Perioperative fluid therapy and postoperative pulmonary edema: cause-effect relationship?

Effect of hyperosmolar sodium lactate infusion on haemodynamic status and fluid balance compared with hydroxyethyl starch 6% during the cardiac surgery

Background and Aim:

No solution has been determined ideal for fluid therapy during cardiac surgery. Previous studies have shown that hyperosmolar sodium lactate (HSL) infusion has improved cardiac performance with smaller volume infusion, which resulted in negative fluid balance. This study compared the effects between a patent-protected HSL infusion and hydroxyethyl starch (HES) 6% on haemodynamic status of the patients undergoing cardiac surgery.

Methods:

In this open-label prospective controlled randomized study, patients were randomly assigned to receive loading dose of either HSL or HES 6%, at 3 mL/kgBW within 15 min, at the beginning of surgery. Haemodynamic parameters and fluid balance were evaluated, while biochemical parameters and any adverse effect were also recorded. Haemodynamic and laboratory parameters were analyzed through repeated measures analysis of variance. Statistical assessment of fluid management was carried out through Student t-test. All statistical analyses were performed using the statistical package for the social sciences^® version 15, 2006 (SPSS Inc., Chicago, IL).

Results:

Out of 100 enrolled patients in this study (50 patients in each arm), 98 patients were included in analysis (50 in HSL group; 48 in HES group). Cardiac index increased higher in HSL group (P = 0.01), whereas systemic vascular resistance index decreased more in HSL than HES group (P = 0.002). Other haemodynamic parameters were comparable between HSL and HES group. Fluid balance was negative in HSL group, but it was positive in HES group (−445.94 ± 815.30 mL vs. +108.479 ± 1219.91 mL, P < 0.009).

Conclusion:

Administration of HSL solution during the cardiac surgery improved cardiac performance and haemodynamic status better than HES did.

[Perioperative fluid management: an analysis of the present situation]

Optimal perioperative fluid management is still controversial. Besides well known perioperative hypovolaemia, hypervolaemia has an influence on perioperative morbidity and mortality, particularly with regard to the patient's medical history, a reduced cardiac and pulmonal function and the operation itself. The concepts of preoperative, intraoperative and postoperative fluid administration are neither adequately validated, nor sufficiently integrated into a perioperative concept. At the present, moderate fluid administration to improve preoperative and postoperative outcome is safe in minor or medium surgical procedures. High-risk surgical patients benefit from a time-oriented or/and goal-oriented monitored fluid therapy. In the past only little attention has been concentrated on postoperative fluid management, but may be stimulated by the new concepts of fast track surgery.

Treating Ischemic Left Ventricular Dysfunction With Hypertonic Saline Administered After Coronary Occlusion in Pigs

OBJECTIVE(S)

The effects of hypertonic saline on ventricular function are controversial, whether it is increasing contractility or preload. There are no data, however, on the influence of hypertonic saline in a stunned myocardium.

DESIGN

This study was prospective and randomized in order to analyze the effects of hypertonic saline solution (7.5%) on myocardial function and systemic hemodynamics in a porcine model of ischemia and reperfusion.

SETTING

A university teaching hospital, animal research laboratory.

PARTICIPANTS

Twelve adult domestic swine.

INTERVENTIONS

Myocardial stunning was produced by the complete occlusion of the proximal left anterior descending artery for 15 minutes followed by reperfusion. Five minutes after reperfusion, the animals were assigned to receive 4 mL/kg of hypertonic saline (n = 7) or normal saline (n = 5) over 10 minutes. Pressure-tipped catheters were placed in the left ventricular cavity and aorta. The dimensions of the left ventricle were measured with ultrasonic microcrystals. Cardiac output was measured with transit time ultrasound. Data were recorded continuously and compared before the occlusion, 5 minutes after reperfusion, and at the end of the infusion.

MEASUREMENTS AND MAIN RESULTS

Compared with baseline, ventricular function was significantly depressed after left anterior descending artery occlusion. Left ventricular dP/dT and its end-systolic pressure-volume slope decreased (38% and 52%, respectively; p < 0.05), with a concomitant increase in systemic vascular resistance. The administration of hypertonic saline significantly improved left ventricular function (Emax 1,422 +/- 198 mmHg/mL, and dP/dT 3.2 +/- 0.4 mmHg/s v normal saline group values of 1,156 +/- 172 and 2.5 +/- 0.5, respectively; p < 0.05), cardiac output (2.5 +/- 0.5 v 1.84 +/- 0.4 L/min, p < 0.05), and lowered systemic vascular resistance (from 28.8 +/- 2.3 to 23.5 +/- 1.4, p < 0.05), with no significant changes with normal saline administration.

CONCLUSIONS

After transient myocardial ischemia, hypertonic saline administered over a short period of time acts as an inodilator by increasing contractility while simultaneously lowering systemic vascular resistance.