Michael W. Hurst

Plasma Cortisol and Growth Hormone Responses to Intravenous Catheterization

Plasma cortisol and growth hormone (HGH) responses to venous catheterization were studied in 29 volunteer subjects. Repeat characterizations were performed in 18 individuals. Mean plasma cortisol levels were significantly elevated during the first hour of the initial catheterization experience. Morning and afternoon levels of cortisol were not distinguishable during the first catheterization, but PM levels were significantly lower than AM levels during the second catheterization experience. Growth hormone responses were much more variable than cortisol and were distributed logarithmically. Growth hormone responses tended to parallel cortisol responses during the first catheterization experience. Individuals who listed more symptoms in response to venipuncture and catheterization after finishing their first catheterization had significantly higher cortisol and growth hormone levels during this experience. These data suggest a definite endocrine adaptation to catheterization by the second or third hour of the experience.

ENDOCRINE ACTIVITY IN AIR TRAFFIC CONTROLLERS AT WORK. I. CHARACTERIZATION OF CORTISOL AND GROWTH HORMONE LEVELS DURING THE DAY

This is the first in a series of three reports on repeated endocrine studies in the working environment for a group of 416 air traffic controllers. Twenty-minute integrated concentrations for plasma cortisol and human growth hormone across five-hr work periods are described and compared with a selection of studies of normal males reported in the literature. On average, across three repeated studies, controllers were secreting more cortisol and less growth hormone than the most comparable group of normal males. Cortisol and growth hormone levels were not appreciably related, and both hormones showed a lack of consistency across repeated studies in terms of average level or measures of episodic secretory activity. Small increases in cortisol secretion in response to venipuncture were apparent in some controllers during the morning hours; on the other hand, no growth hormone responses were evident. Neither hormone showed decreased secretion with repeated blood collections. Relationships between hormone secretion and the work environment, which possibly explain the lack of hormone consistency across time, will be examined in the second report.

Objective Job Difficulty, Behavioural Response, and Sector Characteristics in Air Route Traffic Control Centres∗

Abstract Two thousand observations on 47 radar sectors in Boston and New York were used to determine the principal behavioural stressors in the air traffic control environment. Predictor variables included peak traffic. mean airspeed, sector area, sector type, radio-communication time, and theoretically derived control load factors. Expert observers rated the degree of activity and behavioural arousal of ATCs working the 47 radar sectors at the same time the objective measures were made. These ‘pace’ ratings were significantly related to peak traffic count and duration of radio-communications. The control load factors were not related to behavioural responses. Statistical analyses indicated several refinements for the definition and measurement of the control load factors, For example, airspace control load was reliably estimated by sector type and number of transitioning planes, while co-ordination control load was most appropriately estimated by duration of radio-communications These results suggested t...

ENDOCRINE ACTIVITY IN AIR TRAFFIC CONTROLLERS AT WORK. III. RELATIONSHIP TO PHYSICAL AND PSYCHIATRIC MORBIDITY

This final report in the series of three examines the relationships between physical health change, psychopathology and work responsiveness to cortisol and growth hormone secretion in air traffic controllers. In contrast to expectations, those who had the lowest rates of mild to moderate physical health change showed a modest tendency to have higher average cortisol. Those men who experienced more psychiatric symptomatology in terms of impulse control problems, alcohol abuse and subjective distress had slightly higher average cortisol values at work. Those men who responded to increased workload with increases in cortisol, possibly reflecting increased job involvement, also had higher average cortisol. Physical health change, levels of psychopathology and cortisol responses to increased workload were statistically independent predictors of average cortisol levels.

Objective Workload and Behavioural Response in Airport Radar Control Rooms

Previous research indicated that peak traffic and the duration of radio-communications were good predictors of behavioral response of air traffic controllers working air route traffic control centers. This study investigated whether these two measures of workload are generalizable to controllers (ATCs) working in radar facilities serving major airports. 3,110 observations were made on radar sectors at the 13 major radar control rooms in the U.S.A. A large number of air traffic variables and communication tasks were measured. Behavioral ratings were made by expert-observer ATCs. The results replicated previous findings that peak traffic and the duration of radio-communications functioned as behavioral stressors. Time monitoring and stand-by time also were found to predict behavioral responses. Careful consideration of these and other results led to the conclusion that peak traffic is the most generalizable environmental stressor for ATCs behavior whereas the other workload measures are more correctly viewed as concomitants of the demand characteristics of ATC work.