Renal protection during the operation of infrarenal aorta

INTRODUCTION Despite the progress in surgical and anesthetic management decreased renal function is still observed after abdominal infrarenal aortic surgery and remains an important problem in postoperative period. Although data regarding the efficacy of perioperative renal protection are conflicting, it is widely believed that renal protection before aortic cross-clamping is beneficial and therefore is commonly used. The aim of this study was to evaluate the impact of renal protection in patients undergoing elective infrarenal aortic surgery (1 ARS). PATIENTS AND METHODS We have prospectively studied 80 patients undergoing elective infrarenal aortic surgery from October 1996 to May 1998 in the Clinical Center of Serbia because of aorto-occlusive disease or aortic aneurysm. Patients were excluded from the study for three reasons: prior renal dysfunction suprarenal aortic cross-clamping and ruptured aortic aneurysm. We have randomized the patients in two groups: without renal protection- group A (n = 40) and with renal protection- group V (n = 40). Preanaesthetic medication consisted of midazolam (5 mg i.m).Anesthesia was induced with etomidat 0.3 mg/kg, fentanyl 0.05-0.1 mg and succinil-holin Img/kg. Ventilation was controlled using 50% of nitrous oxide and oxygen. Supplemental anesthesia consisted of isofluran and fentanyl, in order to maintain the mean arterial pressure and heart rate ± 20% regarding preoperative values. In all patients two peripheral vein and radial artery catheters were cannulated before anesthesia. Central venous catheter and Foley urinary bladder catheter were inserted after the induction of anesthesia. Two-lead electrocardiograms were recorded. All patients in group V were given intravenously mannitol (0.3 g/kg) before aortic cross-clamping (ACC). After aortic cross-clamping, these patients received furosemide (20-40 mg) or dopamine (1-3 pg/kg/min) to the end of surgery (Table 1). In 8 time points (preoperatively, after induction during ACC, 2 and 8 hours after ACC, on day 1, 2 and 3 postoperatively) haemodynamic parameters (mean arterial and central venous pressure), volume load, urinary output, creatinine and free-water clearance, serum electrolytes, BUN, creatinine, plasma and urine osmolality and ACC time were analyzed in each patient. Renal complications were classified as transient or persistent. Transient renal dysfunction was defined as a greater rise Belgrade than 20% rise in peak serum creatinine level over baseline serum creatinine level, with a peak of at least 168 pmol/L. Persistent renal insufficiency was defined as a greater rise than 20% rise in discharge serum creatinine level over baseline serum creatinine level, with a peak of at least 168 umol/L. Moreover, renal insufficiency was defined as a free-water clearance greater than -15 ml/h. Aortic cross-clamping time was defined as a period in which the proximal inflow was occluded. The results were expressed as means ± SD. Statistical difference detected with Student's t-test, with p < 0.05 being considered significant. RESULTS Patients in groups A and V were similar regarding the age (64.32 vs. 62.00), sex (males 35, females vs. males 34, females 6) and preoperative diseases. (Tab. 2) No difference was found between groups regarding any of the parameters (BUN, serum creatinine electrolytes, volum load, creatinine and free-water clearance, haemodynamic parameters, plasma and urine osmolality). Urinary output was higher in group V during and 2 hours after ACC. (Graph 1) ACC time was similar in two groups (24.1 min vs 24.5 min). (Graph. 2) Only one patient in group V revealed transitory renal insufficiency, not requiring special treatment. These data indicate that renal protection did not influence renal function. Short ACC time may have impact on the obtained results. Our results suggest that renal protection should not be considered as mandatory for elective infrarenal aortic surgery. Because of the short ACC time observed in this study (in comparision to other studies), further studies of renal protection in patients with longer ACC time are needed

Influence of preoperative parametres on survival of patients with ruptured abdominal aortic aneurysm

Between 1991-2001 total number of 1058 patients was operated at the Institute of Cardiovascular Diseases of Serbian Clinical Centre due to abdominal aortic aneurysm. Of this number, 288 patients underwent urgent surgical treatment because of ruptured abdominal aortic aneurysm. The aim of this retrospective study was to show results of the early outcome of the surgical treatment of patients with ruptured abdominal aortic aneurysm, and to define relevant preopera-tive factors that influenced their survival. There were 83% male and 17% female patients in the study, mean aged 67 years. Intrahospital mortality that included intraoperative and postoperative deaths was 53.7%. Therefore, 46.3% patients survived surgical treatment and were released from hospital. Intraoperative mortality was 13.5%. Statistics showed that the gender and the age did not have any influence on mortality of our patients, as well as their co morbid conditions (p>0.05). Clinical parameters at admission in hospital such as state of consciousness systolic blood pressure, cardiac arrest and diuresis significantly influenced the outcome of treatment, as well as laboratory findings such as levels of hematocrit, hemoglobin, white blood cells, urea and creatinin (p<0.05; p<0.01). Ruptured abdominal aortic aneurysm still remains one of the most dramatic surgical states with very high mortality reported. We assume that importrant preoperative factors that influence the outcome of surgical treatment can be defined, but there is no single parameter which can certainly predict the lethal outcome after surgery. Also, the presence of co morbid conditions does not significantly influence the outcome of treatment in these patients. Therefore, urgent operation should not be withheld in most of the patients with ruptured abdominal aortic aneurysm

Impact of intraoparetive parametres on survival of patients with ruptured abdominal aortic aneurysm

Ruptured abdominal aortic aneurysm is one of the most urgent surgical conditions with high mortality that has not been changed in decades. Between 1991-2001 total number of 1058 patients was operated at the Institute for Cardiovascular Diseases of Clinical Center of Serbia due to abdominal aortic aneurysm. Of this number, 288 patients underwent urgent surgical repair because of ruptured abdominal aortic aneurysm. The aim of this retrospective study was to show results of the early outcome of surgical treatment of patients with ruptured abdominal aortic aneurysm, and to define relevant intraoperative factors that influence their survival. There were 83% male and 17% female patients in the study, mean aged 67 years. Mean duration of surgical procedure was 190 minutes (75-420 min). Most common localization of aneurysm was infrarenal - in 74% of patients, then juxtarenal (12.3%). Suprarenal aneurysm was found in 6.8% of patients, as well as thoracoabdominal aneurysm (6.8%). Retroperitoneal rupture of aortic aneurysm was most common - in 65% of patients, then intraperotineal in 26%. Rare finding such as chronic rupture was found in 3.8%, aortocaval fistula in 3.2% and aorto-duodenal fistula in 0.6% of patients. Mean aortic cross-clamping time was 41.7 minutes (10-150 min). Average intraoperative systolic pressure in patients was 106.5 mmHg (40-160 mmHg). Mean intraoperative blood loss was 3700 ml (1400-8500 ml). Mean intraoperative diuresis was 473 ml (0-2100 ml). Tubular graft was implanted in 53% of patients, aortoiliac bifurcated graft in 32.8%. Aortobifemoral reconstruction was done in 14.2% of patients. These data refer to the patients that survived surgical procedure. Intrahospital mortality that included intraoperative and postoperative deaths was 53.7%. Therefore, 46.3% patients survived surgical treatment and were released from the hospital. Intraoperative mortality was 13.5%. Type of aneurysm had no influence on outcome of patients (p>0.05), as well as type of rupture and level of aortic cross-clamping. Aortic cross-clamping time was significantly shorter in survivors, and longest in patients that died intraoperatively (p<0.05). Intraoperative systolic tension value influenced the outcome in patients; it was significantly higher in survivors (p<0.01). Interposition of tubular graft gave better results compared with aorto-iliac and aorto-femoral reconstruction (p<0.01). Duration of surgery was significantly higher in patients with lethal outcome (p<0.05), as well as intraoperative blood loss (p<0.05). Intraoperative diuresis was significantly lower in patients with lethal outcome (p<0.05). Ruptured abdominal aortic aneurysm still remains one of the most dramatic surgical states with very high mortality. Important intraoperative factors that influence the outcome of surgical treatment can be defined. Therapeutic efforts should be concentrated on those factors that are possible to correct, which would hopefully lead to better survival of patients. Nevertheless, screening for abdominal aortic aneurysm and elective surgical intervention before rupture occurs should be the best solution for this complex problem