Irregular Breathing Patterns Research Articles

Evaluation of a Pilot Workload Metric for Simulated VTOL Landing Tasks

A methodological approach to measuring workload was investigated for evaluation of new concepts in VTOL aircraft displays. Multivariate discriminant functions were formed from conventional flight performance and/or visual response variables to maximize detection of experimental differences. The flight performance variable discriminant showed maximum differentiation between crosswind conditions. The visual response measure discriminant maximized differences between fixed vs. motion base conditions and experimental displays. Physiological variables were used to attempt to predict the discriminant function values for each subject/condition/trial. The weights of the physiological variables in these equations showed agreement with previous studies. High muscle tension, light but irregular breathing patterns, and higher heart rate with low amplitude all produced higher scores on this scale and thus, represented higher workload levels.

Abnormal breathing patterns

In health, breathing is regular and the respiratory rate is sufficiency constant to be useful as a vital sign of health and disease. This regularity depends on a complex interplay of chemical and neural control systems that operate automatically to reset the rate and depth of breathing as changes occur in posture and activity, to adjust the level of ventilation so that changes in gas tensions and pH in the blood and in the brain intersitial fluid are exceedingly modest despite wide swings in metabolic rate and in environmental conditions, and to coordinate ventilation and circulation so that the requirements of individual tissues for O2 delivery and CO2 removal are satisfied. Two broad categories of disorders can result from malfunction of these systems (Table 1): (1) disproportionate ventilation (too high or too low) for the level of metabolic activity, thereby producing severe abnormalities in blood gas tensions or in acid-base balance, and (2) an irregular breathing pattern without eliciting gross changes in blood gas tensions or in acid-base balance. Because of the complexity of the control system, each of these categories represents a final common pathway that can be produced in different ways. In this presentation, we will attempt to describe the general features that characterize the operation of the control system and some new technics that make it possible to trouble-shoot the malfunctioning system in order to identify the mechanism(s) responsible for the abnormality in breathing pattern.

Respiratory Function After Cervical Cordotomy

<h2> </h2> The effect of percutaneous cervical cordotomy on respiratory function was evaluated in 143 patients after unilateral cordotomy and in 37 patients after a bilateral procedure. Cervical cordotomy resulted in a reduction of FVC, MBC, minute ventilation and tidal volume, breathing both air and 5 percent CO₂, an increase in respiratory rate and a more irregular breathing pattern. These changes were greater following bilateral cordotomy than after a unilateral procedure, and were greater in patients who obtained a high level of analgesia. The impairment of motor function, indicated by the reduction of FVC and MBC, has been previously ascribed to section of efferent pathways to the phrenic nerve nuclei. The disturbance of respiratory control mechanisms indicated by hypoventilation, diminished CO₂ response and irregular breathing could not be explained by the reduction of motor function. On the other hand, the similarity of these changes to those seen with lesions of the lateral reticular formation, suggests that the disordered control mechanism following cordotomy is probably due to ablation of reticular formation tracts. Although it remains to be shown whether these are afferent or efferent pathways, the effect of cordotomy is consistent with deafferentation of the reticular formation.