title: Safely prolonging single breath-holds to >5 min in patients with cancer; feasibility and applications for radiotherapy.
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).
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: 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.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Parkes
authors.affiliation: 3 Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Birmingham, UK.
authors.forename: Stuart
authors.initials: S
authors.lastname: Green
authors.affiliation: 3 Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Birmingham, UK.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Stevens
authors.affiliation: 3 Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Birmingham, UK.
authors.forename: Sophia
authors.initials: S
authors.lastname: Parveen
authors.affiliation: 3 Hall Edwards Radiotherapy Group, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Birmingham, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Stephens
authors.affiliation: 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.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Clutton-Brock
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000532:radiotherapy*; D062485:Breath Holding; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D016857:Hypocapnia; D008875:Middle Aged; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D013997:Time Factors