The American review of respiratory disease
-
Am. Rev. Respir. Dis. · Jan 1992
Observer agreement for respiratory signs and oximetry in infants hospitalized with lower respiratory infections.
To determine observer agreement for a clinical score and oximetry in lower respiratory infection in children less than 2 yr of age, a convenience sample of 56 infants hospitalized with bronchiolitis or pneumonia was assessed independently by two observers. A total of 12 infants had chronic lung disease of prematurity or congenital heart disease. Infants in whom oxygen supplementation could not be discontinued for at least 5 min were excluded. ⋯ The median difference between oximetry readings was 1. The correlation coefficient between total score and oximetry was -0.04. The limited agreement for clinical signs makes comparison of patient illness severity between studies difficult.(ABSTRACT TRUNCATED AT 250 WORDS)
-
Am. Rev. Respir. Dis. · Jan 1992
Metabolism of exogenously administered surfactant in the acutely injured lungs of adult rabbits.
Acute lung injury was induced in adult rabbits with a subcutaneous injection of N-nitro-so-N-methylurethane (NNNMU). Clearance of saturated phosphatidylcholine (Sat. PC) from a treatment dose of exogenous surfactant (100 mg/kg) in the injured lungs of these rabbits was similar to normal, control rabbits when measured 24 h after treatment. ⋯ In vivo functional studies of these aggregates were performed by intratracheal injection into surfactant-deficient preterm rabbits. Large aggregates from normal adult rabbits given surfactant had superior functional properties than did the surfactant used for treatment alone, which in turn was better than large aggregates isolated from NNNMU-injured rabbits treated with surfactant. This indicates that the alveolar environment influenced the function of the exogenously administered surfactant differently in normal and injured rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)
-
Am. Rev. Respir. Dis. · Jan 1992
Clinical TrialProportional assist ventilation. Results of an initial clinical trial.
The response to proportional assist ventilation (PAV) was tested in four normal subjects during heavy exercise and in five ventilator-dependent patients recovering from assorted medical disorders. The apparatus consisted of a rolling-seal piston coupled to a motor that generated pressure in proportion to inspired flow and inspired volume, with the gains adjusted such that the proportionality between airway pressure (Paw) and instantaneous patient-generated pressure (Pmus) was approximately 1:1 (i.e., machine-amplified patient effort by a factor of 2). Normal subjects responded to PAV by decreasing their own effort, as judged from esophageal pressure, such that the changes in ventilation and breathing pattern were rather small (VE: 64.8 +/- 3.6 during PAV versus 56.0 +/- 4.3, p less than 0.01; VT: 2.39 +/- 0.24 versus 2.02 +/- 0.17, p less than 0.05; f: 27.5 +/- 1.9 versus 28.0 +/- 2.2, NS). ⋯ After a period of observation during synchronized intermittent mechanical ventilation (SIMV) the patient was switched to PAV and maintained on it for 1 to 3 h. No patient had to be replaced on SIMV because of discomfort or deterioration in any of the monitored variables. During PAV peak airway pressure was less than half the value observed with the IMV breaths (16.6 +/- 2.4 versus 35.4 +/- 3.4 cm H2O, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
-
Am. Rev. Respir. Dis. · Jan 1992
Proportional assist ventilation, a new approach to ventilatory support. Theory.
The relation between inspiratory effort and ventilatory return (flow and volume) is usually abnormal in patients who require ventilatory support because of respiratory distress. Although all available support methods provide the patient with greater ventilation than would obtain with the same effort while unsupported, the relation between instantaneous effort and ventilatory consequences is not normalized. ⋯ This approach is implemented by monitoring the instantaneous rate (V) and volume (V) of gas flow from ventilator to patient and causing applied pressure (P) to change according to the equation of motion [P = f1(V) + f2(V)], where f1 and f2 are appropriately selected functions for the relation between pressure and volume (elastic assist) and pressure and flow (resistive assist). There are several potential advantages to this approach: (1) greater comfort; (2) reduction of peak airway pressure required to sustain ventilation and, hence, the potential for avoiding intubation; (3) less likelihood of overventilation; (4) preservation and enhancement of patient's own reflex, behavioral, and homeostatic control mechanisms since the ventilator essentially becomes an extension of the patient's own muscles; and (5) improved efficiency of negative pressure ventilation.