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Biomedical subjects

J Molloy

Publications and source records attributed to J Molloy.

29 records · Page 2Linked to original sources
PubMed1991

Accuracy of respiratory inductive plethysmograph in measuring tidal volume during sleep.

Respiratory inductance plethysmography (RIP) has been widely used to measure ventilation during sleep, but its accuracy in this role has not been adequately tested. We have thus examined the accuracy of the RIP by comparing tidal volume measured with RIP with that measured by a pneumotachograph in eight unrestrained normal subjects during sleep. We have also studied the effect of posture on the accuracy of the RIP. In all sleep stages the correlation between RIP tidal volume measurements and expired volume showed relatively poor correlations (mean r = 0.49-0.60), and the bias of the measurements varied widely. Changes in posture altered the correlations between the two measurements, with no systematic differences between positions. When the subjects resumed a position, the 95% confidence intervals of tidal volume measurement did not overlap the original confidence limits in that posture on 13 of 25 occasions. This study shows that the RIP does not accurately measure tidal volume during sleep in unrestrained subjects and should only be used for semiquantitative assessment of ventilation during sleep.

Adult↗
PubMed1989

Ventilatory and arousal responses to added inspiratory resistance during sleep.

Airway resistance increases during sleep. We have determined the ventilatory and arousal responses to the addition of inspiratory resistance of 4, 7, or 10 cmH2O/L/s during sleep in 10 normal men who slept wearing valved face masks. Insufficient ventilatory response data were obtained during rapid eye movement (REM) sleep to allow adequate analysis. The immediate responses to loading were decreases in tidal volume (VT), breathing frequency (f), and minute ventilation (VE), with no difference between wakefulness and Stage 2 and Stage 3/4 sleep in the effects of loading on VT and VE, but f fell more during wakefulness than during sleep (p less than 0.05) because of a greater lengthening of inspired time (TI) (p less than 0.05). During the first 10 breaths, occlusion pressure (P0.1) increased similarly in all EEG stages. Averaging responses during the 2-min periods when resistances were applied, the only variable to differ between EEG stages was TI, which increased more in wakefulness than in Stage 2 or Stage 3/4 sleep (p less than 0.01). Arousal within 2 min of application of resistance occurred less frequently from Stage 3/4 sleep than from Stage 2 or REM sleep (p less than 0.02). The study demonstrates that sleep modifies the changes in respiratory timing produced by resistive loading without having a major effect on ventilation or P0.1 responses. The low frequency of arousal from Stage 3/4 sleep with loading may explain why asthmatics rarely awaken from this stage with wheeze.

Adult↗
PubMed1988

Breathing pattern and eye movement density during REM sleep in humans.

Changes in the density of eye movement during rapid eye movement (REM) sleep are associated with changes in ventilation and ventilatory response in animals. Recent data in patients with chronic obstructive pulmonary disease suggest that periods of frequent eye movements may be associated with hypoxemia during REM sleep. We have therefore investigated the association between eye movements and ventilation and ventilatory pattern in 10 normal men. Expired ventilation was measured using a pneumotachograph attached to a valved face mask with a dead space of 50 ml and incorporating a peripheral CO2 leak detector. Ventilation was reduced (p less than 0.02) in all stages of sleep compared with that during wakefulness, with no difference between the level of ventilation in each sleep stage (awake, 7.18 +/- 0.43 SEM; Stage 2, 6.47 +/- 0.43; Stage 3/4, 6.45 +/- 0.52; REM sleep, 6.55 +/- 0.47 L/min). During REM sleep, eye movements (EMs) were associated with rapid shallow breathing. Dividing REM into 20-s epochs with or without EMs, EMs were associated with a raised breathing frequency (no EMs, 14.4 +/- 0.4 breaths/min; EMs, 15.8 +/- 0.5 breaths/min; p = 0.01), reduced tidal volume (0.49 +/- 0.03 L; 0.41 +/- 0.03 L; p less than 0.01), and reduced minute ventilation (6.87 +/- 0.45 L; 6.27 +/- 0.51 L; p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Ototoxic effect of cisplatin in children with brain tumors.

Thirty-four children, age 2-19 years, with brain tumors were treated with surgical resection, irradiation, and a cisplatin (CDDP) containing regimen. Audiologic assessments were conducted prior to each cycle of CDDP to monitor the ototoxic effects of CDDP. Twenty-eight patients with posterior fossa (PF) tumors received 5,040 to 5,650 cGy irradiation to the PF and 0-3,600 cGy to the remainder of the craniospinal (CS) axis. Six patients with supratentorial tumors received 5,140-5,580 cGy to the tumor site and 3,600-4,500 Gy to the remainder of the CS axis. Cycles of CDDP (68 mg/m2), lomustine (75 mg/m2), and vincristine (1.5 mg/m2 weekly for 3 weeks) were given every 6 weeks to 30 children immediately following irradiation, and to 4 at relapse. CDDP was infused over 8 h. Significant hearing loss, defined as a greater than 20-dB change from baseline in the hearing level (HL), occurred in the 250- to 2,000-Hz range in 4 of 29 patients receiving a cumulative dose (CD) of 410 mg/m2, and in 14 of 25 patients receiving a CD of 474 mg/m2. At 4,000 Hz, hearing sensitivity progressed from a HL of 20 +/- 2 dB at a CD of 203 mg/m2 to 31 +/- 6 dB (p less than 0.05) at a CD of 474 mg/m2 (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗