Enrique Pantin

Hypothermia and the approximate entropy of the electroencephalogram.

Background The electroencephalogram is commonly used to monitor the brain during hypothermic cardiopulmonary bypass and circulatory arrest. No quantitative relationship between the electroencephalogram and temperature has been elucidated, even though the qualitative changes are well known. This study was undertaken to define a dose–response relationship for hypothermia and the approximate entropy of the electroencephalogram. Methods The electroencephalogram was recorded during cooling and rewarming in 14 patients undergoing hypothermic cardiopulmonary bypass and circulatory arrest. Data were digitized at 128 Hz, and approximate entropy was calculated from 8-s intervals. The dose–response relationship was derived using sigmoidal curve-fitting techniques, and statistical analysis was performed using analysis of variance techniques. Results The approximate entropy of the electroencephalogram changed in a sigmoidal fashion during cooling and rewarming. The midpoint of the curve averaged 24.7°C during cooling and 28°C (not significant) during rewarming. The temperature corresponding to 5% entropy (T0.05) was 18.7°C. The temperature corresponding to 95% entropy (T0.95) was 31.3°C during cooling and 38.2°C during rewarming (P < 0.02). Conclusions Approximate entropy is a suitable analysis technique to quantify the electroencephalographic changes that occur with cooling and rewarming. It demonstrates a delay in recovery that is of the same magnitude as that seen with conventional interpretation of the analog electroencephalogram and extends these observations over a greater range of temperatures.

Response to Nitric Oxide during Adult Cardiac Surgery

Pulmonary hypertension is associated with significant morbidity and mortality in adult cardiac surgery patients. Inhaled nitric oxide is known to be a selective pulmonary vasodilator in this setting. However, it is not known which cardiac surgery patients benefit most from nitric oxide therapy. This study sought to prospectively determine whether a patients baseline pulmonary vascular resistance could be used to predict responsiveness to inhaled nitric oxide therapy. Subjects were 30 consecutive cardiac surgery patients with pulmonary hypertension immediately prior to induction of anesthesia. There were 2 study groups: Group 1 ( n = 15) had an initial pulmonary vascular resistance between 125 and 300 dyn-s/cm 5 , while group 2 ( n = 15) had an initial pulmonary vascular resistance of greater than 300 dyn-s/cm 5 . Both groups were empirically treated with inhaled nitric oxide (30 ppm) upon separation from bypass. The conduct of anesthesia, surgery, and cardiopulmonary bypass were controlled. A therapeutic algorithm dictated the use of vasoactive substances for all patients. Heart rate, mean arterial pressure, pulmonary vascular resistance, peripheral vascular resistance, cardiac index, and right ventricular ejection fraction were monitored throughout the operative experience. Patients with a higher initial pulmonary vascular resistance had a significantly greater percent reduction in pulmonary vascular resistance after the initiation of nitric oxide therapy. This study suggests that pulmonary vascular resistance is more dramatically affected by inhaled nitric oxide in cardiac surgery patients with a greater degree of pulmonary hypertension.

Noise Levels in Modern Operating Rooms During Surgery

OBJECTIVE To determine if differences in noise levels exist in the cardiac operating room at various critical points. DESIGN Prospective, nonrandomized study. SETTING Cardiac operating rooms of a university hospital. PARTICIPANTS Cardiac surgical patients. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS The noise level was monitored in the operating room for 23 patients undergoing cardiac surgery requiring general anesthesia during room setup, induction, skin incision, 60 minutes after surgical incision, termination of extracorporeal circulation, emergence (drapes down), and transport. RESULTS At each data point (induction, emergence, termination of extracorporeal circulation, emergence [drapes down], and transport), noise levels were louder than the baseline reference at room setup, surgical skin incision, and 60 minutes into the surgery. CONCLUSIONS The aim of this study was to compare the level of noise in the operating room at times determined critical for anesthesiologists compared with other surgical periods. This study consistently showed that noise in the operating room is louder during the critical anesthesia components of the case. Several studies have found that the loudest sound levels recorded in an operating room are related to the use of particular surgical tools, which are not used typically during the induction and emergence from anesthesia. This suggests that the increased sound levels during these periods may be somewhat controllable by the health care providers in the room.

Lower incidence of hypo-magnesemia in surgical intensive care unit patients in 2011 versus 2001.

Background Hypo-magnesemia is described to occur in as many as 65% of intensive care unit (ICU) patients. Magnesium (Mg) is a cofactor in over 300 enzymatic reactions involving energy metabolism, protein, and nucleic acid synthesis. The membrane pump that creates the electrical gradient across the cell membrane is dependent on Mg, and it is important in the activity of electrically excitable tissues. Since Mg regulates the movement of calcium in smooth muscle cells, it is also important in peripheral vascular tone and blood pressure. Studies have linked hypo-magnesemia to multiple chronic diseases and to a higher mortality rate. Methods To explore trends within our own tertiary care surgical ICU, we sampled our patients’ laboratory records in 2001 and in 2011. Hypo-magnesemia in our ICU is defined as an Mg less than 2.0 mg/dL. Results This retrospective review of all SICU patients from October to December revealed that there was a significant increase (P < 0.01) in the patients with their serum Mg level measured between 2001 (89%) and 2011 (95%). There was a significant decrease (P < 0.001) in patients with hypomagnesemia (< 2 mg/dL) between 2001 (47.5%) and 2011 (33.0%). On the other hand, there was a significant increase (P < 0.001) in patients with normal serum Mg level (> 2 mg/dL) between 2001 (52.5%) and 2011 (67.0%). Conclusions There was not only more monitoring of Mg in 2011, but a lower incidence of hypo-Mg compared to 2001. Possible explanations include changing patterns of antibiotic and diuretic use, less amphotericin use, more frequent laboratory surveillance, and better trained ICU practitioners.

Echocardiographic Identification of an Interrupted Inferior Vena Cava with Dilated Azygos Vein During Coronary Artery Bypass Graft Surgery

358 www.anesthesia-analgesia.org February 2016 • Volume 122 • Number 2 A 63-year-old woman with Turner syndrome and coronary artery disease was admitted for elective coronary artery bypass grafting. Intraoperative transesophageal echocardiogram (TEE) showed normal left and right ventricular systolic function, mild left ventricle hypertrophy, mild left and severe right atrial dilations, mild tricuspid and aortic insufficiency, mild dilation of the ascending aorta, and a severely enlarged azygos vein (Fig. 1; Supplemental Digital Content 1, Supplemental Video 1, http://links.lww.com/AA/B281). Dilated hepatic veins were noted, draining via a common vein into the right atrium (RA), and the inferior vena cava (IVC) was not visible. A dual-stage venous cannula was used with the tip of the cannula placed in the RA and, using realtime TEE, care was taken to not insert the cannula into the hepatic vein. Additional images were obtained by postoperative transthoracic echocardiogram (Supplemental Digital Content 2, Video 2, http://links.lww.com/AA/ B282). The patient was weaned from cardiopulmonary bypass with minimal inotropic support and transferred to the intensive care unit sedated for an uneventful postoperative course. Written consent was obtained from the patient for the authors to publish this report. Interrupted IVC with azygos continuation (also known as absence of the hepatic segment of the IVC with azygos continuation) is an uncommon vascular anomaly characterized by absence of the IVC between the renal veins and the hepatic veins and a connection of the caudal IVC to the azygos vein (Fig. 2), which then enters the thorax through the aortic hiatus and joins the superior vena cava (SVC) above its junction with the RA.1 The azygos vein normally connects the IVC and the SVC. Interruption of the IVC with azygos continuation results in a dilated azygos vein system, as seen in our patient on TEE, because of the increased amount of blood from the lower body, which now flows through the azygos. The observed dilated hepatic veins, as well as the inability to observe the IVC on TEE or transthoracic echocardiogram, are consistent with this explanation. The incidence of interrupted IVC was reported to be 0.6% to 2.9% among patients with congenital heart disease undergoing cardiac catheterization.1 Although usually an asymptomatic anomaly, it does carry an increased risk of thrombosis because of venous stasis1 and can complicate cardiopulmonary bypass venous cannulation. It may require a larger size venous cannula placed in the RA (as opposed to placement in the RA with the tip of the cannula sitting in the IVC) to provide adequate venous return2 or could

Increasing Severity of Aortic Atherosclerosis in Coronary Artery Bypass Grafting Patients Evaluated by Transesophageal Echocardiography

Background Atherosclerotic disease in coronary artery bypass grafting (CABG) patients is a potential contributor to complications in the perioperative periods. This study was undertaken to better define how the frequency of aortic atheromatous disease among patients coming for CABG has evolved over the last decade. Methods Data from elective patients coming for CABG who underwent transesophageal echocardiography (TEE) examinations following induction of anesthesia were obtained for the years 2002 and 2009. Aortas were graded according to the method of Kronzon, with the following interpretations: normal = grade I, intimal thickening = 2, atheroma of less than 5 mm = 3, atheroma of > 5 mm = 4, and any mobile atheroma = 5. The data of 124 patients who underwent comprehensive exam of the aorta by one cardiac anesthesiologist were gathered and assigned into two groups based on the year TEE was done. Student’s t-test was used for statistical analysis. A P value < 0.05 was considered significant. The data were presented as mean ± SD. Results There was significant difference between group 2002 (2.05 ± 1.28) and group 2009 (2.59 ± 1.11) in atheroma grade (P = 0.013). Conclusions Patients coming for CABG in group 2009 exhibited significantly higher grades of aortic atheroma on TEE, compared to group 2002. Understanding the risk of atheroma in the elderly CABG population may help in altering surgical approaches to lessen the risk of catastrophic stroke. Potential options needing further study include the off-pump approach and modification of cross-clamp site and technique as well as other modalities.

Cerebral Oximetry Decrease After External Carotid Clamping with Normal Electroencephalography and No Change After Internal Carotid Clamping.

Monitoring of cerebral perfusion by near-infrared spectroscopy estimates regional cerebral oxygen saturation (rSO2). We present a case in which, before clamping the left carotid artery during an endarterectomy, the right and left rSO2 measurements were 72% and 74%, respectively. Within 15 seconds of clamping the external carotid artery, the left rSO2 decreased by 8%, yielding right and left rSO2 measurements of 70% and 66%, respectively. No electroencephalogram changes ensued. The internal carotid artery was clamped 1 minute later, whereas the external carotid remained clamped. No electroencephalogram changes were observed. The rSO2 measurements demonstrate that the value of this cerebral oximetry is not determined solely from internal carotid blood flow and can be significantly affected by the external carotid.

Coiled Impella Drive Line in the Left Ventricle: A Rare Complication of a Left Ventricular Assist Device

CASE REPORT A 71-year-old man with hypertension, chronic renal insufficiency, a right subclavian automatic implantable cardioverterdefibrillator for congestive heart failure secondary to cardiac amyloidosis, an ejection fraction of 15%, and in-home inotropic support was admitted for acute cardiac decompensation. His condition deteriorated to cardiogenic shock not responsive to pharmacologic interventions, requiring an emergent insertion of a left ventricular mechanical support device. Under general anesthesia, a microaxial flow device (Impella 5.0, Abiomed, Inc., Danvers, MA) (Fig 1) was inserted through an 8-mm tube graft sutured to the left axillary artery and its proper positioning guided by TEE. Device flows were appropriate (4.5 L/min). The device was secured to the tube graft and the wound closed. There was no notation done of device depth insertion. The Impella insertion would serve as a potential bridge to a permanent left ventricular assist device. Due to patient advanced age and the fact that heart transplantation survival in patients with amyloidosis is reduced significantly, this option was not considered. 1,2 Routinely, TEE is used to assist Impella

Intra-Arterial Fibrinous Sheath Development as a Potential Complication of the Impella Ventricular Assist Device

THE IMPELLA VENTRICULAR assist device (Abiomed, Inc., Danvers, MA) is a relatively new and rapidly evolving option for short-term support of acute cardiac dysfunction, a bridge for long-term devices, and a temporary support for high-risk cardiac interventions. Several complications have been described with its use, with most related to vessel damage or bleeding. Central line fibrinous sheaths associated with long-term intravascular catheters have been well described, but there have been no reports related to the Impella device. The authors report 3 cases of such a complication observed after the explantation of an Impella CP device. All patients or proxy provided written consent for publication of this case report.

Left Atrial Mass During a Minimally Invasive Thoracic Mitral Valve Replacement

n 1 p e c t w e t A 72-YEAR-OLD man with a history of mitral regurgitation presented for minimally invasive mitral valve surgery hrough a right thoracotomy approach. Two introducers were nserted into the right internal jugular vein for the placement of etrograde cardioplegia and pulmonary artery venting catheters Endoplegia and Endovent, Edwards Lifesciences Inc, Irvine, A). The retrograde catheter was guided percutaneously through he coronary sinus ostium using a modified bicaval transesophaeal echocardiographic view and was advanced slowly while onitoring its position. The final position was confirmed when nflation of the balloon with 0.25 mL of saline resulted in a entricularized waveform. After routine administration of antegrade ardioplegia, retrograde cardioplegia was initiated through the coro-