Hyperventilation reportedly prolongs the seizures during eletroconvulsive therapy (ECT) (Bridenbaugh et al. 1972; Holmberg 1953; Holmberg et al. 1956; Weiner 1979; Chater and Simpson 1988). As these studies did not measure the pCO2 concentration it is unclear if prolongation of seizures was due to hyperoxygenation or hypocapnia. In a controlled study Bergsholm et al. (1984) demonstrated an incr...

Hypercapnia induces cerebral vasodilation and increases cerebral blood volume (CBV), and hypocapnia induces cerebral vasoconstriction and decreases CBV. Cerebral blood volume measured by positron emission tomography (PET) is the sum of three components, that is, arterial, capillary, and venous blood volumes. Changes in arterial blood volume (V(a)) and CBV during hypercapnia and hypocapnia were ...

BACKGROUND Multiple studies have shown that cerebral tissue oxygen saturation (Sct(O(2))) is decreased after phenylephrine treatment. We hypothesized that the negative impact of phenylephrine administration on Sct(O(2)) is affected by arterial blood carbon dioxide partial pressure (Pa(CO(2))) because CO(2) is a powerful modulator of cerebrovascular tone. METHODS In 14 anaesthetized healthy pa...

We studied cerebral blood flow (CBF) autoregulation and intracranial pressure (ICP) during normo- and hyperventilation in a rat model of Streptococcus pneumoniae meningitis. Meningitis was induced by intracisternal injection of S. pneumoniae. Mean arterial blood pressure (MAP), ICP, cerebral perfusion pressure (CPP, defined as MAP - ICP), and laser-Doppler CBF were measured in anesthetized infe...

Augmented breaths promote respiratory instability and have been implicated in triggering periods of sleep-disordered breathing. Since respiratory instability is well known to be exacerbated by hypocapnia, we asked whether one of the destabilizing effects of hypocapnia might be related to an increased prevalence of augmented breaths. With this question in mind, we first sought to determine wheth...

BACKGROUND The arterial partial pressure of carbon dioxide (PaCO2) represents the balance between CO2 production and consumption. Abnormal increase or decrease in PaCO2 can affect the body's internal environment and function. Permissive hypercapnia has aroused more attention as a novel ventilatory therapy. The aim of this study was to elucidate the effects of hypercapnia and hypocapnia on the f...

In adult respiratory distress syndrome (ARDS) pulmonary perfusion failure increases physiologic dead-space (VD/VT) correlating with mortality. High VD/VT results in alveolar hypocapnia, which has been demonstrated to cause edema formation, atelectasis, and surfactant depletion, evoked, at least in part, by apoptosis of alveolar epithelial cells (AEC). However, the mechanism underlying the hypoc...

The effects of hypocapnia [arterial PCO(2) (Pa(CO(2))) 15 Torr] on splanchnic hemodynamics and gut mucosal-arterial P(CO(2)) were studied in seven anesthetized ventilated dogs. Ileal mucosal and serosal blood flow were estimated by using laser Doppler flowmetry, mucosal PCO(2) was measured continuously by using capnometric recirculating gas tonometry, and serosal surface PO(2) was assessed by u...

BACKGROUND Partial pressure of arterial CO2 (Paco(2)) is a regulator of cerebral blood flow after brain injury. Recent guidelines for the management of cardiac arrest recommend maintaining Paco(2) at 40 to 45 mm Hg after successful resuscitation; however, there is a paucity of data on the prevalence of Paco(2) derangements during the post-cardiac arrest period and its association with outcome. ...

The effect on the minimiim alveolar concentration of halothane (MAC) during extretne hypocapnia with oxygen, and with air, was determined in nine dogs. MAC was unaffected by hypocapnia with halothane-oxygen. Changing halothane-oxygen to halothane-air reduced the MAC significantly in only five of nine dogs. The average decrease in this group of nine dogs was H per cent, only slightly more than t...