News HIV/AIDS News & Information - Part 7

09 Jan

Respiratory Acoustic Impedance in Left Ventricular Failure: Results

In Figure 1, the mean resistance and reactance curves obtained in normal subjects (group N), cardiac patients (group C), and asthmatic patients (group A) can be compared. The latter group was characterized by severe airway obstruction as shown by the functional values displayed in the last line of Table 2. In group N, resistance was constant or slightly decreased from 10 to 20 Hz and increased monotonously above 20 Hz. In both patient groups (C and A) resistance decreased from 10 to 20 Hz; this decrease was much more pronounced in group A than in group C. This abnormal frequency dependence of resistance was associated with a downward shift of the reactance curves and an increased resonant frequency (fRES = 27.1 ±9.8 Hz in group C, 38.3±10.6 Hz in group A vs 13.1 ±4.9 Hz in group N, p<0.001 for both N/A and N/C comparisons). The mean values and SDs of the Zrs indices are shown in Figure 2 for each group. Groups C and A were characterized by the following Zrs modifications with respect to group N: (1) an increase in average resistance, predominating at low frequencies; (2) a more negative slope of resistance at low frequencies; and (3) a decrease in average reactance both at low and high frequencies. For each Zrs index, group C lay between groups N and A. Continue Reading »

08 Jan

Respiratory Acoustic Impedance in Left Ventricular Failure: Hemodynamic Measurements

Respiratory Acoustic Impedance in Left Ventricular Failure: Hemodynamic MeasurementsHemodynamic Measurements
Right heart catheterization was performed by the flow-directed balloon-tipped catheter technique. The pressures were measured in the supine position. The hydrostatic zero was set at 5 cm below the sternal angle. Prior to use, the pressure transducer (Trantec, Bentley) was calibrated against a mercury manometer. Cardiac output was determined by the thermodilution technique (78231C cardiac output computer, Hewlett-Packard).
Lung Function Tests
Lung volumes and Raw were measured with a pressure-corrected body plethysmograph (Pulmorex SAB, Fenyves & Gut), and respiratory flow with a Fleisch no. 3 pneumotachograph. Continue Reading »

07 Jan

Respiratory Acoustic Impedance in Left Ventricular Failure: Patients and Methods

All patients had a Swan-Ganz catheter inserted for guiding therapy. All had a pulmonary capillary wedge pressure (Pw) >20 mm Hg. One acute and two follow-up studies were performed. During the acute study, each patient had 2 to 6 Zrs measurements made in a semirecumbent position, the first of those made within the 24 h following the insertion of the Swan-Ganz catheter (Table 1). Pw was recorded on paper and measured at end-expiration: (1) within minutes before each Zrs determination and (2) at least once every 2 h between each Zrs determination. Early and late follow-up studies were performed, respectively, three weeks (14/14 patients) and five to 20 weeks (mean 13 ±3.8 weeks, 12/14 patients) after the first investigation. Follow-up studies included Zrs measured in a semirecumbent position as well as standard lung function tests (Table 2). Continue Reading »

06 Jan

Respiratory Acoustic Impedance in Left Ventricular Failure

Respiratory Acoustic Impedance in Left Ventricular FailureAlterations in lung mechanics have been shown to L occur early in pulmonary vascular congestion. In particular, a reversible decrease in lung compliance has been observed in animal and in man during the phase of rapid rise in left ventricular filling pressure. These modifications appear before accumulation of interstitial fluid and therefore precede clinical signs of left ventricular failure. Similarly, a reversible increase in small airways resistance has been described in dogs when increasing left atrial pressure moderately. Continue Reading »

05 Jan

Laryngeal Complications of Prolonged Intubation: Conclusion

Initial intubation tended to result from an exacerbation of either chronic respiratory or cardiac disease. Few young, previously healthy patients with acute, catastrophic respiratory failure were included. The effect of these demographic characteristics on our findings were probably minimal, though, because age and serum albumin (an indirect marker of chronic illness) were not significantly associated with either adverse effects or laryngeal pathology. Consequently, our results should be applicable to younger patients intubated for ARDS. There is a possibility for observational bias resulting from a series of consecutive cases being studied by a single observer. The inability to photograph the larynxes of the study patients prevented quantification and independent measurement of laryngeal damage, but the strictly defined laryngeal damage classifications minimized any such bias. Continue Reading »

04 Jan

Laryngeal Complications of Prolonged Intubation: Outcome

Laryngeal Complications of Prolonged Intubation: OutcomeThe TLI-induced laryngeal dysfunction may predispose patients to aspiration postextubation. Whited has described bilateral symmetric vocal cord paresis with paramedian positioning postextubation, possibly due to edema, ulcerations and inflammation of the larynx limiting motor function. The translaryngeal tube may also cause a sensory denervation of the larynx and hypopharynx by constant pressure. Sensory denervation compromises normal protective laryngeal mechanisms and eliminates the reflex arc which mediates phasic laryngeal abductor- and pharyngeal muscle function. Lengthy interruption of this reflex arc in animals results in prolonged loss of activity of these laryngeal dilating muscles. Using an insensitive assessment tool, we found that 24 percent of our patients did not have a gag reflex at initial laryngoscopy. Cardiopulmonary arrest may have occurred secondary to aspiration in one of these patients. This indicates pharyngeal and laryngeal sensory deficits are common postextubation and potentially serious. Fortunately, as Whited found with vocal cord mobility, the gag reflex gradually returned to normal over several weeks in our study population. Continue Reading »

03 Jan

Laryngeal Complications of Prolonged Intubation: Mucociliary clearance mechanisms

The normal mucociliary clearance mechanisms will carry bacteria entering the tracheal stoma cephalad, towards the larynx previously damaged by TLI. Because our initial laryngoscopies were performed up to 24 hours after tracheostomy, secondary bacterial infection of the injured larynx might have exacerbated pre-existing laryngeal pathology. These points suggest that abrasion of the larynx by the tracheal tube causes the initial injury, but the severity of laryngeal pathology appears to be determined by nonmechanical factors, possibly tracheostomy related superinfection. Observations in dogs with tracheal tubes sutured into the larynx similarly showed tube placement initiated but did not determine the severity of laryngeal damage. Continue Reading »

Pages: Prev 1 2 3 4 5 6 7 8 9 10 ... 182 183 184 Next

© 2008 HIV/AIDS News & Information