Hydration status after overnight fasting as measured by urine osmolality does not alter the magnitude of XXXX during general anesthesia in low risk @entity1 .

@entity1 @entity9255 @entity1875 @entity2614 @entity551 @entity3575 @entity1937
BACKGROUND: The increased distribution of crystalloid solution into the interstitial space may decrease the effectiveness of intravascular volume loading in @entity1 . We investigated whether preoperative hydration status after overnight fasting affects interstitial fluid redistribution and thus the magnitude of @entity551 during general anesthesia. METHODS: Sixty ASA physical status I/II @entity1 undergoing tympanoplasty fasted from midnight. Anesthesia was induced by @entity3575 and @entity1875 and maintained with @entity2614 and @entity1937 . Coinciding with the induction of anesthesia, 15 mL/kg acetated Ringer solution was infused IV over 60 minutes followed by 1 mL/kg acetated Ringer solution over the next 30 minutes. Urine osmolalities after induction of anesthesia and during the study period (pre-U( @entity9255 ), post-U( @entity9255 )) and percent decreases of whole-body bioelectrical resistance for extracellular fluid relative to baseline at the end of the study period (/\R(e)) were measured. @entity1 with a pre-U( @entity9255 ) < the 25th percentile or with a pre-U( @entity9255 ) > the 75th percentile of pre-U( @entity9255 ) were categorized in the hydrated or the dehydrated group, respectively. A range of variables, including mean arterial blood pressure during the 30- to 90-minute period relative to baseline, and /\R(e), were compared between the groups. RESULTS: The dehydrated group (pre-U( @entity9255 ) >759.5 mOsm/kg, n = 15) had a lower age (44 vs 52 years, P = 0.049) and had a higher post-U( @entity9255 ) (181 vs 55 mOsm/kg, P = 0.001) compared with the hydrated group (pre-U( @entity9255 ) <378.5 mOsm/kg, n = 15). Mean arterial blood pressure during the 30- to 90-minute period relative to baseline (0.67 vs 0.67, P = 0.85) with 95% confidence interval for the difference of means (-0.070 to 0.084) and /\R(e) (5.6% vs 6.0%, P = 0.58) with 95% confidence interval for the difference of means (-1.85% to 1.06%) were similar for the hydrated and dehydrated groups. CONCLUSIONS: Preoperative dehydration after overnight fasting as measured by urine osmolality did not alter the magnitude of @entity551 during general anesthesia. This finding suggests that intravascular volume loading with crystalloid solution to prevent @entity551 during general anesthesia is an unfounded practice for low risk @entity1 after overnight fasting.
