Maturation of Cardiorespiratory Interactions in Spontaneous Recovery from Hypoxic Apnea (Autoresuscitation)

Gershan, William M.; Jacobi, M. S.; Thach, Bradley T.

doi:10.1203/00006450-199008000-00003

Cited by 20 publications

(29 citation statements)

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“…Four target temperatures were studied: 40.5, 41.5, 42.5, and 43.5°C. Immediately after the target temperature was reached, hypoxic apnea was induced by sudden introduction of a 97% N2-3% CO2 gas mixture into the chamber at the same flow rate (9,10,14). Then a flow of 21% O2 (balance N2) was started at the onset of the apnea to allow for successful AR (10).…”

Section: Methodsmentioning

confidence: 99%

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Inhibitory effects of hyperthermia on mechanisms involved in autoresuscitation from hypoxic apnea in mice: a model for thermal stress causing SIDS

Kahraman

Thach

2004

Journal of Applied Physiology

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Kahraman, Levent, and Bradley T. Thach. Inhibitory effects of hyperthermia on mechanisms involved in autoresuscitation from hypoxic apnea in mice: a model for thermal stress causing SIDS. J Appl Physiol 97: 669 -674, 2004; 10.1152/japplphysiol.00895.2003.-The physiological mechanisms that might be involved in an association between heat stress and sudden infant death syndrome (SIDS) are obscure. We tested the hypothesis that a combination of acute hypoxia and elevated body temperature (TB) might prevent autoresuscitation from hypoxic apnea (AR). We exposed 21-day-old mice (total ϭ 216) to hyperthermia (40.5-43.5°C), hypoxia, or a combination of the two. Neither hyperthermia alone (40.5-42.5°C) nor hypoxia alone was found to be lethal, but the combination produced failure to AR during the first hypoxic exposure with increasing frequency as TB increased. The ability to withstand multiple hypoxic exposures was also reduced as T B increased. In contrast, heat stress causing moderate TB increase (40.5°C) had no effect on survival. Increased T B (43.5°C) reduced gasping duration and number of gasps. It increased heart rate during anoxia but did not alter gasping rate. Furthermore, the oxygenindependent increase in heart rate observed before gasping failure was usually delayed until after the last gasp in hyperthermic animals. Mild dehydration occurred during T B elevation, but this did not appear to be a primary factor in AR failure. We conclude that a thermal stress, which by itself is nonlethal, frequently prevents AR from hypoxic apnea. This may be due, at least in part, to decreased gasp number and duration as well as to hyperthermia-related asynchrony of reflexes regulating heart and gasping frequencies during attempted AR. hypoxic gasping; dehydration; hypoxic survival time; sudden infant death syndrome SUDDEN INFANT DEATH SYNDROME (SIDS) occurs in infants during a relatively brief period of development with peak incidence at 2-3 mo of age. It has been suggested that thermal stress with or without actual increase in body temperature (T B ) may be causal in many SIDS cases (6, 12). The primary evidence for this comes from epidemiological studies. These studies have found increased environmental temperature and/or history of heavy sweating in association with some SIDS cases (6,26, 27). Despite this, the potential physiological mechanisms linking heat stress to SIDS are unclear.Healthy infants have frequently been observed to autoresuscitate (AR) from prolonged apnea without apparent ill effects, indicating that this can be an important mechanism for surviving severe episodes of hypoxia (22,32). Failure to AR from hypoxic apnea by gasping is well documented in SIDS cases, and it has been proposed that such failure could be a critical SIDS causal mechanism (21, 25). Examination of terminal recordings of infants dying of SIDS reveals that hypoxic apnea is followed by gasping, and yet AR fails during the first attempt. In contrast, infants with other diagnoses often have repeated successful AR attempts immediately b...

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Section: Methodsmentioning

confidence: 99%

“…As used in prior studies, the point at which heart rate increased to 60% of the baseline (averaged over 2 s) was used as an end point for some of the analyses (9,10).…”

Section: Methodsmentioning

confidence: 99%

Inhibitory effects of hyperthermia on mechanisms involved in autoresuscitation from hypoxic apnea in mice: a model for thermal stress causing SIDS

Kahraman

Thach

2004

Journal of Applied Physiology

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“…First, sympatho-adrenal activation is crucial for "autoresuscitation responses," including centralization of blood flow to vital organs (heart and brain) and arousal from sleep (5,6). These survival responses are triggered by life-threatening stressors such as hypoxemia and apnea (5,6). Second, enhanced parasympathetic tone is expected to have the opposite effect, promoting "resting responses" during vagal stimulation (e.g., apnea/bradycardia during feeding).…”

Section: Discussionmentioning

confidence: 99%

“…This distinctive HRV profile is expected to increase the risk for cardiorespiratory collapse for two reasons. First, sympatho-adrenal activation is crucial for "autoresuscitation responses," including centralization of blood flow to vital organs (heart and brain) and arousal from sleep (5,6). These survival responses are triggered by life-threatening stressors such as hypoxemia and apnea (5,6).…”

Section: Discussionmentioning

confidence: 99%

“…Premature infants have respiratory instability beyond term characterized by life-threatening episodes of apnea and hypoxemia that increase their morbidity and mortality risk (3,4). Preterm birth interrupts the development and maturation of the autonomic nervous system (ANS), which regulates normal ventilatory drive and autoresuscitation responses during periods of apnea and hypoxemia (5,6). Prior studies have confirmed that premature infants have ANS deficits (7), but a comprehensive assessment of the early trajectory of ANS dysfunction in prematurity and subsequent relationship to respiratory outcomes has not been undertaken.…”

Section: To the Editormentioning

confidence: 99%

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Premature Infants Rehospitalized because of an Apparent Life-Threatening Event Had Distinctive Autonomic Developmental Trajectories

Niño

Govindan

Al-Shargabi

et al. 2016

Am J Respir Crit Care Med

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Characterization of successful and failed autoresuscitation in human infants, including those dying of SIDS

Sridhar

Thach

Kelly

et al. 2003

Pediatric Pulmonology

136

106

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Our purpose was to identify and further characterize physiologic mechanisms relevant to autoresuscitation from hypoxic apnea in infants dying suddenly and unexpectedly. We studied cardiorespiratory recordings of 24 infants (age range, 0.8-21 months) who died suddenly while being monitored at home. These recordings were analyzed for features indicated by studies in animal models to be characteristic of hypoxic gasping, and of recovery from bradycardia and apnea associated with gasping (e.g., autoresuscitation). Findings in 5 infants diagnosed as having sudden infant death syndrome were compared with 6 non-SIDS infants whose deaths resulted from other conditions. Additionally, we studied 15 healthy infants during sleep, using home monitor and other respiratory recording techniques, in order to obtain comparison data. We found in recordings from 23 of 24 subjects that hypoxic gasps with characteristic features occurred immediately preceding death. A unique pattern of complex, closely spaced gasps ("double" or "triple" gasps) was present in many subjects. Evidence of partially successful autoresuscitation closely following one or more gasps occurred in 11 subjects, while another 4 had evidence of complete autoresuscitation with return of normal heart rate and resolution of apnea on one or more occasions. Significant differences between SIDS infants and those dying from other causes included increased occurrence of complex gasps and decreased occurrence of partial or complete autoresuscitation in the SIDS infants. The non-SIDS cases were different from the SIDS cases in that only one had "double" gasps (n = 7), while none had "triple" gasps, as compared with 4 out of 5 SIDS cases with these patterns (P < 0.05, chi-square). Also, in contrast with the SIDS cases, more of the cases with specific postmortem diagnoses had evidence of partial (5 out of 6 cases) or complete (1 out of 6 cases) autoresuscitation (P < 0.05, chi-square). We conclude that partial or complete autoresuscitation by gasping is not uncommon in moribund infants during the first year of life. Failure of autoresuscitation mechanisms other than failure to initiate gasping may be characteristic of infants dying of SIDS. Some SIDS infants appear to be different from infants dying with other diagnoses with respect to efficacy and characteristics of hypoxic gasping.

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Maturation of Cardiorespiratory Interactions in Spontaneous Recovery from Hypoxic Apnea (Autoresuscitation)

Abstract: ABSTRAm. The maturation of the process of spontaneous recovery from hypoxic apnea by gasping (autoresuscitation) was characterized in adult, weanling (18-22 d), and infant (5 and 10 d) BALB/c mice. ECG and respiration

Cited by 20 publications

References 12 publications

Inhibitory effects of hyperthermia on mechanisms involved in autoresuscitation from hypoxic apnea in mice: a model for thermal stress causing SIDS

Inhibitory effects of hyperthermia on mechanisms involved in autoresuscitation from hypoxic apnea in mice: a model for thermal stress causing SIDS

Premature Infants Rehospitalized because of an Apparent Life-Threatening Event Had Distinctive Autonomic Developmental Trajectories

Characterization of successful and failed autoresuscitation in human infants, including those dying of SIDS

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