Table 1– Summary of blood gas results grouped according to oxygen saturation levels
Oxygen saturation rangeSamplesHypercapnia#Uncompensated respiratory acidosisCompensated respiratory acidosis+Uncompensated metabolic acidosis§
>98%1458 (41.3)305 (21)83 (6)161 (11)111 (8)
9498%1291 (36.6)294 (23)65 (5)167 (13)90 (7)
92.193.9%237 (6.7)85 (36)14 (6)58 (24)15 (6)
8892%288 (8.2)119 (41)35 (12)61 (21)17 (6)
8087.9%154 (4.3)76 (49)18 (12)41 (27)6 (4)
7079.9%53 (1.5)40 (75)12 (23)21 (40)1 (2)
6069.9%22 (0.6)14 (64)6 (27)4 (18)4 (18)
<60%21 (0.6)15 (71)6 (29)5 (24)2 (10)
Total3524 (100)948 (26.9)239 (6.8)518 (14.7)246 (7.0)
  • Data are presented as n (%). 94–98% is the suggested target range for the majority of acutely unwell patients and 88–92% is the suggested target range for those at risk of hypercapnic respiratory failure [6]. #: carbon dioxide tension (PCO2) >6.0 kPa or 45 mmHg. : pH <7.35, PCO2 >6.0 kPa or 45 mmHg, and normal or elevated base excess. Includes 140 samples with uncompensated respiratory acidosis (base excess -2.0 to +2.0 mmol·L−1) and 99 samples with incompletely compensated respiratory acidosis (pH remains <7.35 despite base excess >2.0 mmol·L−1). +: compensated respiratory acidosis (pH 7.35–7.45, PCO2 >6.0 kPa or 45 mmHg, and base excess >2.0 mmol·L−1 ). §: uncompensated metabolic acidosis (pH <7.35, PCO2 ≤6.0 kPa or 45 mmHg, and base excess <-2.0 mmol·L−1). 65 (1.8%) samples demonstrated mixed metabolic and respiratory acidosis (pH <7.35, PCO2 >6.0 kPa or 45 mmHg, and base excess <-2.0 mmol·L−1).