R-R interval variability (RR variability) is increasingly being used as an index of autonomic activity. High-frequency (HF) power reflects vagal modulation of the sinus node. Since vagal modulation occurs at the respiratory frequency, some investigators have suggested that HF power cannot be interpreted unless the breathing rate is controlled. We hypothesized that HF power during spontaneous br...

High-frequency spinal cord stimulation (HF-SCS) is a novel technique of inspiratory muscle activation involving stimulation of spinal cord pathways, which may have application as a method to provide inspiratory muscle pacing in ventilator-dependent patients with spinal cord injury. The purpose of the present study was to compare the spatial distribution of motor drive to the parasternal interco...

To investigate the interindividual differences in respiratory sinus arrhythmia (RSA), recordings of ventilation and electrocardiogram were obtained from 12 healthy subjects for five imposed breathing periods (T(TOT)) surrounding each individual's spontaneous breathing period. In addition to the spectral analysis of the R-R interval signal at each breathing period, RSA characteristics were quant...

The purpose of this study was to elucidate the influence of inspiratory muscle fatigue on muscle sympathetic nerve activity (MSNA) and blood pressure (BP) response during submaximal exercise. We hypothesized that inspiratory muscle fatigue would elicit increases in sympathetic vasoconstrictor outflow and BP during dynamic leg exercise. The subjects carried out four submaximal exercise tests: tw...

OBJECTIVE The failure to wean from mechanical ventilation is related to worse outcomes after cardiac surgery. The aim of this study was to evaluate whether the serum level of B-type natriuretic peptide is a predictor of weaning failure from mechanical ventilation after cardiac surgery. METHODS We conducted a prospective, observational cohort study of 101 patients who underwent on-pump coronar...

BACKGROUND Delivery of bronchodilator to infants and small children from a pressurized metered-dose inhaler with valved holding chamber (pMDI-VHC) is limited by airway narrowness, short respiratory cycle time, and small tidal volume (V(T)). There is a need for a versatile, efficient VHC, given the variety of treatment modalities. METHODS We tested the AeroChamber Mini VHC (the internal geomet...

Abstract The determination of respiratory parameters via respiration induced surface movements the upper body has been subject research for many years. displacements 102 motion capture markers were evaluated in this study terms their information content with respect to tidal volume recorded parallel using a spirometer. Independent breathing types (spontaneous breathing, abdominal or chest breat...

INTRODUCTION Experimental and clinical studies have shown a reduction in intrapulmonary shunt with spontaneous breathing during airway pressure release ventilation (APRV) in acute lung injury. This reduction was related to reduced atelectasis and increased aeration. We hypothesized that spontaneous breathing will result in better ventilation and aeration of dependent lung areas and in less cycl...

BACKGROUND Weaning patients from mechanical ventilation is an important problem in intensive care units. Weaning is usually conducted in an empirical manner, and a standardized approach has not been developed. METHODS We carried out a prospective, randomized, multicenter study involving 546 patients who had received mechanical ventilation for a mean (+/- SD) of 7.5 +/- 6.1 days and who were c...

Heart rate variability (HRV), the beat-to-beat alterations in heart rate, comprises sympathetic and parasympathetic nerve activities of the heart. HRV analysis is used to quantify cardiac autonomic regulation. Since respiration could be a confounding factor in HRV evaluation, some studies recommend consciously controlled breathing to standardize the method. However, it remains unclear whether c...