Data from good quality randomised controlled trials show that NIV is beneficial as a first-line intervention in conjunction with usual care for reducing the likelihood of mortality and endotracheal intubation in patients admitted with acute hypercapnic respiratory failure secondary to an acute exacerbation of chronic obstructive pulmonary disease (COPD). The magnitude of benefit for these outcomes appears similar for patients with acidosis of a mild (pH 7.30 to 7.35) versus a more severe nature (pH < 7.30), and when NIV is applied within the intensive care unit (ICU) or ward setting.

<b><i>Background:</i></b> Quantitative planar ventilation-perfusion (VQ) has a complementary role in target lobe selection for endobronchial valve lung volume reduction (EBV-LVR), especially in homogenous disease. We investigated a novel method of lung lobar quantitation using VQ single-photon emission computed tomography (SPECT) with computed tomography (CT) to generate a parameter called the ventilation-perfusion differential index (VQDI). <b><i>Aim:</i></b> The aim of this study was to validate VQDI as a parameter for target lobe selection in EBV-LVR against the gold standard test of quantitative computed tomography (qCT). <b><i>Methods:</i></b> This study was a prospective, multi-centre, single-blinded, observational study of EBV-LVR patients. Baseline and 3-month post intervention VQ SPECT and qCT were performed. The target lobe was chosen using qCT and planar VQ report (CT_TL) whilst blinded to VQDI. Post EBV-LVR, our nuclear physician, blinded to CT_TL, selected a target lobe using deidentified VQDI (VQDI_TL). Inter-rater agreement between CT_TL and VQDI_TL was calculated by Kappa statistic. Treatment outcomes were analysed with a linear mixed-effects model. <b><i>Results:</i></b> There was a high concordance between CT_TL and VQDI_TL in 16 patients (89%, Kappa statistic = 0.85). Post EBV-LVR, our subjects showed significant changes in FEV1 (mean difference [MD] +150 mL, <i>p</i> &#x3c; 0.001), target lobe volume reduction (MD −973 mL, <i>p</i> &#x3c; 0.001), residual volume (MD −800 mL, <i>p</i> &#x3c; 0.001), and St. George’s Respiratory Questionnaire score (MD −11, <i>p</i> = 0.001). Improvements in 6-minute walk distances did not reach statistical significance. <b><i>Conclusion:</i></b> In this study of treatment responders, EBV-LVR target lobe selection using VQDI concurs with qCT and thus supports its value for this purpose. It complements qCT and may potentially be of synergistic value especially in homogenous emphysema.

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