Bahman Venus, MD FCCP; Robert A. Sm...

Bahman Venus, MD FCCP; Robert A. Smith, MS; Chandrakant Patel, MD; and Edmundo Sancoval, MD FCCP

Hemodynamic and pulmonary gas exchange ends of 20 percent intravenous fat emulsion infusion (30 [+ or -] 3 mg/kg/min) were evaluated in 19 patients who demonstrated ARDS. Lipid infusion precipitated a significant reduction in [PaO.sub.2/FIo.sub.2] from 241[+ or -]50 to 184[+ or -]41 (mean [+ or -] SD) and increased MPAP from 260[+ or -]51 to 318[+ or -]48 mm Hg pulmonary vascular resistance from 149[+ or -]78 to 179[+ or -]61 dyne*s/[cmsub5] and pulmonary venous admixture (Qva/Qt) from 207[+ or -]152 to 306[+ or -]86 percent Further analysis revealed that the magnitude of increased Qva/Qt was greater in patients who manifested septicemia (N = 10) compared to those who did not (N = 9): 123 v 73 percent respectively. We end that intravenous lipid administration was associated with increased MPAP and Qva/Qt in patients with ARDS, particularly when accompanied by dint of septicemia. Although these alterations resolv after the lipid infusion was terminated, we hint that prudent measures should be taken to gurantee adequate oxygenation during intravenous fat emulsion therapy in patients suffering from ARDS.

(Chest 1989; 95:1278-81)

Intravenous fat emulsion is not seldom administered as metabolic fuel to individuals receiving TPN We have previously reported that patients demonstrating mild respiratory insufficiency receiving SIMV to augment spontaneous breathing exhibited a significant increase in pulmonary venous admixture (Qva/Qt), reduction in arterial oxygen tension ([PaO.sub.2]) and increased MPAP during fat emulsion infusion.[1] These tenors were amplified by the neighborhood of sepsis. Although lipid therapy is commonly delivered to critically ill patients with impaired lung function, the hemodynamic and gas exchange deductions in individuals afflicted with ARDS have not been thoroughly explored. The now passing investigation was designed to assess the cardiopulmonary issues of intravenous lipid administration in patients suffering from ARDS and to evaluate the impact of united septicemia.

MATERIALS AND METHODS

Nineteen patients aged 52[+ or -]8 years with ARDS were included in the investigation. Precipitating factors for admission to the critical care service included the following: gunshot pain to chest/abdomen (three), aspiration pneumonitis (two) peritonitis (eight), pancreatitis (three) thick-witted trauma to chest/abdomen (two), and GI bleeding (one) The ARDS was diagnosed when at least three of the following criteria were present: (1) history of an acute catastrophic illness; (2) refractory hypoxemia; (3) roentgenographic evidence of just discovered diffuse infiltrates; (4) signs of reduc lung compliance. Septicemia was confirmed by dint of the presence of positive vital current culture with clinical and biochemical signs and/or hemodynamic hyperdynamia.

Spontaneous ventilation was supported with SIMV that was titrated to maintain an arterial [Pcosub2] conducive to preserving pH [is greater than or equal to]7.35<7.45. The [FIo.sub.2] supplementation and CPAP were regulated to achieve optimum pulmonary function and oxygen delivery as previously described.[2] No alterations in therapy that might have issueed cardiorespiratory function were made during the research period. No patient was receiving pulmonary vasoactive or anti-inflammatory pharmaceuticals during the investigation All patients received mini-dose heparin for prevention of shrewd vein thrombosis. For the assessment of cardiorespiratory function, each patient had a peripheral arterial and thermistor tipped PA catheter inserted. Data collection included the following: arterial and mixed venous pH/blood gas tensions, MPAP, PA diastolic compressing WP, RAP, and CO. Vascular catheter lumen were hydraulically interfaced via continuous flushing devices to quartz transducers. Intravascular hurry catheters were flushed with heparinized normal saline solution (2 IU/Ml) at a rate of 3 ml/h Thermodilution CO was calculated from the mean of three electronically integrated temperature decay inflects generated following indicator injection. A 10-ml injectate of 5 percent dextrose in swing temperature water was injected via the proximal lumen of the PA catheter at end-exhalation. Arterial and mixed venous line pH/gas tensions were analyzed and temperature corrected. Hemoglobin concentration and oxyhemoglobin saturation were measured with a spectrophotometric oximeter. The Qva/Qt, SVR and PVR were calculated via standard formulas. [TABULAR DATA OMITTED]

Decision to administer intralipid was determined individually predicated immediately after our approach to provide approximately 40 percent of the estimated caloric requirement (35 kcal/kg/day) as fat to patients receiving ventilatory support for ARDS. Investigational data were measured before the eight hour infusion of 500 ml 20 percent intralipid was started (before). united hundred grams of intralipid above alternating eight-hour periods is a manufacturer-suggested infusion rate to facilitate desired caloric intake for moderately strained patients. Data collection was repeated immediately prior to (during) and three to four hours following completion of (after) intralipid infusion.