Page 29 - Effects of radiotherapy and hyperbaric oxygen therapy on oral microcirculation Renee Helmers

Hyperoxia-driven microvascular changes
Anesthesia and instrumentation
Sedation and anesthesia was induced subcutaneously (sc) with a mixture of
ketamine (Nimatek, Eurovet Animal Health BV, Bladel, The Netherlands; 15
mg·kg-1) and dexmedetomidine (Dexdomitor, Pfizer Animal Health BV, Capelle
aan den IJssel, The Netherlands; 0.2 mg·kg-1) for orotracheal intubation and 2 cannulation with indwelling arterial and venous catheters for blood sampling,
monitoring basic hemodynamic parameters, and maintenance anesthesia according to our standardized anesthesia protocol. Prior to endotracheal intubation, an analgesic injection of buprenorphine (Temgesic®, Schering- Plough BV, Utrecht, The Netherlands; 0.03 mg·kg-1 sc) was administered. Within one minute after full anesthesia (paw-pinch test) endotracheal intubation was performed blindly using a cuffed endotracheal tube (MallinckrodtTM Hi- Contour Oral/Nasal Tracheal Tube 3.0 mm Øi/4.3 mm Øo, CovidienTM, Mansfield, Massachusetts, USA). The left central auricular artery was cannulated (BD VenflonTM 20GA 1.0×32 mm, Becton Dickinson infusion Therapy, Helsingborg, Sweden) to obtain baseline whole blood count and subsequently used for serial blood gas sampling. To ascertain the general state of (hematological) health in our animal models (Hewitt et al., 1989),19 baseline whole blood count was determined prior to experimentation by an automated Sysmex XE-5000 (Sysmex Coorporation, Kobe, Japan) blood cell counter from 1 mL of blood withdrawn from the central ear artery and anticoagulated in K2E 7.2 mg EDTA BD Vacutainer® 4 mL tubes (Becton, Dickinson & Co., Plymouth, United Kingdom). The left posterior auricular marginal vein and the right femoral artery were cannulated (BD VenflonTM 22GA 0.8×25 mm, Becton Dickinson infusion Therapy, Helsingborg, Sweden) for maintenance anesthesia and hemodynamic monitoring (heart rate (HR), mean arterial pressure (MAP)) respectively. Prior to transportation to the HB chamber, 40 mL (2×20 mL) of sterile 0.9% NaCl (saline) solution was administered bilaterally via sc bolus (left and right flanks) to maintain hydration without the need for using additional equipment inside the HB chamber.
Inside the HB chamber the auricular intravenous catheter was coupled to a DC-powered infusion pump (IVAC P3000, Alaris Medical Systems, Inc., San Diego, California) and set to infuse midazolam (Actavis, Hafnarfjordur, Iceland; 5.7 mg·kg-1·h-1). The endotracheal tube was connected to a pediatric/neonatal ventilator (Maquet Servo Ventilator 900C, Siemens-Elema AB, Solna, Sweden) and the animals were ventilated at a tidal volume of 40 mL (1.1 L·min-1), a
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