Results

In 2013, Quinette et al conducted a research to study the effects of hypoxia on pilots¹. The study was administered by exposing one group of participants to hypoxic conditions in an experimental chamber and the other group was not. A well-established procedure was administered to test cognitive performance of the subjects from both groups. This article is meta-analysis of the original article.

Table 1 below shows comparison of the oxygen desaturation mean values for different phases of the study. Heart rate results are excluded here since heart rate is not a variable of interest in this study.

Table 1: Oxygen saturation mean values comparison
Phase of the study	Control group	Experimental group
Control	98.1	1.7% higher
Transition (after oxygen starvation)	98.6	1.2% higher
Desaturation	98.9	19% higher
Recovery	98.7	35.6% higher

The results depicted in table 2 show that subjects that were exposed to hypoxic conditions performed badly when memory test was undertaken.

Table 2: Relationship between hypoxia and cognitive performance

	Control group	Experimental group
Overall performance (correct responses)	Higher (65%)	Lower (35%)

Classification of errors (Control v/s experimental group)

Omissions	Higher (under hypoxia)
Miscalculations	Higher (under hypoxia)
Suppression failures	Similar for both groups

Error patterns comparison (Control v/s experiment groups)
Omissions	3x higher in hypoxia group
Suppression	5x higher in hypoxia group
Miscalculations	1.5x higher in control group

Methods

Research approach

This is an exploratory experimental research, to analyse the effects of acute hypobaric hypoxia in young pilots.

Sample

The 57 non-smoking young and healthy pilot participants from Department of Medicine Aeronautical Operations in France participated in this study.

Design

Participants were randomly divided into two groups, experimental group and thecontrol group.

Variables

Dependent variable:
- Cognitive performance
Independent variable:
- Arterial blood oxygen saturation

The independent variable was further classified into three classes:

Miscalculation;
Suppression failures; and
Omission.

Material

Hypobaric chamber;
Pulse oximetry sensor; and
Placed Auditory Serial Additional Test (modified version).

Procedure

The participants were randomly allocated to one of the study groups (control or experimental). The experimental group was exposed to hypoxic conditions in a simulation chamber and the control group was not. All participants were required to have sufficient sleep before partaking in the study.
A series of single digit numbers were displayed to the participants and they had to add two consecutive numbers displayed. Failing to add them correctly was regarded as an error.

The experiment was divided into three different phases:

Initial phase;
Desaturation phase; and
Oxygen restoration phase.

Data analysis

The one-way and two-way ANOVA was used to perform data analysis; and
Correlation between ‘working memory’ performance and the blood oxygen desaturation was also measured.

Generalization potential

Due to the convenient sample used for the research, the results may only be applicable to the similar population.

References

1. MALLE Carine, Peggy QUINETTE, Mickael LAISNEY, Cyprien BOURRILHON, Jacqueline BOISSIN, Beatrice DESGRANGES, Francis EUTACHE & Christophe PIERARD (August 2013). Working memory impairment in pilots exposed to acute hypobaric hypoxia. Aviation, Space, and Environmental Medicine, volume 84, number 8, 2013, pages 773-779.

+++ Notes +++

2. Descriptive statistics of 'string-of-correct/incorrect' responses and the length thereof are omitted in this article because they are considered to be of no value in evaluating the cognitive performance. The reliability of this descriptive is also in question since author doesn't mention the scheme used, if any.

3. The results of the desaturation delay phase (which is 60s after the removal of oxygen supply in an experimental chamber) show minimal variation between groups, for this reason, the results are omitted in this article and this period is considered as transition time between control and experimental phases.

4. This is not first of it's type research but rather expands the knowledge and understanding of acute hypoxia in aviation.