Comparative Evaluation of Effects of Normal Saline and an Acetate-buffered Chloride-reduced Crystalloid on the Need for Vasopressors for Cardio-circulatory Support in Patients Undergoing Major Abdominal Surgery
Introduction
Normal saline 0.9% is currently amongst the most commonly used crystalloids in clinical practice and is the most frequent choice for volume replacement. The association of goal-directed fluid therapy with normal saline or a balanced crystalloid with perioperative vasopressor requirements is unclear.
Aim
To investigate whether normal saline or a balanced crystalloid has distinct effects on vasopressor use in patients undergoing major abdominal surgery
Patient Profile
- Adult, non-pregnant patients who were scheduled for elective major abdominal surgery with an expected surgical duration of a minimum of 2 h
- Major abdominal surgery included all gynaecological, urological, and general surgical operations requiring laparotomy
Methods
- A prospective, double-blind, randomised controlled trial
Exit criteria: If the pH fell below 7.2, the bicarbonate fell below 14 mmol litre_1, or the base excess was below -10 mmol litre-1, and the reaction to catecholamines was insufficient (inability to hold target mean despite adequate catecholamine dosage in the absence of surgical complications, such as bleeding), the study fluid was switched to the acetate-buffered balanced crystalloid, and the study was terminated.
Study Outcomes
- The primary outcome was the need for vasopressors
- The secondary outcomes were the total dose of catecholamines, total perioperative fluid, and unplanned intensive care admissions
Results
|
|
|
Saline Count (%) |
Balanced solution Count (%) |
|
Sex |
Male |
13 (43) |
11 (37) |
|
|
Female |
17 (57) |
19 (63) |
|
Age |
|
30 |
30 |
|
Height |
|
30 |
30 |
|
Weight |
|
30 |
30 |
|
Ideal body weight |
|
30 |
30 |
|
ASA |
1 |
11 (37) |
10 (33) |
|
|
2 |
16 (53) |
16 (53) |
|
|
3 |
3 (10) |
4 (13) |
|
Prior history of hypertension |
No |
19 (63) |
23 (77) |
|
|
Yes |
11 (37) |
7 (23) |
|
Preoperative creatinine (mg dl |
1) |
30 |
30 |
|
Urea (mg dl 1) |
|
30 |
30 |
|
GFR (ml min 1/1.73 m2) |
|
30 |
30 |
|
Type of surgery |
Bladder resection |
0 (0) |
2 (7) |
|
Colorectal resection |
5 (17) |
3 (10) | |
|
Hemihepatectomy |
1 (3) |
0 (0) | |
|
Hysterectomy |
0 (0) |
1 (3) | |
|
Intestinal reconstruction |
1 (3) |
3 (10) | |
|
Nephrectomy |
3 (10) |
1 (3) | |
|
Pancreatectomy |
1 (3) |
1 (3) | |
|
Radical prostatectomy |
2 (7) |
3 (10) | |
|
Small bowel resection |
1 (3) |
3 (10) | |
|
Tumour debulking (colorectal) |
3 (10) |
2 (7) | |
|
Tumour debulking (endometrium) |
2 (7) |
0 (0) | |
|
Tumour debulking (ovaries) |
7 (23) |
7 (23) | |
|
Tumour debulking (cervical) |
4 (13) |
4 (13) |
- The mean duration of anaesthesia was longer in the saline 0.9% group than in the balanced group (P= 0.004)
- Saline group =317 min
- balanced group =234 min
- The normal-saline group developed hyperchloraemic metabolic acidosis.
- More patients needed vasopressors for circulatory support in the normal-saline group compared with the buffered crystalloid group (97% vs 67%, respectively; P=0.033).
- The median dose of norepinephrine adjusted for body weight and duration of anaesthesia was
- Normal saline =0.11 ng kg-1 min-1
- Balanced group=0.00 ng kg-1 min-1 (P=0.003).
- The need for vasopressors was related to a high volume of administered fluid, normal-saline resuscitation, and lower mean arterial blood pressure.
|
Predictor variable |
Hazard ratio |
P-value |
|
Fluid administered (ml min 1 of anaesthesia time) |
1.01 |
0.001 |
|
Group allocation (1=saline; 2=balanced solution) |
0.44 |
0.006 |
|
Mean arterial blood pressure (mm Hg) |
0.97 |
0.027 |
Conclusion
- In patients undergoing major abdominal surgery, the use of normal saline results in saline-induced hyperchloraemia with associated metabolic acidosis and is associated with a dose-dependent increase in vasopressor requirements
- The results show that, even in patients with normal prior kidney function, the chloride load resulting from the infusion of normal saline overcomes normal regulatory mechanisms in a time-/dose-dependent matter
Reference
British Journal of Anaesthesia 2018; 120 (2): 274e283
