Effects of Noradrenaline Administration Combined With Restrictive Intraoperative Fluid Substitution on Blood Loss and Perioperative Outcome in Patients Undergoing Open Radical Cystectomy

Background

Perioperative fluid management in abdominal surgery is a subject of controversy and current standard fluid therapy is not evidence based. Standard fluid therapy includes replacement of basic fluid requirements, loss by perspiration, by exsudation through the surgical wound, and loss into the third space.

Fluid preload before spinal or just after epidural anaesthesia is a common and recognized practice in clinical anaesthesia. Vasodilatation is a well-known side effect of halogenics, of most hypnotics and opiates. Compensating decreasing blood pressure by volume substitution is common praxis. Alternatively the fall in blood pressure due to vasodilatation can be corrected by applying vasoactive agents. A review of the data on the effect of "high volume" perioperative fluid therapy suggests that overhydration may have deleterious effects on cardiopulmonary function (excessive shift to the right on the Starling myocardial performance curve, pneumonia and respiratory failure) as well as on recovery of gastrointestinal motility (prolonged postoperative ileus (PI)), tissue oxygenation and wound healing (anastomosis leakage). A postoperative weight gain of 3-7 kg in patients after major elective surgery therefore seems to represent a genuine fluid overload. Delay in bowel motility may be due to the presence of excess fluid in the intestinal wall resulting from excess perioperative fluid therapy. Increased gut permeability after surgical trauma may also contribute to the development of PI because of enhanced uptake of luminal bacterial products. Postoperative complications were significantly reduced by restricted fluid therapy. A dose response relation between administrated fluid volume and postoperative complications (cardiopulmonary and tissue healing) was found in a randomised assessor blinded multicenter trial for colorectal surgery 11,12. The restricted fluid regimen did not lead to haemodynamic instability and the amount of vasoactive substances administered was similar. No significant difference in urinary output was demonstrated on days 1 and 6. Restrictive fluid administration in fast-track surgery led to no differences in all-over recovery after colonic surgery. Goal-directed intraoperative fluid administration using the oesophageal Doppler monitor to maintain maximal stroke volume has been shown to reduce the length of hospital stay, lower the incidence of postoperative nausea and vomiting and to encourage an early return of bowel function. Oesophageal Doppler monitor permits rapid, minimally invasive and continuous estimation of cardiac output. It can be easily inserted and is not associated with major complications. The investigators will use oesophageal Doppler monitoring for intraoperative monitoring of stroke volume and cardiac output.

In animal experiments on pigs, high (18ml/kg/h) or low (3ml/kg/h) volume crystalloid fluid treatment had no effect on colon tissue oxygenation tension. Three different fluid volume regimens (3ml/kg/h, 7 ml/kg/h and 20ml/kg/h) tested did not affect tissue oxygen pressure in the jejunum and colon, suggesting efficient autoregulation of intestinal blood flow in healthy pigs undergoing uncomplicated abdominal surgery 25. Noradrenaline increased systemic blood flow (mean arterial pressure and cardiac index) and failed to increase microcirculatory blood flow in most abdominal organs in septic pigs. Thoracic epidural anesthesia per se does not affect intravascular volume. Therefore, vasopressors are preferable for treatment of hypotension after epidural anesthesia.

The incidence of postoperative cognitive dysfunction varies greatly with reported rates of 10% to 55%. Patient characteristics such as age, education, type and length of surgical procedure and preoperative cognitive status have been found to affect the incidence and severity of postoperative cognitive dysfunction. The influence of intraoperative volume management on cognitive function has not been assessed.