Elsevier

Psychoneuroendocrinology

Volume 47, September 2014, Pages 221-231
Psychoneuroendocrinology

Effects of 24 h working on-call on psychoneuroendocrine and oculomotor function: A randomized cross-over trial

https://doi.org/10.1016/j.psyneuen.2014.05.019Get rights and content

Summary

Objectives

On-call duty (OCD) is frequently associated with health and safety risks for both physicians and patients. The lack of studies conducted in clinical care environments and the ongoing public dialogue concerning OCD led to a detailed investigation of a working schedule including sleep fragmentation and extended work hours.

Design

Within-person randomized cross-over trial.

Setting

Comparison of a 24 h on-call shift (OCD) compared to a routine working-day (non on call, NOC) in hospital.

Participants

30 residents and senior physicians of the Department of Internal Medicine, Neurology and Otorhinolaryngology at the University Hospital Innsbruck.

Main outcome measures

Sleep variables, cognitive performance (Concentration–Endurance d2 test), emotional status (Eigenschaftswoerterliste 60S), serum-cortisol, urinary cortisol and noradrenaline, heart-rate variability, and saccadic eye movements were determined before and after OCD and NOC respectively.

Results

Concentration-endurance performance was significantly reduced after OCD as compared to NOC by 16.4% (p < 0.001). Changes in emotional status consisted in a reduction of subjective concentration and performance related activation after OCD by 17.4% (p < 0.001) and 16.0% (p < 0.001) respectively together with a 21.8% increase of general deactivation (p < 0.001) and a 29.2% rise of fatigue (p < 0.001). On the contrary, subjective activation and raised mood showed an 18.3% and 21.7% increase after OCD (p < 0.01). Urinary noradrenaline excretion (46 μg/24 h, 19–97) was greater during OCD when compared to NOC (36 μg/24 h, 10–54, p < 0.01). Sympathetic activity measured by heart rate variability was significantly higher during OCD in contrast to NOC (p < 0.05). Serum-cortisol was lower in the morning after (132 ng/l, 60–273) than the morning before OCD (p < 0.01). Finally, the number of short saccadic latencies was reduced after OCD (p < 0.05) compared to NOC.

Conclusions

24 h OCD alters both, the sympathetic-adrenomedullary system as well as the hypothalamic pituitary-adrenocortical axis. Moreover, physicians’ emotional state, cognitive and oculomotor performance seems to be influenced independently from sleep interruptions. The discrepancy between subjective feeling and objective cognitive impairments pose a risk for performing complex manual and cognitive tasks. Hence, our findings argue against an oversimplified interpretation of alterations in the physicians’ psychoneuroendocrine structure in terms of impaired mood and neurocognitive deterioration combined with up-/dysregulated stress axes associated with OCD as a consequence of sleep deprivation.

Introduction

On-call duty (OCD) is a common pattern of working schedule among physicians in European hospitals (Baldwin et al., 2003, Council of the European Union, 2007). For continuous night shift workers, as air traffic controllers or emergency physicians it is well known that they are prone to errors while working night shifts (Smith-Coggins et al., 1994). OCD combines day and night work, and includes extended work hours, frequent stressful situations, sleep deficit and desynchronisation of the circadian rhythm (Akerstedt, 2007). Furthermore, it provides a possibility to maintain compliance with restricting regulatory guidelines although accompanied by risks for the physician's health (Rauchenzauner et al., 2009). In the early 70s, Friedman and colleagues found a reduced ability to judge electrocardiogram (ECG) print-outs during OCD (Friedman et al., 1971). Self-injuries and motor vehicle crashes after extended work hours are known to reflect the negative short-term effects on physician's safety (Barger et al., 2005, Ayas et al., 2006). In 2003, the American Accreditation Council for Graduate Medical Education reacted to the growing concerns about patients’ safety treated by sleep deprived physicians and limited continuous clinical work to 24 h. Time and again OCD shift-systems are the substance of a public dialogue although the clinical importance of sleep curtailment still remains unclear due to the lack of studies conducted in clinical care environments (Gaba and Howard, 2002). The main focus of clinical research deals with performance decrements after nightshift in view of an optimal treatment of patients. However, the physician's emotional state influences the patient-physician interaction and the communication between doctor and patient plays an important role in economic health care issues (Epstein et al., 2005). Data concerning the immediate effects of OCD on the emotional status are sparse and often focus on negative feelings often neglecting affects on positive emotions (Crowley et al., 2004, Rose et al., 2008).

This is a sub study of a trial investigating cardiovascular stress response during OCD (Rauchenzauner et al., 2009). The aims of this study were to:

  • 1.

    Investigate changes in mood, cognitive performance in relation to sympathetic-adrenomedullary axis (SMA) and the hypothalamic-pituitary-adrenocortical axis (HPA) over a 24 h period during OCD as compared to a regular working day (non on call, NOC)

  • 2.

    Determine the causative factors of the observed changes (e.g. sleep deprivation, repeated awakenings by phone calls or the on-call shift itself)

  • 3.

    Identify impairment of neurocognitive function after OCD by analysis of saccadic latency distributions.

Section snippets

Study design (Fig. 1)

Participants were residents and senior physicians of the Department of Internal Medicine, Neurology and Otorhinolaryngology at the University Hospital Innsbruck. Each physician completed two days (24 h) of data collection in a randomized within-person cross-over design as reported previously (Rauchenzauner et al., 2009). To avoid a residual effect of OCD on NOC the minimal interval between OCD and NOC was defined as 7 days at least. Randomization was performed by an external advisor.

The

Results

Forty-four physicians were assessed for eligibility and 40 colleagues agreed to participate in the study. Thereof, seven study participants were lost to follow-up [cancelled consent of participation (n = 4), aborted night shift (n = 1), refused to participate (n = 1), moved away from Innsbruck (n = 1)]. Since three colleagues had to be excluded from analysis due to manifest cardiac abnormality (n = 1) or alcohol consumption on control day (n = 2), 9 female and 21 male physicians remained for data analysis (

Discussion

This is the first randomized cross-over trial investigating changes in cognitive performance and mood related to objective parameters of stress in physicians doing OCD. We found a significant reduction in cognitive performance and alterations in emotional state. These findings were associated with an activation of the SMA-axis and a reduction in short latencies during saccadometry as a sign of fatigue.

Cognitive performance was significantly reduced after OCD when compared to NOC. The d2-test

Conclusion

24 h OCD impairs cognitive performance associated with a distinctive emotional change showing elevated mood. This is accompanied by alterations of both the SMA- and the HPA-axis, which may counteract an impaired oculomotor system. 32 h on-call duties are still legal practice in Austrian hospitals and when one considers another possible 8 h of patient contact these findings are clinically relevant with respect to a balanced patient-interaction and the accuracy of medical decisions.

Role of the funding source

The study was supported by Landessanitätsdirektion für Tirol, Österreich.

Conflict of interest

The authors declare no conflict of interest.

Acknowledgement

We thank all participants of this study for their patience and collegiality during data acquisition.

Glossary

AW
awakenings
CP
concentration performance
ECG
electrocardiogram
EWL
Eigenschaftswoerterliste
fOCD
first nightshift
GD
general deactivation
HPA
hypothalamic pituitary-adrenocortical
LATER
Linear Approach to Threshold with Ergodic Rate
NOC
not on-call
OCD
on-call duty
OCD/m
OCDs per month
OP
overall performance
PRA
performance related activation
SMA
sympathetic-adrenomedulary
TIB
time in bed
TST
total sleep time
TWT
total wake time
VLF
spectral power in very low frequency

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