206 Alteration of Brain Volume-Pressure Response During Octanoate Infusion in Rabbits

Abstract

')fiQ SUBJECTS USING THE COAXIAL AND CIRCLE BREATHINGAnesthesia, Washington, DC ICU's are expensive and account for-1% of the GNP. Many patients (pts) without life threatening dysfunction and not utilizing unique PICU therapies who receive only monitoring could be cared for in other hospital areas a t a significant cost savings. Methods: All admissions to a 16 bed PICU for 13.5 months were evaluated. Daily assessemnts of types of care were accomplished with the Therapeutic Intervention Scoring System (TISS). Each of the TISS components were categorized as PICU therapies (e.g. mech ventilation), montoring: personal intensive (e.g. hourly vital signs), monitoring: technology intensive (e.g. arterial catheter) and routine care. Daily assessments of severity of illness utilized the Physiologic Stability Index (PSI). Patients were divided into low (mortality risk<l%) and high risk groups by an average PSI cutoff of 9. Results: 822 admissions utilizing 3969 days of care were evaluated. 226 pts (27.5%) utilizing 297 days of care (7.5%) did not receive unique PICU therapies (monitoring pts). 94.2% (2131266) Elevated serum concentrations of s h o r t chain f a t t y a c i d s , including octanoate, a r e found i n p a t i e n t s with Reye's Syndrome. Continuous intravenous i n f u s i o n of octanoate i n r a b b i t s has been reported t o r e s u l t i n s i m i l a r c l i n i c a l and chemical changes of Reye's Syndrome including h y p e r v e n t i l a t i o n , coma, s e i z u r e s , increased i n t r a c r a n i a l pressure and hyperammonemia.To f u r t h e r e v a l u a t e t h e e f f e c t of octanoate on b r a i n compliance we evaluated t h e b r a i n volume-pressure response (VPR) during continuous octanoate i n f u s i o n i n r a b b i t s .Volumes of O . l m l were infused i n t o t h e c i s t e r n a l space of cont r o l r a b b i t s (C) infused with normal s a l i n e and r a b b i t s with continuous octanoate i n f u s i o n s a t 1.5mmoles/hr ( 0 ) . VPR was lmmHg (C) v s 4mmHg ( 0 ) . Time t o recovery of i n i t i a l i n t r a c r a n i a l press u r e was <5 seconds (C) v s >10 seconds ( 0 ) . Both groups received pavulon lmklhr and were mechanically v e n t i l a t e d without changes i n pH, pCO o r pO . I n t r a c r a n i a l pressure (ICP) ranged 5-lOmmHg and no difgerencez were noted between (C) o r (0) r a b b i t s (p=ns).We conclude t h a t continuous intravenous i n f u s i o n s of octanoate i n r a b b i t s 1) a l t e r t h e b r a i n VPR, and 2) do not produce elevat i o n s i n ICP a t 1.5mmoles/hr. W e describe a new apparatus f o r non-invasive measurement of V02 i n intubated c h i l d r e n receiving high inspired oxygen concent r a t i o n s . The apparatus i s a modification of t h e closed c i r c u i t system o r i g i n a l l y described by Engstrom e t a1 (Acta Anesth Scand, 1961). I t c o n s i s t s of a standard Emerson 3PV P e d i a t r i c Ventilat o r enclosed i n an a i r t i g h t chamber i n s e r i e s with an Ohio 822 dry r o l l i n g seal spirome...