The Utility of 3D Left Atrial Volume and Mitral Flow Velocities as Guides for Acute Volume Resuscitation.

Left ventricular end-diastolic pressure (LVEDP) is the foundation of cardiac function assessment. Because of difficulties and risks associated with its direct measurement, correlates of LVEDP derived by pulmonary artery (PA) catheterization or transesophageal echocardiography (TEE) are commonly adopted. TEE has the advantage of being less invasive; however TEE-based estimation of LVEDP using correlates such as left ventricular end-diastolic volume (LVEDV) has technical difficulties that limit its clinical usefulness. Using intraoperative acute normovolemic hemodilution (ANH) as a controlled hemorrhagic model, we examined various mitral flow parameters and three-dimensional reconstructions of left atrial volume as surrogates of LVEDP. Our results demonstrate that peak E wave velocity and left atrial end-diastolic volume (LAEDV) correlated with known changes in intravascular volume associated with ANH. Although left atrial volumetric analysis was done offline in our study, recent advances in echocardiographic software may allow for continuous display and real-time calculation of LAEDV. Along with the ease and reproducibility of acquiring Doppler images of flow across the mitral valve, these two correlates of LVEDP may justify a more widespread use of TEE to optimize intraoperative fluid management. The clinical applicability of peak E wave velocity and LAEDV still needs to be validated during uncontrolled resuscitation.

Bronchial thermoplasty: a novel treatment for severe asthma requiring monitored anesthesia care.

Dexmedetomidine used in monitored anesthesia care produces a safe and effective technique well documented in research. We report the successful use of dexmedetomidine for sedation during bronchial thermoplasty, a new treatment for patients with severe persistent asthma refractory to inhaled corticosteroids and long-term beta-2 agonists.

Stroke volume variation during acute normovolemic hemodilution.

BACKGROUND: The intravascular volume of surgical patients should be optimized to avoid complications associated with both overhydration and underresuscitation. In patients undergoing intraoperative acute normovolemic hemodilution, we investigated whether stroke volume variation (SVV) derived from an arterial pressure-based cardiac output (CO) monitor system (FloTrac/Vigileo, Edwards Lifesciences, Irvine, CA) tracked the changes associated with blood removal and replacement. We further evaluated the correlations between SVV and 3-dimensional (3D) transesophageal echocardiographic (TEE) left ventricular (LV) volume measurements. METHODS: Twenty-five patients had procedures during which acute normovolemic hemodilution was a planned part of the intraoperative management. We defined 7 measurement timepoints: baseline, after the removal of 5%, 10%, and 15% of the estimated blood volume (EBV) and after replacement with an equal volume of 6% hetastarch to -10%, -5%, and baseline EBV. At each timepoint, heart rate and systolic, diastolic, and mean arterial blood pressure were obtained from standard monitors, CO and SVV measurements were obtained from the FloTrac/Vigileo monitor, and TEE images were recorded for subsequent off-line reconstruction and determination of LV end-systolic and end-diastolic volumes. For statistical evaluations, we used a mixed models analysis of variance and Dunnett's test for post hoc comparisons with baseline values. Pearson's correlation was used to examine the relationships between SVV and LV volume. RESULTS: Analysis of variance demonstrated no significant change in heart rate or mean arterial blood pressure over the duration of study. CO decreased from 4.9 +/- 0.3 to 4.5 +/- 0.3 L/min after removal of 15% of the EBV and then increased to a final value of 5.4 +/- 0.3 L/min after replacement of 15% of the EBV. SVV increased from 9.2% +/- 0.9% to 20.3% +/- 2.0% (P < 0.001) after removal of 15% of the EBV and returned to a final value of 7.2% +/- 0.9% after replacement of 15% of the EBV. The indexed LV end-diastolic volume decreased from 42.1 +/- 8.3 to 36.9.3 +/- 8.3 mL/m(2) (P < 0.001) after removal of 15% of the EBV and then returned to a final volume of 45.9 +/- 10.3 mL/m(2) after replacement of 15% of the EBV. The measurements of SVV correlated inversely with the 3D TEE LV volume measurements. CONCLUSIONS: The SVV derived from the FloTrac/Vigileo system changes significantly as blood is removed and replaced during hemodilution. These changes correlate with 3D TEE measurements of LV volume. The utility of SVV in guiding optimization of intravascular volume merits further study.

Transesophageal echocardiography as an alternative for the assessment of the trauma and critical care patient.

Transesophageal echocardiography was first described and used to monitor cardiac function in 1976. Initially adopted by cardiac anesthesiologists and cardiologists, it has gained acceptance as an important diagnostic tool in the monitoring and assessment of cardiac status in the critically ill and trauma patient population. Comparative data suggest that transesophageal echocardiography provides rapid real-time noninvasive monitoring of the critically ill and avoids the morbidity and mortality that is associated with more invasive methods of patient monitoring. In addition, transesophageal echocardiography affords the practitioner reliable cardiac filling volumes based on direct left ventricular assessment compared to pressure data that are based on indirect right ventricular and pulmonary occlusive pressures. In a healthcare environment that seeks optimum patient assessment while requiring an approach that encourages cost-effective, noninvasive, and minimal patient risk, those nurse anesthetists who work in institutions that have transesophageal echocardiographic capabilities should learn this newer technology and begin to incorporate it into their practice.

Perioperative considerations in major orthopedic trauma: pelvic and long bone fractures.

Although pelvic fractures constitute a small percentage of total orthopedic injuries, they are associated with highest mortality rate. Pelvic fractures, along with long bone fractures, frequently are the result of significant blunt trauma often encountered in high-speed motor vehicle accidents. However, other types of trauma can cause these devastating injuries. Early recognition and a high index of suspicion are necessary to ensure that effective and aggressive resuscitation is instituted immediately. Expeditious assessment in the emergency department and care of the patient with pelvic and long bone fractures will greatly enhance the ongoing resuscitation in the operating room. Potentially life-threatening associated injuries in these patients make resuscitation even more challenging. Therefore, a basic knowledge of the mechanisms of injury, early treatment in the emergency department, and the factors that affect intraoperative management will help optimize the outcome for patients with these injuries. This course describes the perioperative concerns and the evaluation and treatment of a patient with a pelvic or a long bone fracture.