J Korean Med Sci.  2005 Oct;20(5):764-769. 10.3346/jkms.2005.20.5.764.

Does Hypercapnic Acidosis, induced by Adding CO2 to Inspired Gas, Have Protective Effect in a Ventilator-induced Lung Injury?

• Park CM
• Lim SC
• Kim YI
• Kim KS
• Oh IJ
• Kim SO
• Kim YC

• KMID: 1781758
• DOI: http://doi.org/10.3346/jkms.2005.20.5.764

Abstract

To investigate whether hypercapnic acidosis, induced by adding CO2 to inspired gas, would be protective effect against ventilator-induced lung injury (VILI), we ventilated 55 normal white rabbits for 6 hr or until PaO2/FIO2 <200 mmHg. Control group (n=15) was ventilated with peak inspiratory pressure (PIP) of 15 cm H2O, positive end-expiratory pressure (PEEP) of 3 cm H2O, an inspiration-to-expiration ratio of 1:2, and an inspired oxygen fraction (FIO2) of 0.40. High pressure hypercapnic group (HPHC; n=20) was ventilated with PIP of 30 cm H2O, PEEP of 0 cm H2O, and FIO2 of 0.40. Carbon dioxide was introduced into the inspiratory limb of the ventilator circuit, as necessary to maintain hypercapnia (PaCO2, 65 to 75 mmHg). High pressure normocapnic group (HPNC; n=20) was ventilated with same setting of HPHC, except normocapnia (PaCO2, 35 to 45 mmHg). Bronchoalveolar lavage fluid (BALF) lactate dehydrogenase, aspartate aminotransferase, interleukin-8 were significantly higher in high pressure ventilator group than control group (p<0.05). Wet weight to dry weight (WW/DW) and histologic scores were significantly higher in high pressure ventilator group than control group (p<0.05). However, there were no significant differences in oxygenation, BALF inflammatory markers, WW/DW and histologic scores between HPHC and HPNC groups. These findings suggest that hypercapnic acidosis at least induced by CO2 insufflation would not be protective effect against VILI in this model.

Keyword

Ventilator-induced lung Injury; Ventilator, Mechanical; Hypercapnia; Acidosis, Respiratory

MeSH Terms

Acidosis, Respiratory/*chemically induced/complications/diagnosis/physiopathology
Administration, Inhalation
Animals
Carbon Dioxide/*administration and dosage
Hypercapnia/*chemically induced/complications/diagnosis/physiopathology
Inhalation
Pulmonary Gas Exchange
Rabbits
Research Support, Non-U.S. Gov't
Respiration, Artificial/*adverse effects
Respiratory Distress Syndrome, Adult/diagnosis/*etiology/physiopathology/*prevention and control
Treatment Outcome

Figure

• 

  Fig. 1 Comparisons of arterial CO2 tension and pH among the groups. In the HPHC group (A), PaCO2 was significantly increased quickly after the induction of carbon dioxide and then remained stable throughout the experiment. (B) pH decreased quickly in the HPHC group after the induction of hypercapnia and then remained stable at this reduced value for the remainder of the experiment. Data represent the mean±SD. *p<0.05 vs. baseline values.

• 

  Fig. 2 Comparisons of oxygenation among the groups. PaO2 decreased significantly after 3 and 4 hr in the HPHC and HPNC groups as compared with baseline values, respectively. Data represent the mean±SD. *p<0.05 vs. baseline values.

• 

  Fig. 3 Comparisons of serum levels of AST (A) and LDH (B) between the groups. There were no significant differences of serum levels of AST and LDH between HPHC and HPNC groups at each time point. Data represent the mean±SD. *p<0.05 vs. control group.

• 

  Fig. 4 Comparisons of BALF LDH, AST, and IL-8 between the groups. There were no significant differences of the levels of BALF LDH, AST, and IL-8 between HPHC and HPNC groups. Data represent the mean±SD. *p<0.05 vs. control group.

• 

  Fig. 5 Wet weight to dry weight ratios (WW/DW) between the groups. There were no significant differences of WW/DW between HPHC and HPNC groups. Each values represent mean±SD. *p<0.05 vs. HPHC or HPNC group.

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  Fig. 6 Histologic scores between the groups. There were no significant differences of histologic score between HPHC and HPNC groups. Each values represent mean±SD. *p<0.05 vs. HPHC or HPNC group.

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