182 Peripheral Arterial Infusions: Histologic Findings

Abstract

Simmons), O e m e d m Utah, S a l t Lake C i t y , UT. Laser doppler (LD) velocimetry theoretically offers a noninvasive objective measurement of tissue perfusion, an important The f i r s t o b j e c t i v e o f t h i s study was t o determine i f leakageclinical parameter that is currently only subjectively assessed.(i) through a pneumothorax and chest tube o f i n f a n t s w i t hThe laser doppler (Med Pacific)uses a skin sensor to measure pulmonary disease i s l e s s d u r i n g h i g h frequency j e t v e n t i l a t i o n .reflected light from a helium-neon laser that penetrates tissue (HFJV) than during conventional v e n t i l a t i o n (CV). We measured V about 15 mm over a 1 mm2 area. It utilizes the doppler i n 5 i n f a n t s , who had chest tubes placed t o r e l i e v e tension principle to calculate the rootmean-square frequency of the pneumothoraces w h i l e managed a l t e r n a t e l y on CV and HFJV. I n a l l reflected light. Because of the extremely small cross sectional area of the vessels in the microcirculation that this technique i n f a n t s , 0 was less during HFJV than CV (49+26 vs 1 5 7~8 1 ml/min, samples, this continuously monitored number represents changes in meantSE). However, we a l s o n o t i c e d t h a t s i g n i f i c a n t l y lower tissue blood flow. We used the LD to assess tissue perfusion on mean tracheal airway pressure ( P t m ) were used d u r i n g HFJV than 10 critically ill neonates (480 to 1600 gm) in the NICU to CV ( 9 i l vs 15' 2 cm H 0, p<0.01). PaCO was also l e s s (35+8 V S evaluate the feasibility of its clinical application. During the 45'9 mmHg; p<0.03) a?though Pa0 valueg were n o t s i g n i f i c a n t l y study we recorded temperature, heart rate, blood pressure and d i f f e r e n t . W e then turned t o a6 animal model o f RDS t ohematocrit to determine what factors might influence perfusion.determine t h e e f f e c t s o f PtCJ and mode o f v e n t i l a t i o n on \j. I nWe monitored the infants during procedures that were stressful or would alter cardiac output such as ET tube suctioning, blood 9 s a l i n e lavaged cats we induced pneumothoraces by a p p l i c a t i o n transfusion and intubation. The LD was very sensitive, in fact, o f h i g h airway pressures. F i r s t we adjusted CV and HFJV too sensitive to changes in tissue blood flow. There was no s e t t i n g s so t h a t P t X was lower d u r i n g HFJV; we then adjusted correlation between any of our measured parameters and changes iu t h e v e n t i l a t o r s t o produce s i m i l a r P t G . When Pt% was lowered perfusion as measured by the LD. Obvious stress with procedures from 13'0.3 (CV) t o 10i0.5 cm H 0 (HJFV), V decreased such as suctioning and intubation caused immediate decreases in s i g n i f i c a n t l y (p<0.01) from 651286 t o 2?4+84 mllmin. When PtCJ perfusion, but changes in the readings from minute to minute was h e l d constant (12.7'1 cm H 0 ) mean V values were i d e n t i c a l varied just as much. In fact, moving the skin sensor as little as 1 mm'w...