Intra-operative assessment of human pulmonary alveoli in vivo using Sidestream Dark Field imaging: a feasibility study.
BACKGROUND
In vivo videomicroscopy has been used for years to visualize subpleural alveoli in animal studies. This has led to a better understanding of alveolar physiology. We tested the hypothesis whether a novel handheld videomicroscope could be used for intraoperative detection of alveoli in surgical patients during mechanical ventilation.


METHODS
Using Sidestream Dark Field imaging, we observed 6 patients (3 adults and 3 children) who underwent elective cardiac surgery. In each patient, the tip of the microscope was placed on the visceral pleural surface of the left upper pulmonary lobe after weaning from cardiopulmonary bypass. The acquired images were converted into digital signals and captured on a computer.


RESULTS
Although cardiac motion artifacts were present, visceral pleural microvascular blood flow could be observed in adults and infants. In infants, sub-pleural cavities (alveoli) were observed. These alveoli were remarkably similar in dimension and structure to those identified previously as true alveoli in animal studies. Quantification of these alveoli demonstrated that mean alveolar diameter, perimeter and area increased with age among the investigated infants (all parameters p<0.001).


CONCLUSIONS
High-quality images of visceral pleural microvessels as well as subpleural cavities, reflecting superficial alveoli, could be obtained in infants. These findings create the opportunity to begin human intervention studies, which should investigate alveolar dynamics during mechanical ventilation in cardio-thoracic surgery in more detail.
Departments of Cardiology, Cardiothoracic Surgery and Intensive Care Medicine, Erasmus Medical Center, Thoraxcenter, Rotterdam, The Netherlands. c.denuil@erasmusmc.nl
Corstiaan A
CA
den Uil
Rick
R
Bezemer
Dinis R
DR
Miranda
Can
C
Ince
Wim K
WK
Lagrand
Michael
M
Hartman
Ad J
AJ
Bogers
Peter E
PE
Spronk
Maarten L
ML
Simoons
D000328:Adult; D000369:Aged, 80 and over; D002675:Child, Preschool; D003952:Diagnostic Imaging / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007223:Infant; D007430:Intraoperative Care; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D011650:Pulmonary Alveoli / Q000473:pathology*