Ex Vivo Modeling of Perioperative Air Leaks in Porcine Lungs.

OBJECTIVE: A novel ex vivo model is described to advance the understanding of prolonged air leaks, one of the most common postoperative complications following thoracic resection procedures. METHODS: As an alternative to in vivo testing, an ex vivo model simulating the various physiologic environments experienced by an isolated lung during the perioperative period was designed and built. Isolated porcine lungs were perfused and ventilated during open chest and closed chest simulations, mimicking intra and postoperative ventilation conditions. To assess and validate system capabilities, nine porcine lungs were tested by creating a standardized injury to create an approximately 250 cc/min air leak. Air leak rates, physiologic ventilation, and perfusion parameters were continuously monitored, while gas transfer analysis was performed on selected lungs. Segmental ventilation was monitored using electrical impedance tomography. RESULTS: The evaluated lungs produced flow-volume and pressure-volume loops that approximated standard clinical representations under positive (mechanical) and negative (physiological) pressure ventilation modalities. Leak rate was averaged across the ventilation phases, and sharp increases in leak rate were observed between positive and negative pressure phases, suggesting that differences or changes in ventilation mechanics may strongly influence leak development. CONCLUSION: The successful design and validation of a novel ex vivo lung model was achieved. Model output paralleled clinical observations. Pressure modality may also play a significant role in air leak severity. SIGNIFICANCE: This work provides a foundation for future studies aimed at increasing the understanding of air leaks to better inform means of mitigating the risk of air leaks under clinically relevant conditions.

Long-term detrimental effect of bile duct injury on health-related quality of life.

HYPOTHESIS: Long-term quality of life (QOL) in patients undergoing laparoscopic cholecystectomy (LC) incurring bile duct injury (BDI) and repair is comparable to that of patients undergoing uncomplicated LC. DESIGN: Case comparison study. SETTING: Secondary and tertiary care centers. PATIENTS: Eighty-six patients incurring BDI during LC between January 1, 1991, and July 31, 2003, were surveyed. Comparison subjects underwent uncomplicated LC during the same period. MAIN OUTCOME MEASURES: Health-related QOL as assessed by the Karnofsky Performance Scale, Medical Outcomes Study 36-Item Short Form Health Survey (SF-36), and Psychosocial Adjustment to Illness Scale. RESULTS: Fifty patients with BDI (39 [78%] female; mean +/- SEM age, 55 +/- 2 years) and 74 patients with uncomplicated LC (51 [69%] female, mean +/- SEM age, 52 +/- 2 years) responded. Of the 50 BDI patients, 48 (96%) had no stricture and normal liver function at QOL assessment. The mean +/- SEM follow-up period to QOL assessment for the BDI and uncomplicated LC groups was 62 +/- 6 and 47 +/- 3 months, respectively. The mean +/- SD Karnofsky Performance Scale scores were 77 +/- 9 vs 93 +/- 8 for the 2 groups, respectively (P <.001). The mean +/- SD SF-36 physical component scale scores after BDI vs uncomplicated LC were 36 +/- 11 vs 47 +/- 12, respectively (P <.001), compared with 50 +/- 10 for the normal population (P <.001). The mean +/- SD SF-36 mental component scale scores were 43 +/- 14 vs 49 +/- 11 for the 2 groups, respectively (P =.02), compared with 50 +/- 10 for the normal population (P =.01). Patients with BDI scored poorer on the Psychosocial Adjustment to Illness Scale health care orientation and domestic environment scales (P=.01). CONCLUSION: After BDI and repair, there are long-term detrimental effects of BDI on health-related QOL.