Journal of clinical monitoring and computing
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J Clin Monit Comput · Dec 1999
The influence of left lateral position on cardiac output changes after head up tilt measured by impedance cardiography.
The value of the impedance cardiography (IC) method for measuring cardiac output (CO) with the subject in the left lateral position has not yet been established. We compared the CO after a 30 degrees head-up tilt with the subjects in the supine and left lateral position. ⋯ When using the IC method of SV measurement, the absolute value of the CI changes when moving from the supine to lateral positions. It is not clear whether this change is physiologic or an artifact of the measurement technique. However, changes in CI in response to a 30 degree head up tilt are the same in either position. We conclude that changes in CI can be measured with the IC method in the lateral position.
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J Clin Monit Comput · Dec 1999
Comparative Study Clinical TrialA comparison of lithium dilution cardiac output measurements made using central and antecubital venous injection of lithium chloride.
We have previously described an indicator dilution technique of measuring cardiac output in which lithium chloride is injected as a bolus via a central venous catheter and cardiac output derived from the arterial lithium dilution curve recorded from a lithium-selective electrode, which we have developed for this purpose. It would be an advantage if the lithium could be injected via the basilic vein (in the antecubital fossa) in those patients who do not need central venous catheterisation for other reasons. We have therefore compared cardiac output measurements made using these two routes of lithium chloride administration. ⋯ Injection of lithium chloride via the basilic vein in the antecubital fossa allows accurate lithium dilution cardiac output measurements to be made in patients who do not have central venous catheters in place.
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J Clin Monit Comput · Dec 1999
Comparative Study Clinical TrialA comparison of pulse oximetry and near infrared spectroscopy (NIRS) in the detection of hypoxaemia occurring with pauses in nasal airflow in neonates.
The aim of this study was to compare the ability of NIRS and pulse oximetry to detect changes in cerebral oxygenation occurring in response to a pause in nasal airflow (PNA). ⋯ We conclude that both techniques are sensitive to changes in oxygenation during PNA. Small changes in cerebral Hbdiff and arterial SpO2 do not always correlate for physiological reasons. A change in Hbdiff of >0.3 micromol 100 g brain(-1) is likely to be physiologically significant and is associated with a change in SpO2 of 12%.
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J Clin Monit Comput · Dec 1999
Clinical TrialValidation of the Natus CO-Stat End Tidal Breath Analyzer in children and adults.
The performance of a point-of-care, noninvasive end tidal breath carbon monoxide analyzer (CO-Stat End Tidal Breath Analyzer, Natus Medical Inc.) that also reports end tidal carbon dioxide (ETCO2) and respiratory rate (RR), was compared to established, marketed (predicate) devices in children (n = 39) and adults (n = 48) who are normal or at-risk of elevated CO excretion. ⋯ We conclude that in a clinical environment the Natus CO-Stat End Tidal Breath Analyzer performs at least as well as predicate devices for the measurements of ETCOc, ETCO2, and RR.
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J Clin Monit Comput · Dec 1999
Autoregulation in a simulator-based educational model of intracranial physiology.
To implement a realistic autoregulation mechanism to enhance an existing educational brain model that displays in real-time the cerebral metabolic rate (CMRO2), cerebral blood flow (CBF), cerebral blood volume (CBV), intracranial pressure (ICP), and cerebral perfusion pressure (CPP). ⋯ The autoregulated brain model, with incorporated CO2 responsivity and a variable oxygen extraction, automatically produces changes in CVR, CBF, CBV, and ICP consistent with literature reports, when run concurrently with a METI full-scale patient simulator (Medical Education Technologies, Inc., Sarasota, Florida). Once the model is enhanced to include herniation, vasospasm, and drug effects, its utility will be expanded beyond demonstrating only basic neuroanesthesia concepts.