Search results for "Mean airway pressure"

Lung density distribution in dynamic CT correlates with oxygenation in ventilated pigs with lavage ARDS † †This study contains parts of the doctoral …

2003

Background Fast dynamic computed tomography (dCT) has been used to assess regional dynamics of lung inflation and deflation processes. The aim of this study was to relate ventilation-induced changes in lung density distribution, as measured over several respiratory cycles by dCT, to oxygenation and shunt fraction in a lavage acute respiratory distress syndrome model. Methods Six anaesthetized pigs underwent pressure-constant ventilation (F I O2=1.0, inspiratory:expiratory ratio=1:1) before and after induction of lung damage by saline lavage. Mean airway pressure ( P a μ w μ ) was varied (8, 13, 18, 23, 28, 33, and 38 cm H2O) in random order. At each P a μ w μ level, dCT acquisitions were pe…

High-frequency oscillatory ventilation in adults with traumatic brain injury and acute respiratory distress syndrome

2005

This study observed adverse events of rescue treatment with high-frequency oscillatory ventilation (HFOV) in head-injured patients with acute respiratory distress syndrome (ARDS).Data of five male patients with ARDS and traumatic brain injury, median age 28 years, who failed to respond to conventional pressure-controlled ventilation (PCV) were analyzed retrospectively during HFOV. Adjusted mean airway pressure at initiation of HFOV was set to 5 cm H2O above the last measured mean airway pressure during PCV. Frequency of pulmonary air leak, mucus obstruction, tracheal injury, and need of HFOV termination due to increased intracranial pressure, decreased cerebral perfusion pressure, or deteri…

High-frequency oscillatory ventilation and an interventional lung assist device to treat hypoxaemia and hypercapnia

2004

A male patient accidentally aspirated paraffin oil when performing as a fire-eater. Severe acute respiratory distress syndrome ( P a 2 / F 2 ratio 10.7 kPa) developed within 24 h. Conventional pressure-controlled ventilation (PCV) with high airway pressures and low tidal volumes failed to improve oxygenation. Hypercapnia ( P a 2 12 kPa) with severe acidosis (pH<7.20) ensued. Treatment with high-frequency oscillatory ventilation (HFOV) and a higher adjusted airway pressure (35 cm H2O) improved the P a 2 / F 2 ratio within 1 h from 10.7 to 22.9 kPa, but the hypercapnia and acidosis continued. Stepwise reduction of the mean airway pressure (26 cm H2O), and oscillating frequencies (3.5 Hz), as …

Initiation of high-frequency oscillatory ventilation and its effects upon cerebral circulation in pigs: an experimental study

2006

BACKGROUND: Current practice at high-frequency oscillatory ventilation (HFOV) initiation is a stepwise increase of the constant applied airway pressure to achieve lung recruitment. We hypothesized that HFOV would lead to more adverse cerebral haemodynamics than does pressure controlled ventilation (PCV) in the presence of experimental intracranial hypertension (IH) and acute lung injury (ALI) in pigs with similar mean airway pressure settings. METHODS: In 12 anesthetized pigs (24-27 kg) with IH and ALI, mean airway pressure (P(mean)) was increased (to 20, 25, 30 cm H(2)O every 30 min), either with HFOV or with PCV. The order of the two ventilatory modes (cross-over) was randomized. Mean art…

2006

The objective was to study the effects of a lung recruitment procedure by stepwise increases of mean airway pressure upon organ blood flow and hemodynamics during high-frequency oscillatory ventilation (HFOV) versus pressure-controlled ventilation (PCV) in experimental lung injury. Lung damage was induced by repeated lung lavages in seven anesthetized pigs (23–26 kg). In randomized order, HFOV and PCV were performed with a fixed sequence of mean airway pressure increases (20, 25, and 30 mbar every 30 minutes). The transpulmonary pressure, systemic hemodynamics, intracranial pressure, cerebral perfusion pressure, organ blood flow (fluorescent microspheres), arterial and mixed venous blood ga…

Importance of noninvasively measured respiratory muscle overload among the causes of hospital readmission of COPD patients.

2008

To evaluate the influence of respiratory muscle overload and right cardiac overload among the possible risk factors of hospital readmission in a 1-year follow-up of a cohort of patients with moderate-to-severe COPD.A total of 112 COPD patients who were admitted consecutively to the hospital for acute exacerbation. At hospital discharge, we evaluated the conventional clinical and functional determinations in addition to the pressure-time index (PTI), which is obtained using the equation PTI = (Pawo/Pimax) x (Ti/Ttot) x 100, where Pawo represents the mean airway pressure measured at the mouth during spontaneous breathing, Pimax is the maximal inspiratory pressure, Ti is the inspiratory time, …

A simple noninvasive pressure–time index at the mouth to measure respiratory load during acute exacerbation of COPD A comparison with normal voluntee…

2003

We assessed the validity of the pressure-time index (PTI) measured at the mouth as a noninvasive and simplified alternative to conventional tension-time index for assessing respiratory load and inspiratory muscle force reserve. PTI was measured within 48 h of hospital admission and at 24 h before discharge in 37 consecutive patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) using the equation PTI = (P(awo)/MIP)(T(I)/T(T)) 100, where P(awo) is the mean airway pressure measured at the mouth, MIP the maximal inspiratory pressure, and T(I)/T(T) the inspiratory time (T(I)) to total cycle length (T(T)) ratio. Controls were 30 normal volunteers with similar anthropome…