Intraoperative phase

  • Prevention of temperature drop. In the operating theatre, it is common for the patient's body temperature to drop. A drop in temperature below 36º affects the ability of platelets to stop bleeding in small blood vessels. It is therefore important to maintain patients' temperature at normal levels during surgery to avoid this harmful effect. This can be achieved by using thermal blankets and pre-warming the fluids administered to the patient.
  • Patient positioning. The anaesthetist takes special care when positioning the patient on the operating table to avoid compression causing areas of venous congestion, which would lead to increased bleeding during the operation.
  • Intraoperative blood salvage. In procedures where there is a higher risk of bleeding, intraoperative blood salvage (IOS) devices will be available for use. These devices work by sucking up the blood produced within the surgical field and directing it to a special reservoir, where it is washed and centrifuged to separate it from any elements that cannot subsequently be administered intravenously (fat globules, small fragments of bone or tissue). The blood that is collected, washed, and centrifuged is reinfused into the patient, always maintaining the continuity of the circuit. The system allows blood to be recovered during surgery and immediately after surgery, with the recovered blood being reinfused up to a maximum amount after the procedure. This technique is therefore accepted by patients who refuse blood transfusions for religious reasons. There are various models of intraoperative salvage units, adapted to the type of surgery to be performed. Intraoperative salvage systems cannot be used in every case, e.g., when surgery is performed on an infected area.
  • Administration of intraoperative drugs. In orthopaedic surgery procedures involving significant intraoperative bleeding (knee and hip replacements, etc.), it has been shown that administering a drug called tranexamic acid reduces surgical bleeding by 30%. Tranexamic acid acts by inhibiting the destruction of the clot that forms physiologically to stop bleeding.
  • Acute normovolemic haemodilution. Normovolaemic haemodilution is a simple and safe technique performed at our centre. The technique consists of extracting 1 to 3 units of blood from the patient, through an arterial or venous line, into blood collection bags before or after anaesthetic induction, while replenishing or restoring the circulating volume with colloids or crystalloids in the same amount as the volume extracted. The extracted blood units remain connected to another of the patient's veins without interruption, so people who refuse blood transfusions for religious reasons can use this technique. Normovolaemic haemodilution is only considered in surgical procedures where the estimated blood loss is close to or may exceed 1000–2000 ml. It requires certain preconditions on the part of the patient and preoperative haemoglobin levels of at least 14 grams/litre.