Changes in apnea and autoresuscitation in piglets after intravenous and intrathecal interleukin-1 beta injection

Piglets were given IL-1 beta intravenously (Index I, n = 8) or intrathecally (Index II, n = 9) prior to apnea to test the hypothesis that IL-1 beta may prolong periods of apnea during sleep and infection. Apnea variables and the quality of autoresuscitation were recorded and compared to an apnea control group (Ctr. I, n = 7, apnea without injection of IL-1 beta) and a procedure control group (Ctr. II, n = 6, apnea after intratecally injected sterile water). Hypoxanthine (Hx) and xanthine (X) were analyzed in plasma, CSF and vitreous humor. The duration of apnea was significantly longer in the Index I - mean: 38, intraquartile range: 27-52 sec and Index II-group 26 (24-36) sec than in the Ctr. 1-12 (10-13) sec (p < 0.01) and the Ctr. II-group 14 (6-18) sec (p < 0.01). The number of respirations per 2 min following apnea in the Index I-group mean: 21, intraquartile range: 7-40 and was significantly less than in the Ctr. I-group 109 (39-150) (p < 0.01), while a similar tendency was found in the Index II-group 42 (27-55) (p = 0.06).

IN CONCLUSION

Intravenous and intrathecal injection of IL-1 beta prolong the duration of apnea and modifies autoresuscitation.

Increased cerebrospinal fluid beta-endorphin immunoreactivity in infants with apnea and in siblings of victims of sudden infant death syndrome

To gain further insight into the possible role of endogenous opioid peptides in the respiratory difficulties associated with the apnea of infancy and other disorders possibly related to apnea, the levels of beta-endorphin immunoreactivity were measured in the cerebrospinal fluid (CSF) of five groups of infants: (1) infants with proved apnea, (2) infants with histories of an apparent life-threatening event (ALTE), (3) siblings of victims of the sudden infant death syndrome (SIDS), (4) infants with suspected but unproved apnea, and (5) infants undergoing investigation for other acute illnesses. Twenty-two infants considered at risk for an ALTE (groups 1 to 3) had significantly higher CSF beta-endorphin equivalents (88 +/- 7 pg/mL) than did the 22 control patients in groups 4 and 5 (31 +/- 3 pg/mL). Plasma beta-endorphin immunoreactivity, which was also measured in some of the infants, did not correlate with levels in CSF and, in fact, was significantly lower in the groups at risk for an ALTE (50 +/- 9 pg/mL; n = 14) than in the control subjects (80 +/- 6 pg/mL; n = 11). These studies indicate that elevated beta-endorphin immunoreactivity in CSF may be a marker in infants who have apnea and who may be considered at risk for an ALTE.

Cerebrospinal fluid endorphins and the infant apnea syndrome

Cerebrospinal fluid (CSF) beta-endorphin levels were determined in 16 patients with infant apnea syndrome and 34 control patients. A statistically significant difference (P less than or equal to .0001) was found with the infant apnea syndrome patients having beta-endorphin levels of 14.7 +/- 1.2 pmol/L (mean +/- SE) and the controls having levels of 6.9 +/- 0.6 pmol/L (mean +/- SE). To test whether these elevated CSF beta-endorphin levels were the result or the possible cause of the apneas, three patients with infant apnea syndrome and abnormal CSF beta-endorphin levels participated in a study to determine whether a continuous low-dose infusion (10 micrograms/kg/h) of the narcotic antagonist naloxone would reduce the occurrence of apneas and respiratory pauses during all-night polysomnogram recordings. A fourth patient with documented apneas but normal CSF beta-endorphin levels was also studied while on a regimen of naloxone. In the patients with infant apnea syndrome and abnormal CSF beta-endorphin levels, a significant (P less than or equal to .05) reduction in apneas and respiratory pauses occurred during naloxone infusion. There was no change in the occurrence of apneas or respiratory pauses during naloxone infusion in the patient with normal CSF endorphin levels. Abnormal CSF levels of endorphins may play a role in apneas of infancy and may be amenable to therapy with narcotic antagonists.

Cerebrospinal fluid and plasma beta-endorphin concentrations in prolonged infant apnea (near-miss sudden infant death syndrome)

Elaboration of beta-endorphins (beta-ED) is implicated in the modulation of respiratory control in infants. Therefore, beta-ED concentrations were measured in paired samples of CSF and plasma in three groups of infants. Group 1 and group 3 were used as controls. Group 2 infants suffered prolonged apnea of infancy (near-miss sudden infant death syndrome) and were successfully resuscitated. Age and weight (mean +/- SEM) in groups 1, 2 and 3 were 8.5 +/- 3 months and 7.2 +/- 1.4 kg, 3.8 +/- 0.7 months and 5.2 +/- 0.6 kg, and 3.4 +/- 0.9 months and 3.4 +/- 0.7 kg, respectively. CSF beta-ED concentrations were found to be significantly elevated in group 2, 67.8 +/- 4.7 pg/ml, when compared to group 1, 29.8 +/- 3.1 pg/ml, and group 3, 46.5 +/- 7.2 pg/ml (p less than 0.01). No correlation was observed with plasma and CSF concentrations in all three groups. beta-ED may play a role in the pathophysiology of prolonged infant apnea (near-miss sudden infant death syndrome).

Cerebrospinal fluid concentration of biogenic amine metabolites in idiopathic apnea of prematurity

The concentration of homovanillic acid and 3-methoxy-4-hydroxyphenylglycol (MHPG), the major metabolites of dopamine and norepinephrine, respectively, were studied in the cerebrospinal fluid (CSF) of 34 newborn infants. No significant difference was found in the levels of MHPG and homovanillic acid between preterm and term infants. Apneic preterm infants had significantly higher levels of MHPG than nonapneic prematures. Theophylline did not change the levels of these metabolites in CSF. There was a progressive rise of MHPG levels in CSF in preterm infants as their postnatal age increased. We suggest that idiopathic apnea of prematurity is not associated with depletion of catecholamine stores in the central nervous system. Theophylline does not seem to relieve apnea by stimulation of the central adrenergic system.