Journal of Intensive Care Medicine current issue

Analytic Review: Hyponatremia in Heart Failure

Chatterjee, K. — Wed, 18 Nov 2009 23:09:05 PST

Hyponatremia is one of the newer and emerging risk factors for an adverse prognosis in chronic heart failure. Why decreased serum sodium is associated with worse prognosis remains unclear. It may reflect worsening heart failure and the deleterious effects of activation of neurohormones. The mechanism of hyponatremia in heart failure also remains unclear. A relatively greater degree of free-water retention compared to sodium retention is probably the major mechanism. The treatment of significant hyponatremia in heart failure is difficult. The conventional treatments such as fluid restriction, infusion of hypertonic saline, and aggressive diuretic therapies are not usually effective. Vasopressin receptor antagonists have been shown to enhance aquaresis and correct hyponatremia. However, long-term beneficial effects of such treatments in chronic heart failure have not been documented.

A Simple Physiologic Algorithm for Managing Hemodynamics Using Stroke Volume and Stroke Volume Variation: Physiologic Optimization Program

McGee, W. T. — Wed, 18 Nov 2009 23:09:05 PST

Intravascular volume status and volume responsiveness continue to be important questions for the management of critically ill or injured patients. Goal-directed hemodynamic therapy has been shown to be of benefit to patients with severe sepsis and septic shock, acute lung injury and adult respiratory distress syndrome, and for surgical patients in the operating room. Static measures of fluid status, central venous pressure (CVP), and pulmonary artery occlusion pressure (PAOP) are not useful in predicting volume responsiveness. Stroke volume variation and pulse pressure variation related to changes in stroke volume during positive pressure ventilation predict fluid responsiveness and represent an evolving practice for volume management in the intensive care unit (ICU) or operating room. Adoption of dynamic parameters for volume management has been inconsistent. This manuscript reviews some of the basic physiology regarding the use of stroke volume variation to predict fluid responsiveness in the ICU and operating room. A management algorithm using this physiology is proposed for the critically ill or injured in various settings.

Inhalational Anesthesia: Basic Pharmacology, End Organ Effects, and Applications in the Treatment of Status Asthmaticus

Tobias, J. D. — Wed, 18 Nov 2009 23:09:05 PST

The potent inhalational anesthetic agents are used on a daily basis to provide intraoperative anesthesia. Given their beneficial effects on airway tone and reactivity, they also have a role in the treatment of status asthmaticus that is refractory to standard therapy. Although generally not of clinical significance, these agents can affect various physiological functions. The potent inhalational anesthetic agents decrease mean arterial pressure and myocardial contractility. The decrease in mean arterial pressure reduces renal and hepatic blood flow. Secondary effects on end-organ function may result from the metabolism of these agents and the release of inorganic fluoride. The following article reviews the history of inhalational anesthesia, the physical structure of the inhalational anesthetic agents, their end-organ effects, reports of their use for the treatment of refractory status asthmaticus in the intensive care unit (ICU) patient, and special considerations for their administration in this setting including equipment for their delivery, scavenging, and monitoring.

The Role of Head Computer Tomographic Scans on the Management of MICU Patients With Neurological Dysfunction

Salerno, D., Marik, P. E., Daskalakis, C., Kolm, P., Leone, F. — Wed, 18 Nov 2009 23:09:05 PST

Neurological dysfunction is common in patients admitted to the medical intensive care unit (MICU). However, the indications for head imaging in those patients are unclear. The objective of this study was to assess whether clinical variables would be useful in selecting patients who are likely to have an abnormality on head computerized tomographic (CT) scanning and to determine the impact of such scans on management decisions. We reviewed the charts of 740 patients admitted to our MICU between October 2002 and July 2004. A total of 123 patients (16.6%) had a head CT scan performed, with a new finding being present in 26 (21.1%) patients. In the patients with a new CT finding, there was a change in diagnosis in 11 (42%) patients and a change in treatment in 6 (23%) patients. Logistic regression analysis failed to determine any clinical characteristic that could predict a new finding on the CT scan. This study suggests that clinicians should have a low threshold for ordering a CT scan in MICU patients with acute neurological dysfunction.

Acute Hemodynamic Effects of Recruitment Maneuvers in Patients With Acute Respiratory Distress Syndrome

Wed, 18 Nov 2009 23:09:05 PST

Background: The recruitment maneuver (RM) in acute respiratory distress syndrome (ARDS) can cause hemodynamic derangement. We evaluated circulatory and cardiac changes during RMs.

Methods: We performed sustained inflation (SI) with a pressure of 40 cm H₂O for 30 seconds as an RM on 22 patients with ARDS. Blood pressure (BP) and heart rate were recorded immediately before, every 10 seconds during, and 30 seconds after the RM. Ventricular dimensions were obtained simultaneously using M-mode echocardiography, and tissue Doppler imaging was performed on the left ventricular wall.

Results: Mean, systolic, and diastolic BP decreased at 20 and 30 seconds during 30-second RMs (mean BP: 92 ± 12 at baseline to 83 ± 18 mm Hg at the end of the RM, P < .05) and subsequently recovered. Heart rate decreased at 10 and 20 seconds during the RM, and tended to increase afterward. Both ventricular dimensions decreased significantly during the RM. The left ventricular ejection fraction and peak velocity of the left ventricle during systole remained stable. The fractional changes in mean BP and left ventricular end-diastolic dimension during the RMs were correlated significantly with each other (r_s = 0.59). Static compliance of the respiratory system (Crs) was lower in patients with mean BP change ≥15% than in patients in whom the change was <15% (P < .05).

Conclusions: A transient decrease in mean BP was observed during the RM, and its degree was correlated with the preload decrease, while cardiac contractility was maintained.

Bi-Level Positive Airway Pressure Ventilation in Pediatric Oncology Patients With Acute Respiratory Failure

Schiller, O., Schonfeld, T., Yaniv, I., Stein, J., Kadmon, G., Nahum, E. — Wed, 18 Nov 2009 23:09:05 PST

The aim of the study was to describe our experience with bi-level positive airway pressure (BiPAP) ventilation in oncology children with acute respiratory failure, hospitalized in a single tertiary pediatric tertiary center. This was a retrospective cohort study of all pediatric oncology patients in our center admitted to the intensive care unit with acute hypoxemic or hypercarbic respiratory failure from January 1999 through May 2006, who required mechanical ventilation with BiPAP. Fourteen patients met the inclusion criteria with a total of 16 events of respiratory failure or impending failure: 12 events were hypoxemic, 1 was combined hypercarbic and hypoxemic, and 3 had severe respiratory distress. Shortly after BiPAP ventilation initiation, there was a statistically significant improvement in the respiratory rate (40.4 ± 9.3 to 32.5 ± 10.1, P < .05] and a trend toward improvement in arterial partial pressure of oxygen (PaO₂; 71.3 ± 32.7 to 104.6 ± 45.6, P = .055). The improvement in the respiratory status was sustained for at least 12 hours. In 12 (75%) events there was a need for sedation during ventilation; 12 children needed inotropic support during the BiPAP ventilation. Bi-level positive airway pressure ventilation failed in 3 (21%) children who were switched to conventional ventilation. All of them have died during the following days. One child was recategorized to receive palliative care while on BiPAP ventilator and was not intubated. In 12 of 16 BiPAP interventions (75%; 11 patients), the children survived to pediatric intensive care unit (PICU) discharge without invasive ventilation. No major complications were noted during BiPAP ventilation. Bi-level positive airway pressure ventilation is well tolerated in pediatric oncology patients suffering from acute respiratory failure and may offer noninferior outcomes compared with those previously described for conventional invasive ventilation. It appears to be a feasible initial option in children with malignancy experiencing acute respiratory failure.

Circulatory Arrest in a Brain-Dead Organ Donor: Is the Use of Cardiac Compression Permissible?

Cummings, B., Noviski, N., Moreland, M. P., Paris, J. J. — Wed, 18 Nov 2009 23:09:05 PST

Care of the brain-dead patient is common in intensive care practice. Aggressive donor management is advocated to increase supply of viable organs. Significant controversy exists over cardiac resuscitation in patients determined dead by cardiac criteria. The issue, till now, has not been addressed in brain dead patients. We discuss a case of cardiac resuscitation of a brain-dead donor to ensure organ donation. This case allows us to examine the use of brain death criteria to declare death, the controversy regarding cardiac resuscitation in organ donor patients, and the standards for use of cardiac resuscitation in the organ donor declared dead by brain death criteria. The consent process for organ donation in brain dead patients should address the possibility of subsequent cardiac arrest.

Respect for Persons: Beyond the Mortal World

Bierer, G. — Wed, 18 Nov 2009 23:09:05 PST

Neuroimaging in the Medical Intensive Care Unit: An Essential Complement to the Clinical Examination

Lee, K., Badjatia, N. — Wed, 18 Nov 2009 23:09:05 PST