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Oxygen saturation and breathing patterns during respiratory tract infections in graduates from special care baby units
55
Sighs and heart rate modifications
in sleeping premature and full-term newborns*. L. Curzi-Dascalova,
Lefller** and E. Christova-Gueorguieva
***, Lab. de Physiologie,
C.
Hopital A. BMere, 92141 Clamart (France)
Although sighs arc often considered to represent feelings of sadness, relief, or resignation, their physiological importance is unknown. In particular, sighs provide an opportunity to study cardiorespiratory interactions and the maturity of the autonomic nervous system. With these aims in mind, we quantified heart rate (HR) modifications accompanying sighs during sleep in human neonates. Subjects and methods: We analysed 2955 min of polygraphic recordings of 7 premature (3 l-34 weeks conceptional age, wk CA) and 13 full-term (3941 wk CA) clinically and neurologically normal newborns (age 2-10 days). Sighs were defined as breaths with a sudden increase in respiratory movement (amplitude x 2 or more) and in surface diaphragmatic phasic EMG. Only sighs not preceded by gross body movements, respiratory pauses, or other sighs were studied. Eleven measurements of four consecutive R-R intervals were made for each sigh. Calculation of the control HR was based on 16 R-R intervals preceding the sigh. We also measured R-R intervals just preceding the sigh, during the sigh, and 5 groups of 4 R-R intervals following the sigh. Sighs were grouped according to sleep state and presence of a subsequent respiratory pause. Data were statistically tested by ANOVA and r-test. Results: Eighty-three sighs have been analysed; 69 of them were accompanied by body movements detected by piezo-electric quartz transducers. Results obtained in cases with and without respiratory pauses were similar. In pretnatures, sighs caused no statistically significant HR modifications, although post-sigh HR deceleration was observed in some cases. In full-term infants, sighs provoke significant HR acceleration in both active (AS) and quiet sleep (QS) state (P < 0.001). The characteristics of the subsequent HR deceleration depend upon the sleep state. In AS, HR progressively decreases to the control level, while in QS, HR drops to a value significantly below control (P < 0.001) before returning to the basal level. Conclusion and hypotheses: (a) HR acceleration during sighs is principally the consequence of the accompanying motor activity. (b) The important HR deceleration following sighs in QS is related to a vagovagal reflex to lung volume augmentation. level in full-term infants, but not in 31-34 motor and vagal reactivity in prematures, *Supported by grants **From Harvard-MIT ***Supported
(c) The previous two phenomena are present at a signilicant wk CA prematures. This finding suggests the immaturity of as compared to full-term infants.
RGR62 INSERM-CNAMTS Division of Health Sciences
and INSERM CJF 89-09. and Technology, Boston, MA, U.S.A.
by INSERM.
Oxygen saturation and breathing patterns during respiratory tract infections in graduates from special care baby units. C.F. Poets, V.A. Stebbens and D.P. Southall, Department Hospital and National Heart and Lung Institute, London (U.K.)
of Paediatrics,
Royal
Brompton
Twenty-two infants (19 preterm, 3 fullterm) who were graduates from special care after birth underwent 12 h overnight tape-recordings of oxygen saturation (Sao*) (Nellcor NIOO in the beat-to-beat mode), breathing movements and airflow during an upper (n = 12) or (n = 10) respiratory tract infection. These recordings were compared with those on 22 infants who were free of infection, matched for age, gestational age and birthweight. Baseline Sao, was significantly lower in the infection recordings (median 99.6 vs. lOO%, P <0.05), with 4 patients having values (84.3% 93.2%. 93.4% and 95.5%) below the lower limit of 97% previously observed in healthy fullterm infants. There were no significant differences between cases and controls for the median number of apnoeic pauses (5.7 vs. 9.3/h) or for the median number of desaturations (Saoz I 80%) (2.5 vs. 1.7/h). However, one of the patients had values during infection far above the 95th centile for both apnoeic pauses (48/h) and desaturations (112/h).Neither the four infants with low baseline saturations nor the infants with multiple desaturations were clinically considered hypoxaemic. Undetected hypoxaemia may thus occur during infection in infants graduating from special care baby units. We speculate that such hypoxaemia may predispose the infant to life-threatening cyanotic episodes.
Sighs and heart rate modifications
in sleeping premature and full-term newborns*. L. Curzi-Dascalova,
Lefller** and E. Christova-Gueorguieva
***, Lab. de Physiologie,
C.
Hopital A. BMere, 92141 Clamart (France)
Although sighs arc often considered to represent feelings of sadness, relief, or resignation, their physiological importance is unknown. In particular, sighs provide an opportunity to study cardiorespiratory interactions and the maturity of the autonomic nervous system. With these aims in mind, we quantified heart rate (HR) modifications accompanying sighs during sleep in human neonates. Subjects and methods: We analysed 2955 min of polygraphic recordings of 7 premature (3 l-34 weeks conceptional age, wk CA) and 13 full-term (3941 wk CA) clinically and neurologically normal newborns (age 2-10 days). Sighs were defined as breaths with a sudden increase in respiratory movement (amplitude x 2 or more) and in surface diaphragmatic phasic EMG. Only sighs not preceded by gross body movements, respiratory pauses, or other sighs were studied. Eleven measurements of four consecutive R-R intervals were made for each sigh. Calculation of the control HR was based on 16 R-R intervals preceding the sigh. We also measured R-R intervals just preceding the sigh, during the sigh, and 5 groups of 4 R-R intervals following the sigh. Sighs were grouped according to sleep state and presence of a subsequent respiratory pause. Data were statistically tested by ANOVA and r-test. Results: Eighty-three sighs have been analysed; 69 of them were accompanied by body movements detected by piezo-electric quartz transducers. Results obtained in cases with and without respiratory pauses were similar. In pretnatures, sighs caused no statistically significant HR modifications, although post-sigh HR deceleration was observed in some cases. In full-term infants, sighs provoke significant HR acceleration in both active (AS) and quiet sleep (QS) state (P < 0.001). The characteristics of the subsequent HR deceleration depend upon the sleep state. In AS, HR progressively decreases to the control level, while in QS, HR drops to a value significantly below control (P < 0.001) before returning to the basal level. Conclusion and hypotheses: (a) HR acceleration during sighs is principally the consequence of the accompanying motor activity. (b) The important HR deceleration following sighs in QS is related to a vagovagal reflex to lung volume augmentation. level in full-term infants, but not in 31-34 motor and vagal reactivity in prematures, *Supported by grants **From Harvard-MIT ***Supported
(c) The previous two phenomena are present at a signilicant wk CA prematures. This finding suggests the immaturity of as compared to full-term infants.
RGR62 INSERM-CNAMTS Division of Health Sciences
and INSERM CJF 89-09. and Technology, Boston, MA, U.S.A.
by INSERM.
Oxygen saturation and breathing patterns during respiratory tract infections in graduates from special care baby units. C.F. Poets, V.A. Stebbens and D.P. Southall, Department Hospital and National Heart and Lung Institute, London (U.K.)
of Paediatrics,
Royal
Brompton
Twenty-two infants (19 preterm, 3 fullterm) who were graduates from special care after birth underwent 12 h overnight tape-recordings of oxygen saturation (Sao*) (Nellcor NIOO in the beat-to-beat mode), breathing movements and airflow during an upper (n = 12) or (n = 10) respiratory tract infection. These recordings were compared with those on 22 infants who were free of infection, matched for age, gestational age and birthweight. Baseline Sao, was significantly lower in the infection recordings (median 99.6 vs. lOO%, P <0.05), with 4 patients having values (84.3% 93.2%. 93.4% and 95.5%) below the lower limit of 97% previously observed in healthy fullterm infants. There were no significant differences between cases and controls for the median number of apnoeic pauses (5.7 vs. 9.3/h) or for the median number of desaturations (Saoz I 80%) (2.5 vs. 1.7/h). However, one of the patients had values during infection far above the 95th centile for both apnoeic pauses (48/h) and desaturations (112/h).Neither the four infants with low baseline saturations nor the infants with multiple desaturations were clinically considered hypoxaemic. Undetected hypoxaemia may thus occur during infection in infants graduating from special care baby units. We speculate that such hypoxaemia may predispose the infant to life-threatening cyanotic episodes.