Journal of clinical monitoring
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The purposes of this study were to evaluate the clinical utility of a colorimetric end-tidal CO2 (ETCO2) detector in confirming proper endotracheal intubation in patients requiring emergency intubation, to determine if this new device can be used as an adjunct to judge the effectiveness of cardiopulmonary resuscitation (CPR), and to determine whether the device can predict successful resuscitation from cardiopulmonary arrest. We studied prospectively 110 patients requiring emergency intubation for either respiratory distress (53 patients) or cardiopulmonary arrest (57 patients) by recording the color range of the indicator after the initial intubation. In patients who suffered a cardiopulmonary arrest, the color range was also recorded during CPR after the endotracheal tube was confirmed to be in the tracheal position and perfusion optimized, and at the moment CPR was stopped. ⋯ A low ETCO2 color range in 19 patients undergoing CPR was interpreted as low cardiac output and prompted the physicians to attempt to increase perfusion. Of the patients who underwent CPR, no patient whose ETCO2 level remained less than 2% was successfully resuscitated. Those patients who had an ETCO2 level greater than or equal to 2% had a significantly higher incidence of successful resuscitation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study
End-tidal carbon dioxide pressure in neonates and infants measured by aspiration and flow-through capnography.
In 25 anesthetized, intubated, artificially ventilated, and paralyzed healthy neonates and infants, end-tidal PCO2 (PETCO2) measured by remote multiplexed mass spectrometry was 1.86 +/- 1.58 mm Hg lower than arterial PCO2 (PaCO2). PETCO2 measured by a flow-through cuvette was 1.02 +/- 1.64 mm Hg lower than PaCO2. The difference between the two methods of capnography was not significant. ⋯ Values for PETCO2 obtained with flow-through capnography changed -0.17 +/- 2.17 mm Hg from baseline after 15 minutes. In both methods, the changes from baseline in PETCO2 over time were not significant. These results suggest that both methods of capnography studied are reliable and may be used safely in neonates despite high sample flow rates and added apparatus dead space (0.6 ml for tracheal tubes less than or equal to 4.0 mm OD and 4.9 ml for tracheal tubes greater than 4.0 mm OD).
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We quantitatively compared the acoustic characteristics of passage of an endotracheal tube into the trachea with those of passage into the esophagus by analyzing the loudness and frequency (90% spectral edge frequency) of the sounds when auscultated at the suprasternal notch. We found that there was a significant difference (P less than 0.01) in maximum loudness between esophageal and tracheal intubations (0.15 +/- 0.05 and 0.25 +/- 0.06 V, respectively). However, there were no significant differences between the 90% spectral edge frequencies. We conclude that, without directly comparing the maximal acoustic amplitude of tracheal intubation with that of esophageal in each patient, one cannot distinguish between the two types of intubation by means of auscultation.
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Since pulse oximetry is now an ASA standard for intraoperative monitoring, we sought to determine the intraoperative failure rate for this device. We prospectively evaluated the intraoperative failure rate of our pulse oximeters at the four University of Washington Hospitals (University of Washington Medical Center, Veterans Affairs Medical Center [VAMC], Children's Hospital and Medical Center, and Harborview Medical Center [HMC]) recorded from April 1989 to August 1989. We defined failure as the inability to obtain any oximetry reading for a cumulative period of more than 30 minutes during any anesthetic procedure after all equipment malfunctions had been eliminated. ⋯ When the device did fail in a patient, it did not function for 32% of the mean anesthesia time. We conclude that the intraoperative use of the pulse oximetry can provide information about blood oxygen saturation in most patients. However, in approximately 1% of the patients we studied in the operating room, mechanically functioning pulse oximeters failed to provide readings of blood oxygen saturations during routine operative use.
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Epinephrine is routinely used as a marker for intravascular injection during administration of regional anesthesia. The cardiovascular response of patients on beta-blockers to such a test dose has been reported to be unpredictable. ⋯ The lowest heart rate recorded was 28 beats/min. We conclude that, in middle-aged beta-blocked men, intravenous injection of a standard epinephrine-containing test dose will predictably cause significant hypertension followed by marked bradycardia.