Effects of high frequency ventilation on lung lymph dynamics and prostaglandin generation.
We examined the consequences of high frequency ventilation (HFV) on pulmonary lymph flow (Qlym) in normal lungs and after the lymph flow was increased with an i.v. histamine infusion (2 micrograms/kg/min). Studies were made in the anesthetized sheep prepared with lung lymph fistulas. The sheep were subjected to intermittent positive pressure ventilation (IPPV) (frequency (f) = 12 breaths/min, tidal volume (TV) = 10 ml/kg) and HFV (f = 7 Hz, TV = 1-2 ml/kg). TV was adjusted prior to the experiment to achieve normal arterial blood gases. Histamine infusion doubled Qlym and lymph protein clearance (Qlym X lymph-to-plasma protein concentration ratio) from baseline. HFV did not affect Qlym and lymph protein clearance in normal lungs or after histamine infusion. HFV also did not result in generation of thromboxane (TxA2) and prostacyclin because plasma concentrations of their stable degradation products, TxB2 and 6-ketoprostaglandin F1 alpha, were not significantly elevated. The results indicate that HFV does not alter lymphatic pumping in the normal lung and during increased transcapillary protein transport.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002200:Capillary Resistance / Q000187:drug effects; D002302:Cardiac Output; D006632:Histamine / Q000494:pharmacology; D007384:Intermittent Positive-Pressure Breathing; D008168:Lung / Q000378:metabolism / Q000502:physiology*; D008196:Lymph / Q000502:physiology*; D011453:Prostaglandins / Q000096:biosynthesis*; D011652:Pulmonary Circulation / Q000187:drug effects; D011669:Pulmonary Wedge Pressure / Q000187:drug effects; D012121:Respiration, Artificial; D012756:Sheep; D013997:Time Factors
D011453:Prostaglandins; D006632:Histamine