Unplanned return to operating room after lower extremity arterial bypass is an independent predictor for hospital readmission

OBJECTIVE

Hospital readmissions after surgical operations are considered serious complications and have an impact on health care-associated costs. The Centers for Medicare and Medicaid Services strongly encourage identification and ramification of factors associated with hospital readmissions after operations. Despite advances in endovascular surgery, lower extremity arterial bypass remains the "gold standard" treatment for severe, symptomatic peripheral arterial disease. The purpose of this study was to retrospectively review the factors associated with hospital readmission after lower extremity bypass surgery.

METHODS

The 2013 lower extremity revascularization-targeted American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database and generalized 2013 general and vascular surgery NSQIP Participant Use Data File were used for this study. Patient, diagnosis, and procedure characteristics of patients undergoing lower extremity bypass surgery were assessed. Multivariate logistic regression analysis was used to determine independent risk factors for hospital readmission within 30 days after surgery.

RESULTS

A total of 2646 patients (65% male, 35% female) were identified in the NSQIP database who underwent lower extremity open revascularization during the year 2013. Indications for operations included tissue loss (39%), rest pain (32%), and severe claudication (25%). Preoperative ankle-brachial indices were 0.4 to 0.9 (32%) and <0.4 (16.5%). A total of 425 patients (16%) were readmitted within 30 days of index operation. Risk factors associated with readmission included wound complication (odds ratio [OR], 8.54; 95% confidence interval [CI], 6.68-10.92; P < .001), need for reoperation (OR, 5.95; 95% CI, 4.45-7.97; P < .001), postoperative myocardial infarction (OR, 2.19; 95% CI, 1.25-3.83; P = .006), wound dehiscence (OR, 8.45; 95% CI, 4.54-15.71; P < .001), organ or space surgical site infection (OR, 7.62; 95% CI, 2.89-20.14; P < .001), postoperative pneumonia (OR, 2.66; 95% CI, 1.28-5.52; P = .009), progressive renal insufficiency (OR, 4.12; 95% CI, 1.52-11.11; P = .005), superficial surgical site infection (OR, 7.37; 95% CI, 5.31-10.23; P < .001), urinary tract infection (OR, 2.67; 95% CI, 1.42-5.01; P = .002), and deep wound infection (OR, 14.0; 95% CI, 7.62-24.80; P < .001).

CONCLUSIONS

Readmission after lower extremity bypass surgery is a serious complication. Various factors put a patient at high risk for readmission. Return to the operating room, wound infection, amputation, deep venous thrombosis, and major reintervention on bypass are independent risk factors for hospital readmission. Return to the operating room is associated with a 5.95-fold increase in hospital readmission.

Modified T-Graft for Extracorporeal Membrane Oxygenation in a Patient with Small-Caliber Femoral Arteries

Extracorporeal membrane oxygenation (ECMO) is generally used as a last resort to provide cardiopulmonary support in patients whose advanced cardiac or respiratory failure does not respond to less invasive treatments. Lower-limb ischemia secondary to the large diameter of the arterial cannula is one of ECMO's major limitations: in patients who have small-caliber arteries, the cannulas can reduce native blood flow. The creation of a T-graft-a well-described technique to avoid limb ischemia-enables flow into the ECMO cannula without jeopardizing blood flow to the limb. However, leaving the graft exposed through an open groin wound can result in dislodgment, and it increases the risk of infection. We describe our modification of a conventional T-graft in an 18-year-old woman who had systolic heart failure, acute respiratory distress syndrome, and small-caliber femoral vessels. We tunneled a polytetrafluoroethylene graft inside a Dacron graft, then ran the combined graft through a subcutaneous tunnel similar to that created for a peripheral bypass. Thus, the graft was protected from environmental exposure and the risk of infection. Our technique seems safer and more secure than the original T-graft technique, and we recommend its consideration during ECMO cannulation.

Advances in renal intervention for trauma

Renal trauma is predominantly secondary to blunt trauma and is managed nonoperatively. Endovascular interventions are reserved for patients with a significant vascular injury recognized early. Renal injuries are uncommon among intra-abdominal injuries and account for a minority of injuries treated by the vascular specialist.

Renal vasoconstriction is augmented during exercise in patients with peripheral arterial disease

Peripheral arterial disease (PAD) patients have augmented blood pressure increases during exercise, heightening their cardiovascular risk. However, it is unknown whether patients have exaggerated renal vasoconstriction during exercise and if oxidative stress contributes to this response. Eleven PAD patients and 10 controls (CON) performed 4-min mild, rhythmic, plantar flexion exercise of increasing intensity (0.5-2 kg) with each leg (most and least affected in PAD). Eight patients also exercised with their most affected leg during ascorbic acid (AA) infusion. Renal blood flow velocity (RBFV; Doppler ultrasound), mean arterial blood pressure (MAP; Finometer), and heart rate (HR; electrocardiogram [ECG]) were measured. Renal vascular resistance (RVR), an index of renal vasoconstriction, was calculated as MAP/RBFV. Baseline RVR and MAP were similar while HR was higher in PAD than CON (2.08 ± 0.23 vs. 1.87 ± 0.20 au, 94 ± 3 vs. 93 ± 3 mmHg, and 72 ± 3 vs. 59 ± 3 bpm [P < 0.05] for PAD and CON, respectively). PAD had greater RVR increases during exercise than CON, specifically during the first minute (PAD most: 26 ± 5% and PAD least: 17 ± 5% vs. CON: 3 ± 3%; P < 0.05). AA did not alter baseline RVR, MAP, or HR. AA attenuated the augmented RVR increase in PAD during the first minute of exercise (PAD most: 33 ± 4% vs. PAD most with AA: 21 ± 4%; P < 0.05). In conclusion, these findings suggest that PAD patients have augmented renal vasoconstriction during exercise, with oxidative stress contributing to this response.

Abstract 530: Renal Vasoconstriction is Augmented during Exercise in Peripheral Arterial Disease Patients: Contributions of Muscle Mechanoreflex and Oxidative Stress

Peripheral arterial disease (PAD) patients have augmented blood pressure increases during exercise. It is unknown whether PAD patients have greater renal vasoconstriction during exercise and how much the muscle mechanoreflex or oxidative stress contribute to this response. Eleven PAD patients and 10 healthy controls (CON) performed 4 minutes of mild, rhythmic, plantarflexion exercise of increasing intensity (0.5-2kg) with each leg (most and least affected legs for PAD). Eight PAD patients also performed exercise with their most affected leg during intravenous, high-dose, ascorbic acid (AA) infusion. Renal blood flow velocity (RBFV; Doppler ultrasound), mean arterial blood pressure (MAP; Finometer), and heart rate (HR; ECG) were measured. Renal vascular resistance (RVR), an index of renal vasoconstriction, was calculated as MAP/RBFV. Statistical analysis involved repeated measures ANOVA and paired samples t -tests. Baseline RVR and MAP were similar while HR was higher in PAD compared to CON (RVR: 2.08±0.23 vs. 1.87±0.20 arbitrary units, MAP: 94±3 vs. 93±3 mmHg, and HR: 72±3 vs. 59±3 b.min -1 (p<0.05) for PAD and CON, respectively). PAD had greater RVR increases from baseline during exercise with both the most and least affected legs compared to CON, specifically during the first minute of exercise (PAD most: 2.08±0.23 to 2.60±0.29 (+26±5%) and PAD least: 1.96±0.24 to 2.22±0.25 (+17±5%) vs. CON: 1.87±0.20 to 1.91±0.20 (+3±3%) for the first minute of exercise, both p <0.05). AA infusion did not alter baseline RVR, MAP or HR. AA attenuated the augmented RVR increase in PAD during the first minute of exercise with the most affected leg (PAD most without AA: 2.10±0.31 to 2.78±0.38 (+33±2%) vs. PAD most with AA: 1.88±0.26 to 2.23±0.26 (+21±2%) for the first minute of exercise, p <0.05). In conclusion, these findings suggest that PAD patients have augmented renal vasoconstriction during exercise, with the muscle mechanoreflex and oxidative stress contributing to this increased response.

Physiology in medicine: peripheral arterial disease

Peripheral arterial disease (PAD) is an atherosclerotic condition that can provoke symptoms of leg pain ("intermittent claudication") during exercise. Because PAD is often observed with comorbid conditions such hypertension, dyslipidemia, diabetes, cigarette smoking, and/or physical inactivity, the pathophysiology of PAD is certainly complex and involves multiple organ systems. Patients with PAD are at high risk for myocardial infarction, stroke, and all-cause mortality. For this reason, a better physiological understanding of the pathogenesis and treatment options for PAD patients is necessary and forms the basis of this Physiology in Medicine review.

Oxidative stress contributes to the augmented exercise pressor reflex in peripheral arterial disease patients

Exaggerated blood pressure (BP) responses to dynamic exercise predict cardiovascular mortality in patients with peripheral arterial disease (PAD). However, the underlying mechanisms are unclear and no attempt has been made to attenuate this response using antioxidants. Three physiological studies were conducted in patients with PAD and controls. In Protocol 1, subjects underwent 4 min of low-intensity (0.5-2.0 kg), rhythmic plantar flexion in the supine posture. In Protocol 2, patients with PAD received high-dose ascorbic acid intravenously before exercise. In Protocol 3, involuntary exercise was conducted via electrical stimulation of the tibial nerve. The primary outcome measure was Δ mean arterial pressure (MAP) during the first 20 s of exercise (i.e. the onset of sympathoexcitation by muscle afferents). Compared to controls, patients with PAD had significantly greater ΔMAP during plantar flexion, particularly at 0.5 kg with the most affected leg (11 ± 2 vs. 2 ± 1 mmHg) as well as the least affected leg (7 ± 1 vs. 1 ± 1 mmHg). This augmented response occurred before the onset of claudication pain and was attenuated by ∼50% with ascorbic acid. Electrically evoked exercise also elicited larger haemodynamic changes in patients with PAD compared to controls. Further, the ΔMAP during 0.5 kg plantar flexion inversely correlated with the ankle-brachial index, indicating that patients with more severe resting limb ischaemia have a larger BP response to exercise. The BP response to low-intensity exercise was enhanced in PAD. Chronic limb ischaemia may sensitize muscle afferents and potentiate the BP response to muscle contraction in a dose-dependent manner.

Abstract 198: Oxidative Stress Mediates the Augmented Muscle Mechanoreflex in Peripheral Arterial Disease Patients

Background Exaggerated blood pressure (BP) responses to dynamic exercise predict cardiovascular mortality in peripheral arterial disease (PAD) patients. However, the underlying mechanisms are unclear and no attempt has been made to attenuate this response using antioxidants.

Methods Three physiological studies were conducted in PAD patients and controls. In Protocol 1, subjects underwent four minutes of low-intensity (0.5-2.0 kg), rhythmic plantar flexion in the supine posture. In Protocol 2, PAD patients received high dose ascorbic acid intravenously prior to exercise. In Protocol 3, involuntary exercise was conducted via electrical stimulation of the tibial nerve. The primary outcome measure was the change in mean arterial pressure (ΔMAP) during the first 20 seconds of exercise (i.e. when mechanoreceptors within skeletal muscle activate the sympathetic nervous system).

Results Compared to controls, PAD patients had significantly greater ΔMAP during plantar flexion, particularly at 0.5 kg of the most affected leg (11±2 vs. 2±1 mmHg) as well as the least affected leg (7±1 vs. 1±1 mmHg). This augmented response occurred before the onset of claudication pain and was attenuated by ∼50% (i.e. 6 mmHg) in the presence of ascorbic acid. Electrically evoked exercise also elicited larger hemodynamic changes in the PAD patients compared to controls. Further, the ΔMAP during 0.5 kg plantar flexion inversely correlated with the ankle-brachial index, indicating that patients with more severe resting limb ischemia had a larger BP response to exercise.

Conclusions The BP response to low intensity exercise was enhanced in PAD. Chronic limb ischemia may sensitize muscle afferents and potentiate the autonomic response to muscle contraction in a dose-dependent manner.

Determining who trains vascular surgery fellows in endovascular techniques

OBJECTIVES

Vascular surgery training has evolved from a single clinical year after general surgery training to a multi-year training program to encompass such entities as noninvasive vascular laboratory, office-based procedures, and endovascular techniques. Simultaneously, members of the vascular surgery community have had to undergo significant training to become facile with endovascular techniques. We surveyed vascular surgery trainees on the online Vascular Surgery In-Training Examination (VSITE) in 2008 and 2009 to assess who trained them in percutaneous techniques.

METHODS

Vascular surgery trainees in the Independent (2-year) and Integrated (5-year) training programs were asked to participate in a survey upon completion of the VSITE in 2008 and 2009. Examinees were asked to select whether vascular surgeons, cardiologists, or interventional radiologists trained them in carotid angioplasty and stenting (CAS), thoracic endografts (TEVAR), endovascular abdominal aortic aneurysm repair (EVAR), renal artery intervention, iliac stenting, superficial femoral artery (SFA), and tibial artery percutaneous interventions.

RESULTS

Survey response rate was 79.6% (191 of 240). Results of the survey are shown in Table I. In 2009, vascular surgeons provided more than 84% of the training to vascular surgery residents. Only six respondents had >50% of their percutaneous training with interventional radiology and two with cardiologists.

CONCLUSION

Vascular surgeons involved in resident education have been able to retrain themselves in endovascular techniques such that they are now able to provide greater than 80% of the endovascular experience to vascular surgery residents.