCID: PMC5258146 DOI: 10.1259/bjr.20150741] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Objective: Variability in the breathing pattern of patients with cancer during radiotherapy requires mitigation, including enlargement of the planned treatment field, treatment gating and breathing guidance interventions. Here, we provide the first demonstration of how easy it is to mechanically ventilate patients with breast cancer while fully conscious and without sedation, and we quantify the resulting reduction in the variability of breathing. Methods: 15 patients were trained for mechanical ventilation. Breathing was measured and the left breast anteroposterior displacement was measured using an Osiris surface-image mapping system (Qados Ltd, Sandhurst, UK). Results: Mechanical ventilation significantly reduced the within-breath variability of breathing frequency by 85% (p < 0.0001) and that of inflation volume by 29% (p < 0.006) when compared with their spontaneous breathing pattern. During mechanical ventilation, the mean amplitude of the left breast marker displacement was 5 ± 1 mm, the mean variability in its peak inflation position was 0.5 ± 0.1 mm and that in its trough inflation position was 0.4 ± 0.0 mm. Their mean drifts were not significantly different from 0 mm min−1 (peak drift was −0.1 ± 0.2 mm min−1 and trough drift was −0.3 ± 0.2 mm min−1). Patients had a normal resting mean systolic blood pressure (131 ± 5 mmHg) and mean heart rate [75 ± 2 beats per minute (bpm)] before mechanical ventilation. During mechanical ventilation, the mean blood pressure did not change significantly, mean heart rate fell by 2 bpm (p < 0.05) with pre-oxygenation and rose by only 4 bpm (p < 0.05) during pre-oxygenation with hypocapnia. No patients reported discomfort and all 15 patients were always willing to return to the laboratory on multiple occasions to continue the study. Conclusion: This simple technique for regularizing breathing may have important applications in radiotherapy. Advances in knowledge: Variations in the breathing pattern introduce major problems in imaging and radiotherapy planning and delivery and are currently addressed to only a limited extent by asking patients to breathe to auditory or visual guidelines. We provide the first demonstration that a completely different technique, of using a mechanical ventilator to take over the patients' breathing for them, is easy for patients who are conscious and unsedated and reduces the within-patient variability of breathing. This technique has potential advantages in radiotherapy over currently used breathing guidance interventions because it does not require any active participation from or feedback to the patient and is therefore worthy of further clinical evaluation.
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Affiliation(s)
- Michael J Parkes
- 1 National Institute for Health Research (NIHR)/Wellcome Trust Birmingham Clinical Research Facility, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK.,2 School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - Stuart Green
- 3 Hall Edwards Radiotherapy Research Group, Department of Medical Physics, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Andrea M Stevens
- 4 Department of Oncology , University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Sophia Parveen
- 3 Hall Edwards Radiotherapy Research Group, Department of Medical Physics, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Rebecca Stephens
- 3 Hall Edwards Radiotherapy Research Group, Department of Medical Physics, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Thomas H Clutton-Brock
- 1 National Institute for Health Research (NIHR)/Wellcome Trust Birmingham Clinical Research Facility, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK.,5 Department Anaesthesia and Intensive Care Medicine , University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
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12
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Parkes MJ, Green S, Stevens AM, Clutton-Brock TH. Assessing and ensuring patient safety during breath-holding for radiotherapy. Br J Radiol 2014; 87:20140454. [PMID: 25189121 PMCID: PMC4207152 DOI: 10.1259/bjr.20140454] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Objective: While there is recent interest in using repeated deep inspiratory breath-holds, or prolonged single breath-holds, to improve radiotherapy delivery, breath-holding has risks. There are no published guidelines for monitoring patient safety, and there is little clinical awareness of the pronounced blood pressure rise and the potential for gradual asphyxia that occur during breath-holding. We describe the blood pressure rise during deep inspiratory breath-holding with air and test whether it can be abolished simply by pre-oxygenation and hypocapnia. Methods: We measured blood pressure, oxygen saturation (SpO2) and heart rate in 12 healthy, untrained subjects performing breath-holds. Results: Even for deep inspiratory breath-holds with air, the blood pressure rose progressively (e.g. mean systolic pressure rose from 133 ± 5 to 175 ± 8 mmHg at breakpoint, p < 0.005, and in two subjects, it reached 200 mmHg). Pre-oxygenation and hypocapnia prolonged breath-hold duration and prevented the development of asphyxia but failed to abolish the pressure rise. The pressure rise was not a function of breath-hold duration and was not signalled by any fall in heart rate (remaining at resting levels of 72 ± 2 beats per minute). Conclusion: Colleagues should be aware of the progressive blood pressure rise during deep inspiratory breath-holding that so far is not easily prevented. In breast cancer patients scheduled for breath-holds, we recommend routine screening for heart, cardiovascular, renal and cerebrovascular disease, routine monitoring of patient blood pressure and SpO2 during breath-holding and requesting patients to stop if systolic pressure rises consistently >180 mmHg and or SpO2 falls <94%. Advances in knowledge: There is recent interest in using deep inspiratory breath-holds, or prolonged single breath-holding techniques, to improve radiotherapy delivery. But there appears to be no clinical awareness of the risks to patients from breath-holding. We demonstrate the progressive blood pressure rise during deep inspiratory breath-holds with air, which we show cannot be prevented by the simple expedient of pre-oxygenation and hypocapnia. We propose patient screening and safety guidelines for monitoring both blood pressure and SpO2 during breath-holds and discuss their clinical implications.
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Affiliation(s)
- M J Parkes
- 1 National Institute for Health Research (NIHR)/Wellcome Trust Birmingham Clinical Research Facility, University of Birmingham and University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
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Evaluating the importance of the carotid chemoreceptors in controlling breathing during exercise in man. BIOMED RESEARCH INTERNATIONAL 2013; 2013:893506. [PMID: 24236297 PMCID: PMC3819889 DOI: 10.1155/2013/893506] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 07/08/2013] [Indexed: 01/24/2023]
Abstract
Only the carotid chemoreceptors stimulate breathing during hypoxia in Man. They are also ideally located to warn if the brain's oxygen supply falls, or if hypercapnia occurs. Since their discovery ~80 years ago stimulation, ablation, and recording experiments still leave 3 substantial difficulties in establishing how important the carotid chemoreceptors are in controlling breathing during exercise in Man: (i) they are in the wrong location to measure metabolic rate (but are ideally located to measure any mismatch), (ii) they receive no known signal during exercise linking them with metabolic rate and no overt mismatch signals occur and (iii) their denervation in Man fails to prevent breathing matching metabolic rate in exercise. New research is needed to enable recording from carotid chemoreceptors in Man to establish whether there is any factor that rises with metabolic rate and greatly increases carotid chemoreceptor activity during exercise. Available evidence so far in Man indicates that carotid chemoreceptors are either one of two mechanisms that explain breathing matching metabolic rate or have no importance. We still lack key experimental evidence to distinguish between these two possibilities.
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McLaughlin L. Breathing evaluation and retraining in manual therapy. J Bodyw Mov Ther 2009; 13:276-82. [DOI: 10.1016/j.jbmt.2009.01.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 11/03/2008] [Accepted: 01/11/2009] [Indexed: 10/21/2022]
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Steinback CD, Poulin MJ. Cardiovascular and cerebrovascular responses to acute isocapnic and poikilocapnic hypoxia in humans. J Appl Physiol (1985) 2007; 104:482-9. [PMID: 18263856 DOI: 10.1152/japplphysiol.00553.2007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined the cardiovascular and cerebrovascular responses to acute isocapnic (IH) and poikilocapnic hypoxia (PH) in 10 men (25.7 +/- 4.2 yr, mean +/- SD). Heart rate (HR), mean arterial pressure (MAP), and mean peak middle cerebral artery blood flow velocity (Vp) were measured continuously during two randomized protocols of 20 min of step IH and PH (45 Torr). HR was elevated during both IH (P < 0.01) and PH (P < 0.01), with no differences observed between conditions. MAP was modestly elevated across all time points during IH but only became elevated after 5 min during PH. During IH, Vp was elevated from baseline throughout the exposure with a consistent hypoxic sensitivity of approximately 0.34 cm x s(-1).%desaturation(-1) (P < 0.05). The Vp response to PH was biphasic with an initial decrease from baseline occurring at 79 +/- 23 s, followed by a subsequent elevation, becoming equivalent to the IH response by 10 min. The nadir of the PH response exhibited a hypoxic sensitivity of -0.24 cm x s(-1) x % desaturation(-1). When expressed in relation to end-tidal Pco2, a sensitivity of -1.08 cm x s(-1).Torr(-1) was calculated, similar to previously reported sensitivities to euoxic hypocapnia. Cerebrovascular resistance (CVR) was not changed during IH. During PH, an initial increase in CVR was observed. However, CVR returned to baseline by 20 min of PH. These data show the cerebrovascular response to PH consists of an early hypocapnia-mediated response, followed by a secondary increase, mediated predominantly by hypoxia.
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Affiliation(s)
- Craig D Steinback
- Dept. of Physiology and Biophysics, Faculty of Medicine, Univ. of Calgary, HMRB-212, 3330 Hospital Dr., NW, Calgary, Alberta, Canada T2N 4N1
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