The visceral and parietal pleura are what keeps your thoracic cavity airtight. If the pressure gradient between the outside of your chest and the pleural space that your lungs occupy were compromised, via puncture wound or pneumothorax, then your lungs would crumple up like like a deflated balloon. The parenchyma (part of the lung you’re referring to) is spongy, but it won’t hold any air if it doesn’t have that pressure gradient to keep air in it. It takes very little to compromise that gradent. Two puncture wounds on each side of the chest would be enough

Source: respiratory therapy student