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General anesthesia does not alter the viscoelastic or transport properties of human respiratory mucus
B K Rubin1, B Finegan, O Ramirez
1University of Alberta, Department of Pediatrics (Pulmonary), Edmonton, Canada.
Abstract:
Observations that mucus transport rates (MTR) are depressed in anesthetized animals and humans have led to speculation that general anesthesia depresses ciliary activity or adversely alters the physical properties of the respiratory mucus (RM). We investigated the possibility that anesthesia changes the physical properties of RM in such a way as to depress ciliary transport. We collected 33 samples of RM from the endotracheal tubes (ETTs) of 25 people aged 1 to 79 years undergoing elective surgery who had no clinical evidence of lung disease. We measured the rigidity, viscoelasticity, spinnability, and the percentage of solid composition of these specimens as well as the transport of the collected RM across the mucus-depleted frog palate. These physical properties were not significantly different from RM collected from awake volunteers using the bronchoscopy brush collection technique. Differences in spinnability, transportability, and solid content of paired mucus samples from the inside and outside of the ETTs are suggestive of altered RM hydration, but this requires further study. The decrease in MTR during general anesthesia is probably due to mechanisms other than alterations in the physical properties of mucus.
Insights
General anesthesia does not appear to alter respiratory mucus (RM) physical properties. Studies suggest mucus transport rates (MTR) decrease due to other mechanisms, not changes in mucus.
Area of Science:
- Pulmonary Physiology
- Anesthesiology
Background:
- Mucus transport rates (MTR) are often reduced during general anesthesia.
- This has led to speculation that anesthesia affects ciliary function or respiratory mucus (RM) properties.
Purpose of the Study:
- To investigate if general anesthesia alters the physical properties of RM, impacting ciliary transport.
- To determine if changes in RM properties contribute to decreased MTR during anesthesia.
Main Methods:
- Collected 33 RM samples from endotracheal tubes (ETTs) of 25 patients undergoing elective surgery.
- Measured RM rigidity, viscoelasticity, spinnability, and solid composition.
- Assessed RM transport across a mucus-depleted frog palate model.
Main Results:
- Physical properties of RM from anesthetized patients were not significantly different from awake volunteers.
- Some differences in spinnability and solid content were observed between inside and outside ETT mucus, suggesting potential hydration alterations.
- These findings require further investigation.
Conclusions:
- The decrease in MTR during general anesthesia is likely caused by factors other than changes in the physical properties of respiratory mucus.
- Anesthesia's impact on MTR may involve different physiological or biochemical pathways.