Punarnava (Boerhavia diffusa) is an herb widely used in Ayurvedic medicine, and its application for respiratory conditions, including those similar to emphysema, is primarily based on traditional medical systems, not modern scientific validation. In Ayurveda, Punarnava is considered to have "Shothahara" (anti-inflammatory) and "Mutrala" (diuretic) actions and is often recommended for conditions involving fluid retention, inflammation, and some chronic respiratory disorders. Its use in chronic respiratory conditions like asthma, bronchitis, and sometimes even for symptoms resembling emphysema, is mentioned in classical Ayurvedic texts. The rationale in Ayurveda is that Punarnava helps reduce inflammation and congestion in the respiratory tract and may support overall lung function by aiding the removal of excess fluid and toxins from the body.

From a scientific perspective, there are limited studies on Punarnava for emphysema specifically. Some preclinical studies suggest anti-inflammatory and antioxidant properties, which could theoretically benefit chronic lung diseases, but there is no direct clinical evidence in humans for emphysema. Thus, while its use is deeply rooted in tradition and supported by anecdotal reports and traditional Ayurvedic literature, scientific validation is currently lacking, and more rigorous studies would be needed to confirm its efficacy and safety for emphysema.