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Effects of hypothermia with and without buffering in hypercapnia and hypercapnic hypoxemia
Author(s) -
WETTERBERG T.,
SJÖBERG T.,
STEEN S.
Publication year - 1994
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1994.tb03892.x
Subject(s) - hypercapnia , medicine , hypoxemia , hypothermia , anesthesia , hypoxia (environmental) , oxygen , acidosis , chemistry , organic chemistry
Anesthetized, paralyzed and mechanically ventilated pigs were hypoventilated to extreme hypercapnia (Paco 2 =20 kPa) at Fio 2 0.5, and allotted to receive hypothermia (=31.5˚C) and buffer infusion, (HB–group, n = 6) or to a hypothermic control group (H–group, n = 6). The HB–group had higher arterial pH (7.34 vs 7.09, P < 0.01) and plasma bicarbonate (58.8 vs 35.4 mmol–l ‐1 , P < 0.01) than the controls, but lower mean pulmonary arterial pressure (MPAP), (16 vs 23 mmHg (2.1 vs 3.1 kPa), P < 0.01) and pulmonary vascular resistance (PVR), (512 vs 699 dyn–s–cm ‐5 (5120 vs 6990 μN–s–cm ‐5 ), P < 0.05). Mixed venous Po 2 (Pvo 2 ) was lower in the HB–group (5.1 vs 6.8 kPa, P < 0.01), as well as serum potassium (2.8 vs 3.7 mmol l ‐1 , P <0.01) and ionized calcium (1.01 vs 1.29 mmol l ‐1 , P <0.01). Subsequently, the inspired oxygen fraction (Fio 2 ) was decreased stepwise (0.3, 0.25, 0.21, 0.15, 0.10) at 30 min intervals. At Fio 2 0.3, the HB–group had lower Pvo 2 (6.6 vs 7.8 kPa, P <0.01), O 2 half saturation tension (3.6 vs 4.2 kPa, P <0.01), MPAP (17 vs 25 mmHg (2.3 vs 3.3 kPa, P <0.01) and PVR (598 vs 793 dyn–s–cm ‐5 (5980 vs 7930 μN–S'cm ‐5 , P <0.05) compared with the controls, but higher arterial O 2 saturation (95.3 vs. 88.6%, P < 0.01) and O 2 content (17.7 vs 15.7 ml– 100 ml ‐1 , P <0.05). The groups did not differ in O 2 delivery, in spite of their difference in arterial O 2 content, because of a lower cardiac output in the HB–group (1.6 vs 2.2 l–min ‐1 , P <0.05). Mixed venous O 2 content, O 2 consumption and O 2 extraction did not differ between groups. Combined use of hypothermia and buffering did not improve survival in hypercapnic hypoxemia as compared to a hypothermic regimen without buffer.