John T. Denny

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.

The Optimal Angle of Head Rotation for Internal Jugular Cannulation as Determined by Ultrasound Evaluation

OBJECTIVES The aim of this study was to determine the degree of head rotation that creates the maximal anatomic separation between the right internal jugular vein and the carotid artery. DESIGN Single-center prospective, observational cohort study. SETTING University medical center. PARTICIPANTS Fifty patients aged>21 years and undergoing cardiac surgery. INTERVENTIONS An ultrasound machine equipped with a digital caliper was used to determine the relational anatomy of the internal jugular vein and the carotid artery, with patients in the Trendelenburg position at head angles of -15°, 0°,+15°,+30°,+45°,+60°,+75°, and+90°. MEASUREMENTS AND MAIN RESULTS When examining the percentage of the internal jugular vein vertical diameter that is not overlapped by the carotid artery (vertically unencumbered), there was a difference between the head angle groups (p<0.01). Unencumbered vertical distance was different between+75° versus 0°, and+75° versus+15°. At+75°, 60.3%±5.3% of the internal jugular vein was unencumbered vertically, whereas at 0°, it was 37.2%±3.9%, and at+15° it was 40.3%±3.8%. Only 72% of the patients were able to position their head at+75°, and 54% of the subjects were able to position their head at+90°. CONCLUSION The authors found the internal jugular vein becomes more vertically separated from the carotid artery at more extreme angles of contralateral head rotation.

A new technique for avoiding barotrauma-induced complications in apnea testing for brain death

Prompted by our experience with complications occurring with apnea testing (AT), we discuss complications reported in the literature. AT is an integral part of brain death assessment. Many complications of AT have been described, including hypoxemia, arterial hypotension, tension pneumothorax and cardiac arrest. We conclude that a commonly used technique in conducting AT can create auto-positive end expiratory pressure (PEEP) and contributes to many complications. The mechanism of occult auto-PEEP in AT is discussed. Intensive care unit patients may have a compensated and asymptomatic relative hypovolemia that can be decompensated by a small amount of auto-PEEP produced by air trapping during insufflating oxygen (O2) through a 7.0 endotracheal tube (ETT). It could then lead to decreased preload, decreased stroke volume, decreased cardiac output and thus, to hypotension and a compensatory tachycardia. The placement of the standard O2 tubing (6mm outside diameter [OD]) inside the 7.0 ETT (7mm inside diameter [ID]) greatly decreased the ETT lumen (73%). We changed our practice to instead use readily available small pressure tubing to insufflate O2 for AT to avoid excessive reduction in the ETT lumen. The change from standard O2 tubing (6mm OD) to pressure tubing (3mm OD) will greatly decrease the reduction in cross-sectional area of 7.0 ETT lumen from 73 to 18% and avoid potential complications of air trapping, auto-PEEP and barotrauma. We have successfully used this new simple technique with readily available equipment to eliminate auto-PEEP in AT while preserving oxygenation.

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.

Ropivacaine 0.025% mixed with fentanyl 3.0 μg/ml and epinephrine 0.5 μg/ml is effective for epidural patient-controlled analgesia after cesarean section

Background and Aims: We aimed to determine the ropivacaine concentration that provided adequate analgesia with early ambulation and minimal urinary retention or other side-effects when used with fentanyl and epinephrine for patient-controlled epidural analgesia (PCEA) after elective cesarean section. Material and Methods: Forty-eight patients were randomized to four groups in a double-blinded fashion. All groups received an initial 10 ml/h of epidural study solution for 24 h. The solution contained: 0.2, 0.1, 0.05, or 0.025% ropivacaine for Groups I-IV, respectively, with fentanyl 3.0 μg/ml and epinephrine 0.5 μg/ml. Patients could administer additional PCEA doses of 4 ml of their study solution with a lock-out time of 10 min. Overall satisfaction, side-effects, motor block, neurologic function, and pain using Visual Analog Scale were assessed. Results: Patients in all groups showed no difference in sedation, pruritus, nausea, vomiting, and uterine cramps. Pain scores at rest were lower for Group IV than Groups I-III (P < 0.001). Twelve, five, one, and zero patients could not ambulate in Groups I-IV, respectively. Nine, nine, two, and zero (III <I and II, P = 0.02; IV P = 0.001) patients reported urinary retention in Groups I-IV, respectively. Overall satisfaction scores were high for all groups. Neonatal behavior score was similar and high in all groups. Conclusion: 0.025% ropivacaine PCEA combined with fentanyl and epinephrine provided effective pain relief after cesarean section with early ambulation and without sensory loss, urinary retention, or increase of side-effects.

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.

Preventing "A Bridge Too Far": Promoting Earlier Identification of Dislodged Dental Appliances During the Perioperative Period

The presence of fixed partial dentures presents a unique threat to the perioperative safety of patients that require orotracheal intubation or placement of instruments into the gastrointestinal (GI) tract. There are many chances for the displacement of a fixed partial denture: instrumentation of the airway for intubation, or introduction of temporary devices, such as gastroscopes or transesophageal echo probes. If dislodged, the fixed partial dentures can enter the hypopharynx, esophagus or lungs and cause perforations with their sharp tines. Oral or esophageal perforation can lead to potentially fatal mediastinitis. We describe a case of a patient with a fixed partial denture who underwent cardiac surgery with intubation and transesophageal echocardiography (TEE). His partial denture was intact after the procedure. After extubation, he reported that his teeth were missing. Multiple procedures were required to remove his dislodged partial dentures. In sign-out reports, verbal descriptions of the patient’s partial dentures were not adequate in this case. A picture of the patient’s denture and oral pharynx pre-operatively would have provided a more accurate template for the post-operative team to refer to when caring for the patient. This may have avoided the multiple potentially risky procedures the patient had to undergo. We describe a suggested protocol utilizing a pre-operative photo to reduce the incidence of unrecognized partial denture dislodgement in the perioperative period. Because the population is aging, this will become a more frequent issue confronting practitioners. This protocol could mitigate this complication.

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