Hypoxia is a common condition mainly caused by neurological, cardiac and respiratory disease. Hypoxia is known to affect cognition and driving is dependent on satisfactory cognitive ability. Currently those who are prescribed supplemental oxygen have not been given any guidance from regulatory bodies on whether to use supplemental oxygen while driving. There is very limited research on the possible effects that hypoxia may have on persons whilst driving. This study investigates whether hypoxia influences driving behaviours in healthy subjects using simulated driving. Breathing frequency, oxygen saturation (SpO₂), heart rate variability (HRV) and subjective comments were also collated.

52 healthy subjects participated in this study with written informed consent. The study was approved by the Science & Engineering Ethical Committee, University of Plymouth and procedures were in accordance with the Declaration of Helsinki. Inclusion criteria were ≥18 years old and no history of cardiorespiratory or chronic disease. All subjects had their anthropometric and resting blood pressure, heart rate and SpO₂ data collected. Then they were attached to ECG electrodes, a chest plethysmograph, and an oximeter before they started the simulated driving on an Xbox 360 game console using Forza Horizon 4 software. Each subject had four driving sessions; a 10-minute practice and three randomised interventions: 20-minute normoxic room air (FIO₂ 21%), 20-minute normoxic medical air (FIO₂ 21%) and 20-minute hypoxic air (equal to 15% FIO₂). Driving behaviours (DB) were assessed by the sum of positive and negative scores for each session. HRV and breathing frequency were collected by using LabChart software. Short term HRV was assessed using time domain (heart rate – HR, standard deviation of the RR interval – SDRR), frequency domain (low and high frequency – LF and HF) and Poincaré analysis (SD1 and SD2). The results were statistically analysed in SPSS by repeated measures ANOVA. p < 0.05 was considered as significant.

HR (p<0.0001), SDRR (p=0.03), SD1 (p<0.0001), breathing rate (p=0.01) and SpO2 (p<0.0001) were all significantly different over the three gas interventions (n=52). LH, HF, DB all showed no significant difference. Pairwise comparisons showed that during hypoxia HR increased, while SDRR, SD1, breathing rate and SpO2 were lower, when compared to both normoxic interventions.

The main finding of our study was that hypoxia did not significantly affect simulated driving behaviours in our subjects. Therefore, we believe that the level of hypoxia (FiO2 15%) used in the present study, may not have a great impact during driving. These findings add important significance for legislators and policy makers when making decisions with regard to the road safety of hypoxic patients who drive. Interestingly, HRV was negatively affected by hypoxia whilst driving and provides a starting point for conducting further research on the impact hypoxia may have on driving performance for patients with cardiovascular disease.