The review article of perioperative fluid therapy by Miller and Myles1  provides new recommendations for fluid administration during major surgery. Many studies performed during the past 15 yr show that a restrictive strategy consisting of 3 to 5 ml−1 · kg−1 · h−1 of crystalloid fluid during surgery provides a better outcome in comparison with 10 to 12 ml−1 · kg−1 · h−1. The authors now swing the pendulum once again and recommend the larger amount. The basis for their recommendation consists of only two retrospective studies and their own prospective study, the RELIEF (Restrictive Versus Liberal Fluid Therapy in Major Abdominal Surgery) trial.2 

We believe that the patient's preoperative fluid status should be considered when giving recommendations of this kind. Miller and Myles encourage unrestricted intake of fluids until 2 h before elective surgery,1  but in the RELIEF trial patients had fasted for a median of 9 h, and 25% of them even for 12 h or more, before surgery.2  Moreover, 36% of their patients received bowel preparation, which causes fluid depletion. Therefore, many of the patients in the RELIEF trial were probably dehydrated, or even hypovolemic, when surgery started. Finally, the postoperative fluid administration in the restrictive group in the RELIEF trial amounted to only 0.8 ml−1 · kg−1 · h−1, which is less than the recommended minimum water intake of 1.0 to 1.2 ml−1 · kg−1 · h−1 in conscious healthy humans. Therefore, the higher incidence of postoperative creatinine elevation in the restrictive group might be an expected result of the trial.

The issues we mention may even explain the discrepancy between the RELIEF trial and previous studies in this area which, with few exceptions, favor a restrictive strategy. The new recommendations1  are probably correct for patients with various degrees of preoperative dehydration attributable to lengthy preoperative fasting and bowel preparation, which have fallen out of practice in most parts of the world.3,4  However, we question this liberal approach in patients who are euhydrated before surgery.

The authors declare no competing interests.

1.
Miller
TE
,
Myles
PS
: .
Perioperative fluid therapy for major surgery.
Anesthesiology
.
2019
;
130
:
825
32
2.
Myles
P BR
,
Corcoran
T
,
Forbes
A
,
Wallace
S
,
Peyton
P
,
Christophi
C
,
Story
D
,
Leslie
K
,
Serpell
J
,
McGuinness
S
,
Parke
R
;
Australian and New Zealand College of Anaesthetists Clinical Trials Network, and the Australian and New Zealand Intensive Care Society Clinical Trials Group
: .
Restrictive versus liberal fluid therapy for major abdominal surgery.
N Engl J Med
.
2018
;
378
:
2263
74
3.
Leenen
JPL
,
Hentzen
JEKR
,
Ochuijsen
HDL
: .
Effectiveness of mechanical bowel preparation versus no preparation on anastomotic leakage on colorectal surgery: A systematic review and meta-analysis.
Updates Surg
.
2019
;
71
:
227
36
4.
Feldheiser
A
,
Aziz
O
,
Baldini
G
,
Cox
BPBW
,
Fearon
KCH
,
Feldman
LS
,
Gan
TJ
,
Kennedy
RH
,
Ljungqvist
O
,
Lobo
DN
,
Miller
T
,
Radtke
FF
,
Ruiz Garces
T
,
Schricker
T
,
Scott
MJ
,
Thacker
JK
,
Ytrebo
LM
,
Carli
F
: .
Enhanced recovery after surgery (ERAS) for gastrointestinal surgery, part 2: Consensus statement for anaesthesia practice.
Acta Anaesthesiol Scand
.
2016
;
60
:
289
334