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Query: UMLS:C0020440 (
hypercapnia
)
7,939
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Congenital Central Hypoventilation Syndrome (CCHS) is a rare disorder with failure of automatic control of breathing, defined by lack of an appropriate ventilatory response to
hypercarbia
and hypoxia. However, more detailed evaluation of cardiorespiratory coupling has not been previously performed in those with CCHS. We postulate that those with CCHS have disjointed cardiorespiratory responses to ventilatory challenges due to their alterations in sympathetic modulation. Therefore, we performed ventilatory rebreathing challenges with
hypercarbia
and hypoxia on 5 subjects with CCHS (age 21.2 ± 5.3 years; 3 females) and 7 controls (age 20.0 ± 4.0 years; 4 females). We measured breath-to-breath respiratory parameters (airflow, P<inf>ET</inf>co<inf>2</inf>, S<inf>a</inf>o<inf>2</inf>), ECG, and continuous non-invasive blood pressure. As previously shown, when compared to controls CCHS subjects lacked ventilatory responses to isocapnic hypoxia (p=0.004) and hyperoxic
hypercarbia
(p=0.002). During
hypercapnia
, both control and CCHS subjects had similar rates of decrease in R-R intervals (RRI; slope -1.3 ± 2.5 vs. -1.4 ± 1.1, n.s.) and increase in beat-to-beat averaged blood pressure (
MBP
; slope 1.2 ± 0.3 vs. 0.4 ± 0.1, n.s.) as P<inf>ET</inf>co<inf>2</inf>increased. During hypoxia, both control and CCHS groups had similar rates of decrease in RRI (slope 14.2 ± 3.0 vs. 7.5 ± 3.9, n.s.) and increase in
MBP
(slope -1.11 ± 1.12 vs. -0.9 ± 0.8, n.s.) as S<inf>a</inf>o<inf>2</inf>decreased. We conclude that despite having a markedly diminished ventilatory response to
hypercarbia
and hypoxia, subjects with CCHS have normal cardiovascular responses to these challenges. We speculate that this indicates that chemoreceptors are functional.
...
PMID:Cardio-respiratory Uncoupling in Congenital Central Hypoventilation Syndrome. 1728 Dec 14
PaCO(2) is an important factor in the regulation of cerebral circulation, and it is often used to reduce intracranial pressure through hyperventilation during neurosurgery. Changes in concentration can cause changes in CBF (cerebral blood flow). 20-HETE is a product of CYP4A-mediated AA (arachidonic acid) metabolism and is a powerful endogenous vasoconstrictor; however, its effect on cerebral vasoconstriction in cats, dogs and rats remains to be confirmed. It is known that changes in PaCO(2) can influence the expression of CYP4A in the rat brain, demonstrating the important role of 20-HETE in the mechanism of CO(2)-mediated cerebrovascular reactivity. Thirty healthy adult male Wistar rats that weighed between 200 g and 250 g were randomly divided into three groups (A, B, and C; n=10): group A, normocapnia (PaCO(2) was maintained at approximately 40-45 mmHg); group B, hypocapnia (PaCO(2) was maintained at approximately 20-25 mmHg); and group C,
hypercapnia
(PaCO(2) was maintained at approximately 60-65 mmHg). Physiological parameters, including HR (heart rate),
MBP
(mean blood pressure), PH and PaCO(2) were recorded every 30 min, and there were no significant hemodynamic or body temperature differences. The head was removed after 3.5 h to investigate brain CYP4A by immunohistochemistry. Relative to group A, group B exhibited the following changes: an increased pH, decreased PaCO(2), and increased brain CYP4A protein expression (P<0.05). In contrast, group C exhibited decreased PH, increased PaCO(2) and decreased CYP4A protein expression (P<0.05). CO(2) can decrease the expression of brain CYP4A during
hypercapnia
and increase its expression during hypocapnia.
...
PMID:Arterial carbon dioxide partial pressure influences CYP4A distribution in the rat brain. 2264 45
