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Increased lung inflammation with oxygen supplementation in tracheotomized spontaneously breathing rabbits: an experimental prospective randomized study.

Machado HS, Nunes CS, Sá P, Couceiro A, da Silva ÁM, Águas A - BMC Anesthesiol (2014)

Bottom Line: The hyperoxic environment was confirmed by blood gas analyses in animals that were subjected to oxygen supplementation, and was accompanied with lower mean respiratory rates.The non-oxygen supplemented group had lower mean oxygen arterial partial pressures and higher mean respiratory rates during the procedure.This cellular observation in lung tissue did not correlate with a similar increase in peripheral blood analysis.

View Article: PubMed Central - PubMed

Affiliation: Serviço de Anestesiologia, Centro Hospitalar do Porto, Largo Abel Salazar, Porto, 4099-001 Portugal.

ABSTRACT

Background: Mechanical ventilation is a well-known trigger for lung inflammation. Research focuses on tidal volume reduction to prevent ventilator-induced lung injury. Mechanical ventilation is usually applied with higher than physiological oxygen fractions. The purpose of this study was to investigate the after effect of oxygen supplementation during a spontaneous ventilation set up, in order to avoid the inflammatory response linked to mechanical ventilation.

Methods: A prospective randomised study using New Zealand rabbits in a university research laboratory was carried out. Rabbits (n = 20) were randomly assigned to 4 groups (n = 5 each group). Groups 1 and 2 were submitted to 0.5 L/min oxygen supplementation, for 20 or 75 minutes, respectively; groups 3 and 4 were left at room air for 20 or 75 minutes. Ketamine/xylazine was administered for induction and maintenance of anaesthesia. Lungs were obtained for histological examination in light microscopy.

Results: All animals survived the complete experiment. Procedure duration did not influence the degree of inflammatory response. The hyperoxic environment was confirmed by blood gas analyses in animals that were subjected to oxygen supplementation, and was accompanied with lower mean respiratory rates. The non-oxygen supplemented group had lower mean oxygen arterial partial pressures and higher mean respiratory rates during the procedure. All animals showed some inflammatory lung response. However, rabbits submitted to oxygen supplementation showed significant more lung inflammation (Odds ratio = 16), characterized by more infiltrates and with higher cell counts; the acute inflammatory response cells was mainly constituted by eosinophils and neutrophils, with a relative proportion of 80 to 20% respectively. This cellular observation in lung tissue did not correlate with a similar increase in peripheral blood analysis.

Conclusions: Oxygen supplementation in spontaneous breathing is associated with an increased inflammatory response when compared to breathing normal room air. This inflammatory response was mainly constituted with polymorphonuclear cells (eosinophils and neutrophils). As confirmed in all animals by peripheral blood analyses, the eosinophilic inflammatory response was a local organ event.

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Peripheral white cell count. Legend: (A) first measurement, (B) final measurement at end of procedure, in OSG – oxygen supplemented group and in NOSG - non-oxygen supplemented group.
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Fig1: Peripheral white cell count. Legend: (A) first measurement, (B) final measurement at end of procedure, in OSG – oxygen supplemented group and in NOSG - non-oxygen supplemented group.

Mentions: The first median values of peripheral cell count measurement are shown in Figure 1. OSG showed moderate inflammation in 8 out of 10 subjects, whereas NOSG only did so in 2 rabbits, with an OR = 16 (CI 1.8-143.2); therefore OSG is more likely to have moderate inflation than the other group (Figure 2). The inflammatory cells found in these histological plates were neutrophils and eosinophils; with a proportion of about 80% eosinophils and 20% neutrophils (Figure 3).Figure 1


Increased lung inflammation with oxygen supplementation in tracheotomized spontaneously breathing rabbits: an experimental prospective randomized study.

Machado HS, Nunes CS, Sá P, Couceiro A, da Silva ÁM, Águas A - BMC Anesthesiol (2014)

Peripheral white cell count. Legend: (A) first measurement, (B) final measurement at end of procedure, in OSG – oxygen supplemented group and in NOSG - non-oxygen supplemented group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4197313&req=5

Fig1: Peripheral white cell count. Legend: (A) first measurement, (B) final measurement at end of procedure, in OSG – oxygen supplemented group and in NOSG - non-oxygen supplemented group.
Mentions: The first median values of peripheral cell count measurement are shown in Figure 1. OSG showed moderate inflammation in 8 out of 10 subjects, whereas NOSG only did so in 2 rabbits, with an OR = 16 (CI 1.8-143.2); therefore OSG is more likely to have moderate inflation than the other group (Figure 2). The inflammatory cells found in these histological plates were neutrophils and eosinophils; with a proportion of about 80% eosinophils and 20% neutrophils (Figure 3).Figure 1

Bottom Line: The hyperoxic environment was confirmed by blood gas analyses in animals that were subjected to oxygen supplementation, and was accompanied with lower mean respiratory rates.The non-oxygen supplemented group had lower mean oxygen arterial partial pressures and higher mean respiratory rates during the procedure.This cellular observation in lung tissue did not correlate with a similar increase in peripheral blood analysis.

View Article: PubMed Central - PubMed

Affiliation: Serviço de Anestesiologia, Centro Hospitalar do Porto, Largo Abel Salazar, Porto, 4099-001 Portugal.

ABSTRACT

Background: Mechanical ventilation is a well-known trigger for lung inflammation. Research focuses on tidal volume reduction to prevent ventilator-induced lung injury. Mechanical ventilation is usually applied with higher than physiological oxygen fractions. The purpose of this study was to investigate the after effect of oxygen supplementation during a spontaneous ventilation set up, in order to avoid the inflammatory response linked to mechanical ventilation.

Methods: A prospective randomised study using New Zealand rabbits in a university research laboratory was carried out. Rabbits (n = 20) were randomly assigned to 4 groups (n = 5 each group). Groups 1 and 2 were submitted to 0.5 L/min oxygen supplementation, for 20 or 75 minutes, respectively; groups 3 and 4 were left at room air for 20 or 75 minutes. Ketamine/xylazine was administered for induction and maintenance of anaesthesia. Lungs were obtained for histological examination in light microscopy.

Results: All animals survived the complete experiment. Procedure duration did not influence the degree of inflammatory response. The hyperoxic environment was confirmed by blood gas analyses in animals that were subjected to oxygen supplementation, and was accompanied with lower mean respiratory rates. The non-oxygen supplemented group had lower mean oxygen arterial partial pressures and higher mean respiratory rates during the procedure. All animals showed some inflammatory lung response. However, rabbits submitted to oxygen supplementation showed significant more lung inflammation (Odds ratio = 16), characterized by more infiltrates and with higher cell counts; the acute inflammatory response cells was mainly constituted by eosinophils and neutrophils, with a relative proportion of 80 to 20% respectively. This cellular observation in lung tissue did not correlate with a similar increase in peripheral blood analysis.

Conclusions: Oxygen supplementation in spontaneous breathing is associated with an increased inflammatory response when compared to breathing normal room air. This inflammatory response was mainly constituted with polymorphonuclear cells (eosinophils and neutrophils). As confirmed in all animals by peripheral blood analyses, the eosinophilic inflammatory response was a local organ event.

Show MeSH
Related in: MedlinePlus