Journal of clinical monitoring and computing
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'Standard' or 'extracellular' base excess (SBE) is a modified calculation using one-third the normal hemoglobin concentration. It is a 'CO(2)-invariant' expression of meta- bolic acid-base status integrated across interstitial, plasma and erythrocytic compartments (IPE). SBE also integrates conflicting physical chemical influences on metabolic acid-base status. ⋯ The impact of assum- ing fixed relationships between arterial and venous acid-base and saturation values in sepsis, anaemia and in differing shock states is unclear. Clinicians are also unlikely to accept that unique, accurate IPE volume determinations can be derived from a single set of blood gas and biochemistry results. Nevertheless, volume determinations aside, the tool is likely to become a valuable addition to the diagnostic armamentarium.
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J Clin Monit Comput · Dec 2011
Impact of central hypovolemia on photoplethysmographic waveform parameters in healthy volunteers. Part 1: time domain analysis.
Our study sought to explore changes in photoplethysmographic (PPG) waveform param- eters, during lower body negative pressure (LBNP) which simulated hypovolemia, in spontaneously breathing volunteers. We hypothesize that during progressive LBNP; there will be a preservation of ear PPG parameters and a decrease in finger PPG parameters. ⋯ PPG waveform parameters may prove to be sensitive and specific as early indicators of blood loss. These PPG changes were observed before profound decreases in arterial blood pressure. The relative sparing of central cutaneous blood flow is consistent with the increased parasympathetic innervation of central structures.
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J Clin Monit Comput · Dec 2011
Pulse oximetry saturation patterns detect repetitive reductions in airflow.
Postoperative patients exhibiting signs or symptoms of obstructive sleep apnea (OSA) have been identified to be at increased risk for respiratory compromise. One of the key markers associated with OSA is repetitive reductions in airflow (RRiA). A real-time pulse oximeter saturation pattern recognition algorithm (OxiMax SPD™ intended for adult in-hospital use only) designed to detect specific signatures in the SpO(2) trend associated with RRiA may provide caregivers early indication of its presence so they can treat the patient appropriately. The purpose of our study was to test the performance of saturation pattern detection (SPD) in a clinical study targeting subjects with a high prevalence of RRiA. ⋯ The real-time SPD algorithm was able to detect episodes of RRiA in sleep lab patients with a high degree of sensitivity and specificity.
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J Clin Monit Comput · Dec 2011
Using the inflating syringe as a safety valve to limit laryngeal mask airway cuff pressure.
Hyperinflation of the laryngeal mask airway (LMA) cuff is thought to be the etiology underlying many of the complications associated with the use of this device. Until now, there has not been a clinically acceptable method (besides direct measurement) to assure that the cuff pressure is maintained less than the recommended maximum value of 44 mm Hg (60 cm H(2)O). ⋯ When using specific combinations of syringes, LMA sizes and inflation pressures, these data demonstrate an efficient, practical and easy method to achieve an initial equilibrium recoil LMA cuff pressure that is less than, or very near to, the recommended upper safe limit of 44 mm Hg.
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J Clin Monit Comput · Dec 2011
Capability of a new paediatric oesophageal Doppler monitor to detect changes in cardiac output during testing of external pacemakers after cardiac surgery.
The Cardio QP™ oesophageal Doppler monitor measures the velocity time integral of the blood flow in the descending aorta. Based on system integrated normograms of the aortic cross-sectional area of a paediatric population, the cardiac output is calculated and displayed. ⋯ The Cardio QP™ seems to be capable of detecting slight changes in cardiac output.