OBJECTIVE: To evaluate whether arterial pressure response during a Valsalva maneuver could predict fluid responsiveness in spontaneously breathing patients. DESIGN AND SETTING: Prospective clinical study in a 17-bed multidisciplinary intensive care unit. PATIENTS: Thirty patients without mechanical ventilation and equipped with a radial arterial catheter for whom the decision to ...

Previous research has reported that inhibition of breathing can be observed in hypertensive patients at rest during the daytime, as well as in sleep at night. The present study hypothesized that the variability of breathing and end-tidal CO(2) (PetCO(2)) in seated women at rest is positively associated with their 24-h ...

The present study aimed to explore inspiratory motor drive as measured by inspiratory occlusion pressure (P100) during affective picture viewing. P100 is the decrease in mouth pressure that develops 100 ms after an inspiratory effort against a closed breathing circuit. The P100 is a measure of the "central respiratory drive." ...

OBJECTIVES: Assess the effect of re-expansive respiratory patterns associated to respiratory biofeedback (RBF) on pulmonary function, respiratory muscle strength and habits in individuals with functional mouth breathing (FMB). METHODS: Sixty children with FMB were divided into experimental and control groups. The experimental group was submitted to 15 sessions of re-expansive ...

The objective of this 14-pig study was designed to determine the amount of lung ventilation obtainable by only rhythmic chest compression (100/min, 100 lbs). Tidal volume (TV), dead space (DS), and respiration rate (R) were measured with normal breathing and with rhythmic chest compression during ventricular fibrillation. The ratio of ...

INTRODUCTION: A prospective physiological study was performed in 12 paediatric patients with acute moderate hypercapnic respiratory insufficiency to assess the ability of noninvasive positive pressure ventilation (NPPV) to unload the respiratory muscles and improve gas exchange. MATERIALS AND METHODS: Breathing pattern, gas exchange, and inspiratory muscle effort were measured during ...

OBJECTIVE: Both ventilations and compressions are important for victims of prolonged cardiopulmonary resuscitation (CPR) and asphyxial arrest. Dispatch assistance increases bystander CPR, but the quality of dispatcher-assisted CPR (DA-CPR), especially rescue breathing, remains unsatisfactory. This study was conducted to assess the impact of adding interactive video communication to dispatch instructions ...

Introduction: Preoxygenation optimizes oxygen content in the functional residual capacity (FRC). Creating a better reservoir with the help of inspiratory support and PEEP could improve gas exchange and shorten the time needed for adequate preoxygenation, defined as expiratory oxygen fraction (FEO2) greater than 90%. The goal of this study was ...

PURPOSE OF REVIEW: Predicting volume responsiveness in patients with spontaneous breathing activity is a difficult challenge in the emergency room as well as in the intensive care unit because heart-lung interactions indices cannot be reliably used as they can be in mechanically ventilated patients fully adapted to their ventilator. The ...

OBJECTIVE: To assess if the observed respiratory cycle-related variation in intra-abdominal pressure is reliably quantifiable and a possible indirect indicator of abdominal compliance. Secondary issues were to assess the roles played by respiratory parameters in determining this oscillation and by patients' position in increasing their intra-abdominal pressure. DESIGN AND SETTING: ...

Cheyne-Stokes respiration (CSR) is a periodic breathing pattern, characterized by short intervals of very little or no breathing (apnea), each followed by an interval of very heavy breathing (hyperpnea). This work presents a new compartmental model of the human cardio-respiratory system, simulating the factors that determine the concentrations of carbon ...

Measurement of haemodynamic responses and cutaneous blood flow during an inspiratory-capacity apnoea following spinal cord injury (SCI). To assess the capacity of the sympathetic nervous system to respond to a cardiovascular challenge following SCI. Prince of Wales Medical Research Institute, Australia. Thirteen spinal cord injured subjects with injuries ranging from ...

BACKGROUND: Breathing hydrogen sulfide (H2S) has been reported to induce a suspended animation-like state with hypothermia and a concomitant metabolic reduction in rodents. However, the impact of H2S breathing on cardiovascular function remains incompletely understood. In this study, the authors investigated the cardiovascular and metabolic effects of inhaled H2S in ...

The effect of right, left, and alternate nostril yoga breathing (i.e., RNYB, LNYB, and ANYB, respectively) were compared with breath awareness (BAW) and normal breathing (CTL). Autonomic and respiratory variables were studied in 21 male volunteers with ages between 18 and 45 years and experience in the yoga breathing practices ...

BACKGROUND: A crossover study was performed in healthy volunteers to compare the efficacy of a self-inflating bag with the Mapleson C breathing system for pre-oxygenation. METHOD: 20 subjects breathed 100% oxygen for 3 min using each device, with a 30 min washout period. The end tidal oxygen concentration and subjective ...

This paper presents a simple alternative method and system for noninvasive respiratory airflow monitoring. The proposed system uses a piezoceramic transducer to measure respiratory airflow. When a piezoceramic transducer is impacted by respiratory airflow, there is a piezoelectric and a pyroelectric response to pressure and thermal airflow fluctuations. In this ...

Ventilatory flow measured at the airway opening in humans exhibits a complex dynamics that has the features of chaos. Currently available data point to a neural origin of this feature, but the role of respiratory mechanics has not been specifically assessed. In this aim, we studied 17 critically ill mechanically ...

Inspiratory resistance induced by breathing through an impedance threshold device (ITD) reduces intrathoracic pressure and increases stroke volume (SV) in supine normovolemic humans. We hypothesized that breathing through an ITD would also be associated with a protection of SV and a subsequent increase in the tolerance to progressive central hypovolemia. ...

Competitive breath-hold divers try to achieve maximum times, depths, or distances underwater, thereby risking hypoxic syncope. In the present study, the cardiorespiratory responses to dynamic apnea (simultaneously initiated apneas and dynamic leg exercise) were investigated in 10 breath-hold divers. The divers performed 60 s dynamic apneas with the face in ...

The question of hydrostatic pressure or normal stress dependence of the flow and fracture behaviour of bulk metallic glasses is addressed. Data from several types of mechanical tests indicate that flow is hardly sensitive to pressures or normal stresses, while fracture is normal stress sensitive and not pressure dependent. Besides, ...

OBJECTIVE: To quantify the respiratory and cardiovascular effects of intravenous or subcutaneous buprenorphine in conscious rabbits. STUDY DESIGN: Prospective experimental trial. ANIMALS: Eight healthy, young adult New Zealand white rabbits (four female). METHODS: Rabbits were instrumented with intraabdominal arterial and venous catheters and diaphragmatic electromyographic electrodes 2 weeks before experiments. ...

The impact of the respiratory pattern on respiratory muscle workload represents an unresolved controversy and is important for the treatment of patients with respiratory disorders and respiratory muscle failure. We designed this study to investigate the relationship of respiratory pattern and inspiratory workload. We measured esophageal pressure and inspiratory flow ...

AIM: To evaluate the influence of respiratory muscle overload and right cardiac overload among the possible risk factors of hospital readmission in a 1-year follow-up of a cohort of patients with moderate-to-severe COPD. METHODS: A total of 112 COPD patients who were admitted consecutively to the hospital for acute exacerbation. ...

BACKGROUND: Loads on the respiratory muscles, reflected by noninvasive measurement of the real-time power of breathing (POBn), and tolerance of these loads, reflected by spontaneous breathing frequency (f) and tidal volume (Vt), should be considered when evaluating patients with respiratory failure. Pressure support ventilation (PSV) should be applied so that ...

It has been suggested that impaired respiratory muscle function occurs in patients with PH (pulmonary hypertension); however, comprehensive investigations of respiratory muscle function, including the application of non-volitional tests, needed to verify impairment of respiratory muscle strength in patients with PH have not yet been performed. In the present study, ...

We studied the effects of different respiratory patterns, namely, spontaneous breathing, paced breathing (at a rate of 10 breaths/min and at their mean spontaneous breathing frequency) and breath holding, on the nonlinear characteristics of heart rate variability (HRV). The results showed that paced breathing at both rates significantly diminished the ...

Detection of inspiratory flow limitation (IFL) is being recognized of increasing importance in order to diagnose pathologies related to sleep disordered breathing. Currently, IFL is usually identified with the help of invasive esophageal pressure measurement, still considered the gold-standard reference to assess respiratory effort. But the invasiveness of esophageal pressure ...

An airway monitoring system was developed to record the lung dynamics of sheep using oesophageal pressure techniques. These techniques are minimally invasive and do not impede the animal from breathing spontaneously. This study investigates three methods for deriving lung resistance (R) and compliance (C) by evaluating their ability to select ...

STUDY OBJECTIVES: To analyze the physiologic effects and tolerance of mechanical insufflation-exsufflation (MI-E) by means of mechanical cough assistance (Cough Assist; JH Emerson Company; Cambridge, MA) for children with neuromuscular disease. DESIGN: Prospective clinical trial. SETTING: Physiology laboratory of a pediatric pulmonary department of a university hospital. PATIENTS: Seventeen children ...

BACKGROUND: Tracheostomy decreases airway resistance and work of breathing. No comprehensive data are available on respiratory mechanics after tracheostomy decannulation. We evaluated respiratory mechanics after decannulation. METHODS: Twenty-five patients with tracheostomy were included. Measurement of arterial blood gases, air-flow, and esophageal pressure during spontaneous breathing were evaluated. RESULTS: Overall arterial ...

The effects of inspiratory muscle (IM) warm-up on IM function and on the maximum distance covered in a subsequent incremental badminton-footwork test (FWmax) were examined. Ten male badminton players were recruited to perform identical tests in three different trials in a random order. The control trial did not involve an ...

BACKGROUND: Noninvasive positive-pressure ventilation (NPPV) unloads respiratory muscles. Spontaneous-breathing ventilation modes require patient effort to trigger the ventilator, whereas controlled modes potentially economize on patient triggering effort and thus achieve more complete respiratory muscle rest. Data on controlled NPPV have not been published to date. We hypothesize that controlled ventilation ...

The jeju is a teleost fish with bimodal respiration that utilizes a modified swim bladder as an air-breathing organ (ABO). Like all air-breathing fish studied to date, jeju exhibit pronounced changes in heart rate (fH) during air-breathing events, and it is believed that these may facilitate oxygen uptake (MO2) from ...

For a given neural drive, oesophageal pressure during apnoeic episodes may differ from that during airflow, since inspiratory airflow and increased lung volume both reduce pressure generation. It was, therefore, hypothesised that diaphragm electromyography (EMG) may provide additional data to oesophageal pressure when used for the assessment of neural drive ...

RATIONALE: The assessment of the severity of croup and response to therapy has remained a clinical one. Despite recognition of the importance of a reproducible and easily applicable method for objectively measuring severity, currently, no such technique exists. OBJECTIVES: We postulated that measurements of air flow and intrathoracic pressure changes ...

Breath-hold divers use glossopharyngeal breathing to inhale above total lung capacity (glossopharyngeal insufflation, GI) or exhale below residual volume (glossopharyngeal exsufflation, GE). In these maneuvers, air is moved using glossopharyngeal rather than respiratory muscle activity. Four competitive divers performed several GI and GE maneuvers in sitting or standing position, while ...

We evaluated daily variability in the cardiovascular response to arterial chemoreceptors activation during breath holding in shift workers who were obstructive sleep apnea patients. Ten patients and 10 weight and age-matched control subjects were enrolled in the study. The experimental sessions consisted of 10 episodes of breath holding on inspiration ...

INTRODUCTION: Prolonged +G,-exposure eventually decreases a pilot's ability to maintain an effective anti-G straining maneuver (AGSM). Previous studies have implicated the respiratory muscles (RMs) as main contributors to this AGSM-induced fatigue. Thus, this study aimed to investigate if respiratory muscle training (RMT) may be of benefit to improve RM strength, ...

OBJECTIVE: To investigate whether 10 breaths against a vibration stimulus elicits increments of spontaneous and maximal inspiratory mouth pressure (maxMP) and tidal mean inspiratory flow (iV(T)/T(I)) upon stimulus removal. METHODS: Twelve healthy subjects (8 female, 4 male; 22-50 years old), recruited from the University student body, completed 3 maximal inspirations ...

GOALS: This study assessed the effect of hydromorphone treatment on ventilation and the intensity of dyspnea in palliative care patients. The assessments measured changes in peripheral oxygen saturation (SaO(2)), transcutaneous arterial pressure of carbon dioxide (tcpaCO(2)), respiratory rate (f), and pulse frequency (PF) during the titration phase with hydromorphone for ...

Breathing including abdominal movement could affect the blood velocity (BV) measurement in the visceral arteries. The present study investigated the effect of breathing frequency on the renal artery (RA) and superior mesenteric artery (SMA) BV measurements. We measured mean arterial pressure (MAP), heart rate (HR) and BV in the RA ...

Chronic obstructive pulmonary diseases (COPD) is a pulmonary disease characterized by systemic abnormalities. The aim of this study is to investigate inflammation and systemic effects in mild COPD. Twenty-seven mild stable smoking related COPD patients and 15 age-matched healthy subjects were enrolled in the study. IL-6, TNF-alpha and IL-4 in ...

Inspiratory muscle strength monitoring is crucial in patients with neuromuscular disorders. The sniff nasal inspiratory pressure (SNIP) and maximal inspiratory pressure (P(I,max)) are usually measured. The present study investigated whether the test yielding the best value at baseline continued to yield the best value during follow-up. The present study included ...

OBJECTIVE: To assess whether subtracting the expiratory change in intra-abdominal (bladder) pressure (Delta IAP) from central venous pressure (CVP) provides a reliable estimate of transmural CVP in spontaneously breathing patients with expiratory muscle activity. DESIGN AND SETTING: Prospective observational study in a medical ICU. PATIENTS: Twenty-four spontaneously breathing patients with ...

A readily available assessment of changes in pleural pressure would be useful for ventilator and fluid management in critically ill patients. We examined whether changes in pulmonary artery occlusion pressure (Ppao) adequately reflect respiratory changes in pleural pressure as assessed by changes in intraesophageal balloon pressure (Peso). We studied patients ...

BACKGROUND: The non-invasive photoplethysmographic (PPG) signal reflects blood flow and volume in a tissue. The PPG signal shows variation synchronous with heartbeat (PPGc), as used in pulse oximetry, and variations synchronous with breathing (PPGr). PPGr has been used for non-invasive monitoring of respiration with promising results. Our aim was to ...

BACKGROUND: Selective increase of inspiratory impedance augments blood pressure in healthy subjects through activation of the respiratory pump. We studied the efficacy of respiratory maneuvers to reduce orthostatic hypotension in autonomic failure. METHODS: Mean arterial pressure (MAP) after standing up was recorded in 10 patients in five conditions: normal standing, ...

Over the past decade several studies have assessed the relation of blood pressure with cognitive function and dementia. While some cross-sectional studies have shown an inverse association between blood pressure levels and cognitive performance or dementia, longitudinal studies yielded controversial results. Most studies relating blood pressure levels in mid-life with ...

BACKGROUND: The spontaneous breathing pattern and its relationship to compliance, resistance, and work of breathing (WOB) has not been examined in patients with acute respiratory distress syndrome (ARDS) or acute lung injury (ALI). Clinically, the ratio of respiratory frequency to tidal volume (f/VT) during spontaneous breathing may reflect adaptation to ...

This study addresses the following question: does the ventilatory control system adjust total ventilation in accord with the regulatory demands of the physiological dead space ventilation (VD) when the breathing frequency changes, and if so, how? A simple proportionality between the amplitude of the respiratory motor output (VT) and the ...