Messung des Herzzeitvolumens

[Unexpected increase in extravascular lung water after acute lung injury]

HISTORY AND CLINICAL FINDING

We report on a 27-year-old female patient presenting with pneumonia and developing acute respiratory distress syndrome. Using transpulmonary thermodilution, an elevated extravascular lung water was detected (17 ml/kg). Patient required lung-protective mechanical ventilation and received antibiotic therapy. Negative fluid balance was targeted. Under this treatment, respiratory function improved, inflammation parameters declined, and extravascular lung water was recurrent (10 ml/kg). Subsequently, extravascular lung water increased to 29 ml/kg.

DIAGNOSIS

In a chest x-ray, the central venous catheter tip was dislocated into the right internal jugular vein. 7 days before, the catheter was shown to be in projection of the Vena cava superior in a previous chest x-ray.

THERAPY AND COURSE

After insertion of a new central venous catheter, extravascular lung water was quantified at 10 ml/kg again. After 10 days of mechanical ventilation the patient was successfully extubated.

CONCLUSION

As mechanism for this catheter dislocation, we propose a Valsalva maneuver or spontaneous movements of the upper body of the patient. Sudden increase in extravascular lung water may reflect central venous catheter tip dislocation and chest x-ray should be considered to verify catheter tip position.

A System for Continuous Estimating and Monitoring Cardiac Output via Arterial Waveform Analysis

BACKGROUND

Cardiac output (CO) is the total volume of blood pumped by the heart per minute and is a function of heart rate and stroke volume. CO is one of the most important parameters for monitoring cardiac function, estimating global oxygen delivery and understanding the causes of high blood pressure. Hence, measuring CO has always been a matter of interest to researchers and clinicians. Several methods have been developed for this purpose, but a majority of them are either invasive, too expensive or need special expertise and experience. Besides, they are not usually risk free and have consequences.

OBJECTIVE

Here, a semi-invasive system was designed and developed for continuous CO measurement via analyzing and processing arterial pulse waves.

RESULTS

Quantitative evaluation of developed CO estimation system was performed using 7 signals. It showed that it has an acceptable average error of (6.5%) in estimating CO. In addition, this system has the ability to consistently estimate this parameter and to provide a CO versus time curve that assists in tracking changes of CO. Moreover, the system provides such curve for systolic blood pressure, diastolic blood pressure, average blood pressure, heart rate and stroke volume.

CONCLUSION

Evaluation of the results showed that the developed system is capable of accurately estimating CO. The curves which the system provides for important parameters may be valuable in monitoring hemodynamic status of high-risk surgical patients and critically ill patients in Intensive Care Units (ICU). Therefore, it could be a suitable system for monitoring hemodynamic status of critically ill patients.

Hemodynamic effects of orally administered delta-ALA during radical prostatectomy

PURPOSE

We investigated hemodynamics in patients receiving delta-Aminolevulinic acid (delta-ALA) to visualize tumor margins prior to radical retro pubic prostatectomy.

PATIENTS

Twenty patients undergoing elective open radical retro pubic prostatectomy (RRP).

METHODS

Cohort observational study. Ten patients receiving 20 mg/kg of delta-ALA orally prior to surgery (delta-ALA) and 10 patients undergoing RRP without the application of delta-ALA served as a retrospectively matched cohort (CONTROL).

MEASUREMENTS

Changes in heart rate (HR), mean arterial blood pressure (MAP), and functional hemodynamic parameters were assessed by electrocardiogram, non-invasive and invasive blood pressure monitoring plus transcardiopulmonary thermodilution.

RESULTS

Patients of both groups did not differ in means of age, body mass index, or ASA classification. During surgery, HR and MAP did not differ significantly between both groups. Also, the amount of IV crystalloids and colloids did not differ significantly. In contrast, the amount of vasopressor necessary to maintain MAP within the target range of 70-90 mmHg was significantly higher in delta-ALA when compared to CONTROL (0.08 ± 0.04 μg/kg/min (delta-ALA) vs. 0.03 ± 0.02 μg/kg/min (CONTROL); P < 0.01). Immediately after surgery, patients of delta-ALA showed a significantly higher heart rate (82 ± 18 min(-1) vs. 67 ± 9 min(-1); P < 0.05) compared to patients of CONTROL. Cardiac index, global end-diastolic volume index, and extravascular lung water index were significantly higher after surgery, when compared to baseline values (P < 0.05).

CONCLUSIONS

Orally administered delta-ALA prior to open radical prostatectomy induces hemodynamic instability in the perioperative period requiring vasopressor support. Further, an increase of extravascular lung water points toward an increased vascular permeability induced by delta-ALA.

Cardiac output measurement using an ultrasound dilution method: a validation study in ventilated piglets

OBJECTIVE

To assess agreement between a new method of cardiac output monitoring, using ultrasound dilution technology and ultrasound transit time-based measurement of pulmonary blood flow in a piglet model.

DESIGN

Prospective, experimental juvenile animal study.

SETTING

Animal laboratory of a university hospital.

SUBJECTS

Nine random-bred piglets.

INTERVENTIONS

After the animals received general anesthesia, we placed intravascular arterial and central venous catheters with the tip positioned in the abdominal aorta and the right atrium, respectively. The catheters were connected to the ultrasound dilution cardiac output monitor. An ultrasound transit time perivascular flow probe was positioned around the common pulmonary artery and served as the standard reference measurement. Cardiac output was manipulated during the experiment by creating hemorrhagic hypotension. Ultrasound dilution cardiac output was measured intermittently with injection volumes of 0.5 mL/kg and 1.0 mL/kg of isotonic saline at body temperature.

MEASUREMENTS AND MAIN RESULTS

Ultrasound dilution cardiac output (Q) measurement was compared with pulmonary blood flow (Q). Bias, defined as Q minus Q, was calculated for each measurement. Mean bias with standard deviation was calculated for measurements with volumes of injected saline, 0.5 mL/kg and 1.0 mL/kg, and compared using the Mann-Whitney U test. Mean bias (sd) between Q and Q was 0.040 (0.132) and 0.058 (0.136) L/min for measurement with 0.5 mL/kg and 1.0 mL/kg of isotonic saline, respectively (no statistically significant difference).

CONCLUSIONS

Ultrasound dilution cardiac output measurement is reliable in piglets with the use of a small volume of a nontoxic indicator (isotonic saline).

Noninvasive cardiac output determination: broadening the applicability of hemodynamic monitoring

Although cardiac output (CO) monitoring is usually only used in intensive care units (ICUs) and operating rooms, there is increasing evidence that CO should be determined and optimized as early as possible, even before admission to the ICU, in the care of hemodynamically compromised patients. A variety of different minimally or noninvasive CO determination techniques have been developed, but not all of them are suitable for early hemodynamic monitoring outside the ICU. In this review, the different available methods for CO monitoring are presented and their potential for early hemodynamic assessment is discussed.

[Pulmonary artery catheter in anaesthesiology and intensive care medicine]

The indication for the use of the pulmonary artery catheter (PAC) in high-risk patients is still a matter of discussion. Observational studies suggested that the use of the PAC did not result in decreased mortality but may even lead to increased mortality and morbidity. Therefore, a number of randomized controlled trials have been performed throughout recent years in patients suffering from sepsis/ARDS, congestive heart failure, multi-organ failure and those undergoing high-risk non-cardiac surgery. The majority of recent randomized studies failed to demonstrate any benefit of the PAC with respect to mortality and morbidity. However, the use of the PAC was also regularly not associated with an increase in morbidity and/or mortality. This review gives an overview of measurement parameters obtained by the current generation of PACs, alternatives to the PAC and recent studies on the use of the PAC in clinical practice.