Journal of clinical monitoring and computing
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J Clin Monit Comput · Feb 2015
The effects of cardiac output and pulmonary arterial hypertension on volumetric capnography derived-variables during normoxia and hypoxia.
The aim of this study was to test the effect of cardiac output (CO) and pulmonary artery hypertension (PHT) on volumetric capnography (VCap) derived-variables. Nine pigs were mechanically ventilated using fixed ventilatory settings. Two steps of PHT were induced by IV infusion of a thromboxane analogue: PHT25 [mean pulmonary arterial pressure (MPAP) of 25 mmHg] and PHT40 (MPAP of 40 mmHg). ⋯ The elimination of CO2 per breath decreased by 7% in PHT40 and by 12% in COdown but increased only slightly with COup. Dead space variables did not change significantly along the protocol. At constant ventilation and body metabolism, pulmonary artery hypertension and decreases in CO had the biggest effects on the SnIII of the volumetric capnogram and on the elimination of CO2.
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J Clin Monit Comput · Feb 2015
Effect of mild hypocapnia on hemodynamic and bispectral index responses to tracheal intubation during propofol anesthesia in children.
The purpose of this study was to investigate the effect of mild hypocapnia on hypertension and arousal response after tracheal intubation in children during propofol anesthesia. Forty-four children, American Society of Anesthesiologists physical status I-II patients, aged 3-9 years were randomly allocated to either the normocapnia group [end-tidal carbon dioxide tension (ETCO2=35 mmHg, n=22)] or the hypocapnia group (ETCO2=25 mmHg, n=22). Anesthesia was induced with propofol 2.5 mg/kg. ⋯ The mean value±SD of ΔBIS was 5.7±5.2 and 7.4±5.5 in the normocapnia and hypocapnia groups, respectively, without any intergroup difference. This study showed that mild hypocapnia did not attenuate hemodynamic and BIS responses to tracheal intubation in children during propofol anesthesia. Our results suggested that hyperventilation has no beneficial effect on hemodynamic and arousal responses to tracheal intubation in children.
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J Clin Monit Comput · Feb 2015
Fluid responsiveness is about stroke volume, and not pulse pressure Yogi: the power of Doppler fluid management and cardiovascular monitoring.
Fluid infusion is one of the most common critical care interventions, yet approximately 50% of all fluid interventions are unnecessary and potentially harmful. An improved approach to identification of fluid responsiveness is of clinical importance. Currently fluid responsiveness is most frequently identified by blood pressure (BP) measurements or a surrogate. ⋯ This letter reminds clinicians of the physiologic limitations of PPV as a measure of fluid responsiveness, even when combined with physiologic challenges, and recommends the replacement of BP with SV measurements. The combination of accurate Doppler measurement of SV and physiologic challenges, as Dr Pinsky recommends, is a physiologically rational and effective approach to identification of fluid responsiveness with established evidence. The direct monitoring of SV and SV changes has the potential to improve a long standing critical care and anaesthetic conundrum; when to give fluid and when to stop.
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J Clin Monit Comput · Dec 2014
Clinical TrialAnalysis of plethysmographic waveform changes induced by beach chair positioning under general anesthesia.
During shoulder surgery, patients typically are placed in the beach chair position. In rare cases, this positioning has resulted in devastating outcomes of postoperative cerebral ischemia (Cullen and Kirby in APSF Newsl 22(2):25-27, 2007; Munis in APSF Newsl 22(4):82-83, 2008). This study presents a method to noninvasively and continuously hemodynamically monitor patients during beach chair positioning by using the photoplethysmograph signal recorded from a commercial pulse oximeter. ⋯ The PPG was more accurate at monitoring the change to beach chair position than blood pressure or heart rate. With vasoactive drugs, pulse-associated PPG oscillations decreased only with phenylephrine while respiration-associated oscillations did not change. Frequency domain analysis of the PPG signal may be a better tool than traditional noninvasive hemodynamic parameters at monitoring patients during beach chair position surgery.