Deterioration of gas exchange in subjects with an increase in body mass index at an altitude of 2,240 m above sea level

{Introduction: Alterations of gas exchange (GE) have been recognized in morbid obesity; however, it is not known how their behavior would be as the body mass index (BMI) increases. Objective: The objective of the study was to know the behavior of GE at the level of Mexico City in the development of morbid obesity. Materials and methods: Through analytical design, subjects matched by gender and age were studied from four different groups of BMI (kg/m(2)), normal (18.5-24.9), overweight (25-29.9), obesity (30-39.9), and morbid obesity (>= 40). Their pathological and demographic antecedents, arterial blood gas and simple spirometry variables were obtained. The variables were shown according to their sample characteristic. The differences between groups were made using one-way ANOVA with Bonferroni adjustment, as well as Pearson's correlation for the related variables. Statistical significance was considered with p < 0.05. Results: 560 subjects were studied in four groups. The average age was 49 +/- 11 years old. The highest frequency of diabetes mellitus (34.29%), arterial hypertension (50%), and hyperlipidemia (36.43%) was in the obesity group, and being snoring (73.57%) in morbid obesity. There were differences from the normal group versus morbid obesity: PaCO2 31.37 +/- 2.08 versus 38.14 +/- 5.10 mmHg; PaO2 68.28 +/- 6.06 versus 59.86 +/- 9.28 mmHg; and SaO(2) 93.51 +/- 1.93 versus 89.71 +/- 5.37%, all with p = 0.0001 the IMC-PaCO2 correlation: 0.497, and IMC-PaO2: -0.365