PURPOSE: Postoperative compensatory lung growth (CLG) after lung resection has been established in animal models. However, detecting CLG in clinical patients is limited. Our purpose was to determine CLG by evaluating preoperative and postoperative “estimated quantity of pulmonary tissue (EQPT).”
METHODS: A total of 25 from 735 consecutive patients who underwent lobectomy or bilobectomy for primary lung cancer from 2003 to 2009 were selected. Patients who had chest wall resections, obstructive pneumonia, a tumor > 3 cm in size, or perioperative chemotherapy were excluded. The 25 patients were evaluated by spirometry, 3D CT volumetry, and mean CT numbers (Hounsfield Units) both before and more than one year after surgery. “Estimated quantity of pulmonary tissue” (EQPT) was calculated by multiplying lung volume (ml) and estimated mean lung density (g/ml): density = (mean CT number + 1000) / 1000. Patients were divided into 2 groups: A. Number of resected subsegments ≥ 10 (n=12); B. Number of resected subsegments < 10 (n=13). All parameters were evaluated by “%postoperative values”: actual postoperative values / predicted post operative values (%); prediction was made by: preoperative values x (42 - number of resected subsegments) / 42.
RESULTS: For Group A, the mean time after lung resection was 3.7 ± 1.7 years, and for Group B it was 3.3 ± 1.4 years. FVC and FEV1 “%postoperative values” were 119 ± 11% and 118 ± 15% in A, and 107 ± 9% and 103 ± 7% in B, respectively. In Group A, the %postoperative lung volume on the surgical side was 170 ± 32%, and in Group B it was 120 ± 19%. In Group A, the %postoperative EQPT on the surgical side was 127 ± 34%, and in Group B it was 84 ± 16% (p<0.002).
CONCLUSIONS: EQPT was greater than predicted after major lung resection.
CLINICAL IMPLICATIONS: Major lung resection may trigger CLG that can be clinically evaluated by the “estimated quantity of pulmonary tissue.”
DISCLOSURE: The following authors have nothing to disclose: Teruaki Mizobuchi, Terunaga Inage, Junichi Morimoto, Yuichi Sakairi, Fumihiro Ishibashi, Masako Chiyo, Takurou Kometani, Takekazu Iwata, Yasumitsu Moriya, Hidehisa Hoshino, Shigetoshi Yoshida, Ichiro Yoshino
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