Competency of Autorescusitation (AR) Mechanisms in Sudden Infant Death

Sridhar, Raghunathan; Thach, Bradley T.; Kelly, Dorothy H.; Henslee, Judith A.

doi:10.1203/00006450-199904020-02114

Cited by 7 publications

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“…The importance of gasping in self-resuscitation or autoresuscitation in infants has been emphasized by Peiper (38), Stevens (53), and Thach (55), as well as that repeat exposure to hypoxia can lead to autoresuscitation failure and death. Why autoresuscitation failure occurs is unclear, but clinical reports provide evidence that autoresuscitation can fail following repeat apneic episodes (38,40,51,53). Successful autoresuscitation from hypoxic-induced apnea occurs in three sequential stages: stage I, gasping with marked bradycardia; stage II, cardiac resuscitation with a rapid increase in heart rate; and stage III, respiratory resuscitation with an increase in respiratory rate (11,14,47).…”

Section: Discussionmentioning

confidence: 99%

Threshold levels of maternal nicotine impairing protective responses of newborn rats to intermittent hypoxia

Fewell

Smith

2001

Journal of Applied Physiology

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Experiments were carried out to determine the threshold level of maternal nicotine that impairs protective responses of rat pups to hypoxia. From days 6 or 7 of gestation, pregnant rats received either vehicle or nicotine (1.50, 3.00, or 6.00 mg of nicotine tartrate. kg body wt(-1).day(-1)) or vehicle continuously via a subcutaneous osmotic minipump. On postnatal days 5 or 6, pups were exposed to a single period of hypoxia produced by breathing an anoxic gas mixture (97% N(2) or 3% CO(2)) and their time to last gasp was determined, or they were exposed to intermittent hypoxia and their ability to autoresuscitate from hypoxic-induced primary apnea was determined. Perinatal exposure to nicotine did not alter the time to last gasp or the total number of gasps when the pups were exposed to a single period of hypoxia. The number of successful autoresuscitations on repeated exposure to hypoxia was, however, decreased in pups whose dams had received either 3.00 or 6.00 mg of nicotine tartrate/kg body wt; these dosage regimens produced maternal serum nicotine concentrations of 19 +/- 6 and 35 +/- 8 ng/ml, respectively. Thus our experiments define the threshold level of maternal nicotine that significantly impairs protective responses of 5- to 6-day-old rat pups to intermittent hypoxia such as may occur in human infants during episodes of prolonged sleep apnea or positional asphyxia.

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Section: Discussionmentioning

confidence: 99%

Threshold levels of maternal nicotine impairing protective responses of newborn rats to intermittent hypoxia

Fewell

Smith

2001

Journal of Applied Physiology

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“…Why autoresuscitation failure occurs is unclear, but clinical reports provide evidence that autoresuscitation can fail following repeated apneic episodes (30,31,35,37). Jacobi and Thach (25) have recently defined the cardiorespiratory events that occur during successful autoresuscitation from hypoxic apnea in mice.…”

Section: Discussionmentioning

confidence: 99%

Postnatal age influences the ability of rats to autoresuscitate from hypoxic-induced apnea

Fewell

Smith

et al. 2000

American Journal of Physiology-Regulatory, Integrative and Comp

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Failure to autoresuscitate from apnea by gasping has been suggested to have a role in sudden infant death. Little is known, however, about the factors that influence the ability of gasping to sustain life during acute hypoxia in the newborn. The present experiments were carried out on 105 rat pups to investigate the influence of postnatal age on the time to last gasp during a single hypoxic exposure and on the ability to autoresuscitate from primary apnea during repeated hypoxic exposures. On days 1-2, 5-6, 10-11, 15-16, and 19-20 postpartum, each pup was placed into a temperature-controlled chamber regulated to 37 +/- 1 degrees C and was exposed either to a single period of hypoxia produced by breathing an anoxic gas mixture (97% N(2)-3% CO(2)), and the time to last gasp was determined, or repeated exposure to hypoxia was performed, and the ability to autoresuscitate from primary apnea was determined. Increases in postnatal age decreased the time to last gasp following a single hypoxic exposure and decreased the number of successful autoresuscitations following repeated hypoxic exposures. Thus our data provide evidence that postnatal age influences protective responses that may prevent death during hypoxia as may occur during episodes of prolonged sleep apnea.

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“…It does seem probable, however, that some deaths diagnosed as SIDS result, in part at least, from elevated T B resulting from increased environmental temperatures, febrile illnesses, overbundling, and prone sleeping position or a combination of these factors (23,26,27). In home-monitored SIDS deaths, gasping is present but bradycardia persists and AR is unsuccessful (21,25). If an hypoxic event such as that associated with sleep apnea were to coincide with increased T B , then our findings that elevated T B can prevent AR in a manner similar to that occurring in SIDS would offer a plausible explanation for an association between heat stress and SIDS.…”

mentioning

confidence: 67%

“…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.…”

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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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Competency of Autorescusitation (AR) Mechanisms in Sudden Infant Death

Cited by 7 publications

References 0 publications

Threshold levels of maternal nicotine impairing protective responses of newborn rats to intermittent hypoxia

Threshold levels of maternal nicotine impairing protective responses of newborn rats to intermittent hypoxia

Postnatal age influences the ability of rats to autoresuscitate from hypoxic-induced apnea

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

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