Effects of acute hypercapnia on the cardiovascular system (CYS) were studied in the anesthetized cat. After surgery the animal was exposed to a gas mixture of 12% CO2 and 25% O2 in nitrogen, and hypercapnia with low levels of arterial pH (pHa) was produced for 20 minutes. In the second run the same level of hypercapnia was induced by ventilating the same cat from the above gas mixture but pHa w...

Hypercapnia elicits hypothermia in a number of vertebrates, but the mechanisms involved are not well understood. In the present study, we assessed the participation of the nitric oxide (NO) pathway in hypercapnia-induced hypothermia and hyperventilation by means of NO synthase inhibition by using Nomega-nitro-L-arginine (L-NNA). Measurements of ventilation, body temperature, and oxygen consumpt...

Excessive oxygen administration in hypercapnic chronic obstructive pulmonary disease predisposes to worsening respiratory failure during intercurrent respiratory illness. Chronic hypercapnia is thought to downregulate carbon dioxide chemoreceptor sensitivity, adversely affecting respiratory function/mechanics and worsening ventilation-perfusion inequality. These patients are dependent on hypoxi...

We measured the field potential and the changes in local cerebral blood flow (LCBF) response during somatosensory activation (evoked LCBF) in alpha-chloralose--anesthetized rats by laser-Doppler flowmetry under normocapnia (PaCO(2)=34.3+/-3.8 mmHg) and hypercapnia (PaCO(2)=70.1+/-9.8 mmHg). Somatosensory activation was induced by electrical stimulation (0.2, 1, and 5 Hz with 1.5 mA for 5 s) of ...

BACKGROUND The ventilatory capacity of the respiratory neuromuscular system can be studied with the hypercapnia test. OBJECTIVE To determine whether decreased response to the hypercapnia test is associated with failure to pass a spontaneous breathing trial (SBT) or extubation failure. METHODS We studied 103 intubated patients ready for SBT. We used a hypercapnia test in which we approximate...

BACKGROUND Mild hypercapnia is permitted during surgeries in sitting position under general anesthesia to maintain cerebral regional oxygen saturation (rSO2). However, since hypoventilation may cause gas exchange impairment, we evaluated effects of mild hypercapnia on lung oxygenation during shoulder arthroscopy in sitting position. MATERIAL AND METHODS Forty patients were randomly allocated to...

BACKGROUND Patients with severe cardiogenic pulmonary edema (CPE) are frequently hypercapnic, possibly because of associated underlying chronic lung disease (CLD). Since hypercapnia has been associated with outcome, we aimed to identify factors associated to hypercapnia and its role on outcome of patients with CPE and no underlying CLD. METHODS Observational cohort study using data prospectiv...

Hypercapnia is clinically defined as an arterial blood partial pressure of CO2 of above 40 mmHg and is a feature of chronic lung disease. In previous studies we have demonstrated that hypercapnia modulates agonist-stimulated cAMP levels through effects on transmembrane adenylyl cyclase activity. In the airways, cAMP is known to regulate cystic fibrosis transmembrane conductance regulator (CFTR)...

Hypercapnia impairs cerebrovascular control during rapid changes in blood pressure (BP); however, data concerning the effect of hypercapnia on steady state, nonpharmacological increases in BP is scarce. We recruited fifteen healthy volunteers (mean ± SD: age, 28 ± 6 years; body mass, 77 ± 12 kg) to assess the effect of hypercapnia on cerebrovascular control during steady-state elevations in mea...