Local search such as Ejection Chain Methods (ECMs) based on the stem-and-cycle (S&C) reference structure, Lin-Kernighan (LK) heuristics, as well as the recently proposed Multi-Neighborhood Search (MNS), are among the most competitive algorithms for the Traveling Salesman Problem (TSP). In this paper, we carry out a large-scale experiment with all 110 symmetric instances from the TSPLib to inves...

AIMS In chronic heart failure (CHF) patients, the ventilation (Ve) needed to eliminate metabolically produced CO(2) during exercise (i.e. the Ve/Vco(2) slope) is a strong prognosticator. Ve/Vco(2) slope determinants are the dead space-tidal volume (Vd/Vt) ratio and the arterial CO(2) partial pressure (Paco(2)). We aimed at defining the respective prognostic role of these two variables. METHOD...

The human pulmonary vasculature constricts in response to hypercapnia and hypoxia, with important consequences for homeostasis and adaptation. One function of these responses is to direct blood flow away from poorly-ventilated regions of the lung. In humans it is not known whether the stimuli of hypercapnia and hypoxia constrict the pulmonary blood vessels independently of each other or whether...

STUDY OBJECTIVES To determine if 100% oxygen administration adversely influences gas exchange in acutely ill asthmatic subjects. DESIGN Prospective preinterventional and postinterventional comparison. SETTING University hospital emergency department. PATIENTS Thirty-seven asthmatic subjects seeking care for symptomatic exacerbations. INTERVENTIONS Twenty minutes of 100% oxygen administr...

17 patients with chronic ventilatory failure (including 14 with chronic obstructive pulmonary disease) were studied to determine the causes of carbon dioxide retention and the chronic effect of medroxyprogesterone acetate on ventilatory drive and acid-base status. Carbon dioxide retention in patients with high mechanical loads occurred concomitantly with a higher than normal inspiratory effort ...

BACKGROUND Ventilation using low tidal volumes with permission of hypercapnia is recommended to protect the lung in acute respiratory distress syndrome. However, the most lung protective tidal volume in association with hypercapnia is unknown. The aim of this study was to assess the effects of different tidal volumes with associated hypercapnia on lung injury and gas exchange in a model for acu...

BACKGROUND Wound infections are common, serious, surgical complications. Oxidative killing by neutrophils is the primary defense against surgical pathogens and increasing intraoperative tissue oxygen tension markedly reduces the risk of such infections. Since hypercapnia improves cardiac output and peripheral tissue perfusion, we tested the hypothesis that peripheral tissue oxygenation increase...

We investigated ventilation (V(.)E) control factors during recovery from light impulse-like exercise (100 watts) with a duration of 20 s. Blood ions and gases were measured at rest and during recovery. V(.)E, end tidal CO(2) pressure (PETCO(2)) and respiratory exchange ratio (RER) were measured continuously during rest, exercise and recovery periods. Arterial CO(2) pressure (PaCO(2) (pre) was e...

We investigated ventilation (V ． E) control factors during recovery from light impulse-like exercise (100 watts) with a duration of 20 s. Blood ions and gases were measured at rest and during recovery. V ． E, end tidal CO 2 pressure (PETCO 2) and respiratory exchange ratio (RER) were measured continuously during rest, exercise and recovery periods. Arterial CO2 pressure (PaCO 2 pre) was estimat...

BACKGROUND Home mechanical ventilation is usually started in hospital as arterial blood gas sampling is deemed necessary to monitor CO(2) and O(2) adequately during institution of ventilatory support. A non-invasive device to reliably measure CO(2) transcutaneously would alleviate the need for high care settings for measurement and open the possibility for home registration. OBJECTIVES In thi...