Biomedical subjects

P Duffty

Publications and source records attributed to P Duffty.

24 records · Page 2Linked to original sources

PubMed1983

Effects of a face mask and pneumotachograph on breathing in sleeping infants.

The effect of facial attachments on breathing was measured by respiratory induction plethysmography (RIP) during quiet sleep in 32 studies in 18 infants. The addition of a face mask plus pneumotachograph led to an increase in tidal volume (VT) (22.0 +/- 13.5%, p less than 0.01) during 5-min sleep studies when compared to measurements using RIP alone. Applying only the mask rim also led to an increase in VT (14.6 +/- 3.1%, p less than 0.05). A significant increase in VT was noted in 3 of 6 infants studied when a lightweight cardboard ring was in place perinasally. Respiratory frequency fell significantly in the mask/pneumotachograph group (-5.9 +/- 10.0%, p less than 0.05) and with the mask rim (-7.4 +/- 8.8%, p less than 0.01), but there was individual infant variation. Minute ventilation rose significantly (19.1 +/- 16.9%, p less than 0.01) only with the addition of the mask and pneumotachograph. Instrument deadspace can account for some of the increase in VT noted, but in its absence, sensory stimulation of the trigeminal area can augment tidal breathing.

Humans↗

PubMed1983

Hyaline membrane disease treated with bovine surfactant.

Six preterm infants with severe hyaline membrane disease requiring ventilation were treated, at a median age of 15.5 hours, with a single intratracheal bolus of a bovine surfactant suspension. Arterial oxygenation increased dramatically, and chest radiograms showed improvement after two to four hours. However, a variable degree of deterioration occurred within 24 hours. All of the infants required oxygen therapy for several weeks, and one developed severe bronchopulmonary dysplasia.

Animals↗

PubMed1982

Calibration of respiratory induction plethysmography (Respitrace) in infants.

To determine whether the recently increased sensitivity of the variable frequency oscillator and the use of separate rib cage and abdominal transducers made calibration of the Respitrace system easier, we performed 106 different calibration procedures against a pneumotachygraph in 36 normal infants, 41 using 2 separate periods of quiet sleep, 49 using quiet and REM sleep, and 16 using 2 separate periods of REM sleep. When the calibration was done using 2 separate periods of quiet sleep, or using periods of quiet and REM sleep, a change of at least 50% in the amplitudes of both the abdominal and rib cage signals between the 2 sleep periods, gave accurate calibration factors in 92%, compared with only 30% when the amplitude of either signal changed by less than 50%. Calculation of the calibration factors can be done either by the least squares method or by solving simultaneous equations with no significant difference between the results.

Humans↗

PubMed1982

Home apnea monitoring in 'near-miss' sudden infant death syndrome (SIDS) and in siblings of SIDS victims.

Electronic monitors were used at home to detect apnea in 134 infants who were considered to be at risk for sudden infant death syndrome (SIDS). Seventy-two infants had idiopathic apnea at a mean age of 2.2 +/- 1.4 (+/- 1 SD) months. Of these, 31 subsequently had prolonged apnea (greater than 20 seconds) with the last spell occurring at 6.2 +/- 3.2 months of age. Fourteen infants required vigorous stimulation on at least one occasion and 14 had more than ten separate episodes. Eighteen infants with awake apnea had a significantly smaller chance of subsequent spells (P less than .05). Ten additional term infants had apnea during the first week of life but none had subsequent episodes. Of 52 siblings of SIDS victims, only seven had had apnea before monitoring started. Sixteen had prolonged apnea while on a monitor; seven required vigorous stimulation on at least one occasion and one infant died despite cardiopulmonary resuscitation. The first documented spell in these 16 infants was at 2.6 +/- 2.1 months and the last at 7.2 +/- 2.7 months of age. Ten infants had more than ten subsequent spells. A tendency to clustering of spells was noted. Preceding events, especially a mild upper respiratory tract infection, were noted in 36 of the 47 infants who had apnea on the home monitor.

Apnea↗

PubMed1981

Treatment of RDS by high-frequency oscillatory ventilation: a preliminary report.

The feasibility of high-frequency oscillatory ventilation was investigated in eight neonates with severe RDS. Low-volume, high-frequency flow oscillations were generated by a piston pump and delivered through standard endotracheal tubes. Oscillatory frequencies ranged from 8 to 20 Hz and mean airway pressure from 9 to 20 cm H2O. Heart rate, airway pressures, and arterial blood gases and blood pressure were monitored during both continuous positive pressure ventilation and HFO. During HFO mean PaCO2 was 44.0 +/- 4.8 mm Hg. During CPPV immediately prior to oscillation an FIO2 of 0.66 +/- 0.15 resulted in a PaO2 of 59.6 +/- 17.0 mm Hg. Oxygenation improved during HFO such that a mean FIO2 of only 0.41 +/- 0.11 was needed for similar oxygenation. Improvements in oxygenation correlated directly with increases in mean airway pressure. Based on an animal model the phasic pressure swings during HFO are estimated to be 5 to 7 cm H2O in the trachea, much less than conventional ventilation. We conclude that HFO shows great promise in the support of gas exchange in infants with RDS. The use of small phasic volume and pressure swings should minimize pulmonary barotrauma. HFO should also permit the use of lower inspired oxygen fractions.

Humans↗

PubMed1981

Respiratory induction plethysmography (Respitrace): an evaluation of its use in the infant.

Respiratory Induction Plethysmography (RespitraceTM) is a recently described method for noninvasive respiratory monitoring in adults. We report here on its calibration and use in 15 infants. Tidal volume, as measured by this method, was compared with the tidal volume integrated from a pneumotachygraph attached to a tightly fitted face mask. The 2 volumes had a correlation greater than 0.85 (p less than 0.001) with a slope between 0.9 and 1.1. The results were similar in both quiet and rapid eye movement sleep demonstrating that the method can accurately follow paradoxical inward rib cage movement. However, the accuracy decreased at respiratory rates above 80 breaths/min. When the minute ventilation was computed over the same sampling interval by both methods, the mean difference was +0.2 +/- 3.4% (+/- 1 SD) in quiet sleep and +0.8 +/- 4.5% in rapid eye movement sleep. We concluded that this is an accurate method of measuring long-term minute ventilation and tidal volume in small infants, provided that both the calibration procedure and measurements are made in the same posture, and the infant's respiratory rate is less than 80 breaths/min.

Adult↗