The The Psychophysiology of Breathing Omer Van den Bergh - PDF document

14/09/2010 The The Psychophysiology of Breathing Omer Van den Bergh Research Group on Health Psychology University of Leuven, Belgium Content • What is breathing? • How to measure it? • How to manipulate and study it? • Respiratory psychophysiology : some examples 1

14/09/2010 What is breathing? RESPIRATORY PHYSIOLOGY Breathing… • Biggest oscillator in the body • Double control system – Voluntarily – Autonomically • Relatively little investigated in psychophysiology – No “pure” (unsuspect) N “ ” ( t) psychophysiological measure – Difficult to measure without altering it 2

14/09/2010 Breathing… To keep blood gas levels within (pre-set) boundaries (pre set) boundaries O 2 • Arterial O 2 saturation (SpO 2 ) • 93 – 100 % Hb fully saturated by O 2 CO 2 CO 2 • Alveolar PCO 2 (PACO 2 ) • Arterial PCO 2 (PaCO 2 ) • End-tidal P ET CO 2 (mmHg) or F ET CO 2 (%). • Normal PETCO 2 ± 40 mmHg • Normal F ET CO 2 (%) = ± 4.8 à 5% Gas exchange in alveoli • 300 million alveoli (0.05 to 0.25 mm each) • ±100 m² surface in contact with the outside air • Inspired air = 21% O 2 - 0 to 0.5% CO 2 • Expired air = 16,5% O 2 - ± 5% CO 2 3

14/09/2010 Respiratory control • Rhythmicity center of the medulla (brain-stem) medulla (brain stem) – I neurons – E neurons • Apneustic center (pons) – stimulate I neurons • Pneumotaxic center – inhibits apneustic center inhibits apneustic center – inhibits inspiration Respiratory control • Sensors in different places in the body monitor breathing behavior and gas exchange • Mammals are most sensitive to CO 2 levels – varies most in respiration in response to different metabolic and environmental conditions. 4

14/09/2010 Feedback system Hypocapnia Hypocapnia Cfr. HV Hypercapnia Respiratory control 5

14/09/2010 Important effects of respiration on other systems Respiratory gating (Eckberg, 2003) • More parasympathetic outflow during expiration than p y p g p during inspiration – RSA : Respiratory sinus arrythmia • HR increases during inhalation and decreases during exhalation – Also other cardiorespiratory interactions • Fierce debate on HRV : What it means and yes/no correction for respiratory variables? – Startle response modulation ? – ?? Respiratory sensation Bottom-up AND top-down processes Davenport , P. in: O‘Donnell et al. (2007). Proc Am Thorac Soc , 4, 145-168 6

14/09/2010 How to measure breathing ? MEASURES AND PARAMETERS Time related • Respiratory band (chest) • Straps • Termistors (nose) Termistors (nose) • …. • Ti : inspiratory time (s) (1,5-2 s) • Te : expiratory time (s) • Pauses (Pinexp – Pexpin) • f = 60/(Ti+Te) (10-12 br/min) • Ti/T TOT : duty cycle time – Reflects activity of respiratory rhythmic controller 7

14/09/2010 Volume related pneumotachograph V T = tidal volume 500-600 ml RIP : respiratory inductive plethysmography Time x Volume • V E = f x V T (minute ventilation, L/min; normaal ±6 L/min) • Inspiratory drive : V T /Ti • … Pressure parameters • P100 : inspiratory occlusion pressure 100 ms after the onset of an inspiratory effort against a closed airway – reflects the summed motor output of the central respiratory controller (or the ‘‘central respiratory drive’’) 8

14/09/2010 Central respiratory drive Van Diest et al., 2009 Breathing patterns • Respiratory variability • Sighs 9

14/09/2010 Gas exchange - capnopgraphy CO 2 • PetCO 2 (mmHg) • PetCO 2 (mmHg) FetCO 2 (%) O 2 • PO 2 • SaO 2 Photosensitive plethysmography Clinical variables • Flow-volume loop • FVC • FEV1 • PEF • … • Airway resistance – FOT : Forced oscillation technique 10

14/09/2010 MANIPULATIONS IN THE LAB Dyspneic Stimuli: CO 2 -inhalation 35% → Panic !! CO 2 -inhalation (5% - 7.5% - 10%) • Chemoreceptors (pH/CO 2) • Rise in ventilation, HR, BP • Breathlessness - air hunger • Dizziness, warmth 11

14/09/2010 Dyspneic Stimuli: respiratory load Flow resistors (loads) • Mechanoreceptors • Breathing muscles work harder • Breathlessness – effort • Fatigue Other • Occlusions • Breath holding RESPIRATORY PSYCHO(PHYSIO)LOGY 12

14/09/2010 Special Issue Biological Psychology Ritz, T., & Van den Bergh, O . (2010). Psychobiology of respiration and the airways . Biological Psychology, 84 (1). 13

14/09/2010 Research Group on Health Psychology - Leuven Dyspnea perception => symptom perception • Perceptual-cognitive processes • Affective-motivational responses • Clinical implications (asthma, COPD) Emotion and breathing regulation • Breathing during defensive response mobilization • Why do you sigh? • Feedforward-regulation of breathing • Interoceptive fear conditioning to respiratory cues • Breathing and relaxation 14

14/09/2010 Research Group on Health Psychology - Leuven Dyspnea perception => symptom perception • Perceptual-cognitive processes • Affective-motivational responses • Clinical implications (asthma, COPD) Emotion and breathing regulation • Breathing during defensive response mobilizationn • Why do you sigh? • Feedforward-regulation of breathing • Interoceptive fear conditioning to respiratory cues • Breathing and relaxation THE PLASTICITY OF SELF REPORTED SYMPTOMS THE PLASTICITY OF SELF-REPORTED SYMPTOMS 15

14/09/2010 Dyspnea as a Multidimensional Experience Dyspnea/breathlessness… „… a subjective experience of breathing discomfort that consists of qualitatively distinct sensations and affective-motivational responses that vary in intensity „… experience derives from interactions among i d i f i t ti multiple physiological, psychological , social , and environmental factors...“ American Thoracic Society (1999). American Journal of Respiratory and Critical Care Medicine, 159, 321-340 Dyspnea - breathlessness Distinct Sensations • Air hunger – suffocation g – Mismatch ventilatory drive – actual ventilation • Effort - work of breathing – Respiratory muscles must work harder • Chest tightness – Bronchoconstriction Bronchoconstriction Simon et al. (1990). American Review of Respiratory Disease , 142,1009-1014 Banzett & Moosavi, APS Bulletin, 11, 2001 16

14/09/2010 Large individual differences Treating Dyspnea 20 to 36 % Physiologic Mechanisms Psychologic Mechanisms - Mechanoreceptors • Cognitive factors Dyspnea - Chemoreceptors • Learning processes - Afferent mismatch • Memory representations • Emotional factors (fear) - ……. • Social context….. • 3rd major complaint in medicine 3 d j l i t i di i after fatigue and pain (cardio)pulmonary disorders neuromuscular 70% of terminal cancer patients • % explained by either set varies • among persons • as a function of time/learning experiences within person 17

14/09/2010 Top-down processes • Perceptual-cognitive factors – Attention – Interpretation (“catastrophizing”) – Expectancies/learning – Memory • Emotional factors – Fear – Controllability • Social context… Acquiring bodily symptoms Odor-CO 2 inhalation paradigm P Predictive cues di ti CO i h l ti CO 2 inhalation trials t i l • odors • fast breathing • mental images • smothering sensations • chest tightness • feelings of choking • pounding heart • sweating • hot flushes • lump in throat • headache • tension, anxious feelings 18

14/09/2010 Methods valve valve odors odors subject subject subject subject C O air air 2 Odor CSs ACQUISITION 2 min breathing trials •Ventilation (f, V T , V E ) CS+ Odor 1+ 7.5 % CO 2 •FETCO 2 •HR •Subjective symptoms CS- Odor 2+ room air TEST TEST •Ventilation (f, V T , V E ) Odor 1+ room air CS+ •FETCO 2 •HR CS- Odor 2+ room air •Subjective symptoms 19

14/09/2010 Acquired symptoms to harmless odors symptoms 24 24 CS+ 23 CS- 22 21 20 19 18 17 Ammon CS+ Niaouli CS+ • Symptom learning to unpleasant odor only! • No difference in contingency awareness Van den Bergh et al., 1995, 1997, 1999 More elevated in high NA and in clinical MUS patients symptoms symptoms CS+ CS+ 28 22 CS- CS- 21 26 20 24 19 18 18 22 17 16 20 High NA Low NA Normals Patients Van den Bergh et al., 1998, 1999 20

14/09/2010 Respiratory learning paradigm ACQUISITION 10 s + 80 s •Ventilation (f, V T , V E ) CS+ Odor 1+ HypC HV •FETCO 2 • TCD Odor 2+ NorC HV CS- • Lightheadedness TEST Odor 1+ NorC HV CS+ •Ventilation (f, V T , V E ) Odor 2+ NorC HV CS- •FETCO 2 • TCD CS+ Odor 1+ Norm Br •Lightheadedness CS- Odor 2+ Norm Br Transcranial Doppler Ultrasonography TCD TCD Online LH rating Online LH rating scale scale Respiratory Respiratory measures measures CO CO 2 added added through through inspiratory inspiratory tube tube 21

14/09/2010 Mid Cerebral Artery (MCA) (MCA) Recovery (a) 7 Hyper- Baseline 6 ventilation 5 etCO 2 (%) 4 End-tidal CO 2 3 2 (fractional concentration) 1 0 0 0 120 120 240 240 360 360 Time Time (b) (sec) 80 70 60 Cerebral Blood Flow Vm (cm/sec) 50 (mean velocity in rMCA) 40 30 20 10 0 Time 0 120 240 360 (c) (sec) 100 100 Lightheadedness 80 LH (0-100) 60 (rating 0-100) 40 20 0 Time 0 120 240 360 (sec) (a) FetCO 2 (b) Vm (c) LH during 3 phases in 1 subject 22