Descending aortic blood flow during aortic cross-clamp indicates postoperative splanchnic perfusion and gastrointestinal function in patients undergoing aortic reconstruction

Risk Factors and Early Outcomes for Gastrointestinal Complications in Patients Undergoing Open Surgery for Type A Aortic Dissection

BACKGROUND

Gastrointestinal complications need to be paid more attention, especially in critically ill patients. The purpose of this study was to identify the risk factors and short-term outcomes of gastrointestinal complications after open surgery for type A aortic dissection.

METHODS

A retrospective single-institutional study including patients who underwent open surgery for type A aortic dissection during 2012-2020 was conducted. Univariate analysis and logistic regression analysis were used to identify risk factors associated with gastrointestinal complications. The related clinical outcomes were compared between the patients with and without gastrointestinal complications.

RESULTS

Among the 2746 patients, 150 developed gastrointestinal complications. The development of gastrointestinal complications contributed to the higher rate of mortality (P = .008), longer stay in the intensive care unit (P < .001), and longer hospital stay (P < .001). Logistic regression analysis showed that age (odds ratio [OR] 1.020; 95% confidence interval [CI] 1.005-1.057; P = .011), American Society of Anesthesiologists classification greater than grade III (OR 1.724; 95%CI 1.179-2.521, P = .005), pre-induction mean arterial pressure (OR 0.978; 95%CI 0.965-0.990, P = .001), aortic cross-clamp time (OR 1.012; 95%CI 1.005-1.019, P = .001), cardiopulmonary bypass time (OR 1.007; 95%CI 1.002-1.011, P = .002), and intraoperative transfusion of red blood cells (OR 1.214; 95%CI 1.122-1.314, P = .001) were independent risk factors for gastrointestinal complications.

CONCLUSIONS

The incidence of gastrointestinal complications after open surgery for type A aortic dissection was 5.5%, resulting in increased mortality and prolonged hospital stay. It is necessary to take suitable strategies to reduce the incidence of gastrointestinal complications.

Delayed stomach necrosis in a patient with injured celiac artery branches after penetrating abdominal trauma

Injuries of the celiac artery and its branches are rare, but potentially lethal. Ligation of these arteries is performed to control significant hemorrhage. However, few reports have described the adverse effects of ligating these arteries. A 69-year-old woman with a self-inflicted stab wound was brought to our hospital. Her blood pressure could not be measured, therefore aortic cross-clamping was performed, and epinephrine was administered for resuscitation, an emergency laparotomy was performed, and the roots of splenic artery and common hepatic artery were ligated. The left gastric artery which was anomalous and arose directly from the aorta, was also injured and had to be ligated. Norepinephrine was required after the surgery. Enhanced computed tomography performed on hospital day 4 revealed a disrupted celiac artery. The patient developed gastric necrosis on hospital day 23 and, hence, underwent total gastrectomy was performed. The possibility of delayed stomach necrosis should be considered during the postoperative management of patients who undergo ligation of all of the celiac artery branches and experience global hypoperfusion after the surgery.

Parameter estimation to study the immediate impact of aortic cross-clamping using reduced order models

Aortic cross-clamping is a common strategy during vascular surgery, however, its instantaneous impact on hemodynamics is unknown. We, therefore, developed two numerical models to estimate the immediate impact of aortic clamping on the vascular properties. To assess the validity of the models, we recorded continuous invasive pressure signals during abdominal aneurysm repair surgery, immediately before and after clamping. The first model is a zero-dimensional (0D) three-element Windkessel model, which we coupled to a gradient-based parameter estimation algorithm to identify patient-specific parameters such as vascular resistance and compliance. We found a 10% increase in the total resistance and a 20% decrease in the total compliance after clamping. The second model is a nine-artery network corresponding to an average human body in which we solved the one-dimensional (1D) blood flow equations. With a similar parameter estimation method and using the results from the 0D model, we identified the resistance boundary conditions of the 1D network. Determining the patient-specific total resistance and the distribution of peripheral resistances through the parameter estimation process was sufficient for the 1D model to accurately reproduce the impact of clamping on the pressure waveform. Both models gave an accurate description of the pressure wave and had a high correlation (R² > .95) with experimental blood pressure data.

Effects of Cross-Clamping on Vascular Mechanics: Comparing Waveform Analysis With a Numerical Model

BACKGROUND

Immediate changes in vascular mechanics during aortic cross-clamping remain widely unknown. By using a numerical model of the arterial network, vascular compliance and resistance can be estimated and the time constant of pressure waves can be calculated and compared with results from the classic arterial waveform analysis.

METHODS

Experimental data were registered from continuous invasive radial artery pressure measurements from 11 patients undergoing vascular surgery. A stable set of beats were chosen immediately before and after each clamping event. Through the arterial waveform analysis, the time constant was calculated for each individual beat and for a mean beat of each condition as to compare with numerical simulations. Overall proportional changes in resistance and compliance during clamping and unclamping were calculated using the numerical model.

RESULTS

Arterial waveform analysis of individual beats indicated a significant 10% median reduction in the time constant after clamping, and a significant 17% median increase in the time constant after unclamping. There was a positive correlation between waveform analysis and numerical values of the time constant, which was moderate (ρ = 0.51; P = 0.01486) during clamping and strong (ρ = 0.77; P ≤ 0.0001) during unclamping. After clamping, there was a significant 16% increase in the mean resistance and a significant 23% decrease in the mean compliance. After unclamping, there was a significant 19% decrease in the mean resistance and a significant 56% increase in the mean compliance.

CONCLUSIONS

There are significant hemodynamic changes in vascular compliance and resistance during aortic clamping and unclamping. Numerical computer models can add information on the mechanisms of injury due to aortic clamping.