Heart rate variability during static and dynamic breath-hold dives in elite divers.

The purpose of this study was to assess the differences in cardiac autonomic modulation during maximal static (SA) and dynamic (DA) underwater apneas. Arterial oxygen saturation (SpO(2)), heart rate (HR) and HR variability (SD1 from Poincaré plot and short-term fractal-like scaling exponent, α(1)) were analyzed at the immersed baseline (3 min) and initial, mid- and end-phases (each 30s) of SA and DA in nine elite breath-hold divers. DA and SA lasted 78 ± 8 and 225 ± 20s (mean ± SEM), respectively, and resulted in similar decrements in end-stage SpO(2) (78 ± 3 and 75 ± 3%, p=0.

Cardiovascular changes during underwater static and dynamic breath-hold dives in trained divers.

Limited information exists concerning arterial blood pressure (BP) changes in underwater breath-hold diving. Simulated chamber dives to 50 m of freshwater (mfw) reported very high levels of invasive BP in two divers during static apnea (SA), whereas a recent study using a noninvasive subaquatic sphygmomanometer reported unchanged or mildly increased values at 10 m SA dive. In this study we investigated underwater BP changes during not only SA but, for the first time, dynamic apnea (DA) and shortened (SHT) DA in 16 trained breath-hold divers.

Advanced instrumentation for research in diving and hyperbaric medicine.

Improving the safety of diving and increasing knowledge about the adaptation of the human body to underwater and hyperbaric environment require specifically developed underwater instrumentation for physiological measurements. In fact, none of the routine clinical devices for health control is suitable for in-water and/or under-pressure operation. The present paper addresses novel technological acquisitions and the development of three dedicated devices: * an underwater data logger for recording O2 saturation (reflective pulsoxymetry), two-channel ECG, depth and temperature; * an underwater blood pressure meter based on the oscillometric method; and * an underwater echography system.

A novel wearable apnea dive computer for continuous plethysmographic monitoring of oxygen saturation and heart rate.

We describe the development of a novel wrist-mounted apnea dive computer. The device is able to measure and display transcutaneous oxygen saturation, heart rate, plethysmographic pulse waveform, depth, time and temperature during breath-hold dives. All measurements are stored in an external memory chip.

An underwater blood pressure measuring device.

Measurement of arterial blood pressure is an important vital sign for monitoring the circulation. However, up to now no instrument has been available that enables the measurement of blood pressure underwater. The present paper details a novel, oscillometric, automatic digital blood pressure (BP) measurement device especially designed for this purpose.