BACKGROUND Ventilator resetting is frequently needed to adjust tidal volume, pressure and gas exchange. The system comprising lungs and ventilator is so complex that a trial and error strategy is often applied. Comprehensive characterization of lung physiology is feasible by monitoring. The hypothesis that the effect of ventilator resetting could be predicted by computer simulation based on a p...

BACKGROUND AND PURPOSE The purpose of this study was to examine the effects of diabetes mellitus and its severity on the cerebral vasodilatory response to hypercapnia. METHODS Thirty diabetic patients consecutively scheduled for elective major surgery were studied. After induction of anesthesia, a 2.5-MHz pulsed transcranial Doppler probe was attached to the patient's head at the right tempor...

Many clinical and research situations require maintenance of isocapnia, which occurs when alveolar ventilation (V'A) is matched to CO2 production. A simple, passive circuit that minimizes changes in V'A during hyperpnoea was devised. It is comprised of a manifold, with two gas inlets, attached to the intake port of a nonrebreathing circuit or ventilator. The first inlet receives a flow of fresh...

Borel J-C, Melo-Silva CA, Gakwaya S, Sériès F. Influence of CO2 on upper airway muscles and chest wall/diaphragm corticomotor responses assessed by transcranial magnetic stimulation in awake healthy subjects. J Appl Physiol 112: 798–805, 2012. First published December 8, 2011; doi:10.1152/japplphysiol.00713.2011.—Rationale: functional interaction between upper airway (UA) dilator muscles and th...

BACKGROUND The non-rebreather mask (NRBM) is used for many applications and in many patient care scenarios in which hypoxemia and resultant hypoxia are a concern. The NRBM is a low-flow oxygen delivery system that is easily deployed and capable of delivering a relatively high fraction of inspired oxygen (FiO2).The potential for ineffective carbon dioxide (CO2) removal at low flow rates is a saf...

BACKGROUND Hypertension is associated with cognitive deficits, particularly executive function, and decreased cerebral microvascular responsiveness to CO2 (CO2 vasoreactivity). The relation between CO2 vasoreactivity and executive function is not known. Protocols to assess CO2 vasoreactivity are cumbersome and require inhaling a CO2-enriched gas. We explored the ability to measure CO2 vasoreact...

To examine whether CPB influences pulmonary vascular sensitivity to CO2, we compared the effect of slight induced hypocarbia and hypercarbia on pulmonary circulation before and after CPB in ten mechanically ventilated patients undergoing CABG. Hypocarbia was produced by increasing tidal volume slightly and hypercarbia was then induced by adding CO2 to the inspired gas mixture. In another ten pa...

The urge to breathe, as stimulated by hypercapnia, is generally considered to cause a breath-hold diver to end the breath-hold, and pre-breath hold hyperventilation has been suggested to cause hypoxic loss of consciousness (LOC) due to the reduced urge to breathe. Competitors hyperventilate before "Static Apnea", yet only 10% surface with symptoms of hypoxia such as loss of motor control (LMC) ...

Endotracheal tube (ETT) cuff herniation is not an uncommon event in Intensive Care Units and operating rooms. The cause for this can be displacement of the tube or overinflation of ETT cuff.[1] Usually, it is noticed by the sound of gas leaking around the tube or when there is a fall in tidal volume and end-tidal carbon dioxide (CO2). Confirmation and repositioning of the ETT require direct lar...