Chest
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Review Randomized Controlled Trial Clinical Trial
Continuous lateral rotational therapy and nosocomial pneumonia.
The adverse effects of prolonged immobility are due primarily to gravitational effects on blood flow and ventilation, impairment of the normal mucociliary escalator and possibly an increase in extravascular lung water. However, CLRT theoretically should reverse these abnormalities. The sequence of events that culminate in LRTI or pneumonia is unclear; however, low tidal volumes, increased extravascular lung water and the accumulation of bronchopulmonary secretions may lead to atelectasis, a well-known precursor of pneumonia. ⋯ The prevention of pneumonia and more rapid transfer from the ICU should offset the additional expense of a specialized bed. The data suggest that a multicenter study with accrual of a large number of patients to evaluate this form of therapy in a prospective, randomized study is necessary. If the hypothesis that CLRT decreases the incidence of nosocomial pneumonia in the ICU is proven, the impact on critical care in the 90s would be substantial.
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An 80-year-old man remained conscious due to vigorous deep breathing during 100 s of ventricular arrest which was recorded on a Holter ECG. Arterial blood flow is considered to have been maintained by changes in intrathoracic pressure produced by deep respiratory movements. This case may represent a pure model of the "thoracic pump" mechanism.
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During continuous positive pressure ventilation (CPPV), mean airway pressure and lung volume will be influenced both by the tidal volume (VT) employed and the amount of positive end-expiratory pressure (PEEP). The effect of varying levels of CPPV on PaO2 and cardiac output (Q) has been previously assessed by adjusting the level of PEEP at constant VT. This study examined the influence of a 200-ml reduction in VT, at a constant PEEP of 15 cm H2O, on the PaO2 and Q of 21 patients with adult respiratory distress syndrome (ARDS). ⋯ Cst increased with VT reduction (+ 3.1 +/- 1.8 ml/cm H2O). There was only a modest correlation (r = +0.42, p = 0.06) between delta Q percent and delta Cst following VT reduction. VT reduction at high level PEEP may yield a significant improvement in Q and net O2 delivery, but the degree of hemodynamic improvement is variable and is not reliably predicted noninvasively by measurement of Cst.
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Comparative Study
Thoracocardiography. Part 2: Noninvasive measurement of changes in stroke volume; comparisons to impedance cardiograph.
The thoracocardiograph (TCG) displays cardiac oscillations transmitted to the external surface of the thorax through inductive plethysmographic transducers placed transversely around the thorax near or about the xiphoid process. Such signals, with the appearance of ventricular volume curves, were used to compute changes of stroke volume (SV) and cardiac output (CO) in normal subjects. Their values were compared with changes of SV and CO measured with the impedance cardiograph (IC). ⋯ MAST suit application increased CO measured with TCG but not with IC. Neither TCG nor IC revealed alteration of CO with nasal CPAP up to 10 cm H2O despite a rise in functional residual capacity (FRC) level of 870 ml. This investigation indicates that TCG has promise as a near continuous, noninvasive monitor of SV and CO in normal subjects if postural axis is fixed and does not require highly trained personnel or labor-intensiveness for its operation.
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The adult respiratory distress syndrome (ARDS) is a form of diffuse lung injury associated with multiple risk factors. Patients with severe hypoxemia who meet blood gas criteria defined by the extracorporeal membrane oxygenation trial (ECMO) of 1974 to 1977 have a reported survival of 11 percent. The reported survival has remained unchanged for 15 years despite numerous technologic advances. ⋯ Fifty-one of these patients met ECMO blood gas criteria and 23 (45 percent) survived (p less than 0.001 vs ECMO trial). No obvious differences in etiology, APACHE II score, organ system failure, or the incidence of sepsis was found between survivors and nonsurvivors. We conclude that survival of ARDS patients who met ECMO blood gas criteria in our institution is higher than that previously reported from both other centers and our own hospital.