Use of pulse transit time as a measure of inspiratory effort in patients with obstructive sleep apnoea

Abstract

U Us se e o of f p pu ul ls se e t tr ra an ns si it t t ti im me e a as s a a m me ea as su ur re e o of f i in ns sp pi ir ra at to or ry y e ef ff fo or rt t i in n p pa at ti ie en nt ts s w wi it th h o ob bs st tr ru uc ct ti iv ve e s sl le ee ep p a ap pn no oe ea a ABSTRACT: Pulse transit time (PTT) is the time taken for the arterial pulse pressure wave to travel from the aortic valve to a peripheral site. For convenience, it is usually measured from the R wave on the electrocardiogram to the pulse wave arrival at the finger. Pulse transit time is inversely proportional to blood pressure, and the falls in blood pressure which occur with inspiration (pulsus paradoxus) correspond to rises (lengthening) in pulse transit time. In awake normal subjects, the size of these inspiratory rises in pulse transit time correlate well with the degree of inspiratory effort. The aim of this study was to investigate whether inspiratory rises in pulse transit time could provide a quantitative measure of inspiratory effort in patients with obstructive sleep apnoea. Eight patients with obstructive sleep apnoea, attending the laboratory for institution of nasal continuous positive airway pressure, took part in the study. Once asleep, airway pressure was varied between optimal treatment level and minimum pressure, to produce a range of inspiratory efforts whilst continuous recordings of oesophageal pressure and pulse transit time were made.There was an excellent correlation between the size of the swings in oesophageal pressure and the size of the swings in pulse transit time (mean r=0.94).Pulse transit time may, therefore, provide a clinically useful noninvasive and quantitative measure of inspiratory effort in patients with sleep-related breathing disorders.

Age-related factors that confound peripheral pulse timing characteristics in Caucasian children

“…Regardless of this, PTT has become an increasingly popular noninvasive measure of abrupt changes in arterial stiffness or fluid properties of blood. 11,12 In this study, a trough in arterial distensibility was unable to be located at the age of 10 years as reported. 7 This is perhaps expected as progressive medial degeneration is probably the major underlying factor; however, this needs further clarification.…”

“…8 The greater PTT value at the toes can be easily explained by its relatively longer artery length the pulse wave needs to propagate. 11,12 HR effects on PWV was often dismissed or even overlooked; however, recent studies have suggested otherwise. Studies conducted on animals have established that arterial distensibility is a function of HR.…”

“…PTT is usually measured between the R-wave of an electrocardiogram (ECG) and a predetermined amplitude threshold at the photoplethysmographic (PPG) signal. 11,12 Previous studies have established that changes in the arterial wall stiffness can be reflected by observing the relative changes in PTT. 12 Its usefulness in respiratory sleep studies in both children 13 and adults 12 are known.…”

Obstructive sleep apnea syndrome: effect of respiratory events and arousal on pulse wave amplitude measured by photoplethysmography in NREM sleep

“…Previous works have suggested that there could be other markers of arousal which are much easier to measure than EEG and which could assess the true extent of sleep fragmentation. This is the case for the pulse transit time, a non-invasive measure of blood pressure, a semiquantitative measure of respiratory effort [25][26][27] and a sensitive marker of autonomic arousals [20]. The recently developed peripheral arterial tonometry, based on detection of peripheral vasoconstriction, has been shown to be a sensitive marker of sympathetic arousal [28] and apneas [9,29].…”

Steering simulation performance in patients with obstructive sleep apnoea and matched control subjects

“…The pulse transit time provided information on inspiratory effort [20] and autonomic arousals [19,21]. All studies were analysed by standard procedures used in the authors' unit.…”