Can pulse transit time be useful for detecting hypertension in patients in a sleep unit?
BACKGROUND
Pulse transit time (PTT) is the time that a pulse wave takes to travel between two different arterial points, and may be useful in estimating blood pressure. This noninvasive technique, which does not add any cost to the procedure, offers the advantage of avoiding 'arousals' during sleep measurement as occurs with ambulatory blood pressure monitoring (ABPM). We aim to confirm the usefulness of PTT for the detection of hypertension, and to study the correlation between both measurements.


METHODS
Prospective observational study in a multidisciplinary sleep unit. We recruited 30consecutive patients attending a sleep clinic and ran a baseline polysomnography followed by an ABPM the following day. Average systolic and diastolic blood pressure (SBP, DBP) by PTT were calculated and compared with ABMP results. In accordance with international guidelines, patients with mean nocturnal ABMP ≥ 120/70 mmHg were diagnosed as having arterial hypertension.


RESULTS
Mean age of 60years; 66% male, 80% suffered from sleep apnoea (OSAS). Taking the ABPM as the reference technique, we found that the diagnostic sensitivity of PTT is 85% with a specificity of 88% in the case of SBP, with a positive predictive value of 85% and negative predictive value of 88%. By studying the relationship between mean SBP measured by ABPM and PTT, we found a linear correlation coefficient (R) of 0.88, showing a distribution of all subjects with a difference of between ±15mmHg between tests. There is also a positive correlation between mean DBP measured for the two tests, with a weaker linear correlation.


CONCLUSIONS
Pulse transit time shows a strong correlation with blood pressure (measured by ABPM). PTT provides continuous, non-invasive, cuffless blood pressure monitoring free of additional cost and could be an alternative for screening hypertension.
Servicio de Neumología, Respiratory Research Group-CIBERES, IIS Fundación Jiménez Díaz, Madrid, España. Electronic address: tgomez.garcia@fjd.es.
Maria Teresa
MT
Gómez García
Servicio de Neumología, Respiratory Research Group-CIBERES, IIS Fundación Jiménez Díaz, Madrid, España.
Maria Fernanda
MF
Troncoso Acevedo
Servicio de Neumología, Respiratory Research Group-CIBERES, IIS Fundación Jiménez Díaz, Madrid, España.
Marcel
M
Rodriguez Guzmán
Servicio de Nefrología, IIS Fundación Jiménez Díaz, Madrid, España.
Raquel
R
Alegre de Montaner
Servicio de Nefrología, IIS Fundación Jiménez Díaz, Madrid, España.
Beatriz
B
Fernández Fernández
Servicio de Pediatría, IIS Fundación Jiménez Díaz, Madrid, España.
Genoveva
G
del Río Camacho
Servicio de Neumología, Respiratory Research Group-CIBERES, IIS Fundación Jiménez Díaz, Madrid, España.
Nicolás
N
González-Mangado
D018660:Blood Pressure Monitoring, Ambulatory; D005260:Female; D006757:Hospital Units; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011446:Prospective Studies; D063177:Pulse Wave Analysis; D020181:Sleep Apnea, Obstructive / Q000150:complications
Arterial hypertension; Hipertensión arterial; Polisomnografía; Polysomnography; Pulse transit time; Sleep apnea; Sleep-disordered breathing; Síndrome de apneas e hipopneas del sueño; Tiempo de tránsito de pulso; Trastornos respiratorios del sueño