Chest
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We studied the correspondence between fluctuations of esophageal pressure measured before and after placement of a nasogastric (NG) tube in six normal volunteers. Flow, airway pressure, and esophageal pressure data from at least 20 breaths were recorded in seven ventilatory conditions in two body postures: 0 degree (supine) and 60 degrees (upright). The conditions studied included normal quiet breathing, added resistance, reduced compliance, increased frequency, increased tidal volume, continuous positive airway pressure, and volume-cycled ventilation with positive pressure. ⋯ We calculated average VT, TI, and esophageal pressure fluctuation (delta Pes) for the matched breaths from each subject during every condition. The delta Pes values with and without NG tube were not statistically different in any tested condition (p > 0.05). Our data indicate that the presence of an NG tube does not invalidate the accuracy of delta Pes measurements made using a well-positioned balloon catheter in the tested conditions.
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Optimal myocardial protection during cardiac surgery with ischemic arrest is predicated on among other variables, homogeneous cardioplegia distribution. Contrast echocardiography has been shown to provide information regarding the intramyocardial distribution of cardioplegia solution. To test the hypothesis that information regarding cardioplegia distribution derived from contrast echocardiography may be associated with immediate clinical outcome after cardiac surgery, data from 21 patients were examined retrospectively. ⋯ Contrast echocardiography makes possible an evaluation of the intensity and distribution of contrast-enhanced cardioplegia delivery and we believe the efficacy of intraoperative myocardial protection. Although low preoperative ejection fraction is a known predictor of poor immediate postoperative outcome following cardiac surgery, not all patients with low preoperative ejection fractions require inotropic support postoperatively. Our results suggest that monitoring cardioplegia distribution with contrast echocardiography may offer insight for better patient stratification based on intraoperative myocardial protection in patients with low ejection fraction. We believe a more extensive evaluation of this relationship should be pursued in a prospective manner.
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The physiologic dead space/tidal volume ratio (VD/VT) at rest and during exercise is a sensitive measurement of gas exchange that reflects matching of ventilation to perfusion, but requires an invasive measurement for its calculation. Determining VD/VT noninvasively uses estimations of arterial PCO2 based on the end-tidal PCO2. To further standardize incremental cardiopulmonary exercise testing, we compared actual VD/VT with estimated VD/VT values in 35 patients referred for evaluation of dyspnea. ⋯ Actual VD/VT identified 18 (69 percent) patients as abnormal vs 13 (50 percent) so identified by VD/VT(J). With exercise, VD/VT(J) was no better than VD/VT(ET). We conclude that during incremental exercise in a patient population, methods for estimating VD/VT progressively underestimate this measurement; and therefore, "normal" estimated VD/VT values may fail to identify underlying pulmonary and/or pulmonary vascular impairment.
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A man with traumatic thoracic duct injury developed a lymphocele causing upper airway obstruction. Despite drainage of the chylothorax, tracheal compression persisted due to a thoracic duct tear. Operative repair of the tear resulted in resolution of the airway obstruction.
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The effect of continuous positive airway pressure (CPAP) applied via a mask covering the nose and mouth (oral-nasal CPAP = ONCPAP) on obstructive sleep apnea (OSA) was studied in ten male patients with a mean (+/- SD) age of 48.1 +/- 11.1 years who could not tolerate nasal CPAP (NCPAP) due to nasal congestion. Using ONCPAP at pressures of 11.0 +/- 4.5 cm H2O, the apnea+hypopnea index was reduced from 58.3 +/- 22.3 (baseline night) to 5.2 +/- 1.6 events per hour (ONCPAP night) (p < 0.001). Five of these patients were studied on a subsequent night with a dual chamber mask allowing separate measurement of nasal and oral flow. ⋯ In a separate study, we compared the effects of a therapeutic level of CPAP pressure (12.8 +/- 2.5 cm H2O) applied through a nasal mask (NCPAP) and ONCPAP in a different group of patients (mean age 60 +/- 14.6 years) with moderate to severe OSA using NCPAP on a long-term basis. The apnea-hypopnea indexes on NCPAP nights (7.2 +/- 3.5) and ONCPAP nights (7.6 +/- 4.9 events per hour of sleep) were very similar. We conclude that ONCPAP may be a reasonable treatment alternative in patients who cannot tolerate NCPAP due to nasal congestion and that the pressure required to maintain upper airway patency may be similar to the level required using NCPAP.