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Correlation of lung collapse and gas exchange - a computer tomographic study in sheep and pigs with atelectasis in otherwise normal lungs.

Wolf SJ, Reske AP, Hammermüller S, Costa EL, Spieth PM, Hepp P, Carvalho AR, Kraßler J, Wrigge H, Amato MB, Reske AW - PLoS ONE (2015)

Bottom Line: Shunt was 39 (29-51) % in sheep and 15 (11-20) % in pigs.In lung-healthy pigs, these correlations were significantly weaker, likely because pigs have stronger hypoxic pulmonary vasoconstriction (HPV) than sheep and humans.Nevertheless, correlations improved also in pigs after blunting of HPV during ARDS.

View Article: PubMed Central - PubMed

Affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital Leipzig, Leipzig, Germany.

ABSTRACT

Background: Atelectasis can provoke pulmonary and non-pulmonary complications after general anaesthesia. Unfortunately, there is no instrument to estimate atelectasis and prompt changes of mechanical ventilation during general anaesthesia. Although arterial partial pressure of oxygen (PaO2) and intrapulmonary shunt have both been suggested to correlate with atelectasis, studies yielded inconsistent results. Therefore, we investigated these correlations.

Methods: Shunt, PaO2 and atelectasis were measured in 11 sheep and 23 pigs with otherwise normal lungs. In pigs, contrasting measurements were available 12 hours after induction of acute respiratory distress syndrome (ARDS). Atelectasis was calculated by computed tomography relative to total lung mass (Mtotal). We logarithmically transformed PaO2 (lnPaO2) to linearize its relationships with shunt and atelectasis. Data are given as median (interquartile range).

Results: Mtotal was 768 (715-884) g in sheep and 543 (503-583) g in pigs. Atelectasis was 26 (16-47) % in sheep and 18 (13-23) % in pigs. PaO2 (FiO2 = 1.0) was 242 (106-414) mmHg in sheep and 480 (437-514) mmHg in pigs. Shunt was 39 (29-51) % in sheep and 15 (11-20) % in pigs. Atelectasis correlated closely with lnPaO2 (R2 = 0.78) and shunt (R2 = 0.79) in sheep (P-values<0.0001). The correlation of atelectasis with lnPaO2 (R2 = 0.63) and shunt (R2 = 0.34) was weaker in pigs, but R2 increased to 0.71 for lnPaO2 and 0.72 for shunt 12 hours after induction of ARDS. In both, sheep and pigs, changes in atelectasis correlated strongly with corresponding changes in lnPaO2 and shunt.

Discussion and conclusion: In lung-healthy sheep, atelectasis correlates closely with lnPaO2 and shunt, when blood gases are measured during ventilation with pure oxygen. In lung-healthy pigs, these correlations were significantly weaker, likely because pigs have stronger hypoxic pulmonary vasoconstriction (HPV) than sheep and humans. Nevertheless, correlations improved also in pigs after blunting of HPV during ARDS. In humans, the observed relationships may aid in assessing anaesthesia-related atelectasis.

No MeSH data available.


Related in: MedlinePlus

Correlation between atelectasis, oxygenation and shunt.Linear regression of raw PaO2 (upper row), ln-transformed PaO2 (lnPaO2, second row) and intrapulmonary (Bergren’s) shunt (lower row), respectively, on the amount of atelectasis (percentage of total lung mass). Only data points from the “atelectasis” columns in Table 1 were used. Berggren’s shunt was calculated according to [28]. We transformed PaO2 values logarithmically (lnPaO2) to linearize the relationship between PaO2 and atelectasis.
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pone.0135272.g001: Correlation between atelectasis, oxygenation and shunt.Linear regression of raw PaO2 (upper row), ln-transformed PaO2 (lnPaO2, second row) and intrapulmonary (Bergren’s) shunt (lower row), respectively, on the amount of atelectasis (percentage of total lung mass). Only data points from the “atelectasis” columns in Table 1 were used. Berggren’s shunt was calculated according to [28]. We transformed PaO2 values logarithmically (lnPaO2) to linearize the relationship between PaO2 and atelectasis.

Mentions: In sheep, regression analyses of shunt, untransformed PaO2 and lnPaO2 on atelectasis (using only the data points of the “atelectasis” columns in Table 1) showed strong correlations between these parameters (R2 values for correlation with atelectasis were 0.77 for PaO2, 0.78 for lnPaO2 and 0.79 for shunt; all P values < 0.0001, Fig 1).


Correlation of lung collapse and gas exchange - a computer tomographic study in sheep and pigs with atelectasis in otherwise normal lungs.

Wolf SJ, Reske AP, Hammermüller S, Costa EL, Spieth PM, Hepp P, Carvalho AR, Kraßler J, Wrigge H, Amato MB, Reske AW - PLoS ONE (2015)

Correlation between atelectasis, oxygenation and shunt.Linear regression of raw PaO2 (upper row), ln-transformed PaO2 (lnPaO2, second row) and intrapulmonary (Bergren’s) shunt (lower row), respectively, on the amount of atelectasis (percentage of total lung mass). Only data points from the “atelectasis” columns in Table 1 were used. Berggren’s shunt was calculated according to [28]. We transformed PaO2 values logarithmically (lnPaO2) to linearize the relationship between PaO2 and atelectasis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4530863&req=5

pone.0135272.g001: Correlation between atelectasis, oxygenation and shunt.Linear regression of raw PaO2 (upper row), ln-transformed PaO2 (lnPaO2, second row) and intrapulmonary (Bergren’s) shunt (lower row), respectively, on the amount of atelectasis (percentage of total lung mass). Only data points from the “atelectasis” columns in Table 1 were used. Berggren’s shunt was calculated according to [28]. We transformed PaO2 values logarithmically (lnPaO2) to linearize the relationship between PaO2 and atelectasis.
Mentions: In sheep, regression analyses of shunt, untransformed PaO2 and lnPaO2 on atelectasis (using only the data points of the “atelectasis” columns in Table 1) showed strong correlations between these parameters (R2 values for correlation with atelectasis were 0.77 for PaO2, 0.78 for lnPaO2 and 0.79 for shunt; all P values < 0.0001, Fig 1).

Bottom Line: Shunt was 39 (29-51) % in sheep and 15 (11-20) % in pigs.In lung-healthy pigs, these correlations were significantly weaker, likely because pigs have stronger hypoxic pulmonary vasoconstriction (HPV) than sheep and humans.Nevertheless, correlations improved also in pigs after blunting of HPV during ARDS.

View Article: PubMed Central - PubMed

Affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital Leipzig, Leipzig, Germany.

ABSTRACT

Background: Atelectasis can provoke pulmonary and non-pulmonary complications after general anaesthesia. Unfortunately, there is no instrument to estimate atelectasis and prompt changes of mechanical ventilation during general anaesthesia. Although arterial partial pressure of oxygen (PaO2) and intrapulmonary shunt have both been suggested to correlate with atelectasis, studies yielded inconsistent results. Therefore, we investigated these correlations.

Methods: Shunt, PaO2 and atelectasis were measured in 11 sheep and 23 pigs with otherwise normal lungs. In pigs, contrasting measurements were available 12 hours after induction of acute respiratory distress syndrome (ARDS). Atelectasis was calculated by computed tomography relative to total lung mass (Mtotal). We logarithmically transformed PaO2 (lnPaO2) to linearize its relationships with shunt and atelectasis. Data are given as median (interquartile range).

Results: Mtotal was 768 (715-884) g in sheep and 543 (503-583) g in pigs. Atelectasis was 26 (16-47) % in sheep and 18 (13-23) % in pigs. PaO2 (FiO2 = 1.0) was 242 (106-414) mmHg in sheep and 480 (437-514) mmHg in pigs. Shunt was 39 (29-51) % in sheep and 15 (11-20) % in pigs. Atelectasis correlated closely with lnPaO2 (R2 = 0.78) and shunt (R2 = 0.79) in sheep (P-values<0.0001). The correlation of atelectasis with lnPaO2 (R2 = 0.63) and shunt (R2 = 0.34) was weaker in pigs, but R2 increased to 0.71 for lnPaO2 and 0.72 for shunt 12 hours after induction of ARDS. In both, sheep and pigs, changes in atelectasis correlated strongly with corresponding changes in lnPaO2 and shunt.

Discussion and conclusion: In lung-healthy sheep, atelectasis correlates closely with lnPaO2 and shunt, when blood gases are measured during ventilation with pure oxygen. In lung-healthy pigs, these correlations were significantly weaker, likely because pigs have stronger hypoxic pulmonary vasoconstriction (HPV) than sheep and humans. Nevertheless, correlations improved also in pigs after blunting of HPV during ARDS. In humans, the observed relationships may aid in assessing anaesthesia-related atelectasis.

No MeSH data available.


Related in: MedlinePlus