Anesthesia and analgesia
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Anesthesia and analgesia · May 2016
Analysis of Transpulmonary Thermodilution Data Confirms the Influence of Renal Replacement Therapy on Thermodilution Hemodynamic Measurements.
Transpulmonary thermodilution (TPTD) is used frequently in the intensive care unit to determine cardiac index (CI), intrathoracic blood volume index (ITBVI), and extravascular lung volume index (EVLWI). Renal replacement therapy (RRT) influences TPTD results, but the underlying mechanisms are not completely understood. We hypothesized that RRT blood flow induces errors in TPTD measurements. ⋯ Analysis of TPTD data shows that thermodilution curve forms are modified with RRT, resulting in an erroneous calculation of thermodilution-derived hemodynamic parameters.
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Anesthesia and analgesia · May 2016
Capnographic Parameters in Ventilated Patients: Correspondence with Airway and Lung Tissue Mechanics.
Although the mechanical status of the lungs affects the shape of the capnogram, the relations between the capnographic parameters and those reflecting the airway and lung tissue mechanics have not been established in mechanically ventilated patients. We, therefore, set out to characterize how the mechanical properties of the airways and lung tissues modify the indices obtained from the different phases of the time and volumetric capnograms and how the lung mechanical changes are reflected in the altered capnographic parameters after a cardiopulmonary bypass (CPB). ⋯ In mechanically ventilated patients, the capnographic parameters from the early phase of expiration (SII and D2min) are linked to the pulmonary elastic recoil, whereas the effect of airway patency on SIII dominates over the lung tissue stiffness. However, severe deterioration in lung resistance or elastance affects both capnogram slopes.
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Anesthesia and analgesia · May 2016
Comparative StudyThe Accuracy of Temperature Measurements Provided by the Edwards Lifesciences Pulmonary Artery Catheter.
Pulmonary artery catheters (PACs) are frequently used for monitoring patient temperatures in the intensive care unit. Nevertheless, data regarding the accuracy of these measurements are lacking, and few data testify to the accuracy of temperatures recorded after the PAC has been in place for several days. The absolute values of such measurements are relevant for critical care because patient temperatures are often used as diagnostic criteria for sepsis and antibiotic therapy. We thus hypothesized that the Edwards Lifesciences PAC would accurately measure blood temperature. To test our hypothesis, we compared temperature measurements obtained from PACs inserted in patients for different lengths of time with measurements of a reference platinum resistance thermometer (PRT). ⋯ We conclude that temperature measurements obtained using the Edwards Lifesciences PACs are thus sufficiently accurate to be used for clinical temperature monitoring in critically ill patients.
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The nasopharynx is considered 1 of the 4 generally reliable core temperature measurement sites. But curiously, there is no consensus on how far past the nares to insert the probe. Insertion depth is likely to influence the accuracy of nasopharyngeal temperature measurements because probes near the nares will be cooled by ambient air; similarly, probes inserted too far may approach the airway and be cooled by ventilation gases. We thus determined the range of nasopharyngeal probe insertion depths that best approximate reference core temperature measured in the distal esophagus. ⋯ Any nasopharyngeal probe insertion depth between 10 and 20 cm well represents core temperature in adults having noncardiac surgery.
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Anesthesia and analgesia · May 2016
Comparative StudyThe Effects of Lidocaine on Central Respiratory Neuron Activity and Nociceptive-Related Responses in the Brainstem-Spinal Cord Preparation of the Newborn Rat.
Lidocaine is widely used in the clinical setting as a local anesthetic and antiarrhythmic drug. Although it has been suggested that lidocaine exerts inhibitory effects on the central and peripheral neurons, there are no reports on its effects on central respiratory activity in vertebrates. In this study, we examined the effects of lidocaine on respiratory rhythm generation and nociceptive response in brainstem-spinal cord preparations from the newborn rats. ⋯ Our findings indicate that lidocaine depressed nociception-related responses at lower concentrations than those that induced respiratory depression. Our report provides the basic neuronal mechanisms to support the clinical use of lidocaine, which shows antinociceptive effects with minimal side effects on breathing.