• 16
    Apr
  • Treatment for Collapsed Lung in Critically III Patients: DISCUSSION

DISCUSSION

Collapsed lung is one of the important problems in critically ill patients, and the clinical condition may worsen rapidly. Treatment with a therapeutic fiber­optic bronchoscopic procedure at the bedside was introduced and good results were reported in many studies. This therapeutic procedure includes repet­itive sputum suctioning and bronchial washing with normal saline solution; complete or partial re-expan­sion of atelectasis was attained in 60 to 90 percent of the cases.

When the lung volume decreases, the alveolar radius will decrease and the alveolar pressure rise according to Laplace relationship: Рт = 2 T/r (Рт-alveolar pres­sure, T-alveolar surface tension, r-alveolar radius). In these conditions, the surfactant will work to lower the alveolar surface tension; this reduction in surface tension offsets the reduction in alveolar radius and prevents alveolar pressure from rising. But if the atelectasis is profound, the reduction in surface ten­sion can not overcome the reduction in alveolar radius, and the alveolar pressure will rise and create a higher critical opening pressure in the atelectatic alveoli and lower lung compliance. The above findings are espe­cially common in cases with a small area of collapse. In these cases, the transpulmonary pressure of the atelectatic alveoli is often too low to overcome the critical pressure. These refractory atelectasis do not easily re-expand even after the above broncho­scopic procedures. It would be useful if we could introduce positive pressure ventilation directly into the collapsed area to overcome the critical opening pressure. But if we can not sufflate the air directly into the atelectatic alveoli, the insufflated air will tend to be distributed into the noncollapsed areas because of lower airway resistance and higher lung compliance. This will result in a hyperinflated normal lung area which in turn will compress the collapsed area.

In order to introduce air selectively into the atelec­tatic alveoli only, a few methods and devices were designed using a rigid or fiberoptic bronchoscope with a balloon cuff. After the bronchoscope was introduced into the collapsed lobar bronchus, the cuff was inflated to close the bronchus during air insufflation. Al­though these special devices obtained good results, they are still complex and not readily available. Therefore, we simply wedged the bronchoscope into each segment or subsegment of the collapsed lobe to close the bronchus. eriacta tablets

Harada et al stated that the atelectatic lung barely reexpanded following positive pressure ventilation through the endotracheal tube under about 20 cm H20 airway pressure when observed during fluoro­scopic roentgenograms or surgery. Mutsuda et alexerted positive pressure in the lung of adult dogs through the trachea after tracheostomy and found no damage to the lungs at pressures under 30 cm H20; however, rupture and bleeding of alveoli were ob­served under 60 cm H20. So, in this study the peripheral airway pressure was monitored by a pres­sure gauge connected to the bronchoscope and it was kept around 30 cm H20, or 10 cm H20 higher than the previous airway pressure during air insufflation. This pressure was high enough to overcome the critical opening pressure, but did not result in complications such as pneumothorax or pulmonary hemorrhage.

In seven of our 14 procedures, the duration of collapse had been more than 48 hours. In nine, the atelectatic areas were limited to one lobe. In three, the chest x-ray film showed air bronchograms in the collapsed lung. All of the above conditions were documented to be handicaps to reexpansion of atelec­tasis in previous studies.

The collapsed lung reexpanded completely soon after 12 of the bronchoscopic procedures, and partially in two. Arterial blood gas values following the proce­dure showed apparent improvement of Pa02 and P(A-a)02 in all. No significant complications resulted from these 14 bronchoscopic procedures, although transient tachycardia or hypertension developed in some cases.

Marini et al described that intensive respiratory care had the same effect on acute lobar collapse when compared with bronchoscopic procedures, but half of our cases suffered from chest trauma or spinal cord injury. These cases were excluded from his study for intolerance of respiratory care. Moreover, all of our cases were in critical condition and might not survive if we could not correct the pulmonary impairment immediately.
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In conclusion, we suggest a new simpler, effective method to introduce selective intrabronchial positive ventilation. We just wedge the bronchoscope into each segment or subsegment of the collapsed lobe instead of using the balloon cuff to close the bronchus. There were no complications even in critical cases.

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