Biological research for nursing
-
Variations in intrathoracic pressure generated by different ventilator weaning modes may significantly affect intrathoracic hemodynamics and cardiovascular stability. Although several investigators have attributed cardiovascular alterations during ventilator weaning to augmented sympathetic tone, there is limited investigation of changes in autonomic tone during ventilator weaning. Heart rate variability (HRV), the analysis of beat-to-beat changes in heart rate, is a noninvasive indicator of autonomic tone that might be useful in the identification of patients who are at risk for weaning difficulty due to underlying cardiac dysfunction. ⋯ The increase in intrathoracic pressure reduced right ventricular end-diastolic volume (preload). This hemodynamic alteration generated a change in autonomic tone, so that cardiac output could be maintained. Individuals with autonomic and/or cardiovascular dysfunction may not be capable of this type of response and may fail to successfully wean from mechanical ventilation.
-
Comparative Study
Comparison of autonomic nervous system indices based on abdominal pain reports in women with irritable bowel syndrome.
Abdominal pain is an important symptom in irritable bowel syndrome (IBS), but patients report typical pain intensities ranging from mild to very severe. In a sample of women, the authors sought to determine whether measures of systemic autonomic activity are related to self-reported pain intensity and the occurrence of pain in the postprandial period. ⋯ Even after statistically controlling for age, body mass index, and psychological distress, vagal heart rate variability measures were markedly lower in women reporting high pain (P < 0.01) and markedly higher in women reporting postprandial pain (P < 0.02). The vagal component of heart rate variability appears to be reduced in women with severe abdominal pain, especially in those whose pain is not postprandial.
-
The immediate transition from positive pressure mechanical ventilation to spontaneous ventilation may generate significant cardiopulmonary hemodynamic alterations based on the mode of weaning selected, particularly in individuals with preexisting cardiac dysfunction. The purpose of this study was to compare hemodynamic responses associated with the initial transition to 3 modes of ventilator weaning (spontaneous ventilation/T-piece, pressure support [PS], and continuous positive airway pressure [CPAP]). Right ventricular hemodynamic responses were evaluated with a thermodilution pulmonary artery catheter; while left ventricular hemodynamic responses were measured by a transducer-tipped Millar catheter and conductance catheter. ⋯ Baseline ventricular function influenced hemodynamic response to the immediate transition from mechanical to spontaneous ventilation. There were also differential hemodynamic responses based on the ventilatory mode. Consideration of baseline cardiac function may be an important factor in the selection of an appropriate mode of spontaneous ventilation following controlled MV.
-
Comparative Study
Effect of aerobic fitness on the physiological stress response in women.
Stress reactivity was assessed in aerobically fit (n = 14) and unfit (n = 8) females during the follicular phase of the menstrual cycle. Participants completed the Spielberger State-Trait Anxiety Inventory and provided a urine sample for catecholamine analysis before and after mental stress testing, Stroop Color-Word Test. ⋯ Fit and unfit participants differed significantly in baseline heart rate but not in stress reactivity or in state or trait anxiety. These data suggest that aerobic fitness does not attenuate the stress response in women prior to menopause.