Key result
Pre-operative fasting for 10 hours did not significantly reduce total intravascular blood volume compared to calculated normal values (4123 vs 3882 ml), suggesting patients remain normovolaemic.
Why the study?
Does 10 hours of pre-operative fasting reduce intravascular blood volume compared to calculated normal values in gynaecological patients?
Observational (n=53)
Does 10 hours of pre-operative fasting reduce intravascular blood volume compared to calculated normal values in gynaecological patients?
Absolute Event Rate: 4123% vs 3882%
p-value: p=not significant
Cardio-pulmonary healthy patients remain intravascularly normovolaemic even after prolonged pre-operative fasting, suggesting hypotension during anaesthesia induction should be treated with vasopressors rather than volume loading.
Fasting for 10 hours was not associated with reduced blood volume in healthy gynaecological patients; leaves open whether vasopressors should supplant volume loading for induction hypotension.
BACKGROUND: Pre-operative fasting is assumed to cause a deficit in intravascular blood volume (BV), as a result of ongoing urine production and insensible perspiration. Standard regimes consist of volume loading prior or simultaneous to any anaesthetic procedure to minimise the risk of hypotension. However, fluid overload in the context of major abdominal surgery has been shown to deteriorate patient outcome. Our study aimed to quantify total intravascular BV after fasting by direct measurements and to compare it with calculated normal values in comparable non-fasted patients. METHODS: After 10 h of fasting, total plasma volume (PV) and red cell volume (RCV) were measured via the double-label technique (indocyanine green dilution and erythrocytes labelled with fluorescein, respectively) following induction of general anaesthesia in 53 gynaecological patients suffering from malignoma of the cervix. The corresponding normal values were calculated individually from age, body height and body weight. RESULTS: Measured BV, RCV and PV after fasting were 4123+/-589, 1244+/-196 and 2879+/-496 ml, respectively. The differences to the corresponding calculated normal values were not significant (3882+/-366, 1474+/-134 and 2413+/-232 ml, respectively). The measured haematocrit reflected a slight anaemic state (0.35+/-0.03). CONCLUSION: Our data suggest that even after prolonged pre-operative fasting, cardio-pulmonary healthy patients remain intravascularly normovolaemic. Therefore, hypotension associated with induction of general or neuraxial anaesthesia should perhaps be treated with moderate doses of vasopressors rather than with undifferentiated volume loading.
No takes yet. Share an insight, caveat, or question.
Jacob et al. (2008) conducted an observational in Malignoma of the cervix (n=53). 10 h of pre-operative fasting vs. Calculated normal values was evaluated on Total intravascular blood volume (BV) (p=not significant). Pre-operative fasting for 10 hours did not significantly reduce total intravascular blood volume compared to calculated normal values (4123 vs 3882 ml), suggesting patients remain normovolaemic.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: