Buprenorphine hydrochloride

Following survival surgeries, muscle layers were sutured with 4–0 silk sutures (Covidien) and the skin was closed with surgical staples (Braintree Scientific). The surface of the skin was treated with a topical iodine solution. Immediately following the procedure, rats were treated with 5-ml subcutaneous injections of lactated Ringer’s solution (Hospira), buprenorphine hydrochloride (0.05 mg/kg; Hospira) and cefazolin (6 mg; Hospira). Rats were then placed in a clean cage on a surgical heating pad set to 37°C (Gaymar). At 12 and 24 h after surgery, each rat was given an additional dose of buprenorphine hydrochloride (0.05 mg/kg) and 5 ml of lactated Ringer’s solution and monitored for pain/distress.

Yorkshire pigs (5–7 months of age, weighing 40–60 kg) underwent general anesthesia via intramuscular induction with Telazol (5 mg/kg, Zoetis) and buprenorphine hydrochloride (0.03 mg/kg, Hospira), and maintenance with continuous intravenous infusions of fentanyl citrate (0.1 mg/kg/h, West-Ward,), midazolam (1.5 mg/kg/h, Akorn), and inhaled isoflurane (1–5% in oxygen, Henry Schein). A median sternotomy was performed. A bolus of heparin (30,000 U IV) was given (Sagent Pharmaceuticals), and a cannula was placed and secured within the main pulmonary artery. Blood was collected in citrate phosphate dextrose (CPD) collection bags (Chinook Medical) and stored at 8 °C. Once a non-perfusing rhythm was observed, a cold anterograde low-potassium dextran flush (Perfadex; Vitrolife) with alprostadil (25 mg/kg, Prostin VR Pediatric^®, Pfizer) was given, and the appendage of the left atrium was cut. Topical cooling was applied, the lungs were inflated to a sustained airway pressure of 15 cmH₂O, and the trachea was stapled (Endo GIA™ device, Medtronic). The heart and lungs were explanted en bloc and placed on ice on a sterile table. The heart was removed and arterial and venous cannulas were secured. Lungs were then placed on the ex-vivo lung perfusion (EVLP) system and perfused with whole blood collected at the time of donor lung harvest.

Donor swine (n = 8) underwent general anesthesia via intramuscular induction with Telazol (5 mg kg⁻¹, Zoetis) and buprenorphine hydrochloride (0.03 mg kg⁻¹, Hospira). Following induction and intubation, the anesthetic regimen consisted of continuous infusions of midazolam (1.5 mg kg⁻¹ h⁻¹, Akorn), fentanyl citrate (0.1 mg kg⁻¹ h⁻¹, West-Ward), and inhaled isoflurane (1–5% in oxygen, Henry Schein). Gastric aspiration injury was adapted from previously established injury models^{21 (link),25 (link),36 (link)}. Following donor sedation, a bronchoscope was introduced into the lower lobe of a single lung, and the location of the bronchoscope tip was confirmed by chest X-ray. Standardized gastric contents (2 mL kg⁻¹; pH 2) were delivered bronchoscopically while withdrawing the tip of the bronchoscope to a position approximately 1 cm distal to the carina to avoid introduction of gastric contents into the contralateral (control) lung. This distance was established prior to delivery of standardized gastric contents by measuring the length of the bronchoscope as it was advanced past the carina. After delivery, animals remained under general anesthesia and standardized gastric contents remained in donor lungs for 6 h to allow development of a unilateral acute lung injury in vivo.