Case Study Fluid Management for Craniofacial Resection with Rectus Free-Flap D. John Doyle MD PhD FRCPC Cleveland Clinic Foundation doylej@ccf.org March 2003

Case: Craniofacial Resection with Rectus Free-Flap A 76 year-old male, weighing 81 kg who was 185 cm tall, presented with complaints of facial pain and swelling. The patient had smoked a pack of cigarettes a day for almost 50 years. About 10 years ago, he developed angina while playing tennis. The angina was treated with the beta-blocker atenolol and the patient quit his smoking habit. At the time of diagnosis, the patient reported that his infrequent angina attacks responded quickly to sublingual nitroglycerine tablets. He described his exercise tolerance as good, being able to climb three flights of stairs before "getting pooped". The patient took no other medications and had no allergies.

Remember 76 year-old male Former smoker CHD Complaints of facial pain and swelling

Diagnosis A diagnosis of squamous cell carcinoma of the maxillary sinus was made by magnetic resonance imaging and confirmed by biopsy following a workup.

Surgical Plan 10-hour craniofacial resection 3 L expected blood loss SURGERY The surgical plan was to undertake a 10-hour craniofacial resection of the right maxilla and orbit and to replace the defect with a rectus muscle free- flap using microvascular techniques. A three litre blood loss is expected. 10-hour craniofacial resection 3 L expected blood loss

Preoperative Tests Laboratory results included a hemoglobin concentration of 13 g/dL, a creatinine of 1.1 mg/dL. Vital signs, serum electrolytes, electrocardiogram and chest X-ray were all unremarkable. · Hb 13 g/dL · Creatinine 1.1 mg/dL

Coronary Artery Disease Although this patient appeared to be in fairly good shape, with good exercise tolerance, he had known coronary artery disease. Because of his coronary artery disease, most anesthesiologists would not allow his hemoglobin to drop significantly below 10 g/L.

Blood Volume Estimate Using 65 mL/kg as a blood volume estimate, his blood volume (BV) was calculated to be about 5300 mL.

ABL=2(5300) x (130-100)/(130+100) =1400 mL (approx.) This suggests that with appropriate fluid replacement using crystalloid or colloid, the patient could lose up to about 1400 mL of blood, before a transfusion of packed red blood cells would likely become necessary. If serial blood samples were taken from an arterial line, it would be possible to know exactly when a minimum acceptable hemoglobin or hematocrit had been reached.

ABL Formula The allowable blood loss (ABL) was estimated using the following formula: ABL=2BV x (Starting Hb-Allowable Hb)/(Starting Hb+Allowable Hb) ABL=2(5300) x (130-100)/(130+100) =1400 mL (approx.)

Two options to replace ongoing blood losses 4:1 with a crystalloid such as saline or Ringer’s lactate solution or 1:1 with a colloid such as PENTASPAN® (10% pentastarch in 0.9% sodium chloride injection) This is given in order to keep the patient isovolemic.

Rule of Thumb One often used "rule of thumb" is to replace initial blood losses with crystalloid such as saline on a 4:1 basis until blood losses reach 15-20% of blood volume. Replace subsequent losses 1:1 with a colloid such as PENTASPAN® (to keep patient isovolemic) until the hemoglobin or hematocrit falls below the "transfusion trigger".

Rule of thumb: Start Colloids at 15 - 20% Blood Volume Loss Example (20% blood loss rule of thumb) 77 kg man Blood volume estimated at 65 ml/kg x 77 kg = 5 liters 20% blood volume = 1 liter of blood Crystalloid replacement for 1 liter blood is 3-4 liters Thus, consider starting a colloid after 3-4 liters of crystalloid given to replace lost blood

Transfusion Trigger In this case, a transfusion trigger of 10 g/dL would be used because of the patient's cardiopulmonary disease. In a much younger patient without any known cardiopulmonary disease, the trigger level might be set at 8 or even 7 g/L, depending on clinical judgement.

Remember ABL 1400 mL 4 L of crystalloid replaces 1 L of blood loss Further blood loss replaced with PENTASPAN® Transfusion trigger 10 g/L

Preoperative Fluid Deficits Preoperative fluid deficits are often estimated using the 4-2-1 rule. For an 81 kg patient this amounts to about 130 mL/hr. Assuming that the patient has been NPO for about 10 hours preoperatively and has had no IV prior to going to the OR, the preoperative fluid deficit would be about 130 mL/hr x 10 hrs = 1300 mL. Many anesthesiologists attempt to replace this deficit over about a two hour span at the beginning of the case.

4-2-1 Rule 4 ml/kg/hr for first 10 kg 2 ml/kg/hr for next 10 kg 1 ml/kg/hr thereafter EXAMPLES 10 kg 40 ml/hr 20 kg 60 ml/hr 30 kg 70 ml/hr 40 kg 80 ml/hr 70 kg 120 ml/hr

Maintenance Fluid Requirements Maintenance fluid requirements would amount to about 130 mL/hr

Third Space Losses Third space losses include both evaporative losses from surgical area and fluid that enters the interstitium as a result of tissue trauma. For a case such as this one, a reasonable estimate of the third space losses would be about 4 mL/kg/hr or about 320 mL/hr.

Remember Preoperative fluid deficit anticipated at 1300 mL Third space losses of 320 mL/hr expected Maintenance fluid requirements of 130mL/hr expected

Desired Fluid Therapy 1 Run the IV at 450 mL/hour (130 mL/hr maintenance + 320 mL/hr third space loss replacement) throughout course of treatment. In addition, for the first two hours add 650 mL/hr to the above amount to replace the 1300 mL deficit over 2 hours. The infusion rate will then be 1100 mL/hr (=450 mL/hr + 650 mL/hr) for the first two hours.

Desired Fluid Therapy 2 Switch predominately to PENTASPAN® 1:1 to replace the ABL of 1400 mL, with use of crystalloids as judged clinically appropriate by anesthesiologist. Transfuse packed cells when hemoglobin falls below the "transfusion trigger" of 10 g/dL.

Remember Run IV at 450 mL/hr. throughout treatment course to replace intra-op fluid losses Add 650 mL/hr over first two hours to replace pre- op deficit Add PENTASPAN® to replace ABL of 1400 mL Transfuse with packed cells when transfusion trigger of 10 g/dL of hemoglobin is reached

Final Note Note: These are starting points only. Most anesthesiologists would insert a CVP line, an arterial line and a Foley catheter in this patient to further guide fluid therapy. Fluid delivery may have to be increased should oliguria or hypotension occur.

The End