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PubMed1990

[Pulmonary gas exchange in conventional ventilation and high frequency ventilation in severe respiratory insufficiency].

During high frequency jet ventilation (HFJV) adequate alveolar ventilation may be achieved with lower (-35%, p less than 0.0005) central airway pressures than during conventional mechanical ventilation (CMV). Due to increasing ventilation-perfusion inequalities, however, intrapulmonary shunt is then considerably increased (+52%, p less than 0.0005). In disease states with extensive shunting (e.g. ARDS) both ventilation modes can provide sufficient oxygenation only if high PEEP is applied.

High-Frequency Jet Ventilation↗
PubMed1988

Lung pathology after high frequency jet ventilation combined with low rate intermittent mandatory ventilation in a canine model of meconium aspiration.

The microscopic appearance of lungs subjected to six hours of conventional ventilation (CV), standard high frequency jet ventilation (HFJV), and HFJV combined with low rate intermittent mandatory ventilation (CHFJV) was studied in 22 mongrel puppies. A lung injury model was created by insufflating 4 ml/kg of a 20% mixture of meconium into the trachea. The animals were initially ventilated at the same mean airway pressure (Paw). Subsequently, if PCO2 fell below 20 torr, peak and mean airway pressures were reduced. A scoring system was devised which assigned 0-3 points for each of eight lung injury parameters, and a total lung injury score (TLIS) was calculated. CHFJV resulted in significantly less bronchopneumonia and edema, when compared to CV. A consistent, though not significant, trend toward lesser injury scores in CHFJV animals was noted for several other parameters. Six of eight lungs exposed to CV had TLIS greater than 5 compared to only 1 of 9 ventilated by CHFJV. (P = 0.02). It is concluded that CHFJV may have a protective effect on the lung, perhaps because effective gas exchange is achieved with a lower pressure amplitude and at lower Paw.

Animals↗
PubMed1980

Limits of high frequency percutaneous transtracheal jet ventilation using a fluidic logic controlled ventilator.

A study was undertaken on dogs to find the limit of carbon dioxide exchange with high frequency jet ventilation using a fluidic logic controlled oxygen jet ventilator. Fifteen dogs were ventilated through a transtracheal catheter at respiratory rates up to 600 per minute. The following were recorded: aortic, pulmonary artery, pulmonary arterial wedge, and central venous blood pressures; intratracheal pressure, electrocardiogram; inspiratory and expiratory time of the jet; arterial and central venous blood gases; intermittent cardiac output. Normal gas exchange was found up to a respiratory rate of 400 per minute with low tidal volume and low intratracheal pressures. There were no adverse circulatory effects up to a rate of 400 per minute. At rates of 500 and 600 per minute, cardiac contractility was unaffected, but a decreased heart rate and increased peripheral resistance produced a fall in cardiac output. There was no interference with the resumption of spontaneous ventilation during weaning. In a control series of five dogs, apnoeic oxygenation was used. The PaCO2 was allowed to reach 15.96 kPa (120 torr). High frequency jet ventilation was then started at a rate of 600 per minute and decreased in increments to 100 per minute. Arterial blood gases were continuously recorded through an intra-arterial catheter connected to a mass spectrometer. The PaCO2 gradually declined to normal levels as the rate decreased.

Animals↗
PubMed1994

[Determination of intrinsic PEEP during mechanical ventilation. Validation of a new optional method of measurement provided by the EVITA mechanical ventilator].

Intrinsic positive end-expiratory pressure (PEEPi) occurring during mechanical ventilation depends on expiratory time constants, expiratory volume and expiration time as well as on external flow resistance (tubes, valves, etc.). It is not routinely determined in mechanically ventilated patients, but it is necessary to optimize respirator settings. The aim of the present study was the validation of an automated PEEPi determination method implemented in the respirator EVITA (Drägerwerke, Lübeck) in mechanically ventilated patients with acute lung failure. PATIENTS. The method was validated in ten sedated, myorelaxed patients with respiratory insufficiency of different etiologies (five with restrictive, and five with obstructive pulmonary disease). PEEPi was determined using the volume constant ventilatory mode at ZEEP or at an external PEEP of 5 as well as 10 cm H2O. METHOD. PEEPi was first determined with the automated method implemented in the EVITA (five measurements at each end-expiratory pressure level; PEEPEvita). Steady-state was attained between each measurement. These values were compared to the results obtained with end-expiratory occlusion (external, computer-controlled valve in the inspiratory limb of the circuit) at the respective pressure levels (PEEPEEO). The average of five measurements at each PEEP level with each method was defined as PEEPi for the particular ventilatory situation. Gas flow was measured at the proximal end of the endotracheal tube with a heated pneumotachometer (Fleisch no. 2, Fleisch, Lausanne, Switzerland) and a differential pressure transducer. Tracheal pressure was determined in the same position with a further differential pressure transducer (Dr. Fenyves & Gut, Basel, Switzerland). After A/D conversion, data were sampled with a frequency of 20 Hz and processing as well as for control of the occlusion valve was self-programmed. For the statistical analysis we used the Mann-Whitney U-test or Wilcoxon signed-ranks test; a P value less than 0.05 was considered significant. RESULTS. At the given respiratory setting and without PEEP patients with obstructive lung disease had a higher PEEPi (median: 6.4 cm H2O; range: 5.0-9.6 cm H2O) than those with restrictive pulmonary disease (median: 2.3 cm H2O; range: 0.8-3.0 cm H2O) (P < 0.05). Increasing external PEEP to 5 or 10 cm H2O significantly decreased the pressure difference between PEEPi and external PEEP (P < 0.05), but was unable to eliminate it completely. There was no statistically significant difference between PEEPEEO and PEEPEvita (P = 0.43; Wilcoxon signed-ranks tests). Regression analysis showed a highly significant correlation between PEEPEEO and PEEPEvita values (r = 0.985, P < 0.001; y = 1.03 x-0.18). DISCUSSION. PEEPi occurs during ventilation in patients with obstructive and restrictive lung disease. The difference between external end-expiratory pressure and PEEPi decreases with increasing external PEEP. However, PEEPi may increase with increasing external PEEP in some instances. The reason for this may be that the PEEPi determined at the proximal end of the endotracheal tube represents only a mean value of different PEEPi values of various lung regions. Increasing external PEEP only partially alters this mean value due to an effect on PEEPi values lower than external PEEP. The PEEPi values measured by the EVITA respirator compared with classical end-expiratory occlusion with an external valve were nearly identical. Unfortunately, PEEPi measurement of the EVITA can only be performed during controlled and not during assisting (PSV, BIPAP etc.) ventilation. Optimal respirator settings require a knowledge of PEEPi (i.e., adaption of external PEEP for lowering the work of breathing in COPD patients or prolongation of the expiratory phase to avoid unwanted side effects of an occult PEEPi on the circulation). Since mo

Aged↗
PubMed1999

Patient-ventilator asynchrony during noninvasive ventilation: the role of expiratory trigger.

OBJECTIVE: Air leaks around the mask are very likely to occur during noninvasive ventilation, in particular when prolonged ventilatory treatment is required. It has been suggested that leaks from the mask may impair the expiratory trigger cycling mechanism when inspiratory pressure support ventilation (PSV) is used. The aim of this study was to compare the short-term effect of two different expiratory cycling mechanisms (time-cycled vs flow-cycled) during noninvasive inspiratory pressure support ventilation (NIPSV) on patient-ventilator synchronisation in severe hypoxemic respiratory failure. STUDY POPULATION: Six patients with acute lung injury (ALI) due to acquired immunodeficiency syndrome (AIDS)-related opportunistic pneumonia were enrolled in the protocol. INTERVENTION: Each subject was first studied during spontaneous breathing with a Venturi oxygen mask (SB) and successively submitted to a randomly assigned 20' conventional flow-cycling (NIPSVfc) or time-cycling inspiratory pressure support ventilation (NIPSVtc). The pre-set parameters were: inspiratory pressure of 10 cm H2O, PEEP of 5 cm H2O for the same inspired oxygen fraction as during SB. A tight fit of the mask was avoided in order to facilitate air leaks around the mask. The esophageal pressure time product (PTPes) and tidal swings (delta Pes) were measured to evaluate the patient's respiratory effort. A subjective "comfort score" and the difference between patient and machine respiratory rate [delta RR(p-v)], calculated on esophageal and airway pressure curves, were used as indices of patient-machine interaction. RESULTS: Air leaks through the mask occurred in five out of six patients. The values of PEEPi (< 1.9 cm H2O) excluded significant expiratory muscle activity. NIPSVtc significantly reduced PTPes, delta Pes, and delta RR(p-v) when compared to NIPS-Vfc [230 +/- 41 (SE) vs 376 +/- 72 cm H2O.s.min-1; 8 +/- 2 vs 13 +/- 2 cm H2O; 1 +/- 1 vs 9 +/- 2 br.min-1; respectively] with a concomitant significant improvement of the "comfort score". CONCLUSIONS: In the presence of air leaks a time-cycled expiratory trigger provides a better patient-machine interaction than a flow-cycled expiratory trigger during NIPSV.

AIDS-Related Opportunistic Infections↗
PubMed1982

A new ventilator for physiologic studies during high-frequency ventilation.

Research in the field of high frequency ventilation (HFV) has been hampered by the difficulty of collecting and analyzing expired gas, uncontaminated by gas of inspiratory composition, at ventilatory frequencies in the relevant range. A new mechanical ventilator is described, which has been designed to facilitate studies on the respiratory physiology of small animals during HFV. Ventilation is controlled by a single rotary valve, which alternately switches the airway to an approximately constant-flow gas source during inspiration, and to gas measurement and analysis apparatus during expiration, which takes place passively. Theoretical and experimental studies, using the techniques of mechanical and mathematical modelling, are used to measure the performance of the ventilator and to demonstrate that it allows the quantitative collection of expired gas during ventilation at rates up to at least 20 Hz. The advantages and limitations of this approach are discussed.

Animals↗
PubMed1985

Effects of high frequency oscillatory ventilation compared to conventional ventilation upon pulmonary vascular prostanoid production in neonatal piglets.

In order to investigate the possibility that high-frequency oscillatory ventilation (HFO) might preferentially stimulate intrapulmonary prostacyclin (PGI2) synthesis thereby decreasing pulmonary vascular smooth muscle tone, we determined pulmonary prostacyclin and thromboxane production in neonatal piglets ventilated by conventional means and by HFO (8 Hz). There was no detectable release of prostacyclin or thromboxane into blood passing through the lungs (i.e., pulmonary arterial concentrations were greater than aortic concentrations) during ventilation by conventional means or during HFO. Furthermore, there were no differences between the two modes of ventilation in cardiac output, systemic or pulmonary vascular resistance, or pulmonary vascular response to hypoxia/hypercapnia. We conclude that HFO does not stimulate pulmonary prostacyclin production and does not affect pulmonary vascular resistance or the pulmonary vasoconstriction associated with alveolar hypoxia/hypercapnia when compared to conventional ventilation in anesthetized newborn piglets.

6-Ketoprostaglandin F1 alpha↗
PubMed2006

Adjunctive therapy to mechanical ventilation: surfactant therapy, liquid ventilation, and prone position.

Acute lung injury and acute respiratory distress syndrome are associated with significant morbidity and mortality in critically ill patients. Although lung protective mechanical ventilation is the only therapy shown to reduce mortality and development of organ failure, several biologic pathways have been identified and provided an opportunity for therapeutic interventions. No pharmacologic or adjunctive treatments are available. Clinical studies demonstrated that prone position results in significant and clinically relevant improvement in oxygenation and ventilation, which persist when patients are returned to supine position; the beneficial response is not limited to patients turned early in disease course. Few complications are associated with prone ventilation. Clinical experience suggests that prone ventilation may protect the lung from potential detrimental effects of mechanical ventilation. Further studies are needed.

Humans↗
PubMed2006

Efficacy and safety of intrapulmonary percussive ventilation superimposed on conventional ventilation in obese patients with compression atelectasis.

PURPOSE: To investigate the efficacy and safety of intrapulmonary percussive ventilation (IPV) in obese patients, we assessed their respiratory and hemodynamic functions during IPV superimposed on conventional ventilation. MATERIALS AND METHODS: Ten obese patients with acute respiratory failure due to compression atelectasis who had not improved by conventional ventilation were treated with IPV. Hemodynamic parameters, ventilator settings, and intracranial pressure (n = 1) were recorded every hour. Arterial blood gas was analyzed every 3 hours. The efficacy and safety of IPV was assessed at the start of weaning. RESULTS: Before IPV, Pao(2)/Fio(2) ratio remained low (189 +/- 63 mm Hg), which significantly increased to 243 +/- 67 mm Hg at 3 hours from the initiation of IPV (P < .01). Furthermore, it continuously increased to 280 +/- 50 mm Hg at 24 hours (P < .01). Intrapulmonary percussive ventilation induced significant increase in dynamic compliance from control value of 30 +/- 8 mL/cm H(2)O at 0 hours to 35 +/- 9 mL/cm H(2)O at 12 hours (P < .05) and to 38 +/- 8 mL/cm H(2)O at 24 hours (P < .01). Heart rate and mean arterial pressure were not significantly changed during IPV. Improvement of compression atelectasis was confirmed by their chest computed tomographic scans. Adverse effects such as pneumothorax and intracranial hypertension were not seen. CONCLUSIONS: These results demonstrated that IPV was effective and safe in improving compression atelectasis without adverse effects in obese patients.

Adult↗
PubMed1999

Effects of smaller tidal volumes during basic life support ventilation in patients with respiratory arrest: good ventilation, less risk?

OBJECTIVE: When ventilating an unintubated patient in cardiac or respiratory arrest, smaller tidal volumes of 500 ml instead of 800-1200 ml may be beneficial to decrease peak airway pressure, and to minimise stomach inflation. The purpose was to determine the effects of small (approximately 500 ml) versus large (approximately 1000 ml) tidal volumes given with paediatric versus adult self-inflatable bags and approximately 50% oxygen on respiratory parameters in patients during simulated basic life support ventilation. METHODS: While undergoing induction of anaesthesia, patients were randomised to three minutes of ventilation with either an adult (n = 40) or paediatric (n = 40) self-inflatable bag. RESULTS: When compared with an adult self-inflatable bag, the paediatric bag resulted in significantly lower mean (+/- standard deviation) exhaled tidal volume (365 +/- 55 versus 779 +/- 122 ml; P < 0.0001), peak airway pressure (20 +/- 2 versus 25 +/- 5 cm H2O; P < 0.0001), but comparable oxygen saturation (97 +/- 1% versus 98 +/- 1%; NS (nonsignificant)). Stomach inflation occurred in five of 40 patients ventilated with an adult self-inflatable bag, but in no patients who were ventilated with a paediatric self-inflatable bag (P = 0.054). CONCLUSION: Administering smaller tidal volumes with a paediatric instead of an adult self-inflatable bag in unintubated adult patients with respiratory arrest maintains good oxygenation and carbon dioxide elimination while decreasing peak airway pressure, which makes stomach inflation less likely.

Adult↗
PubMed1999

High-frequency oscillatory ventilation is not superior to conventional mechanical ventilation in surfactant-treated rabbits with lung injury.

The aim of this study was to compare high-frequency oscillatory ventilation (HFOV) with conventional mechanical ventilation (CMV) with and without surfactant in the treatment of surfactant-deficient rabbits. A previously described saline lung lavage model of lung injury in adult rabbits was used. The efficacy of each therapy was assessed by evaluating gas exchange, lung deflation stability and lung histopathology. Arterial oxygenation did not improve in the CMV group without surfactant but increased rapidly to prelavage values in the other three study groups. During deflation stability, arterial oxygenation decreased to postlavage values in the group that received HFOV alone, but not in both surfactant-treated groups (HFOV and CMV). The HFOV group without surfactant showed more cellular infiltration and epithelial damage compared with both surfactant-treated groups. There was no difference in gas exchange, lung deflation stability and lung injury between HFOV and CMV after surfactant therapy. It is concluded that the use of surfactant therapy in combination with high-frequency oscillatory ventilation is not superior to conventional mechanical ventilation in improving gas exchange, lung deflation stability and in the prevention of lung injury, if lungs are kept expanded. This indicates that achieving and maintaining alveolar expansion (i.e. open lung) is of more importance than the type of ventilator.

Administration, Topical↗
PubMed2005

Randomized, multicenter trial of conventional ventilation versus high-frequency oscillatory ventilation for the early management of respiratory failure in term or near-term infants in Colombia.

OBJECTIVE: To determine the efficacy and safety of high-frequency oscillatory ventilation (HFOV) compared to conventional ventilation (CV) for the treatment of respiratory failure in term and near-term infants in Colombia. STUDY DESIGN: Eligible infants with moderate to severe respiratory failure were randomized to early treatment with CV or HFOV. Ventilator management and general patient care were standardized. The main outcome was neonatal death or pulmonary air leak. RESULTS: A total of 119 infants were enrolled (55 in the HFOV group; 64 in the CV group) during the study period. Six infants in the HFOV group (11%) and two infants in the CV group (3%) developed the primary outcome (RR: 3.6, 95% CI: 0.8-16.9). Five infants in the HFOV group (9%) and one infant in the CV (2%) died before 28 days of life (RR: 5.9 CI: 0.7-48.2). Secondary outcomes were similar between groups. CONCLUSION: HFOV may not be superior to CV as an early treatment for respiratory failure in this age group. Standardization of ventilator management and general patient care may have a greater impact on the outcome in Colombia than mode of ventilation.

High-Frequency Ventilation↗
PubMed2001

Correlation of impedance minute ventilation with measured minute ventilation in a rate responsive pacemaker.

Although rate responsive pacing based on impedance minute ventilation (IMV) is now standard, there is almost no data confirming the relationship between IMV from an implanted pacemaker and measured minute ventilation (VE) during exercise. Nineteen completely paced adults implanted with Medtronic Kappa 400 pacemakers underwent symptom-limited maximal metabolic treadmill testing using a modified Minnesota Pacemaker Response Protocol. Minute ventilation (VE, L/min) was simultaneously measured using the flowmeter of a respiratory metabolic gas analysis system and the transthoracic impedance minute ventilation circuitry of the pacemaker. Correlation coefficients (r) were used to find the best fit line to describe the relationship between the two measurements. Mean (+/- SD) r values for the first, second, and third order polynomial equations and for log and exponential equations were: 0.92 +/- 0.08, 0.94 +/- 0.04, 0.95 +/- 0.04, 0.91 +/- 0.06, and 0.91 +/- 0.07, respectively. None of the r values were statistically different from the first order equation. Transthoracic IMV as measured by the Medtronic Kappa 400 is closely correlated to measured minute ventilation and is represented well by a first order (linear) equation.

Adult↗
PubMedDate not supplied

[Simple nuclear magnetic resonance tomography compatible pediatric ventilator system. Ventilation and MRI].

BACKGROUND: The widespread tunnel-shaped construction of magnetic resonance tomography (MRT) machines requires a remote device free of metal for ventilation of the comatose patient not breathing spontaneously. PATIENT AND METHOD: In order to ventilate a 3 year old boy, we modified an open-circuit bag ventilation system according to requirements. Fresh gas was insufflated into the patient's tube connector using a 6 m small sized silicon rubber hose, thus providing the required distance from the metallic gas supply. A second branch of the tube connector was connected to 1 m of wide tubing ending in the bag (Kuhn-system). RESULTS: The system proved its competence during a 1 hour session, and did not result in MRT artefacts. CONCLUSIONS: Due to the system design, the extension of the tubing does not result in significant dead space ventilation provided there is adequate fresh gas flow. The proposed system is simple in construction, easy to handle, and ideal for use on comatose children urgently requiring MRT. Thus, any delay due to preparations for anaesthesia and mechanic ventilation can be avoided.

Child↗
PubMed2003

Impact of a program of intensive surveillance and interventions targeting ventilated patients in the reduction of ventilator-associated pneumonia and its cost-effectiveness.

OBJECTIVE: We hypothesized that a program of prospective intensive surveillance for ventilator-associated pneumonia (VAP) and concomitant implementations of multimodal, multidisciplinary preventive and intervention strategies would result in a reduction in the incidence of VAP and would be cost-effective. SETTING: Medical and surgical intensive care units (ICUs) in a university teaching hospital. INTERVENTIONS: All ventilated patients in the medical and surgical ICUs were monitored for VAP from January 1997 through December 1998. Interventions including elevation of the head of the bed, use of sterile water and replacement of stopcocks with enteral valves for nasogastric feeding tubes, and prolongation of changing of in-line suction catheters from 24 hours to as needed were implemented. RESULTS: The rates of VAP decreased by 10.8/1,000 ventilator-days in the medical ICU (CI95, 4.65-16.91) and by 17.2/1,000 ventilator-days in the surgical ICU (CI95, 2.85-31.56) when they were compared for 1997 and 1998. With the use of the estimated cost of a VAP of dollars 4,947 from the literature, the reduction resulted in cost savings of dollars 178,092 and dollars 148,410 in the medical and surgical ICUs, respectively, for a total of dollars 326,482. In addition, dollars 25,497 was saved due to the lengthening of the time for the change of in-line suction catheters, resulting in a cost savings of dollars 351,979. This total cost savings of dollars 351,979 minus the cost of enteral valves of dollars 2,100 resulted in total net savings of dollars 349,899. CONCLUSION: Intensive surveillance and interventions targeted at ventilated patients resulted in reduction of VAP and appeared to be cost-effective.

Cost-Benefit Analysis↗
PubMed1983

Intermittent positive pressure ventilation and high frequency ventilation in dogs with experimental bronchopleural fistulae.

This study evaluated respiratory and cardiovascular responses of canines in whom bilateral bronchopleural fistulae were created surgically, and in whom ventilation was varied between intermittent positive pressure ventilation (IPPV) and high frequency ventilation (HFV). An Emerson prototype ventilator was used for HFV at rates of 300-1400/min at driving pressures of 2.5, 5.0, and 10 psi. Gas exchange was judged by arterial and mixed venous blood gases. Cardiac performance was measured by cardiac index, heart rate, stroke index, stroke work index, systemic and pulmonary vascular pressures and resistances. Ventilation during IPPV with the fistula open resulted in a statistically significant increase in PaCO2 and a decrease in PaO2 when compared to both HFV modes. Variations in cardiac function in these open-chested animals were insignificant for all variables tested except pulmonary artery pressures which rose significantly in the IPPV group.

Animals↗
PubMed1998

Comparison of oxygen cost of breathing with pressure-support ventilation and biphasic intermittent positive airway pressure ventilation.

OBJECTIVE: To assess the oxygen cost of breathing with either pressure-support ventilation (PSV) or biphasic intermittent positive airway pressure ventilation (BIPAP). DESIGN: Prospective, randomized, crossover study. SETTING: Medical intensive care unit of a university hospital. PATIENTS: Twenty clinically stable and spontaneously breathing patients after long-term mechanical ventilation. INTERVENTIONS: Patients were randomized to start on either PSV or BIPAP, and measurements were performed after an adaptation period of 30 mins. Immediately after, the ventilatory mode was changed and after another 30-min adaptation period, the same measurements were performed. MEASUREMENTS AND MAIN RESULTS: Indirect calorimetry was performed during each ventilatory mode for a period of 30 mins. Oxygen consumption, energy expenditure, CO2 production, and respiratory quotient did not differ significantly between the two ventilatory modes, regardless of the patients' randomization. There were no statistically significant differences with regard to respiratory rate, minute volume, and blood gas analysis. All patients tolerated both ventilatory modes without any signs of discomfort. CONCLUSIONS: Pressure support ventilation and BIPAP are both used for weaning patients gradually from the ventilator. BIPAP may be advantageous in patients not breathing sufficiently with PSV, since no patient effort is necessary with use of this ventilatory mode.

Adult↗
PubMed2001

Partial liquid ventilation in severely surfactant-depleted, spontaneously breathing rabbits supported by proportional assist ventilation.

OBJECTIVE: We hypothesized that partial liquid ventilation (PLV) would improve oxygenation in nonparalyzed, surfactant-deficient rabbits breathing spontaneously while supported by proportional assist ventilation (PAV). This ventilation mode compensates for low pulmonary compliance and high resistance and thereby facilitates spontaneous breathing. DESIGN: Randomized trial. SETTING: University animal research facility. SUBJECTS: Twenty-six anesthetized New Zealand white rabbits weighing 2592 +/- 237g (mean +/- sd). INTERVENTIONS: After pulmonary lavage (target Pao2 <100 mm Hg on mechanical ventilation with 6 cm H2O of positive end-expiratory pressure [PEEP] and an Fio2 of 1.0), rabbits were randomized to PAV (PEEP of 8 cm H2O) with or without PLV. PLV rabbits received 25 mL/kg of perfluorocarbon by intratracheal infusion (1 mL/kg/min). Pao2, Paco2, tidal volume, respiratory rate, minute ventilation, mean airway pressure, arterial blood pressure, heart rate, pulmonary compliance, and airway resistance were measured. Evaporated perfluorocarbon was refilled every 30 mins in PLV animals. After 5 hrs, animals were killed and lungs were removed. Lung injury was evaluated using a histologic score. MAIN RESULTS: Pao2 and compliance were significantly higher in PLV rabbits compared with controls (p <.05, analysis of variance for repeated measures). All other parameters were similar in both groups. CONCLUSIONS: PLV improved oxygenation and pulmonary compliance in spontaneously breathing, severely surfactant-depleted rabbits supported by PAV. The severity of lung injury by histology was unaffected.

Analysis of Variance↗