2002 [33]
Near maximal stroke volume EDM (CardiQ®)
Total 64 ml/kg (GDT) vs. 55 ml/kg
Mortality: 0 (GDT) vs. 1
2002 [34]
Near maximal stroke volume, EDM (CardiQ®)
Cryst: 4,405 (GDT) vs. 4375
No difference for morbidity.
Mortality not reported
Near maximal stroke volume EDM (CardiQ®)
Cryst: 3,000 both groups
Zero mortalities in 30 days, 1 (control) after 60 days
Near maximal stroke volume EDM (CardiQ®)
Cryst: 2,298 (GDT) vs. 2,625
Mortality: 0 (GDT) vs. 1 (control)
Pulse pressure variation (PPV)
Cryst: 2,176 (GDT) vs. 1,563
Mortality: 2 (GDT) vs. 5 (followed until discharge)
Stroke volume variation (PiCCOplus®)
Cryst: 4,500 (GDT) vs. 4,250
Mortality: 1 patient in control group “after several weeks.” “All others discharged from ICU alive”
Pleth variability index (PVI)
Cryst: 1,363 (GDT) vs. 1,815
Col: 268 (GDT) vs. 358. Cryst: 3,107 (GDT) vs. 3,516
No difference in morbidity.
Mortality: 2 (GDT) vs. 0
Stroke volume variation (SVV) (FloTrac®)
Cryst: 2,489 (GDT) vs. 3,153
Mortality: 2 in each group
Stroke volume variation (SVV) (FloTrac®)
Cryst: 2,321 (GDT) vs. 2,459
Col: 0 vs. 0
Cryst: 1,587 (GDT) vs. 1,528
Mortality: 1 (GDT) vs. 2
Near maximal stroke volume EDM (CardiQ®)
Cryst: 3,479 (GDT) vs. 3,593
2,083 (GDT) vs. 2,011
Mortality 30 days: 2 vs. 2.
90 days: 5 (GDT) vs. 4
Pulse pressure variation (PPV) and CI monitoring
Cryst: 2,862 (GDT) vs. 2,680
Coll: 57 (GDT) vs. 147. Cryst: 3,204 (GDT) vs. 3,452
Mortality: not given
Fluid volumes are in ml.
LOS, length of stay; EDM, esophageal Doppler monitoring; CI, cardiac index; HES, hydroxyethyl starch; GI, gastrointestinal.
NOTE: One reference was excluded from the table because inclusion and exclusion criteria were unclear.[44]
An interesting feature is that the increase in stroke volume was achieved with a colloid solution while at the same time all the patients, regardless of the stroke volume measurements, received large amounts of crystalloid. This may have two interpretations: either the crystalloid is given as pure fluid overload and leaves the circulation almost immediately (as crystalloid fluid does when given to normovolemic persons), or crystalloid cannot raise stroke volume significantly.
Most of the trials have in common that the patient sample is small, and the trials are powered to show a difference in length of hospital stay, but also that the GDT intervention in most cases improved the outcome relative to standard fluid therapy. It is interesting that colloid including hydroxyethyl starch (Voluven) apparently has beneficial effects on outcome in elective bowel surgery, and not the side effects seen in a population of septic patients.[27] Recently the so-called “restricted fluid therapy approach” (zero fluid balance) has been tested against GDT without the fluid overload with crystalloid (GDT on a zero balance basis) (Table 21.2).
| Author | Surgery | No. of patients | Blinding and intervention | Primary outcome | Intervention fluid | Preoperative fluid volume | Intraoperative fluid volume | Postoperative fluid volume | Results |
|---|---|---|---|---|---|---|---|---|---|
| Brandstrup et al. 2012 [45] | Elective laparoscopic or open colectomy | 150 in two groups: GDT vs. “restricted” | Observer blinded. Near maximal stroke volume (EDM) (CardiQ®) | Patients with postop. complications | HES 6% (Voluven®) | 2 h fasting for fluid. 500 ml saline if no fluid in 6 h | Coll: 810 (GDT) vs. 475 Total volume 1,877 (GDT) vs. 1,491 (restricted) | Oral fluid in an enhanced recovery protocol. i.v. fluid if oliguria, tachycardia, or hypotension | No difference in morbidity or LOS. Mortality: 1 in each group |
| Zhang et al. 2012 [46] | Elective open GI surgery | 60 in three groups: 4 ml/(kg h) and GDT-Ringer’s; 4 ml/(kg h) and GDT-HES; and 4 ml/(kg h) Ringer’s | Observer blinded. Pulse pressure variation (PPV) | LOS | Ringer’s lactate and HES 6% | Not given | Total volume: GDT-Ringer’s: 2,109 vs. GDT-colloid: 1,742 vs. restricted Ringer’s 1,260 | 1.5–2.0 ml/(kg h) crystalloid for 3 days. Oral intake not mentioned | LOS was shortest in GDT-colloid group, longest in the GDT-Ringer’s group. Morbidity: no difference. Mortality: none |
| Srinivasa et al. 2013 [47] | Elective laparoscopic or open colectomy | 85 in two groups GDT vs. “restricted” | Observer blinded. Near maximal stroke volume (EDM) (CardiQ®) | Surgical Recovery Score (SRS) | Succinylated gelatin colloid solution Gelofusine | 13 patients with bowel preparation: 1,000 ml crystalloid | Coll: 591 (GDT) vs. 297 Total volume: 1,997 (GDT) vs. 1,614 (restricted) | Oral fluid in an enhanced recovery protocol. i.v. fluid if oliguria, tachycardia, or hypotension | No difference in SRS, LOS, or postoperative morbidity. Mortality: none |
| Phan et al. 2014 [48] | Elective colorectal surgery | 100 in two groups GDT vs. “restricted” | Near maximal stroke volume (EDM) (CardiQ®) | LOS | Total volume 2,115 (GDT) vs. 1,500 (restricted) | Oral fluid in an enhanced recovery protocol | No difference in LOS or postoperative morbidity Mortality: none |
LOS, length of stay; EDM, esophageal Doppler monitoring. Fluid volumes are in ml.
The two regimens have shown an equally good outcome for the patients. However, all clinical randomized trials of fluid therapy in general have weaknesses. Firstly, it is very difficult to blind randomized clinical trials of fluid therapy. The fluids cause changes in the patient’s body weight and in the urinary output, and if more than 20% of the extracellular fluid volume is given (≥3 liters for a 75 kg person), a visible subcutaneous edema is formed. The latter means that only trials with a fluid difference less than 3 liters between groups are possible to blind effectively.
Secondly, one has to be very careful in the choice of endpoints. Length of stay (LOS) has especial problems. The introduction of fast-track surgery has illustrated that the most important factor for LOS is expectations from patients as well as the doctors. They simply stay in hospital as long as everybody expects them to. Other important factors are traditions including the use of drains, the allowance of the patient to return to oral food, and the type of analgesia used postoperatively.
Thirdly, in all research concerning surgical patients, the many confounders are at best difficult- to control. This is especially a problem for trials including a small number of patients. Large numbers of patients will equalize the confounders between the groups compared. For example, postoperative nausea and vomiting (PONV) is highly influenced by the fact that opiates have pronounced PONV side effects.
Intraoperative fluid therapy in outpatient surgery
The trials of different fluid volumes during outpatient and minor abdominal surgery are shown in Table 21.3.
| Author | Surgery | No. of patients | Blinding | Duration of surgery | Intervention | Fast | Postop. oral fluid intake | Results |
|---|---|---|---|---|---|---|---|---|
| Keane & Murray 1986 [49] | Mixed outpatient surgery | 212 in 2 groups | No | 18 min | 1,000 ml Hartmann’s solution + 1,000 ml DW vs. No fluid | ? | ? | Fluid reduces thirst and drowsiness, and increases well-being. No effect on nausea |
| Spencer 1988 [50] | Minor gynecological surgery | 100 in 2 groups | No | 8 min | 1,000 ml CSL vs. No fluid | ? | ? | Fluid reduces dizziness and nausea |
| Cook et al. 1990 [51] | Gynecological laparoscopy | 75 in 3 groups | Yes | 20 min | CSL 20 ml/kg vs. CSL + DW 20 ml/kg vs. No fluid | 11–16 h | ? | Fluid reduces dizziness and drowsiness. Hospital stay reduced in dextrose group |
| Yogendran et al. 1995 [52] | Mixed outpatient surgery | 200 in 2 groups | Yes | 28 min | Plasma-Lyte 20 ml/kg (1,215 ml) vs. Plasma-Lyte 2 ml/kg (164 ml) | 8–13 h | ? | Fluid reduces thirst, dizziness and drowsiness. No effect on nausea |
| McCaul et al. 2003 [53] | Gynecological laparoscopy | 108 in 3 groups | Yes | 22 min | CSL 1.5 ml/kg per fasting hour (1,115 ml) vs. CSL + DW 1.5 ml/kg per fasting hour (1,148 ml) vs. No fluid | 11.5 h | ? | No significant differences between the groups |
| Magner et al. 2004 [54] | Gynecological laparoscopy | 141 in 2 groups | Yes | 20 min | CSL 30 ml/kg vs. CSL 10 ml/kg | 13 h | ? | Fluid reduced nausea and vomiting. No effect on dizziness or thirst |
| Holte et al. 2004 [29] | Laparoscopic cholecystectomy | 48 in 2 groups | Yes | 68 min | LR 15 ml/kg (998 ml) vs. 40 ml/kg (2,928 ml) | 2 h | Mean 600 ml | Fluid reduces thirst, nausea, dizziness, drowsiness; improves well-being and pulmonary function; and shortens hospital stay |
DW, dextrose in water 5%; CSL, compound sodium lactose (Na:131, K:5, Ca:2, Cl:111, lactate:29 mmol/l); LR, lactated Ringer’s solution.
These trials have shown that approximately 1 liter of fluid i.v. causes better postoperative well-being (less PONV) in patients undergoing outpatient surgery. This finding seems logical because patients undergoing outpatient surgery are told to fast from midnight before surgery, i.e. they have a fluid deficit of approximately 1 liter.[28]
A surprising finding was that by Holte et al. [29] who examined the effect of 3 liters versus 1 liter of fluid on PONV, postoperative ability to run on a treadmill, and pulmonary function measured by spirometry. The trial showed that patients receiving 3 liters had less PONV and better exercise performance than the patients given 1 liter. This trial has, however, a problem with the doses of postoperative opiates, with smaller doses given to the patients in the group given most fluid.
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