THE RELATIONSHIP OF SUBCUTANEOUS OXYGEN TENSION TO SYSTEMIC HEMODYNAMIC AND OXYGENATION VARIABLES IN CARDIAC SURGICAL ADULTS.
Contributors: University of California, San Francisco.
Published: 1994
Number of pages: 172
Subjects: Health Sciences, Nursing.; Health Sciences, Medicine and Surgery.
Description: Background. Covert tissue hypoperfusion is a state where conventional, systemic vital signs remain normal but some tissues receive inadequate blood flow. It is common among critically ill adults and is associated with high morbidity and mortality. Few tissue-based measures exist to detect it. Blood supply to subcutaneous tissue decreases early during altered perfusion so, the measurement of subcutaneous oxygen tension holds promise. The purpose of this study was to determine the relationship between subcutaneous oxygen tension and systemic hemodynamic and oxygenation variables in adults 48 hours after cardiac surgery.

Methods. Subcutaneous tonometers were placed under sterile conditions in the upper lateral arm of thirteen patients after anesthetic induction for cardiac surgery. Subcutaneous oxygen tension (PsqO2) was measured with an optical fluorescent sensor. Subcutaneous blood flow was quantitated using the Subcutaneous Flow Index (FI). Measurements of PsqO2, subcutaneous temperature, mean arterial pressure, heart rate, central venous and pulmonary capillary wedge pressures, arterial and mixed venous blood gases, cardiac output, and urine output were obtained hourly for eight hours and then every four hours for up to 48 hours.

Results. Mean Subcutaneous FI was consistently below normal limits during the first 24 postoperative (PO) hours. Most of the systemic hemodynamic and oxygenation variables were normal or near normal during this time. Subcutaneous FI was weakly related to systemic hemodynamic and oxygenation variables. Subcutaneous hypoperfusion was present 59% of the time during the first 8 PO hours and 61% during the subsequent 40 PO hours.

Conclusion. Subcutaneous hypoperfusion, as measured by the Subcutaneous FI, is often compromised in adults males following cardiac surgery. Weak correlation of Subcutaneous FI and systemic variables was primarily due to the maintenance of normal or near normal level of systemic variables in this sample; that is, covert tissue hypoperfusion was common in this sample. This study validated the clinical use of a subcutaneous tonometer and optode system in critically ill adults over a 48 hour period. Future studies of covert tissue hypoperfusion in critically ill adults needs should explore the effects of subcutaneous hypoperfusion on clinical outcome and the effect of fluid intervention trials.
Notes: Source: Dissertation Abstracts International, Volume: 55-09, Section: B, page: 3824.

Thesis (PH.D.)--UNIVERSITY OF CALIFORNIA, SAN FRANCISCO, 1994.

School code: 0034.