Retrograde Air Embolization during Routine Radial Artery Catheter Flushing in Adult Cardiac Surgical Patients: An Ultrasound Study

Background: Rapid flushing of radial artery catheters may result in retrograde embolization of air into the cerebral circulation. This study examined the incidence of central air embolization during and after flushing of an arterial pressure monitoring system.

Methods: One hundred adult patients undergoing cardiac surgical procedures were enrolled in this study. Ten ml of saline and blood were withdrawn into a syringe in the arterial flushing-sampling pressure system and then readministered to the patient through a 20-gauge radial artery catheter over 3-12 s. The right carotid artery, left carotid artery, and aortic arch were visualized using ultrasound imaging techniques during three manual flushes of the system. The left and right common carotid arteries were examined for the presence of macrobubbles or microbubbles using a linear array ultrasound transducer. The aortic arch was imaged using transesophageal echocardiography to detect retrograde air emboli. The severity of air embolization was quantified using a modification of an established grading system.

Results: A total of 298 ultrasound studies in 100 patients were recorded and analyzed after radial artery catheter flushing. Two aortic arch images were not obtained because of an inability to place the probe. Most clinicians (54%) returned flush solution to patients at near-maximal injection rates (2-3 ml per second). No air emboli (macrobubbles or microbubbles) were detected in the carotid arteries or aortic arch of any subject.     

Ultrasound-Guided Central Venous Cannulation in Bariatric Patients

Background  

Central venous catheterization may be difficult in morbidly obese patients because anatomic landmarks are often obscured.     

Clevidipine in Adult Cardiac Surgical Patients: A Dose-finding Study

Background: Treatment of elevated blood pressure is frequently necessary after cardiac surgery to minimize postoperative bleeding and to attenuate afterload changes associated with hypertension. The purpose of this study was to investigate the pharmacodynamics and pharmacokinetics of a short-acting calcium channel antagonist, clevidipine, in the treatment of hypertension in postoperative cardiac surgical patients.

Methods: Postoperative cardiac surgical patients were randomized to receive placebo or one of six doses of clevidipine. Hemodynamic parameters were recorded and blood samples were drawn for determination of clevidipine plasma concentrations during infusion and after discontinuation of clevidipine. The concentration-response relation was analyzed using logistic regression, and pharmacokinetic models were applied to the data using population analysis.

Results: There were significant decreases in mean arterial blood pressure and systemic vascular resistance at doses greater than or equal to 1.37 [mu]g [middle dot] kg-1 [middle dot] min-1. There were no changes in heart rate, central venous pressure, pulmonary artery occlusion pressure, or cardiac index with increasing doses of clevidipine. The clevidipine C50 value for a 10% or greater decrease in mean arterial pressure was 9.7 [mu]g/l and for a 20% or greater decrease in mean arterial pressure was 26.3 [mu]g/l. The pharmacokinetics of clevidipine were best described with a three-compartment model with a volume of distribution of 32.4 l and clearance of 4.3 l/min. The early phase of drug disposition had a half-life of 0.6 min. The context-sensitive half-time is less than 2 min for up to 12 h of administration.     

Open Versus Tunneling Radial Artery Harvest for Coronary Artery Grafting

Abstract We present a less traumatic surgical technique for harvesting the radial artery as a coronary artery bypass graft that does not require any special equipment or skills. We prospectively randomized 40 patients undergoing coronary artery bypass grafting with the radial artery into two groups on the basis of harvest techniques: tunneling excision and conventional open method. The less‐invasive tunneling technique is safe, easily applicable, and preferred by patients because of the superior cosmetic result . (J Card Surg 2010;25:504‐507)     

Cardiorespiratory Effects of Nalbuphine and Morphine Premedication in Adult Cardiac Surgical Patients

Premedication for cardiac surgical patients attempts to achieve relief of anxiety with minimal or no cardiorespiratory changes. Nalbuphine (NUBAIN) and morphine produced similar decreases in respiratory rate (1-3 breaths per min) and PaO2 (averaging 1.34 kPa), and increases in arterial PaCO2 (averaging 0.56 kPa). Cardiovascular changes were not seen with either agent. A similar degree of sedation and relief of anxiety was achieved with both drugs. Side effects were minimal and infrequent. Nalbuphine produces respiratory depression and sedation without cardiovascular changes which is comparable to an equivalent dose of morphine in patients with either valvular or coronary artery disease.     

Analysis of Surgical Treatment of Patients with Carotid Artery Stenosis Endarterectomy Versus Stenting

The aim of this paper is to characterize a group of patients with internal carotid artery stenosis and to analyze the outcome of internal carotid artery stenosis treatment. The outcome of treatment of 230 patients with internal carotid artery stenosis hospitalized from 1^st January 2004 to 31^st August 2006 was analyzed. Twenty nine percent of the patients were selected for medical treatment, 70.4% received surgical or endovascular treatment (83.3% of all invasive procedures were endarterectomies, versus 16.7% stenting). The peri-procedural stroke-death rate was 4.9% of patients [3.7% after CEA and 11.1% after CAS (N.S.)]. Statistical analysis disclosed that endarterectomy was associated with a longer in-hospital stay (p < 0.001). In conclusion: Both surgical methods, endarterectomy and stenting are equivalent in safety and present comparable clinical outcomes in selected subgroups of patients (classified to the specific procedure on the basis of the type of atherosclerotic plaque).     

Effect of Pancuronium on Plasma Free-Norepinephrine and Epinephrine in Adult Cardiac Surgical Patients

Since diazepam-ketamine induction sequences in healthy humans cause no significant increase in plasma free-norepinephrine and epinephrine, blood pressure and heart rate, we have frequently used a diazepam-ketamine pancuronium sequence for induction of anesthesia in patients undergoing open-heart surgery. In order to assess objectively the influence of pancuronium on sympathetic activity in cardiac patients, plasma free-norepinephrine and free-epinephrine were measured by Vend-salu's method in the arterial blood of 12 patients who were to undergo valve replacement or coronary bypass. At the same time, arterial pressure measured by a strain-gauge from the radial artery and heart rate measured by ECG were continuously recorded during induction with diazepam 0.3 mg/kg, followed 10 min later by ketamine 2.0 mg/kg. No significant changes occurred in these parameters before pancuronium administration. Plasma free-norepinephrine and free-epinephrine concentrations before and 5 min after pancuronium 0.1 mg/kg given over a 1-min period were 0.42±0.05 (mean ± s.e.mean) and 0.45±0.05 ng/ml ( P >0.1) and 0.01±0.003 and 0.02±0.009 ng/ml ( P> 0.1), respectively. A significant increase in heart rate followed pancuronium administration from 75.0±4.0 to 90.0±6.0 beatslmin ( P <0.001). The corresponding systolic and diastolic direct arterial pressures were 148.0±9.4/74.0±6.0 and 153.0±8.3/81.0±5.2 mmHg (P>0.05). Although a statistically significant increase in heart rate was observed after pancuronium, no significant increase was found in plasma free-norepinephrine, epinephrine or direct arterial pressure.     

Before Cannulation of the Radial Artery: Collateral Arterial Supply Evaluated by Strain-Gauge Plethysmography

Systolic arterial pressure in the thumb was measured using strain-gauge plethysmography before and after compression of the radial artery in 259 patients (aged 11–75 years), undergoing vascular or open-heart surgery. In 38 hands (in 27 patients aged 37–75 years), manual compression of the radial artery reduced the arterial pressure in the thumb to less than 40 mmHg (5.3 kPa), and consequently the collateral ulnar arterial supply was judged to be inadequate. Because 27 out of 259 patients (10.4%) would be without adequate blood supply to one or both thumbs following occlusion of the radial arteries, cannulation of the radial artery should be performed only after ensuring the presence of an adequate collateral ulnar arterial supply.     

Pulmonary Artery Pressure Measurements in Surgical Patients

In 23 patients, Swan-Ganz catheters for the measurement of the pulmonary artery pressure (PAP) were introduced on the day before elective vascular surgery. the following parameters were measured: pulmonary artery mean pressure (PAMP), pulmonary capillary wedge pressure (PCWP), pulmonary artery end-diastolic pressure (PAED), central venous pressure (CVP), arterial blood pressure (BP), pulse, plasma colloid osmotic pressure (COP) and blood volume. Pre-operatively, resting pressures and pressures during exercise and fluid infusion were measured. Continuous pressure measurements were made during induction of anaesthesia and operation and during the first 24 postoperative hours. the pre-operative PAP was an important parameter among those contra-indicating operation, particularly so in 5 patients, in 3 of whom the ultimate decision was made as a direct consequence of PAP. in one case, a sudden marked increase in PAP preceded all other signs of severe deterioration in the patient's condition by some 7 hours. in the period of apnoea immediately prior to and during endotracheal intubation, PAP and CVP rises were as marked as during the pre-operative exercise test. This exercise was strenuous, and the exercise PAP is thought to give perhaps the most reliable expression of the cardiac reserve. Finally, PAP was found to be a substantially more sensitive parameter of blood loss and adequacy of replacement than CVP.     

Anticoagulation and Hemostasis in Cardiac Surgical Patients

Optimizing anticoagulation and hemostasis during cardiopulmonary bypass and perioperatively helps to ensure the best possible clinical outcome. This article reviews the pharmacology of unfractionated and low-molecular weight heparin, aprotinin, desmopressin, dextran, antiplatelet agents, warfarin, and direct thrombin inhibitors. Their use is discussed in the context of coronary artery surgery, valvular surgery, and mechanical cardiac support devices, as well as in the management of acute ischemic syndromes, atrial fibrillation, and prevention and treatment of venous thromboembolism. Progress in the development and utilization of these anticoagulants and antiplatelet agents has supported the major advances that have been achieved in cardiac surgery.