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At least 577 records · Page 32Linked to original sources
PubMed1996

Pulmonary epithelial permeability. An animal study of inverse ratio ventilation and conventional mechanical ventilation.

STUDY OBJECTIVE: To compare pressure-controlled inverse ratio ventilation (PCIRV) with volume-controlled ventilation with positive end-expiratory pressure (VCV PEEP) at equal levels of end-expiratory alveolar pressure. The primary focus of the study was on pulmonary epithelial permeability. Histologic and gravimetric indicators of lung injury were also studied. DESIGN: Randomized animal study. SETTING: Experimental investigation at Södersjukhuset, Stockholm, Sweden. ANIMALS: Thirty-two New Zealand white rabbits. INTERVENTIONS: Ventilation with PCIRV or VCV PEEP for 6 h at an end-expiratory pressure level of 5 cm H2O. MEASUREMENTS AND RESULTS: Lung mechanics, heart rate, BP, and gas exchange. Measurement of pulmonary epithelial permeability by 99mTc-DTPA lung clearance. Extravascular lung water by gravimetric analysis. Morphology by light microscopy after a perfusion fixation procedure. Mean and peak airway pressures were 12.4 +/- 4.3 and 15.9 +/- 4.5 cm H2O with PCIRV and 8.6 +/- 0.8 (p < 0.001) and 19.9 +/- 4.1 cm H2O (p < 0.03) with VCV PEEP at 6 h. Mean systemic BP was lower with PCIRV (58 +/- 9 mm Hg) than with VCV PEEP (68 +/- 7 mm Hg) at 6 h (p < 0.003). At 6 h, PaCO2 was lower with PCIRV (3.2 +/- 0.6 kPa) than with VCV PEEP (4.1 +/- 0.8 kPa) (p < 0.02). There was no difference in blood oxygenation between PCIRV and VCV PEEP. 99mTc-DTPA lung clearance curves were monoexponential with both PCIRV and VCV PEEP. Mean lung clearance expressed as T 1/2 was 16 +/- 9 min with PCIRV and 107 +/- 74 min with VCV PEEP (p < 0.001). Morphologic examination revealed no differences between the groups and no evidence of significant lung injury. CONCLUSIONS: The observations reported in this article imply that PCIRV causes an alteration in lung epithelial or membrane function in comparison to VCV PEEP. This functional difference is most likely caused by the large time-adjusted lung volume produced by pressure control in combination with a prolonged inspiration. It remains to be established whether this early functional effect of PCIRV is relevant with regard to structural lung injury in mechanically ventilated subjects.

Animals↗
PubMed1999

Exacerbation of acute pulmonary edema during assisted mechanical ventilation using a low-tidal volume, lung-protective ventilator strategy.

STUDY OBJECTIVES: To assess the magnitude of negative intrathoracic pressure development in a patient whose pulmonary edema acutely worsened immediately following the institution of a low-tidal volume (VT) strategy. DESIGN: Mechanical lung modeling of patient-ventilator interactions based on data from a case report. SETTING: Medical ICU and laboratory. PATIENT: A patient with suspected ARDS and frank pulmonary edema. INTERVENTIONS: The patient's pulmonary mechanics and spontaneous breathing pattern were measured. Samples of arterial blood and pulmonary edema fluid were obtained. MEASUREMENTS: A standard work-of-breathing lung model was used to mimic the ventilator settings, pulmonary mechanics, and spontaneous breathing pattern observed when pulmonary edema worsened. Comparison of the pulmonary edema fluid-to-plasma total protein concentration ratio was made. RESULTS: The patient's spontaneous VT demand was greater than preset. The lung model revealed simulated intrathoracic pressure changes consistent with levels believed necessary to produce pulmonary edema during obstructed breathing. A high degree of imposed circuit-resistive work was found. The pulmonary edema fluid-to-plasma total protein concentration ratio was 0.47, which suggested a hydrostatic mechanism. CONCLUSION: Ventilator adjustments that greatly increase negative intrathoracic pressure during the acute phase of ARDS may worsen pulmonary edema by increasing the transvascular pressure gradient. Therefore, whenever sedation cannot adequately suppress spontaneous breathing (and muscle relaxants are contraindicated), a low-VT strategy should be modified by using a pressure-regulated mode of ventilation, so that imposed circuit-resistive work does not contribute to the deterioration of the patient's hemodynamic and respiratory status.

Adult↗
PubMed2000

Prospective randomized trial comparing pressure-controlled ventilation and volume-controlled ventilation in ARDS. For the Spanish Lung Failure Collaborative Group.

STUDY OBJECTIVES: To compare in-hospital mortality of patients with ARDS ventilated with either pressure-controlled ventilation (PCV) or volume-controlled ventilation (VCV) with a square-wave inspiratory flow. DESIGN: : Multicenter and randomized trial. SETTING: Twelve medical-surgical ICUs located in tertiary-care hospitals. PATIENTS: Seventy-nine patients having ARDS, as defined by the American-European Consensus Conference. INTERVENTIONS: Patients were randomly assigned to be ventilated with either PCV (n = 37) or VCV (n = 42). In both instances, inspiratory plateau pressure was limited to < or = 35 cm H(2)O. MEASUREMENTS AND RESULTS: There were no significant differences among the studied groups at the moment of randomization, although there was a trend toward greater renal failure in patients assigned to VCV. Ventilatory settings and blood gases did not significantly differ over time between the two groups. Patients in the VCV group had both a significantly higher in-hospital mortality rate than those in the PCV group (78% vs 51%, respectively) and a higher number of extrapulmonary organ failures (median, 4 vs 2, respectively). The development of renal failure during the study period was also significantly more frequent among VCV patients (64% vs 32%, respectively). Multivariate analysis showed that factors independently associated with an increased mortality rate were the presence of two or more extrapulmonary organ failures (odds ratio [OR], 4.61; 95% confidence interval [CI], 1.38 to 15.40) and acute renal failure (OR, 3.96; 95% CI, 1.10 to 14.28) but not the ventilatory mode used. CONCLUSIONS: The increased number of extrapulmonary organ failures developed in patients of the VCV group was strongly associated with a higher mortality rate. The development of organ failures was probably not related to the ventilatory mode.

Adult↗
PubMed1983

Prevention of suctioning-related arterial oxygen desaturation. Comparison of off-ventilator and on-ventilator suctioning.

The purpose of this study was to determine the frequency and severity of arterial oxygen desaturation during and after endotracheal suctioning in a group of ventilator-dependent patients with acute respiratory failure (the majority of whom had underlying obstructive lung disease) and to evaluate the efficacy of several maneuvers designed to minimize desaturation. The adaptor method presented obviates both removal from and reconnection to the ventilator during suctioning, as well as the need to alter ventilator settings. It is concluded that on-ventilator adaptor suctioning is a simple and effective measure for minimizing suctioning-related arterial oxygen desaturation.

Arteries↗
PubMed1989

Pressure control inverse ratio ventilation as a method to reduce peak inspiratory pressure and provide adequate ventilation and oxygenation.

Nineteen patients with ARDS or pneumonia who were ventilated with PcIRV on the Siemens-Elema Servo 900 C were retrospectively reviewed. The PcIRV reduced peak airway pressure, PEEP, increased Paw, and improved ventilation and oxygenation in these patients. When these patients were compared with themselves on prior conventional IPPV, all had a decrease in PIP, an increase in Paw and most had a decrease in VE, with no change in PaCO2 and an increase in PaO2. The increase in Paw may have contributed to this improved arterial oxygenation. High levels of PIP and PEEP during IPPV have been identified as risk factors in the development of barotrauma and residual parenchymal pulmonary damage. We propose that PcIRV allows for adequate ventilation and oxygenation with decreases in PIP, extrinsically added PEEP and inspired O2 concentration. This mode of ventilation may decrease the morbidity associated with IPPV utilizing high PIP and PEEP.

Adolescent↗
PubMed1984

Effect of high-frequency ventilation versus conventional mechanical ventilation on ICP in head-injured dogs.

Changes in intrathoracic pressure may influence intracranial pressure (ICP), presumably by affecting venous return. High-frequency ventilation (HFV) has been associated with lower intrapleural and airway pressures and has the potential to lower ICP. To evaluate the effects of HFV compared to conventional ventilation on ICP, normocarbia was maintained in nine dogs while alternating between conventional ventilation and HFV at 200 breaths/min. The mean ICP was raised from 6.3 +/- 6.1 to 24.7 +/- 1.04 mm Hg by inflation of Fogarty balloons implanted in the epidural space. The ICP peaks associated with positive inflation pressures were eliminated with HFV, but mean ICP was not significantly different between the two ventilatory modes (23.4 +/- 9.7 mm Hg for the conventional system versus 26.0 +/- 10.0 mm Hg for HFV). Four dogs exhibited neurogenic pulmonary edema: they developed elevated pulmonary artery and intrathoracic pressures and required increased inspiratory flow with HFV to maintain normocarbia. The authors conclude that, in this head-injury model, there did not seem to be an advantage of HFV over conventional ventilation.

Animals↗
PubMed2000

[Influence of the subglottic secretion drainage on the morbidity of ventilator associated pneumonia in mechanically ventilated patients].

OBJECTIVE: To assess the influence of the subglottic secretion drainage on the morbidity of ventilator associated pneumonia in mechanically ventilated patients. METHODS: All cases requiring intubation in SICU were intubated with a special type endotracheal tube which has a small-bore cannula in its wall for subglottic secretion drainage. They were randomly divided into two groups received subglottic secretion drainage(SSD) and usual care(NON-SSD) respectively. Bacterial culture of samples from the oropharynx, subglottic secretions and lower respiratory tract were obtained periodically. The amount of subglottic secretion aspirated daily, ventilated days and the number of cases with VAP were recorded. Etiologic diagnosis of VAP was based on the quantitative bacterial culture of secretions obtained by protected specimen brush(PSB). RESULTS: The morbidity of VAP in the SSD group (n = 35) (23%) was lower than that in the NON-SSD group (n = 33) (45%) (P < 0.05). The difference was due to the significant reduction of VAP caused by gram-positive cocci and Haemophilus influenzae organisms. However, no difference was observed in the incidence of VAP caused by non-fermental bacteria. After intubation the onset of VAP was delayed in SSD group (14 +/- 8 day) as compared with the NON-SSD group (6 +/- 4 day) (P < 0.05). The same organisms were isolated by PSB among 61% (14/23) patients with VAP as what were previously isolated from the subglottic secretions. CONCLUSIONS: The presence of subglottic secretion may be an origin of the pathogenetic organisms of VAP. The morbidity of VAP in mechanically ventilated patients can be reduced by SSD, especially for VAP caused by gram-positive cocci and Haemophilus influenzae organisms. SSD may be a simple and effective method for prevention of VAP.

Glottis↗
PubMedDate not supplied

[Evaluation of 2 techniques for ventilation support during single-lung ventilation].

In a group of 22 patients undergoing thoracotomy we compared two techniques of ventilatory assistance to the nondependent lung during single lung ventilation. We simultaneously administered a 0.5% FiO2 to the dependent lung. We used a CPAP system with continuous O2 flow limited by an underwater valve at a pressure of +5 cmH2O. We performed 33 ventilatory assistances: in 15 cases to the nondependent lung (CPAP group) and in 18 patients to the lower lobe of the nondependent lung (lobar CPAP group). Evaluation of both techniques was performed by means of arterial blood gas measurement and the mean values were compared using the student's t test. During single lung ventilation the PaO2 in CPAP group increased from 85.86 +/- 22.28 mmHg to 155.52 +/- 59.54 mmHg (p less than 0.001) and in the lobar CPAP series it increased from 88.75 +/- 24.34 mmHg to 122.36 +/- 43.21 mmHg (p less than 0.01). In 11 out of the 22 patients we firstly applied the lobar CPAP and thereafter the CPAP to the whole lung in order to compare the efficacy of both techniques in the same patient. The PaO2 during single lung ventilation was 86.9 +/- 22.7 mmHg and it increased to 111.1 +/- 37.9 mmHg after lobar CPAP (p less than 0.01) ant to 163.3 +/- 64 mmHg after total lung CPAP ventilation (p less than 0.001). Our results confirm the usefulness of both techniques and they indicate that CPAP to the whole nondependent lung is the most effective.

Adult↗
PubMedDate not supplied

[Implementation of modern trends in the methods of the ventilation support in the new apparatus for artificial lung ventilation Avenir-221 P].

In the new ventilator Avenir-221 P modern lines of development of ventilation support in intensive therapy of adults and children are implemented. The capacities of the ventilator are successfully combined with its technical decisions which include microprocessor parametrical controlling, programming-controlled electric drive, an information saturation, intuitively clear control system, protection against interruption of power supply sources and oxygen feeding falls. A set of functional characteristics (modes VCV, PCV, Ass/Contr, PSV, SIMV, PEEP, Sigh, etc.) in combination with an original design make the device the most accessible and promising for application in intensive care and resuscitation units of a wide network of Russian hospitals and clinics. The ventilator Avenir-221 P has passed all required tests and is presently commercially available.

Adolescent↗
PubMed1988

[Behavior of respiratory tract, esophagus and pulmonary artery pressure in bronchoscopies in normofrequent jet ventilation in comparison with Friedel's ventilation technics].

The dynamics of selected physiological respiratory parameters were studied in a total of 29 patients. During slight hyperventilation and good oxygenation by both Friedel's and jet ventilation (driving pressure 0.3 and 0.4 MPa, respectively), comparably low respiratory tract pressures were observed. Transmission to intrathoracic (44-46%) and mean pulmonary artery pressure (11-13%) indicates only a low-grade ventilation-induced hemodynamic influence. By contrast, clear increases in pulmonary artery pressure due to intubation were recorded. Thus, the employed normofrequent jet ventilation with its continuous open-tube ventilation which is independent of the undisturbed bronchological examination possesses beneficial properties from a cardiorespiratory view.

Adult↗
PubMed1987

Pulmonary embolism: high-frequency jet ventilation offers advantages over conventional mechanical ventilation.

After injecting autologous muscle to induce massive pulmonary embolism, the effects of high-frequency jet ventilation (HFJV) were compared with those of controlled mechanical ventilation (CMV) in anesthetized, paralyzed dogs. HFJV better maintained both alveolar ventilation and oxygenation than did CMV. Moreover, PaO2, cardiac index, and oxygen delivery were greater with HFJV than with CMV when the two modes of ventilation were compared at the same PaCO2.

Animals↗
PubMed1982

[Working conditions and complications during laryngomicroscopies under endotracheal ventilation via intubation tubes or injection ventilation].

During a period of 7 years 693 laryngomicroscopies (LAR) were performed on 490 patients. General anaesthesia was given by 21 anaesthesists: 5 applied ventilation only through a conventional intubation tube. Of the remaining 16 anaesthesists, 8 constantly prefered, 4 used occasionally jet ventilation (JET), and 4 applied both methods alternatively. No rationale was found for this choice. Laryngomicroscopies were performed by 14 ENT surgeons. One case of subcutaneous emphysema and two of pneumothorax were obtained with JET, obviously because of inexperience and neglect of precautions. Two epidermoid carcinomas in the left posterior commissure escaped the primary LAR, most probably because of poor vision due to the intubation tube, and were found during subsequent procedures with JET. In spite of the risk of complications (mostly avoidable with care and increasing experience), the main advantage of JET is the better chance of revealing of carcinoma in an earlier phase, when it is more amenable to curative therapy. Therefore, we no longer recommend ventilation through an intubation tube for laryngomicroscopies, but prefer intratracheal jet-ventilation for this purpose.

Anesthesia↗
PubMedDate not supplied

High-frequency ventilation: a promising new approach to mechanical ventilation.

Adequate pulmonary ventilation can be achieved in experimental animals and in humans using tidal volumes on the order of the anatomic dead space volume applied at very high ventilatory frequencies (3-30 Hz). Classical mechanism of gas exchange cannot account for these paradoxical observations, but theories based on the concept of augmented diffusion may provide an adequate explanation for this phenomenon. Even though the exact mechanisms accounting for gas exchange are not well understood, a number of successful ventilators have been designed and tested based on the concept of small volume/high frequency ventilation. The differences among these various ventilators are compared and contrasted and possible clinical uses of the technique are discussed.

Animals↗
PubMed1989

Comparison of high-frequency oscillatory ventilation and high-frequency jet ventilation in cats with normal lungs.

Four adult cats received alternating high-frequency oscillatory ventilation (HFOV) and high-frequency jet ventilation (HFJV) at equivalent proximal airway pressures. Physiologic measurements were made before and after each ventilator change. Proximal airway pressures were then adjusted as necessary to reestablish normal pH and PaCO2 values. Aortic, pulmonary artery, and central venous pressures were monitored. Cardiac outputs were measured. Pulmonary and systemic vascular resistance, intrapulmonary shunt, and alveolar-arterial oxygen gradient were determined. Following the change from HFOV to HFJV at similar proximal airway pressures, HFJV always produced higher pH values (P less than 0.0001), higher PaO2 values (P less than 0.05), lower PaCO2 values (P less than 0.0001), as well as higher cardiac outputs (P less than 0.01), lower pulmonary artery pressures (P less than 0.001), and lower pulmonary vascular resistances (P less than 0.001). Following the reciprocal crossover, from HFJV to HFOV, HFJV pH values were again higher (P less than 0.001), and PaCO2 values were again lower (P less than 0.001). A comparison of HFOV and HFJV at similar pH and PaCO2 values showed that HFOV consistently required higher peak inspiratory pressures (P less than 0.001), higher mean airway pressure (P less than 0.001), and higher pressure wave amplitudes (P less than 0.001). Under the circumstances of this study, HFJV produced better gas exchange at lower proximal airway pressures.

Airway Resistance↗
PubMed2005

Effect of the Y-piece of the ventilation circuit on ventilation requirements in extremely low birth weight infants.

OBJECTIVE: Volutrauma caused by high tidal volumes contributes considerably to the development of bronchopulmonary dysplasia. Yet high tidal volumes are required to overcome dead space. In an experimental arrangement we tested whether reduction of dead space might reduce ventilation requirements and thus reduce volutrauma in preterm infants. MATERIALS AND METHODS: The time required to eliminate CO2 by standardized mechanical ventilation from a preterm infant's test lung flooded with CO2 was measured. Four different Y-pieces and flow sensor combinations were tested with and without a device for closed suction: Y-piece without flow sensor; integrated flow sensor; small dead-space flow sensor; and a new dead-space free-flow sensor for preterm infants. CO2 concentrations were measured by a capnograph. Mean CO2 elimination times (+/-SD) were compared. RESULTS: Mean CO2 elimination time was 37.5 s (+/-1.18 s) with and 37.4 s (+/-0.97 s) without closed suction device for the Y-piece without flow sensor, 47.7 s (+/-0.82 s) and 45.5 s (+/-1.18 s) for the integrated flow sensor, 42.5 s (+/-1.27 s) and 41.1 s (+/-0.99 s) for the small dead-space flow sensor and 38.3 s (+/-1.16 s) and 36.8 s (+/-0.79 s) for the dead-space free-flow sensor. CONCLUSION: CO2 elimination time with and without closed suction device was nearly identical for the Y-piece without flow sensor and for the dead-space free-flow sensor. With both systems, ventilation requirements were significantly lower than for the integrated flow sensor and for the small dead-space flow sensor (integrated flow sensor vs dead-space free-flow sensor 23.6 and 24.5%, respectively, small dead-space flow sensor vs dead-space free flow sensor 11.7 and 10.9%, respectively); thus, we think that introduction of the innovative dead-space free-flow sensor into clinical practice might reduce incidence and severity of bronchopulmonary dysplasia by reduction of volutrauma.

Bronchopulmonary Dysplasia↗
PubMed1999

The open lung concept: pressure-controlled ventilation is as effective as high-frequency oscillatory ventilation in improving gas exchange and lung mechanics in surfactant-deficient animals.

OBJECTIVE: To demonstrate in experimental animals with respiratory insufficiency that under well-defined conditions, commercially available ventilators allow settings which are as effective as high-frequency oscillatory ventilators (HFOV), with respect to the levels of gas exchange, protein infiltration, and lung stability. DESIGN: Prospective, randomized, animal study. SETTING: Experimental laboratory of a university. SUBJECTS: 18 adult male Sprague-Dawley rats. INTERVENTIONS: Lung injury was induced by repeated whole-lung lavage. Thereafter, the animals were assigned to pressure-controlled ventilation (PCV) plus The Open Lung Concept (OLC) or HFOV plus OLC (HFO(OLC)). In both groups, an opening maneuver was performed by increasing airway pressures to improve the arterial oxygen tension/fractional inspired oxygen (PaO(2)/FIO(2)) ratio to L 500 mm Hg; thereafter, airway pressures were reduced to minimal values, which kept PaO(2)/FIO(2) L 500 mm Hg. Pressure amplitude was adjusted to keep CO(2) as close as possible in the normal range. MEASUREMENTS AND RESULTS: Airway pressure, blood gas tension, and arterial blood pressure were recorded every 30 min. At the end of the 3-h study period, a pressure-volume curve was recorded and bronchoalveolar lavage was performed to determine protein content. After the recruitment maneuver, the resulting mean airway pressure to keep a PaO(2)/FIO(2) L 500 mm Hg was 25 +/- 1.3 cm H(2)O during PCV(OLC) and 25 +/- 0.5 cm H(2)O during HFOV(OLC). Arterial oxygenation in both groups was above L 500 mm Hg and arterial carbon dioxide tension was kept close to the normal range. No differences in mean arterial pressure, lung mechanics and protein influx were found between the two groups. CONCLUSIONS: This study shows that in surfactant-deficient animals, PCV, in combination with a recruitment maneuver, opens atelectatic lung areas and keeps them open as effectively as HFOV.

Animals↗
PubMed1996

Home mechanical ventilation for amyotrophic lateral sclerosis: nasal compared to tracheostomy-intermittent positive pressure ventilation.

People with amyotrophic lateral sclerosis (ALS) usually die from respiratory failure unless they use mechanical ventilation (MV). Many die of respiratory failure without being adequately informed about the available options, such as MV that can provide symptomatic relief and prolong survival. The traditional method of MV used for persons with ALS has been tracheostomy-intermittent positive pressure ventilation (IPPV). However, the advent of nasal-IPPV has provided a new option for relieving respiratory symptoms and prolonging survival among selected individuals. The ALS Association Data on 75 ALS patients using MV is reviewed. Twenty-five patients used nasal-IPPV, all started electively. Survival with nasal-IPPV ranged from 6 to 64 months for non-bulbar patients, or until the onset of severe bulbar dysfunction when nasal-IPPV no longer was effective. Fifteen of these non-bulbar patients used nasal-IPPV from 20 to 24 h daily; one of these patients used nasal-IPPV continuously for 24 h daily for 24 months. One hundred percent of the users indicated they were glad they chose nasal-IPPV. In contrast, 50 have used tracheostomy-IPPV, usually as a result of emergency hospitalization without advance decision making. Twenty-five patients (50%) lived in a sub-acute skilled nursing facility (SNF) and only 18 of these (72%) were satisfied with their quality of life. Patients using tracheostomy-IPPV with good care are able to live many years: 27 of the 50 (54%) are still living, including one patient who is still living after 14 years of MV. In conclusion, home mechanical ventilation with nasal or tracheostomy-IPPV are options for selected people with ALS. Nasal-IPPV offers may advantages; it was only used when MV was planned and desired. Nasal-IPPV can be used unless bulbar impairment is severe.

Aged↗
PubMed1988

Low-compliance, volume-controlled, high-frequency positive-pressure ventilation versus conventional ventilation during coronary artery bypass grafting.

Low-compliance, volume-controlled, high-frequency positive-pressure ventilation (HFPPV) was compared to conventional intermittent positive-pressure ventilation (IPPV) immediately before and after surgery in a series of ten patients who underwent coronary artery bypass grafting (CABG). Direct and indirect hemodynamic and respiratory variables were recorded and calculated. All patients were adequately ventilated with either HFPPV or IPPV. No significant differences in hemodynamic stability were noted either before or after cardiopulmonary bypass (CPB). Airway pressures were lowered significantly by HFPPV as compared to IPPV. This may be useful in cases in which increased airway pressure might be harmful due to decreased venous return and cardiac output (CO).

Aged↗