The influence of collateral vascularisation on haemodynamic performance during abdominal aortic surgery

Comparison of supramesenteric aortic cross-clamping with supraceliac aortic cross-clamping for aortic reconstruction

OBJECTIVE

Supraceliac aortic cross-clamping (SCXC) is routinely used during open aortic reconstruction (OAR) of pararenal aortic disease when suprarenal control is not feasible. On occasion, however, aortic control may be obtained at the supramesenteric level by supramesenteric cross-clamping (SMXC) between the superior mesenteric artery and the celiac axis. The purpose of this study was to compare outcomes between patients who had SMXC vs SCXC during OAR for both aneurysmal and occlusive diseases.

METHODS

A retrospective chart review identified 69 patients who underwent elective OAR requiring SMXC (n = 18) or SCXC (n = 51). All patients with thoracoabdominal aneurysms and those who had inframesenteric (suprarenal and infrarenal) aortic control were excluded. Propensity score-based matching was performed to adjust for confounding factors in a 1:1 ratio to compare outcomes. Late survival was estimated by Kaplan-Meier methods.

RESULTS

Propensity score-based matching was performed at a 1:1 ratio; 18 SMXC cases were matched with 18 SCXC cases. The average age was 66.7 years, and men constituted 72%. Baseline characteristics were matched, except for the incidence of peripheral vascular occlusive disease (72.2% in the SMXC group vs 33.3% in the SCXC group; P = .04). A majority (80.6%) of patients underwent OAR for aneurysmal disease (72.2% in the SMXC group, 88.9% in the SCXC group). Intraoperatively, there were no differences in operative times (325 minutes for SMXC vs 298 minutes for SCXC; P = .48), but the SMXC group had a longer renal ischemia time (40 minutes vs 28 minutes; P = .03). There were no significant differences in intraoperative blood loss (2.4 L vs 1.6 L; P = .2) or blood product transfusion requirements (packed red blood cells, 2.2 units vs 1.6 units [P = .5]; Cell Saver, 1.3 L vs 0.7 L [P = .09]). Overall complication rates did not differ significantly (27.8% for SMXC vs 44.4% for SCXC; P = .24). Thirty-day mortality rates did not differ between the two groups (0% for SMXC vs 5.6% for SCXC; P = 1).

CONCLUSIONS

In this study, there were no differences in early morbidity or mortality between SMXC and SCXC during aortic reconstruction. SMXC, however, can be performed safely and effectively in properly selected patients. A larger, multicenter prospective study would help elucidate the potential benefits.

Aortic aneurysm disease vs. aortic occlusive disease: differences in outcome and intensive care resource utilisation after elective surgery: an observational study

CONTEXT

Abdominal aortic surgery is a high-risk procedure, with aortic aneurysm and aortic occlusive diseases being the main indications. These groups are often regarded as having equal perioperative risk profiles. Previous reports suggest that the haemodynamic and inflammatory response to aortic clamping is more pronounced in patients with aortic aneurysm disease, which may affect outcome.

OBJECTIVES

The aim of this observational cohort study was to evaluate outcome after open elective abdominal aortic surgery, hypothesising a higher 30-day mortality, a higher incidence of postoperative organ dysfunction and a longer length of stay in patients with aortic aneurysm compared with aortic occlusive disease.

DESIGN

Cohort observational study based on prospective registrations from national databases.

SETTING

Eight Danish hospitals, including four university and four non-university centres, from 1 January 2007 to 1 March 2010.

PATIENTS

One thousand two hundred and ninety-three patients scheduled for primary open elective, aortoiliac bypass or aortofemoral bypass procedures or abdominal aortic aneurysm repair.

MAIN OUTCOME MEASURES

Mechanical ventilation, acute dialysis, use of vasopressors or inotropes, ICU stay more than 24 h, hospital length of stay and mortality.

RESULTS

Compared with aortic occlusive disease, more patients with aortic aneurysm disease had ICU stays more than 24 h (62 vs. 45%, P < 0.001) and more often needed acute dialysis or ventilatory support (17 vs. 11%, P = 0.04). No difference was found in hospital length of stay, 30-day mortality or overall risk of death. Mortality after 1 year was higher in patients with aortic aneurysm disease (8 vs. 4.7%, P = 0.04).

CONCLUSION

Patients with abdominal aortic aneurysms were at higher risk of developing postoperative organ dysfunction and required more ICU resources than patients with occlusive disease, despite no differences in hospital length of stay or 30-day mortality. Distinguishing between these two diseases may be useful in planning and distribution of ICU resources and for in future studies.

Proximal suture line support in open abdominal aortic aneurysm repair: a comparative study

OBJECTIVES

The aim of this study was to determine whether the collar graft (standard dacron graft with a customized flexible collar attached to the proximal rim) decreased anastomotic bleeding and the overall clamp time.

DESIGN

Prospective randomised single center study.

METHODS

Between November 2003 and January 2006, 21 patients were treated with a collar graft and 19 with a standard dacron graft. Routine endoaneurysmorraphy was used. Only infra-renal aneurysms between 5.5cm and 6.5cm were included. Aneurysms were diagnosed by CT scans. The total number of bleeding points, the total clamp time, and the number of teflon felt pledgets, was determined.

RESULTS

The total number of bleeding points; the number of aortic re-clamps and total clamp time (minutes) per patient were all significantly lower in the collar graft group (1.2 versus 2, p<0.04; 0.5 versus 2.0, p<0.001; 13.6 versus 20.1, p<0.003 respectively). The number of teflon felt pledgets and new sutures used was significantly lower in the collar graft group (p<0.001 and p<0.003 respectively).

CONCLUSION

The collar graft resulted in fewer anastomotic bleeding points and a shorter clamp time.

Epidural anesthesia may attenuate lipid peroxidation during aorto-femoral surgery

PURPOSE

To determine the effect of epidural anesthesia (EP) on oxygenation of the chronically ischemic limb in patients undergoing aorto-femoral bypass grafting and to assess whether it produces an alteration of lipid peroxidation and antioxidant status following revascularization.

METHODS

In this prospective, randomized, single-blinded study 40 ASA II or III patients undergoing elective aorto-femoral bypass grafting were allocated to receive general anesthesia (group GA, n = 20), or epidural + GA (group EP, n = 20) during surgery. Femoral venous blood-gas status, activities of the protecting antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GSH-px), glutathione reductase (GSH-rd), glutathione (GSH) and thiobarbituric acid-reactive substances (TBARS) as a marker of lipid peroxidation were determined in blood samples taken from the femoral vein at different intervals before and after revascularization.

RESULTS

Before the induction of anesthesia in group EP, femoral venous PO(2) [mean (standard deviation), 95% confidence interval] increased after achieving an adequate level of blockade by EP extending to the dermatomal level of T6-8 [29.32 (4.6), 26.34-32.30 to 36.29 (4.6), 33.37-39.22 mmHg, P < 0.05]. Femoral venous PO(2) was similar in both groups thereafter. In the GA group a significant increase in erythrocyte TBARS was observed immediately after restoration of blood flow when compared with baseline values [221.32 (102), 148.35-294-29 to 337.26 (123) 248.99-425.53 nmol*g(-1) hemoglobin, P < 0.01] but not at any other moment. In the EP group TBARS did not increase throughout the study. Within group comparisons revealed no significant differences in GSH, GSH-px, GSH-rd and SOD.

CONCLUSION

In patients with atherosclerotic aorto-iliac occlusive disease EP may possibly attenuate lipid peroxidation following revascularization but has no effect on antioxidant enzyme activities.

Monitoring of end-tidal carbon dioxide partial pressure changes during infrarenal aortic cross-clamping: a non-invasive method to predict unclamping hypotension

BACKGROUND

To assess the variations in end-tidal CO2 in response to aortic cross-clamping and the relationship with systolic arterial pressure (SAP) changes induced by unclamping.

METHODS

Thirty-three patients undergoing infrarenal aortic abdominal aneurysm repair by aorto-aortic prothetic bypass were prospectively studied. All patients were anesthetized with i.v. midazolam (0.05 mg x kg(-1)), thiopentone (3-5 mg x kg(-1)), fentanyl (5 microg x kg(-1)), pancuronium (0.1 mg x kg(-1)) and the maintainance of anesthesia used was 1-1.5% end-tidal isoflurane and i.v. fentanyl. The perioperative management was standardized. End-tidal CO2 and SAP were measured 5 min before (Pre-XAA), 15 min after infrarenal aortic cross-clamping (XAA), 5 min before (Pre-UXAA) and immediately after unclamping (UXAA).

RESULTS

A total of 16 (48.5%) from 33 patients presented decrease in SAP following aortic unclamping, and 13 out of these patients had arterial hypotension defined as SAP<90 mmHg. End-tidal CO2 variation (PreXAA-PreUXAA) induced by aortic clamping was correlated with SAP variation (PreUXAA-UXAA) induced by unclamping (r=0.763; P=0.0001). An end-tidal CO2 reduction above 15% after aortic cross-clamping was found to have a 100% sensitivity to detect a SAP decrease greater than 20% after unclamping, with a 100% specificity and a negative predictive value of 1.0. Complete aortic occlusion duration was not correlated to SAP unclamping variation (deltaSAP). Intraoperative characteristics (fluid loading, hematocrits, urinary output) were comparable, although blood loss was higher in patients experiencing deltaSAP>20%.

CONCLUSIONS

End-tidal CO2 variation monitoring during aortic cross-clamping may provide a reliable and non-invasive method to predict unclamping hypotension. When the aortic clamp was released, systolic hypotension (>20%) occurred in those subjects who had a decrease in end-tidal CO2 greater than 15% during aortic cross-clamping.

A haemodynamic comparison of intrathecal morphine and sufentanil supplemented with general anaesthesia for abdominal aortic surgery

The haemodynamic changes associated with intrathecal morphine (IM) compared to intrathecal sufentanil (IS) as a supplement to general anaesthesia for elective bypass grafting in patients with aortoiliac occlusive disease were studied. Thirty-six, ASA Grade 2, patients randomly received morphine hydrochloride (0.1%) 50 micrograms kg-1 (n = 18) or undiluted sufentanil, 150 micrograms (n = 18) intrathecally at T12-L1, combined with light general anaesthesia. Haemodynamics were measured before and after endotracheal intubation, abdominal incision, aortic cross-clamping and the first revascularisation. The major differences were recorded after abdominal incision. Heart rate, systemic blood pressure and coronary perfusion pressure were significantly lower in the IS group. The probable cause was greater systemic absorption of sufentanil and its faster binding to the specific opiate receptors, resulting in a more efficacious supraspinal and spinal blockade during the first surgical period. However, both opioids provided adequate analgesia during the whole surgical procedure.

Dipyridamole-thallium myocardial scanning in the preoperative assessment of patients undergoing abdominal aortic aneurysmectomy

Dipyridamole thallium scanning (DTS) is an imaging technique with good sensitivity for coronary artery disease (CAD). The purpose of this study was to compare the haemodynamic courses and the correlation between pulmonary capillary wedge pressure (PCWP) and central venous pressure (CVP) in patients with normal DTS (Group 1: n = 12) with those whose scans demonstrated CAD (Group 2: n = 11). Haemodynamic profiles were obtained prior to anaesthesia and at several times during surgery. The haemodynamic courses in both groups were similar with significant decreases in cardiac index, stroke index, and left ventricular stroke work index during aortic cross-clamping compared with values prior to anaesthesia. There were no significant changes in PCWP and CVP throughout the study. The correlations between PCWP and CVP were significant in both groups as were the correlations between the changes in PCWP and the changes in CVP observed at the time of cross-clamping. These correlations all had large standard errors of the estimate, however, making it impossible to predict the PCWP from the CVP with precision. It is concluded that, in a limited study population, an abnormal DTS did not identify patients in whom the PCWP and CVP correlated poorly during abdominal aortic aneurysmectomy.