Page 30 - Effects of radiotherapy and hyperbaric oxygen therapy on oral microcirculation Renee Helmers

Chapter 2
frequency of 30 breaths·min-1, and a positive end-expiratory pressure (PEEP)
of 2 mmHg at an initial baseline fraction of inspired oxygen (FiO2) of 21%.
Arterial carbon dioxide (paCO2) was maintained between 35 and 40 Torr. For
hemodynamic monitoring and peripheral capillary oxygen saturation (SpO2),
the right femoral artery cannula was connected to an Infinity® HemoMedTM pod
(Dräger Medical Systems, Inc. Danvers, Massachusetts, USA) and a clip pulse
oximeter sensor was attached to the animal’s right ear. Both hemodynamic and
SpO data respectively were obtained from an Infinity® Delta multiparameter 2
monitor (Dräger Medical Systems, Inc. Danvers, Massachusetts, USA) inside the NB chamber.
After infusion pump, ventilator, and hemodynamic monitoring apparatus coupling, the animals were restrained in a sternally recumbent position into a tabletop rodent mouth gag apparatus (Veterinary Instrumentation Limited, Sheffield, South Yorkshire, United Kingdom) with the jaws fixed in an open configuration; details on correct animal and apparatus adjustments have been described elsewhere.29 In brief, the restrainer platform was adjusted at an inclination of 30° to reduce stress on both the neck and back muscles and to avoid excessive traction on the incisor teeth. Mandibular extension adjustments were carefully set to avoid injuring muscles and articular ligaments from excessive stretching. Since the left side of the oral commissure was used for positioning and immobilizing the endotracheal tube on the restrainer platform, the free access on the right side of the oral cavity to the sublingual mucosa was used for microcirculation assessments. All equipment used in this study was thoroughly inspected by two experienced HB chamber electrical technicians of the Royal Netherlands Navy and approved exclusively for HBO application with regard to this study specifically.
Microcirculation imaging
Continuous monitoring of the sublingual microcirculation was performed by SDFI (MicroScan Video Microscope System, MicroVision Medical, Amsterdam, The Netherlands); details on this technique have been described elsewhere.15,28 Briefly, the SDFI technique is incorporated into a portable handheld (347 gr) video microscopy instrument, allowing real-time noninvasive observations of tissue subsurface microcirculation. The absorption of 530-nm wavelength (green light), projected directly onto the tissue surface via stroboscopic light- emitting diodes (13 ms illumination intervals),28 is absorbed by hemoglobin in red blood cells (RBCs) yielding images of well-defined dark globules (i.e. RBCs)
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