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At least 415 records · Page 23Linked to original sources
PubMed2002

Noninvasive ventilation in acute exacerbations of chronic obstructive pulmonary disease in patients with and without home noninvasive ventilation.

OBJECTIVE: The frequency of home ventilation has increased greatly. The objective of the study was, first, to compare the outcome of episodes of acute exacerbation of chronic obstructive pulmonary disease treated with mask intermittent positive-pressure ventilation (MIPPV) in patients with home MIPPV and in patients without home ventilatory support and, second, for each category of patients, to compare patients successfully ventilated with MIPPV with those who failed with MIPPV. DESIGN: Prospective, controlled, nonrandomized clinical study. SETTING: Medical intensive care unit of a university hospital. PATIENTS: In the groups with and without home MIPPV, respectively, 31 and 78 episodes of acute exacerbations of chronic obstructive pulmonary disease were studied. INTERVENTIONS: MIPPV was performed in a sequential mode and delivered through a full-face mask with a bilevel positive airway pressure system. MEASUREMENTS AND MAIN RESULTS: The clinical and functional characteristics of the two groups, at admission, were similar. In groups with and without home ventilation, respectively, success rates were 68% and 72% (p =.68), length of intensive care unit stay was 8 +/- 6 and 10 +/- 4 days (p =.02), and intensive care unit deaths were 13% and 8% (p =.30). In survivors and in groups with and without home ventilation, respectively, the total time of ventilatory assistance in intensive care unit was 5 +/- 4 and 8 +/- 4 days (p =.004), and the length of intensive care unit stay was 7 +/- 5 and 10 +/- 4 days (p =.003). A greater correction of pH, after 45 mins of MIPPV with optimal settings, was recorded in the success patients than in the failure patients, respectively; in the group with home MIPPV, the pH after 45 mins was 7.34 +/- 0.04 vs. 7.31 +/- 0.04 (p =.06), and in the group without home MIPPV, pH was 7.34 +/- 0.04 vs. 7.30 +/- 0.04 (p =.001). CONCLUSION: MIPPV may also be favorable during episodes of acute exacerbations in patients with chronic obstructive pulmonary disease. Experience with MIPPV could benefit selected patients in the management of acute respiratory failure.

Acute Disease↗
PubMed1983

Mechanical ventilation with air-oxygen mixtures during total intravenous anaesthesia. An evaluation of the Penlon Nuffield Series 400 ventilator.

Mechanical ventilation with air-oxygen mixtures during total intravenous anaesthesia is discussed with the associated problem of obtaining a medically suitable source of air in British rooms. Independently powered ventilators capable of entraining filtered room air were thought to be the best solution. The Penlon Nuffield Series 400 ventilator was modified and assessed for use in this mode. An entrainment adapter and circuit was devised which allowed the ventilator to entrain more than sufficient ambient air, premixed with added oxygen for patient ventilation even under adverse conditions. The entrainment system ensured good mixing of the entrained air and oxygen and allowed accurate determination of oxygen concentration in the patient system using a suitable nomogram and without an oxygen analyser. An assessment of one-way patient valves was also undertaken. The Laerdal valve was found to be the most suitable for use with the system described.

Air↗
PubMed2005

Bi-level positive airway pressure ventilation reduces the oxygen cost of breathing in long-standing post-polio patients on invasive home mechanical ventilation.

BACKGROUND: Today, patients with chronic respiratory failure are commonly treated with non-invasive bi-level positive airway pressure ventilation, supporting spontaneous breathing. However, in conformity with previous clinical routine, many post-polio patients with chronic respiratory failure are still treated with invasive (i.e. via a tracheostomy) controlled mechanical ventilation (CMV). The aim of the study was to investigate the effect of invasive bi-level positive airway pressure ventilation on the work of breathing compared with that during the patients' ordinary CMV and spontaneous breathing without mechanical support. METHODS: Nine post-polio patients on invasive (tracheostomy) nocturnal CMV were investigated. Work of breathing was analysed by assessing differences in oxygen consumption (VO2) using indirect calorimetry. Hereby, the oxygen cost of breathing during the various ventilatory modes could be estimated and related to one another. Data on energy expenditure were also obtained. RESULTS: The oxygen cost of breathing decreased by approximately 15% during bi-level positive airway pressure ventilation compared with CMV and spontaneous breathing. There was no difference between predicted (Harris-Benedict equation) and measured energy expenditure. CONCLUSION: Invasive bi-level positive airway pressure ventilation reduces the oxygen cost of breathing in long-standing tracheostomized post-polio patients, compared with CMV. Furthermore, the Harris-Benedict equation provides a reasonable prediction of energy expenditure in this group of patients.

Aged↗
PubMed1999

Monitoring regional lung ventilation by functional electrical impedance tomography during assisted ventilation.

A new approach in discriminating the regional air volume changes in the lungs associated with either spontaneous or mechanical ventilation during assisted ventilation is presented. Impedance data are obtained by conventional electrical impedance tomography (EIT). The data are filtered in the range of either the spontaneous or the ventilator rate and processed by the functional EIT (f-EIT) evaluation technique, whereby the variation of the respective EIT data with time is determined and imaged. EIT measurements performed in an infant during synchronized intermittent mandatory ventilation were evaluated with this method and indicated that the specific local lung volume swings related to spontaneous and mechanical inhalations can be separated and imaged as tomograms. This noninvasive approach may become useful in optimizing the ventilatory pattern during advanced forms of artificial ventilation and may help the clinician in the therapy management of individual patients.

Blood Gas Analysis↗
PubMed2005

Ventilation strategies and outcome in randomised trials of high frequency ventilation.

OBJECTIVE: Randomised controlled trials comparing elective use of high frequency ventilation (HFV) with conventional mechanical ventilation (CMV) in preterm infants have yielded conflicting results. We hypothesised that the variability of results may be explained by differences in study design, ventilation strategies, delay in initiation of HFV, and use of permissive hypercapnia. METHODS: Randomised controlled trials comparing the elective use of HFV with any form of CMV were identified. Trials were classified according to the ventilation strategies used for HFV and CMV and oscillator device employed. For cumulative meta-analyses, trials were arranged by the following covariables: mean duration until randomisation, Paco(2) limits, publication date, and sample size. Odds ratios (OR) and 95% confidence intervals were calculated using fixed and random effects models. RESULTS: Seventeen randomised trials enrolling 3776 patients were included. Unlike previous meta-analyses, there was no significant difference in the incidence of bronchopulmonary dysplasia or death (OR 0.87, 0.75-1.00) and severe intraventricular haemorrhage grade 3-4 (1.14, 0.96-1.37). The incidence of air leaks (OR 1.23, 1.06-1.44) was significantly increased with HFV. Subgroup analyses and cumulative meta-analyses demonstrated that trial results were related to the ventilation strategies used for HFV and CMV. No influence was found for mean time to randomisation, degree of permissive hypercapnia, or sample size. CONCLUSIONS: Heterogeneity among trials of elective HFV compared to CMV in preterm infants is mainly due to differences in ventilatory strategies. Optimising CMV strategy appeared to be as effective as using HFV in improving pulmonary outcome in preterm infants.

High-Frequency Ventilation↗
PubMed2006

Randomised trial of high frequency oscillatory ventilation or conventional ventilation in babies of gestational age 28 weeks or less: respiratory and neurological outcomes at 2 years.

BACKGROUND: The long term outcome of children entered into neonatal trials of high frequency oscillatory ventilation (HFOV) or conventional ventilation (CV) has been rarely studied. OBJECTIVE: To evaluate respiratory and neurodevelopmental outcomes for children entered into the United Kingdom Oscillation Study, which was designed to evaluate these outcomes. METHODS: Surviving infants were followed until 2 years of age corrected for prematurity. Study forms were completed by local paediatricians at routine assessments, and parents were asked to complete a validated neurodevelopmental questionnaire. RESULTS: Paediatricians' forms were returned for 73% of the 585 surviving infants. Respiratory symptoms were common in all infants, and 41% had received inhaled medication. Mode of ventilation had no effect on frequency of any symptoms. At 24 months of age, severe neurodevelopmental disability was present in 9% and other disabilities in 38% of children, but the prevalence of disability was similar in children who received HFOV or CV (relative risk 0.93; 95% confidence interval 0.74 to 1.16). The prevalence of disability did not vary by gestational age, but boys were more likely to have overall disability. Developmental scores were unaffected by mode of ventilation (relative risk 1.13; 95% confidence interval 0.78 to 1.63) and were lower in infants born before 26 weeks gestation compared with babies born at 26-28 weeks. CONCLUSIONS: Initial mode of ventilation in very preterm infants has no impact on respiratory or neurodevelopmental morbidity at 2 years. HFOV and CV appear equally effective for the early treatment of respiratory distress syndrome.

Child Development↗
PubMed2002

Weaning from mechanical ventilation by long-term nasal positive pressure ventilation in two patients with acute respiratory distress syndrome associated with pneumococcal sepsis.

Only few data concerning weaning by nasal positive pressure ventilation (NPPV) are available, and successful weaning by using NPPV in patients with acute respiratory distress syndrome (ARDS) and severe complications has not yet been described. Two cases with ARDS and both preexisting thoracopulmonary disease (infundibulum abnormality and suspected COPD) and associated complications (recurrent sepsis, acute renal failure, need for lobectomy, severe malnutrition) could not be weaned by invasive ventilatory techniques. Both patients presented with rapid shallow breathing and PaCO(2) values >60 mm Hg during intermittent trials of spontaneous breathing, although the primary pathology and associated complications had been resolved. Patients were successfully adapted on NPPV in a stepwise approach after 93 days and 67 days of invasive ventilation. In one patient withdrawal from NPPV was possible after 2 months. In the other patient the duration of daily ventilation could be significantly reduced from 18 to 6 h/day after 9 months on NPPV. Therefore, patients with ARDS who cannot be weaned by invasive ventilatory strategies might be removed successfully from invasive mechanical ventilation by using NPPV even when there are preexisting thoracopulmonary disease and major complications during invasive ventilation.

Adult↗
PubMed1994

Ventilation-perfusion distributions during mechanical ventilation with superimposed spontaneous breathing in canine lung injury.

Biphasic positive airway pressure (BIPAP) allows unrestricted spontaneous breathing throughout mechanical ventilation. Effects of spontaneous breathing during BIPAP on pulmonary gas exchange were studied on a randomized basis in 12 dogs with oleic acid-induced lung injury using the multiple inert gas elimination technique. Spontaneous breathing during BIPAP, accounting for 10% of minute ventilation (VE), increased PaO2 from 61 +/- 2 to 78 +/- 3 mm Hg (mean +/- SE) (p < 0.01), cardiac output from 4.2 +/- 0.3 to 4.6 +/- 0.3 L/min (p < 0.05), and oxygen delivery from 537 +/- 51 to 716 +/- 58 ml/kg/min (p < 0.05), whereas oxygen consumption and total VE remained unchanged. Improved pulmonary gas exchange caused by better ventilation/perfusion (VA/Q) matching was indicated by a 17 +/- 3% decrease (p < 0.01) in blood flow to shunt units (VA/Q < 0.005), a 15 +/- 3% increase (p < 0.05) in perfusion of normal VA/Q units (0.1 < VA/Q < 10), and a 6 +/- 3% reduction in ventilation of dead space (VA/Q > 100) areas (p < 0.05). Spontaneous breaths superimposed on mechanical ventilation may convert shunt VA/Q units to normal by increased ventilation of poorly or nonventilated units and/or increase blood flow to previously minimal or nonperfused areas.

Animals↗
PubMed1999

Calibration of seven ICU ventilators for mechanical ventilation with helium-oxygen mixtures.

The study evaluated seven intensive care unit (ICU) ventilators (Veolar FT, Galileo, Evita 2, Evita 4, Servo 900C, Servo 300, Nellcor Puritan Bennett 7200 Series) with helium-oxygen (HeO2), using a lung model, to develop correction factors for the safe use of HeO2. A 70:28 helium-O2 mixture (heliox) replaced air and combined with O2 (HeO2). Theoretical impact of HeO2 on inspiratory valves and gas mixing was computed. True fraction of inspired oxygen (FIO2del) was compared with fraction of inspired oxygen (FIO2) set on the ventilator (FIO2set). True tidal volume (VTdel) was compared with VT set on the ventilator (VTset) in volume control and with control VTdel at FIO2 1.0 in pressure control. FIO2del minimally exceeded FIO2set (</= 5%) except with the 7200 Series (FIO2del > FIO2set by 125%). In volume control, with the Veolar FT, Galileo, Evita 2, and Servo 900C, VTdel > VTset, with the 7200 Series VTdel < VTset (linear relationship, magnitude of discrepancy inversely related to FIO2set). With the Evita 4, VTdel > VTset (nonlinear relationship), whereas with the Servo 300 VTdel = VTset. In pressure control, VTdel was identical to control measurements, except with the 7200 Series (ventilator malfunction). Correction factors were developed that can be applied to most ventilators.

Calibration↗
PubMed1999

Influence of ventilator settings in determining respiratory frequency during mechanical ventilation.

During mechanical ventilation, changes in inspiratory flow and tidal volume (VT) have been shown to alter respiratory frequency (f ). However, the changes in flow and VT have been accompanied by alteration in ventilator inspiratory time (TI,(vent)), and it is not clear which variable is the primary determinant. To address this issue, we employed four protocols in 15 healthy volunteers receiving assist-control ventilation. When VT was fixed and flow was delivered at 30, 60, and 90 L/min, f increased as a function of the increase in flow and the decrease in TI,(vent). When flow was held constant and VT was changed among 0.5, 1.0, and 1.5 L, f increased as a function of the decreases in VT and TI,(vent). When flow was increased from 60 to 90 L/min and these changes were balanced with VT settings of 1.0 and 1.5 L to maintain a constant TI,(vent), f did not change. When flow and VT were held constant and TI,(vent) was varied by the application of inspiratory pauses (0 to 2 s), f decreased as a function of the increase in TI,(vent) (p < 0.001). In conclusion, the imposed ventilator inspiratory time during mechanical ventilation can determine f independently of delivered inspiratory flow and VT.

Adult↗
PubMed2002

Noninvasive ventilation after intubation and mechanical ventilation.

Patients with chronic airflow obstruction who are difficult to wean from mechanical ventilation are at increased risk of intubation-associated complications and mortality because of prolonged invasive mechanical ventilation. Noninvasive positive pressure ventilation may revert most of the pathophysiological mechanisms associated with weaning failure in these patients. Several randomized controlled trials have shown that use of noninvasive ventilation to achieve earlier extubation in difficult-to-wean patients or in patients who develop respiratory failure after apparently successful extubation can result in reduced periods of endotracheal intubation and complication rates and improved survival. However, this is not a consistent finding, and the currently available published data with outcome as the primary variable are exclusively from patients who had pre-existing lung disease. In addition, the patients were haemodynamically stable, with a normal level of consciousness, no fever and a preserved cough reflex. It remains to be seen whether noninvasive positive pressure ventilation has a role in other patient groups and situations, such as prevention of postextubation failure or unplanned extubation. The technique is, however, a useful addition to the therapeutic armamentarium for a group of patients who pose a significant clinical and economic challenge.

Algorithms↗
PubMed1998

Assessment of ventilation-perfusion mismatching in mechanically ventilated patients.

The multiple inert gas elimination technique (MIGET) is a robust tool to assess both ventilation-perfusion (V'A/Q') distributions and the role of extrapulmonary factors determining arterial oxygenation during spontaneous breathing and in mechanically ventilated patients. Mixed expired gas sampling used in the MIGET is most often obtained from a 10-L mixing box (10L-MB) placed in the expiratory side of the ventilator circuit. Consequently, a considerable increase in the compression volume (Vc) would be expected which, in turn, can give rise to potential errors in the estimation of the effective tidal volume delivered to the patient. The effects of the 10L-MB on the Vc were compared with those produced by a newly designed 1-L, mixing box (IL-MB). At a given peak pressure (Ppeak) within the ventilator circuit, the Vc generated by the 10L-MB was about six-times higher than that produced by the 1L-MB. At a Ppeak =50 cmH2O, the Vc were 377 mL (10L-MB) and 67 mL (1L-MB) (p<0.001). In six patients, the mixed expired partial pressures of the six inert gases simultaneously collected from the two mixing boxes fell on the identity line. V'A/Q' distributions recovered using each of the two mixing boxes were equivalent. With the IL-MB, the effects of different positive end-expiratory pressure levels (0, 6 and 12 cmH2O) on Vc and arterial carbon dioxide tension were negligible. In conclusion, the new 1-L mixing box provides efficient gas mixing and substantially decreases the compression volume. It is, therefore, recommended when studies requiring mixed expired gas are performed in ventilated patients.

Aged↗
PubMed1994

Can anesthesia ventilators provide high-frequency ventilation?

We measured the tidal volumes (VT) delivered by two anesthesia ventilators (the Narkomed 2B and the Ohmeda 7800) to a model lung at frequencies of 60 breaths/min and 99-100 breaths/min under two conditions of compliance and resistance designed to mimic mild and severe adult respiratory distress syndrome (ARDS) (mild ARDS = S1 and severe ARDS = S2). The VT produced were measured with a pneumotachometer at the ventilator outflow and distal to the anesthesia circuit. With the Narkomed 2B, the VT measured at the entrance to the model lung decreased from 216 mL to 129 mL in S1, and from 152 mL to 88 mL in S2 as the ventilatory frequency increased from 60 to 99 breaths/min. With the Ohmeda 7800, the VT decreased from 213 mL to 118 mL in S1, and from 134 mL to 73 mL in S2 when the frequency was changed from 60 to 100 breaths/min. Since the delivered VT are similar to those previously reported to maintain adequate ventilation at these rates using standard high-frequency ventilation (HFV), it may be possible to use these newer anesthesia ventilators for this purpose.

Anesthesia↗
PubMed2005

High-frequency ventilation versus conventional ventilation for the treatment of acute lung injury and acute respiratory distress syndrome: a systematic review and cochrane analysis.

In this review, we examine outcomes from using high-frequency ventilation compared with conventional ventilation as therapy for acute lung injury and acute respiratory distress syndrome in children and adults. We conducted a systematic search of the literature based on the guidelines of the Cochrane Collaboration. Two trials met the inclusion criteria; one recruited children (n = 58), and the other recruited adults (n = 148). Both trials used a high-frequency oscillatory ventilator as the intervention and included variable use of lung-volume recruitment strategies. The intervention groups showed a trend toward less 30-day mortality (children: relative risk [RR], 0.83; 95% confidence interval [CI], 0.43-1.62; adults: RR, 0.72; 95% CI, 0.50-1.03), although neither study showed a statistically significant difference. Similarly, there was no statistically significant difference between the intervention and control groups for "total length of ventilator days." There was a statistically significant reduction in the risk of requiring supplemental oxygen among survivors at 30 days in the pediatric study (RR, 0.36; 95% CI, 0.14-0.93). Overall there is not enough evidence to conclude that high-frequency ventilation reduces mortality or long-term morbidity in patients with acute lung injury or acute respiratory distress syndrome. (This review is published as a Cochrane Review in The Cochrane Library 2004, Issue 3. Cochrane Reviews are regularly updated as new evidence emerges and in response to comments and criticisms, and The Cochrane Library should be consulted for the most recent version of the Review.).

Adolescent↗
PubMed1993

Comparison of BiPAP nasal ventilation and ventilation via iron lung in severe stable COPD.

The effects of noninvasive ventilators on COPD remain controversial because of their obscure mechanisms. A randomized crossover study, using iron lung and positive pressure nasal ventilation (BiPAP) each for 40 min, was performed in 11 stable patients with severe COPD. Throughout the study, we monitored surface EMGdi, EMGst, ECG, SaO2, ETCO2, and the movements of RC and AB. Afterwards the data were replayed to calculate VT, RR, PR, VT/TI, iEMG, and phase angle. No statistically significant improvement was found in view of the above parameters. However, the percentage of iEMGst change after 40-min BiPAP ventilation, compared with the baseline, was much more significant in patients with FEV1 below 0.55 L than those with FEV1 above 0.55 L (n = 4:7, delta iEMGst -62.93 percent +/- 23.27 percent vs 32.45 percent +/- 42.79 percent, p = 0.0056). delta iEMGst correlated significantly with FEV1 during BiPAP ventilation (p < 0.05, r = 0.59). We conclude that the iEMGst during short-term BiPAP ventilation correlates with the severity of the disease.

Aged↗
PubMed1990

Reduction of peak inspiratory pressure using high frequency jet ventilation and pressure control ventilation following pneumonectomy.

High peak inspiratory pressure (PIP) during mechanical ventilation is associated with increased risk of barotrauma. High frequency jet ventilation (HFJV) and pressure control ventilation (PCV) have been advocated for the reduction of PIP. The Food and Drug Administration has approved HFJV, respiratory frequency as high as 150 breaths per minute (bpm); however, bpm greater than 150 are still considered for experimental use. At less than 40 bpm, the point where HFJV is no longer considered to be high frequency, PCV is substituted which then becomes the mode of choice because of the ability to control ventilating pressures by setting the PIP. We present a case in which we used these two forms of ventilation for reducing the risk of stump blowout and barotrauma following pneumonectomy.

Barotrauma↗
PubMedDate not supplied

Ventilation and ventilators.

The history of ventilation is reviewed briefly and recent developments in techniques of ventilation are discussed. Operating features of ventilators have changed in the past few years, partly as the result of clinical progress; yet, technology appears to have outstripped the clinician's ability to harness it most effectively. Clinical discipline and training of medical staff in the use of ventilators could be improved. The future is promising if clinician and designer can work together closely. Ergonomics of ventilators and their controls and the provision of alarms need special attention. Microprocessors are likely to feature prominently in the next generation of designs.

Adult↗
PubMedDate not supplied

Bi-level home ventilators for non invasive positive pressure ventilation.

With the widespread use of non-invasive positive pressure mechanical ventilation, great efforts have been made to produce machines, the bi-level home ventilators, which are less sophisticated, cheaper and able to better compensate air leaks with respect to the domiciliary volume-target machines and the traditional ventilators used in intensive care unit. As consequence of quick technologic evolution, bi-level home ventilators may be nowadays successfully applied for both the non-invasive ventilatory domiciliary treatment of chronic respiratory failure and the management of acute respiratory failure especially outside the intensive care setting. In this paper, the author describes the technical aspects, the individual characteristics and the clinical applications of the most common used bi-level ventilators.

Equipment Design↗