Gregory W. Fischer

Successful use of a 20% lipid emulsion to resuscitate a patient after a presumed bupivacaine-related cardiac arrest.

The patient was a 58-yr-old, 82-kg, 170-cm male who presented for arthroscopic repair of a torn rotator cuff in the right shoulder. His medical history was significant for coronary artery bypass graft surgery at age 43 yr. He gave a history of angina upon exertion and occasionally at rest. He declined further preoperative cardiac workup but was considered by his cardiologist to be stable on medical therapy. This included nitroglycerine as needed, lisinopril, atenolol isosorbide mononitrate, and clopidogrel and enteric-coated aspirin, both of which had been discontinued 1 week previously. His preoperative electrocardiogram revealed a right bundle-branch block, a left anterior hemiblock, and evidence of an old anterior wall myocardial infarction. The patient arrived at the operating room holding area, where standard monitors were applied. Blood pressure was 120/80 mmHg, room air oxygen saturation measured by pulse oximetry was 98%, and heart rate was 60 beats/min. Supplemental oxygen was delivered at 3 l/min via a nasal cannula. A 20-gauge intravenous catheter was placed in the dorsum of his left hand, through which 2 mg midazolam and 50 g fentanyl were administered. A 50-mm, 22-gauge Stimuplex insulated needle was connected to a Stimuplex-DIG nerve stimulator (both B. Braun, Inc., Bethlehem, PA), and the interscalene groove was identified at the level of C6. The brachial plexus was identified by eliciting biceps stimulation (0.1-ms duration, 2 Hz) at 0.34 mA, following which 40 ml local anesthetic solution (20 ml bupivacaine, 0.5%, and 20 ml mepivacaine, 1.5%) were injected slowly (over approximately 2.5 min) in 5-ml increments with gentle aspiration between doses. The patient was awake and conversant during the performance of the block. At no time was any blood aspirated, nor did he report pain or paresthesias. Approximately 30 s after removal of the block needle, the patient became incoherent and then developed a tonic–clonic seizure. Oxygen was delivered by a facemask attached to a self-inflating resuscitation bag while 50 mg propofol was injected intravenously. The seizure stopped, and spontaneous respirations resumed. Approximately 90 s later, the patient began to seize again; this time, 100 mg intravenous propofol was administered. The electrocardiogram showed asystole, and no pulse, by carotid or femoral palpation, or blood pressure was detectable. Advanced cardiac life support was immediately started. The trachea was intubated, and end-tidal carbon dioxide was detected with an EasyCapII (Nellcor Inc., Hayward, CA). Tube position was confirmed by auscultation, after which chest compressions were immediately resumed. During the first 20 min of advanced cardiac life support, a total of 3 mg epinephrine, given in divided doses, 2 mg atropine, 300 mg amiodarone, and 40 U arginine vasopressin were administered. In addition, monophasic defibrillation was used at escalating energy levels—200, 300, 360, and 360 J, according to the advanced cardiac life support protocol. Cardiac rhythms included ventricular tachycardia with a pulse, pulseless ventricular tachycardia that momentarily became ventricular fibrillation, and eventually asystole. The arrhythmias observed during most of the resuscitation period were pulseless ventricular tachycardia and asystole. After 20 min, at which time plans were being made to institute cardiopulmonary bypass, the administration of a lipid emulsion was suggested, and 100 ml of 20% Intralipid (for Baxter Pharmaceuticals by Fresenius Kabi, Uppsala, Sweden) was given through the peripheral intravenous catheter. Cardiac compressions continued, and a defibrillation shock at 360 J was given. Within seconds, a single sinus beat appeared on the electrocardiogram, and 1 mg atropine and 1 mg epinephrine were administered. Within 15 s, while external chest compressions were continued, the cardiac rhythm returned to sinus at a rate of 90 beats/min. The blood pressure and pulse became detectable. An infusion of lipid emulsion was started and continued at 0.5 ml · kg 1 · min 1 over the following 2 h and then discontinued. The patient remained in sinus rhythm. He was weaned from mechanical ventilation, and his trachea was extubated, approximately 2.5 h later. He was awake and responsive, and had right upper extremity weakness consistent with a brachial plexus block. No neurologic sequelae were sustained, and he was subsequently transferred to a monitored setting for overnight observation. There was no evidence of complications secondary to the administration of intralipid (i.e., pancreatitis) during the following 2 weeks. Because the patient had a cardiac arrest after which he had increased levels of cardiac enzymes, he agreed to undergo cardiac catheterization. This revealed total occlusion of the right coronary artery and a left ventricular ejection fraction of 32%. As a consequence, an automatic implantable cardiac defibrillator was inserted without any complications, and the patient was discharged home.

Early On–Cardiopulmonary Bypass Hypotension and Other Factors Associated With Vasoplegic Syndrome

Background— Vasoplegic syndrome is a form of vasodilatory shock that can occur after cardiopulmonary bypass (CPB). We hypothesized that the severity and duration of the decline in mean arterial pressure immediately after CPB is begun can be used as a predictor of patients will develop vasoplegia in the immediate post-CPB period and of poor clinical outcome. We quantified the decline in mean arterial pressure by calculating an area above the mean arterial blood pressure curve. Methods and Results— We retrospectively analyzed 2823 adult cardiac surgery cases performed between July 2002 and December 2006. Of these 2823, 577 (20.4%) were vasoplegic after separation from CPB. We found that 1645 patients (58.3%) had a clinically significant decline in mean arterial pressure after starting CPB (area above the mean arterial blood pressure curve >0) and were significantly more likely to become vasoplegic (23.0% versus 16.9%; odds ratio, 1.26; 95% confidence interval, 1.12 to 1.43; P<0.001). These patients were also far more likely either to die in hospital or to have a length of stay >10 days (odds ratio, 3.30; 95% confidence interval, 1.44 to 7.57; P=0.005). Additional risk factors for developing vasoplegia that were identified included the additive euroSCORE, procedure type, prebypass mean arterial pressure, length of bypass, administration of pre-CPB vasopressors, core temperature on CPB, pre- and post-CPB hematocrit, the preoperative use of β-blockers or angiotensin-converting enzyme inhibitors, and the intraoperative use of aprotinin. Conclusions— The results of this investigation suggest that it is possible to predict vasoplegia intraoperatively before separation from CPB and that the presence of a clinically significant area above the mean arterial blood pressure curve serves as a predictor of poor clinical outcome.

Vasoplegia during cardiac surgery: current concepts and management.

Vasoplegic syndrome (VS) is a recognized and relatively common complication of cardiopulmonary bypass (CPB), appearing with an incidence ranging between 5% and 25%. It is characterized by significant hypotension, high or normal cardiac outputs and low systemic vascular resistance (SVR), and increased requirements for fluids and vasopressors during or after CPB. Patients developing VS are at increased risk for death and other major complications following cardiac surgery. This review will focus on the pathophysiology and contemporary strategies of treating VS encountered after CPB.

The role of imaging in chronic degenerative mitral regurgitation.

Chronic degenerative mitral regurgitation (MR) is a complex problem, which requires an integrated assessment of etiology, pathophysiology, and severity to enable informed clinical decision-making. A multidisciplinary approach is required, with input from the clinician, imager, and surgeon. This review begins with a discussion of essential echocardiographic and surgical mitral valve (MV) anatomy, which dictates suitability for repair when indicated. The echocardiographic and Doppler principles, which underlie the quantitation of MR severity, are summarized in the next section, followed by a critical examination of left ventricular systolic function in this disorder. A brief discussion of the important role of imaging in the developing field of percutaneous MV repair is included. The methodical and objective noninvasive assessment of degenerative MR herein reviewed is intended to help guide management decisions for patients with this challenging valve lesion.

Recent advances in application of cerebral oximetry in adult cardiovascular surgery.

Cerebral oximetry is a noninvasive technology that continuously monitors cerebral tissue oxygen saturation, which is a sensitive index of global cerebral hypoperfusion. On the basis of near-infrared spectroscopy technology, information is provided on the availability of oxygen in brain tissue at risk during numerous pathological conditions. Complementary to the arterial oxygen saturation measured by pulse oximetry, cerebral tissue oxygen saturation reflects regional cerebral metabolism and the balance of local cerebral oxygen supply/demand. Recently, patient management with the guidance of cerebral oximetry has resulted in improved patient outcomes. This review will briefly describe the physics behind cerebral oximetry and will provide an overview of the literature focusing primarily on articles published within the past 5 years.

The Use of Cerebral Oximetry as a Monitor of the Adequacy of Cerebral Perfusion in a Patient Undergoing Shoulder Surgery in the Beach Chair Position

Four cases of ischemic injury have been reported in patients undergoing orthopedic surgery in the upright position. We describe the use of cerebral oximetry as a monitor of the adequacy of cerebral perfusion in a 63‐year‐old woman who underwent arthroscopic rotator cuff surgery in a beach chair under general anesthesia. During positioning, a decrease in blood pressure was accompanied by a decrease in cerebral oxygen saturation (SctO2) and was treated with phenylephrine. When spontaneous ventilation resumed, an increase in end‐tidal carbon dioxide was accompanied by an increase in SctO2. Cerebral oximetry may prove useful as a guide monitor and manage nonsupine patients.

Can three-dimensional echocardiography accurately predict complexity of mitral valve repair?

OBJECTIVE Feasibility of mitral repair is a key factor in the decision to operate for mitral regurgitation. Repair feasibility is highly dependent on surgical experience and repair complexity. We sought an objective means of predicting complexity of repair using three-dimensional (3D) transoesophageal echocardiography. METHODS In a cohort of 786 patients who underwent mitral valve surgery between 2007 and 2010, 3D transoesophageal echocardiography was performed in 66 patients with mitral regurgitation prior to the institution of cardiopulmonary bypass. The surgeon reviewed the 2D echocardiographic images for all patients pre-operatively, but did not view the 3D echocardiographic quantitative data or volumetric analysis until after surgery. Repairs involving no or a single-segment leaflet resection, sliding-plasty, cleft closure, chordal or commissural repair techniques were classed as standard repairs. Complex repairs were defined as those involving bileaflet repair techniques, requiring multiple resections or patch augmentation. Disease aetiology included Barlows disease (n = 18), fibroelastic deficiency (n = 22), ischaemic (n = 5), endocarditis (n = 5), rheumatic (n = 2) and dilated cardiomyopathy (n = 2). RESULTS No patient required mitral replacement or had more than mild mitral regurgitation on pre-discharge echocardiography. Anterior and posterior leaflet areas, annular circumference, anterior and posterior leaflet angles, prolapse and tenting heights and volumes were most strongly predictive of repair complexity. As 21 of the 22 patients with bileaflet pathology and multisegment prolapse were complex repairs, we sought to develop a model predicting repair complexity in the remaining patients. The most predictive model with a c-statistic of 0.91 included three predictors: multisegment pathology, prolapsing height and posterior leaflet angle. After bootstrap validation, the revised c-statistic was 0.88. CONCLUSIONS 3D transoesophageal echocardiography provides an objective means of predicting mitral repair complexity in mitral regurgitation due to a range of aetiology.

Predicting systolic anterior motion after mitral valve reconstruction: using intraoperative transoesophageal echocardiography to identify those at greatest risk

OBJECTIVES We set out to determine if intraoperative pre-bypass transoesophageal echocardiography could assist in predicting which patients are at greatest risk for systolic anterior motion (SAM) after mitral valve repair (MVR). METHODS Three hundred and seventy-five consecutive patients who underwent reconstructive MVR surgery for degenerative disease were included. Data were collected using intraoperative echocardiographic images taken prior to the initiation of cardiopulmonary bypass. Based on the physiology of SAM, we postulated that 11 parameters could be potential risk factors for SAM: left ventricular ejection fraction (LVEF), left ventricular end-systolic dimension, left ventricular end-diastolic dimension (LVEDD), basal septal diameter (basal-interventricular septal diameter in diastole (IVDd)), mid-ventricular septal diameter (mid-IVDd), coaptation-septal distance (c-sept), anterior leaflet height, posterior leaflet height, aorto-mitral angle, mitral annular diameter and left atrial diameter. These parameters were measured and recorded by a blinded single operator. Independent predictors of SAM were identified using multiple logistic regression analysis. RESULTS Of the 375 patients, 345 (92%) did not develop SAM (No-SAM group), while 30 (8%) developed intraoperative or postoperative SAM (SAM group). The mean age was 56.8 ± 12.8 and 56.7 ± 13.8 in the No-SAM and SAM groups, respectively. The incidence of fibroelastic deficiency, forme fruste and Barlows disease was similar in both groups. All patients received a complete annuloplasty ring as part of the repair. There was no statistical difference in the mean ring size used in each group. EF was similar in the No-SAM (56.2% ± 8.1) and SAM (57.0% ± 9.2) P = 0.63) groups. Independent predictors of developing SAM after valve repair were: EDD <45 mm [odds ratio (OR) 3.90; P = 0.028], aorto-mitral angle <120° (OR 2.74; P = 0.041), coaptation-septum distance <25 mm (OR 5.09; P = 0.003), posterior leaflet height >15 mm (OR 3.80; P = 0.012) and basal septal diameter ≥ 15 mm (OR 3.63; P = 0.039). CONCLUSIONS The risk for SAM can be predicted using intraoperative transoesophageal echocardiography. The combination of a smaller left ventricle, tall posterior leaflet, narrow aorto-mitral angle and enlarged basal septum significantly increases the risk for SAM. Knowing these parameters prior to valve repair can assist the surgeon in adjusting their repair technique to minimize the risk.

Management of patients undergoing multivalvular surgery for carcinoid heart disease: the role of the anaesthetist

BACKGROUND The management of patients with carcinoid heart disease poses two major challenges for the anaesthetist: carcinoid crisis and low cardiac output secondary to right ventricular (RV) failure. Carcinoid crises may be precipitated by the administration of catecholamines and histamine-releasing drugs. METHODS We analysed a series of 11 patients [six males, median (range) age 60 (42-73) yr] with severe symptomatic carcinoid heart disease who underwent multivalve surgery (right-sided valves, n=8; right- and left-sided valves, n=3) between 2001 and 2007. RESULTS All patients received octreotide intraoperatively [650 (300-1050) microg] to prevent carcinoid symptoms and vasoplegia. Those patients on a greater preoperative octreotide regime required additional intraoperative octreotide [median (range) dose 320 (300-850) vs 750 (650-1050) mug]. Similarly, the use of greater doses of aprotinin (> 5 KIU) was associated with greater requirements for octreotide [475 (300-700) vs 750 (320-1050) microg] and higher glucose levels (> or =8.5 mmol litre(-1)). Catecholamines were generally required in those patients who presented with a worse New York Heart Association functional class. Overall mortality was 18% (n=2) and only one episode of mild intraoperative carcinoid crisis was observed. CONCLUSIONS Carcinoid crisis and RV failure still remain the primary challenges for the anaesthesiologist while managing patients with carcinoid heart disease. Our study supports the administration of catecholamines to wean patients off cardiopulmonary bypass, particularly in the presence of myocardial dysfunction. Those patients on higher octreotide dosages may require close intraoperative glucose monitoring. Despite high operative mortality, surgical outcome has been improved potentially due to earlier patient referral and better perioperative management.

An update on anesthesia for thoracoscopic surgery.

Purpose of review The surgical management of patients partly determines the anesthetic management. A shift has taken place in thoracic surgery, with a large portion of procedures now being performed through a video-assisted thoracoscopic surgery (VATS) approach. This review is intended to provide the anesthesiologist with an update on the management of thoracic surgical patients presenting for VATS. Recent findings Although there are cosmetic and economical advantages to the VATS approach, large randomized controlled trials are still lacking documenting the benefit of VATS versus conventional ‘thoracotomy’. The classic division in absolute and relative indications for one-lung ventilation (OLV) should be viewed as antiquated. All VATS procedures represent an indication for OLV. A better classification is to divide the purpose of OLV: separation versus isolation. Treatment for hypoxemia during OLV also needs to be modified. Patient expectations are also different as a minimal invasive approach is often falsely associated with minimal risk. This leads to an additional stress factor imposed upon the anesthesiologist. Summary Minimal invasive VATS is gaining widespread popularity among our surgical colleagues. The anesthesiologist must recognize the impact that this change in surgical philosophy will have upon the anesthetic management of these complex patients.