Femoral Arterial Line Research Articles

Iatrogenic femoral artery pseudoaneurysm: Studies relating to the current treatment strategies including observation, ultrasound-guided compression, and duplex-directed thrombin injection

These articles demonstrate 3 “conservative” management strategies for postcatheterization femoral artery pseudoaneurysms. The continuum of watchful waiting in selected patients to ultrasound-guided compression, to ultrasound-guided thrombin injection mirrors many of the changes in the surgical treatment of myriad disease states. Operative repair of these lesions, such as open cholecystectomy, is not going to be of historical importance because many of these lesions will still require open repair. However, with the ever-increasing use of catheter-based therapies, minimally invasive techniques that demonstrate similar efficacy and safety are needed. The most frequent complication of femoral artery catheterization is the development of a femoral artery pseudoaneurysm. Approximately 500,000 interventional cardiologic procedures are performed in the United States every year. This does not take into account the interventional radiologic and other (femoral arterial line placement) procedures used to gain access to the central arterial system via the femoral artery. The reported incidence of complications after femoral artery catheterization ranges from 0.2%–9%. Pseudoaneurysm formation has been reported as a complication in 0.05%–5% of all femoral artery catheterizations. Obviously, with the large number of procedures being performed each year, femoral artery pseudoaneurysm formation is not an uncommon lesion referred to general and vascular surgeons. The first article reviewed explores the conservative management of femoral artery pseudoaneurysms. This article is important in that it documents the benign natural history of a large number of these lesions. Although the conservatively managed patients were a relatively select group, they were not so select that the findings of the study become uninterpretable. This study demonstrates that many of these lesions can in fact be observed with frequent spontaneous resolution. The second article discusses another “conservative” management strategy for the treatment of femoral artery pseudoaneurysms, involving ultrasound-guided compression of the lesion. Ultrasound-guided compression has been adopted in many centers and has shown very good results. Success rates of 70%–100% have been reported. Unfortunately, a recurrence rate of 20% is still seen, especially in patients undergoing anticoagulant therapy. Also, a large number of patients fail this therapeutic method secondary to intolerance of the pain associated with compression. Still, it is clear that ultrasound-guided compression is a highly effective choice in many patients. The third article addresses duplex-directed thrombin injection, a novel technique that is being employed in certain centers. This technique appears to be quite effective and safe. Although this study included only 11 patients, this paper is one of a series of papers that have documented the efficacy and safety of the technique. Duplex-directed thrombin injection is also very expeditious with thrombosis, occurring in only 30 seconds in most patients. Surgical repair of femoral artery pseudoaneurysms will always be necessary for a number of these lesions. However, many can be observed with spontaneous thrombosis. Other techniques have been and are being designed to treat this common condition. With the economic pressure for decreased in-patient treatment, the conservative strategies that have been reviewed will continue to occupy a central role in the management of these lesions.

A Comparison of Demand‐valve and Bag‐Valve Ventilations in a Swine Pneumothorax Model

Two means of delivering artificial ventilation readily available to out-of-hospital personnel are the bag-valve (BV) and the O2-powered demand-valve (OPDV). However, use of the OPDV has been limited because of concerns that it may worsen an underlying pneumothorax. This study compared the changes in size of pneumothorax in swine ventilated with the 2 devices. Three swine were anesthetized, intubated, and instrumented with a femoral arterial line and a pediatric Swan-Ganz catheter. A chest tube was placed, the chest was opened, and the lung parenchyma was visualized. The lung was disrupted by a single stab with a #10 scalpel; the chest was then sealed; and a pneumothorax was created by injecting 30 mL of air through the chest tube. The animals were ventilated by 12 emergency medical technicians using either BV or OPDV. After 10 minutes of ventilation, the pneumothorax volume was measured. When comparing final pneumothorax volumes after 10 minutes of ventilation with the 2 devices, there was no significant difference (mean +/- SD = 40.8 +/- 28.2 mL vs 52.3 +/- 23.1 mL, p = 0.286). There is no difference in final pneumothorax volumes after OPDV or BV ventilation.

REGIONAL INFUSION OF HYPOTHERMIC ADENOSINE IS INEFFECTIVE IN PREVENTING SPINAL CORD ISCHEMIA IN A PIG MODEL

S91 Introduction: Several thousand vascular, orthopedic, and neurosurgical operations are performed annually that can be associated with spinal cord ischemia, and if the latter is severe, paraplegia can result. All techniques to prevent spinal cord ischemia are only moderately effective. We determined the effectiveness of a regional hypothermic infusion of adenosine for the prevention of spinal cord ischemia in a pig model. Methods: With IAICUC approval, 16 pigs were randomly assigned in a prospective double blind fashion to receive regional infusion of hypothermic adenosine (25 mg/kg in 30ml/kg at 8[degree sign]C) or hypothermic normal saline (30ml/kg at 8[degree sign]C). Under general anesthesia with ketamine and forane, a right femoral arterial line and pulmonary artery catheter were placed. A left thorocotomy was performed and the left atrium and proximal aorta were cannulated. The aorta was cross-clamped at the level of the diaphragm for one hour. During the time of aorta cross-clamping, hypothermic adenosine or normal saline was infused distal to the aortic cross-clamp. Fluorescent microspheres were injected in the left atrium to determine regional blood flow in the peri-aortic cross-clamp period. Following the time of cross-clamping, wounds were closed. Neurologic status via Tarlov scale [1] and blood urea nitrogen (BUN) were observed for 72 hours by a blinded observer. Results: Every adenosine treatment animal had complete hind limb spastic paraplegia following aortic cross-clamping (all Tarlov grade 0). Of the control animals, one had complete neurologic recovery (Tarlov 4), and the rest of the pigs had complete hind limb spastic paraplegia (Tarlov 0). There were no differences in hemodynamics and temperature between the two groups. Discussion: Herold et al [2] found that regional infusion of hypothermic adenosine was able to completely prevent neurologic injury in a rabbit 40 minute of spinal cord ischemia model compared to hypothermic normal saline infusion which had no benefit. In a pig model we found that regional infusion of hypothermic adenosine had no benefit in preventing neurologic injury compared to hypothermic normal saline infusion.

Thoracic aortic operations: management of maldistribution of arterial flow during cardiopulmonary bypass

On three occasions during operations for aortic aneurysm involving the ascending aorta it was noted that upon the release of the aortic clamp the grafted segment remained collapsed, indicating very little or no flow reaching the lumen of the reconstructed aorta. This was promptly and successfully remedied in 2 patients by perfusing the graft directly with a pediatric arterial catheter attached to a pump head while the femoral arterial line maintained systemic arterial inflow. This simple, safe, and highly effective technique adds to the surgeon's repertoire to manage yet another intriguing intraoperative development during thoracic aortic operations.

Emergency vascular access in a patient with limb agenesis

A 19-year-old white man with congenital agenesis of all four limbs arrived in the emergency room in full cardiopulmonary arrest secondary to Reye's syndrome. The patient was intubated but had no vascular access. After a percutaneous femoral venous line proved unsuccessful, an internal jugular line was placed for venous access. Repeated attempts at percutaneous femoral and axillary arterial line placements were unsuccessful. A femoral cutdown showed 2-mm femoral vessels. The autopsy showed increasingly hypoplastic aortic, iliac, and femoral vessels below the takeoff of the renal vessels. The subclavian vessels were reasonably normal in caliber. This case shows that femoral or axillary vessels in a congenitally amputated limb are not useful for vascular access, and a low threshold should exist for using internal jugular/subclavian veins and the subclavian/carotid arteries if emergency access is necessary.

Endoscopic tonometric assessment of intestinal perfusion in a canine model

In an anesthetized canine model tonometric balloons were colonoscopically placed into the right colon, left colon, and rectum. A femoral arterial line was established for the measurement of blood pressure and arterial bicarbonate. Laparotomy was performed and additional balloons were placed, via enterotomies, into the duodenum, jejunum, and ileum. Baseline measurements of intramural pH were obtained, and then the origin of the superior mesenteric artery was occluded. Additional measurements in all areas were made for two 1-hour intervals. Results showed rapid and marked acidosis as demonstrated by significant (p less than 0.001) pH changes in the jejunum, ileum, and right colon. There were no significant changes in the pH in the duodenum, left colon, or rectum. Systemic arterial pH remained normal. These data demonstrate that tonometric balloons endoscopically placed into the right colon will reflect superior mesenteric artery occlusion at an early stage, and that similar information is likely to be gained by endoscopic placement of these balloons into the jejunum.

Toxicité cardiaque de la bupivacaïne et diazépam. Etude expérimentale chez le chien anesthésié

The use of diazepam has been suggested for the treatment of convulsions resulting from accidental high plasma levels of local anaesthetics. However, it has been reported that this drug may increase the cardiac effects of bupivacaine in dogs. The present study aimed to assess the effects of diazepam on the electrophysiological signs of a high-dose intravenous bolus of bupivacaine in fourteen dogs, divided into two groups, and anaesthetized with thiopentone and ventilated. All the animals were given a bolus dose of 4 mg · kg −1 bupivacaine. Immediately afterwards, group I (n = 7) received 0.8 ml · kg −1 normal saline solution and group II (n = 7) was given 4 mg · kg −1 diazepam over 1 min. The parameters measured on lead II of the electrocardiogram were : cycle length (R-R interval), QRS length (QRS) and QT interval corrected for heart rate (cQT). Intranodal (AH) and His-Purkinje (HV) conduction times were measured with recording bipolar stimulation electrodes (USCI 6F). Mean aortic pressure (P̄ao) was measured via a femoral arterial line. In the two groups, the parameters were recorded before and 2, 5, 10 and 15 min after the bupivacaine bolus. Arterial blood samples for measurement of bupivacaine and diazepam serum levels were obtained before and 3, 15 and 30 min after the bupivacaine bolus. There was no significant difference between the two groups in the electrophysiological or haemodynamic parameters at any time. However, the increase in HV and QRS length was a little higher in group I than in group II. The administration of diazepam after bupivacaine resulted in lower serum levels of local anaesthetic : 5.1 ± 0,5 vs 7.6 ± 1.4 μg · ml −1 (p < 0.01) at the 3rd min, and 2.14 ± 0.03 vs 3.0 ± 0.4 μg · ml −1 (p < 0.02) at the 5th min. No pharmacokinetic explanation could be found to explain these results that do not confirm previous studies. It was concluded that high doses of diazepam did not increase cardiac electrophysiological or haemodynamic effects of high plasma levels of bupivacaine.

Naloxone does not improve hemodynamics following graded hemorrhage in a canine model

Two recent studies have demonstrated no improvement in hemodynamic parameters or survival following naloxone administration in hemorrhagic shock. This finding is in contrast to those of earlier studies, which consistently demonstrated a beneficial effect. The current study evaluated naloxone's ability to improve hemodynamics when administered following a fixed-volume hemorrhage, during a period of partial hemodynamic compensation. Thirteen conditioned beagles were anesthetized with pentobarbital (25 mg/kg intravenously), endotracheally intubated, and instrumented with a femoral arterial line and a pulmonary artery thermodilution catheter. Animals were then subjected to an estimated 50% graded hemorrhage (45 ml/kg) over one hour. Following hemorrhage, animals were observed for 90 minutes, then reinfused with shed blood over 30 minutes, and finally observed for an additional 60 minutes. Six animals received naloxone (2 mg/kg intravenously) 30 minutes after completion of hemorrhage and then 2 mg/kg/hr for the duration of the study. Seven control animals received an equivalent volume of saline. Heart rate, mean arterial pressure, central venous pressure, cardiac output, arterial and mixed venous blood gases, and serum lactate level were measured at regular intervals throughout the study. Cardiac index and systemic vascular resistance index were calculated at the same intervals. Overall, there were no statistically significant differences in the mean data values for mean arterial pressure, cardiac index, systemic vascular resistance index, or lactate, although lactate values were consistently higher in the naloxone group (two-tailed independent Student's t test). We conclude that naloxone does not significantly improve hemodynamics when administered after a fixed-volume hemorrhage.

Cardiovascular effects of toxic concentrations of theophylline in the dog

A canine model of theophylline toxicity was used to study the cardiovascular effects seen in severe theophylline poisoning. Eight mongrel dogs were divided equally into two groups. The dogs were anesthetized with pentobarbital and paralyzed with pancuronium bromide. They were ventilated with 100% oxygen and underwent the placement of pulmonary arterial, central venous, femoral arterial, and peripheral venous lines. Group 1 animals received 5.6 mL/kg D5W intravenously (IV) over 20 minutes. Group 2 animals received 140 mg/kg (5.6 mL/kg) of aminophylline IV over the same period. Peak theophylline levels in Group 2 animals averaged 208.9 micrograms/mL. Group 2 animals suffered a marked fall in mean arterial pressure (MAP) and an increase in heart rate. In spite of the fall in MAP (P less than .01), cardiac index actually was increased almost two-fold over Group 1 animals, due mainly to a fall in systemic vascular resistance index (P less than .01). There were no physiologically significant differences in ventricular filling pressures or stroke index between the two groups.