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PubMedDate not supplied

[Assisted ventilation of newborn infants during sleep. Study of factors modifying adaptation to ventilation].

During sleep, of ventilated newborns and young infants, spontaneous respiratory movements may occur, unrelated to the ventilation impulsions. The respiratory pattern is then classified as "active". On the contrary, the respiratory pattern is classified as "passive", when all respiratory movements are related to the ventilation insufflation. The factors which influence the dependence on the ventilator are studied in a group of 20 newborn and young infants. Prematurity, some biological data such as hyperoxia, hypocapnia, seem to favor this dependence. A rapid rate of ventilation (superior to 30/minute) is rarely related to an active respiration; a slow rate of ventilation seems favor this respiratory pattern. It is clear that adaptation to artificial ventilation is better during quiet sleep than during active sleep. Some physiopathological considerations are developed.

Adaptation, Physiological↗
PubMed1996

[Ventilation via a transnasally placed pharyngeal tube. Comparison with mask ventilation].

OBJECTIVE: The present prospective study was designed to investigate the respiratory function during ventilation via a tube inserted through the nose into the pharynx. Results were compared with respiratory parameters measured during conventional mask ventilation in the same patients. METHODS: 20 ASA physical status I-II patients were studied after approval by the local Ethics Committee. Anaesthesia was induced with alfentanil 15 micrograms/kg and propofol 2.5-3.0 mg/kg and maintained with propofol, 12-15 mg/kg/h. Patients were ventilated via a facemask with oxygen and a tidal volume of approximately 8ml/kg (measurement A). After insertion of a tube (I.D. 7.0-7.5 mm) through the nostril into the pharynx ventilation was repeated in the same manner (measurement B). To secure airway seal a second person closed the patient's mouth and exerted cricoid pressure. Following neuromuscular blockade with suxamethonium (1.5 mg/kg) respiratory parameters were measured again (C). Measurements included pulse oximetry and side stream spirometry with continuous collection of the following data: airway pressure, inspired and expired tidal volume, dynamic compliance, expired volume in one second, inspiratory and expiratory oxygen and carbon dioxide concentration. Pressure-volume and flow-volume loops were displayed continuously. RESULTS: Ventilation via facial mask or via pharyngeal tube with and without relaxation showed normal endtidal FECO2. The mean values were 4.5 +/- 0.7%, 4.8 +/- 0.4% and 4.6 +/- 0.7%, respectively. Mean oxygen saturation exceeded 98% in each period. Leakage during mask ventilation was 59.3 +/- 65.5 mL and decreased to 40.5 +/- 62.1 mL with the pharyngeal tube, whereas relaxation resulted in a significant increase to 92.3 75.0 mL. Compliance (Cdyn) and expired volume in one second (V 1.0) did not change significantly during the entire period of measurement. CONCLUSION: The use of a pharyngeally placed tube proved adequate compared to conventional mask ventilation in 20 patients without underlying airway disease.

Adolescent↗
PubMed1986

What changes can be expected during high frequency jet ventilation when the rate of ventilation, the I:E ratio and the driving pressure are modified? A laboratory study.

Changes in minute ventilation, tracheal airway pressure and lung volume have been measured using a jet ventilator (VS 600) during different rates of ventilation, I:E ratios and driving pressures. A lung model with a slightly increased compliance and an increased airway resistance was used. Five rates of ventilation (from 60 to 230 b.p.m.), three I:E ratios (0.25, 0.43, 0.67) and three driving pressures (200, 300 and 400 kPa) were studied. The increases in the rate of ventilation did not modify minute ventilation significantly, decreased peak airway pressure only slightly and increased end-expiratory pressure and lung volume. The increases in I:E ratio produced increases in minute ventilation, peak airway pressure, end-expiratory pressure and lung volume. The increases in driving pressure induced changes similar to those produced by the alterations in I:E ratio.

Airway Resistance↗
PubMed1979

Influence of an end inspiratory pause on pulmonary ventilation, gas distribution, and lung perfusion during artificial ventilation.

Using a constant tidal volume and ventilatory frequency, anesthetized piglets were ventilated with a new tidal volume ventilator. A short inspiratory time without a pause (10% of breathing cycle) was compared with a longer inspiratory time with a pause (33%) both with and without bronchial obstruction. Mechanics of ventilation, pulmonary ventilation, gas exchange, gas distribution, and lung perfusion were measured. The longer inspiratory time with a pause resulted in lower peak airway and end inspiratory pressures and a higher total compliance. Dead space/tidal volume ratio was reduced and the RQ was increased. While the cranial pulmonary fields were less well ventilated, the right caudal field was better ventilated. In the presence of bronchial obstruction, better alveolar ventilation was achieved when an end inspiratory pause was added. The results emphasize the importance of static end inspiratory tracheal conditions although the tidal volumes were kept unchanged.

Animals↗
PubMed2000

Effect of non-invasive mechanical ventilation on sleep and nocturnal ventilation in patients with chronic respiratory failure.

BACKGROUND: Chronic respiratory failure (CRF) is associated with nocturnal hypoventilation. Due to the interaction of sleep and breathing, sleep quality is reduced during nocturnal hypoventilation. Non-invasive mechanical ventilation (NMV), usually performed overnight, relieves symptoms of hypoventilation and improves daytime blood gas tensions in patients with CRF. The time course of the long term effect of NMV on sleep and breathing during both spontaneous ventilation (withdrawing the intervention) and NMV was investigated in patients with CRF due to thoracic restriction. METHODS: Fifteen consecutive patients (13 women) of mean (SD) age 57.9 (12.0) years with CRF due to thoracic restriction were included in the study. During the one year observation period four polysomnographic studies were performed: three during spontaneous breathing without NMV-before initiation of NMV (T0) and after withdrawing NMV for one night at six months (T6) and 12 months (T12-)-and the fourth during NMV after 12 months (T12+). Daytime blood gas tensions and lung function were also measured. RESULTS: Spontaneous ventilation (in terms of mean oxygen saturation) progressively improved (from T0 to T12-) during both REM sleep (24.8%, 95% CI 12.9 to 36.9) and NREM sleep (21.5%, 95% CI 12.4 to 30.6). Sleep quality during spontaneous ventilation also improved in terms of increased total sleep time (26. 8%, 95% CI 11.6 to 42.0) and sleep efficiency (17.5%, 95% CI 5.4 to 29.6) and decreased awakenings (54.0%, 95% CI 70.3 to 37.7). Accordingly, REM and NREM sleep stages 3 and 4 significantly improved. However, the most significant improvements in both nocturnal ventilation and sleep quality were seen during NMV at 12 months. CONCLUSIONS: After long term NMV both spontaneous ventilation during sleep and sleep quality in patients with CRF due to thoracic restriction showed evidence of progressive improvement compared with baseline after withdrawal of NMV for a single night at six and 12 months. However, the greatest improvements in nocturnal ventilation and sleep were achieved during NMV at 12 months.

Chronic Disease↗
PubMed1992

Delivery of a nebulized aerosol to a lung model during mechanical ventilation. Effect of ventilator settings and nebulizer type, position, and volume of fill.

Several factors may affect the delivery of a nebulized aerosol to the lung through an endotracheal tube during mechanical ventilation. To study these factors in vitro, a model representing ventilation of an adult patient was constructed by linking a Servo 900C ventilator to a standard humidified circuit and an endotracheal (ET) tube positioned within a pipe representing the trachea. This was connected via a filter to a lung simulator. Nebulizers filled with 99mTc human serum albumin were positioned in the circuit, and the delivery of nebulized aerosol through the ET tube into the filter was measured using a gamma camera. With the use of an inspiratory phase-activated System 22 Acorn jet nebulizer, typical adult ventilator settings, and a 3-ml nebulizer solution volume, 5.4% of the nebulizer dose reached beyond the end of the ET tube. This was increased by increasing the inspiratory time, reducing the respiratory rate or respiratory minute volume, and by repositioning the nebulizer on the inspiratory limb of the Y-piece and was reduced by slowing the driving gas flow to the nebulizer. Under the same conditions, delivery was 3.1 and 4.4% using the Samsonic and Fisoneb ultrasonic nebulizers, respectively. Increasing the fill volume and the addition of an aerosol storage chamber increased delivery with all three nebulizers. These experiments suggest some simple ways of improving aerosol delivery during mechanical ventilation, including increasing the volume of nebulizer fill, repositioning the nebulizer in the ventilator circuit, adding an aerosol storage chamber, and adjusting ventilator settings to maximize delivery.

Adult↗
PubMed2003

Clinical analysis of patients requiring long-term mechanical ventilation of over three months: ventilator-associated pneumonia as a primary complication.

OBJECTIVE: To evaluate the clinical features, etiology, and prognosis of patients who required long-term mechanical ventilation (LMV) of over three months for respiratory failure following underlying disease, and observation of their clinical course until death. PATIENTS: Thirty-seven patients (27 males, 10 females) treated in the internal and medical intensive care unit at Kawasaki Medical School Kawasaki Hospital over the 16-year period from April 1985 to March 2001 were retrospectively studied. RESULTS: Many of these patients were elderly males with respiratory disease such as pulmonary emphysema or old pulmonary tuberculosis, which had developed into acute respiratory failure resulting in respiratory tract infection and initiation of mechanical ventilation. The survival rates of one year, three years and five years after the start of mechanical ventilation were 60%, 30%, and 16%, retrospectively, and the prognoses were poor. Respiratory tract infection was the most common and serious complication. Specifically, ventilator-associated pneumonia (VAP) was a complication in 21 patients and also the main-cause of death. VAP was observed 2.3 years after the initiation of mechanical ventilation with significant differences in the following risk factors being observed between VAP (+) and VAP (-) groups: chronic obstructive pulmonary disease, duration of mechanical ventilation, prior antibiotics, aspiration of gastric contents and use of histamine-type II receptor antagonist. The causative pathogens of VAP were Pseudomonas aeruginosa and Staphylococcus aureus, which were frequently isolated from tracheal aspirates. All patients with VAP caused by MRSA died shortly after contracting the infection. CONCLUSIONS: This study has demonstrated that appropriate treatment for respiratory tract infections such as VAP and the prevention of nasocomial infection due to MRSA is of paramount importance for patients requiring long-term mechanical ventilation of over three months.

Adult↗
PubMedDate not supplied

[High frequency oscillation ventilation compared to conventional mechanical ventilation plus exogenous surfactant replacement in rabbits]

OBJECTIVES: (a) to evaluate the effect on oxygenation and ventilation of rabbits with induced surfactant depletion when they are submitted to a conventional mechanical ventilation, plus a small dose of exogenous surfactant; (b) to compare this group with another group submitted to a High Frequency Oscillation (HFO) without exogenous surfactant administration.METHODS: Twenty New Zealand White rabbits weighing (-/+ 3 kg) were anaesthetized and artificially induced to a endogenous surfactant depletion by successively lung lavage with normal saline (aliquots of 25 ml/kg) until to reach a persistent PaO(2) less than 100 mmHg when submitted to a mechanical ventilation in a pressure control mode with a target tidal volume of 10ml/kg, PEEP of 5cm H(2)O, FiO(2) 1.0, respiratory rate 30/min, and inspiratory time of 0.65 s. Then the rabbits were divided in (a) CMV+S group, submitted to a conventional mechanical ventilation plus exogenous surfactant replacement; (b) HFO group, submitted to a High Frequency Oscillation Ventilation. Arterial blood gases were measured at control period, post lung lavage, 15, 16 and 120 minutes after treatment started. The groups were compared using Student t test.RESULTS: The post lung lavage PaO(2) in both groups was lower than 50mmHg (p=0.154), increasing after 15 min of treatment to 254 mmHg (CMV+S) and 288 mmHg (HFO, p=0.626). The PaO(2) at 60 and 120 minutes were higher (p=0.001) in the HFO group (431 e 431 mmHg) when compared with the CMV+S group, which showed a progressive fall (148 e 126 mmHg). At 60 minutes of treatment, the PaCO(2) was lower (p=0.008) in the CMV+S group (29 versus 41 mmHg).CONCLUSIONS: In ARDS animal model a protect mechanical ventilation strategy as HFO by itself promotes a fast and persistent increase in the oxygenation, with superior levels than those observed in animals treated with conventional mechanical ventilation plus exogenous surfactant replacement.

Journal Article↗
PubMed1998

Microenvironment in Ventilated Animal Cages with Differing Ventilation Rates, Mice Populations, and Frequency of Bedding Changes.

The purpose of the study was to assess the microenvironment in separately ventilated mouse cages at differing ventilation rates, mice populations, and frequency of bedding changes. We monitored intracage temperature, relative humidity, and concentrations of ammonia and carbon dioxide during 3 experiments. First, the effect of ventilation rate on the microenvironment of cages housing adult male mice was evaluated at 30, 40, 60, 80 and 100 air changes/h. For all ventilation rates tested, ammonia concentration was less than 3 ppm, carbon dioxide concentration ranged from 840 to 3,300 ppm, relative humidity ranged from 42 to 65%, and temperature ranged from 23.2 to 25.3 C. Second, we monitored cage microenvironment continually in experiments during which changing of bedding was delayed. Male mice were used in the experiment, and cages were ventilated (60 air changes/h). Cages were allowed to accumulate soiled material for 26 days, during which time ammonia concentration and relative humidity did not exceed 10 ppm and 45%, respectively. Third, we tested ventilation rate and frequency of bedding changes in ventilated cages containing breeding trios (2 females, 1 male) and their pups. Ammonia concentrations remained at 25 ppm or less for 30, 60, and 100 air changes/h when bedding was changed weekly and for 100 air changes/h when bedding was changed every 2 weeks. We concluded that 30 air changes/h was sufficient to maintain a healthful microenvironment in cages that were housing adult male mice in which bedding was changed weekly. When frequency of bedding changes was reduced to every 2 weeks, 60 air changes/h was sufficient for cages housing adult males, but 100 air changes/h was necessary for cages housing breeding trios and pups.

Journal Article↗
PubMed2001

Partial liquid ventilation compared with conventional mechanical ventilation in an experimental model of acute lung injury.

OBJECTIVE: To compare the effects of partial liquid ventilation with conventional mechanical ventilation on oxygenation and pulmonary mechanics in saline lavaged rabbits. METHODS: Following acute lung injury (saline-lavage), rabbits were assigned to continue conventional mechanical ventilation (n = 6) or commence partial liquid ventilation (n = 6). In both groups the inspired oxygen concentration was 100% throughout the study. The target PaCO2 of 40-60 mmHg was accomplished by keeping the tidal volume between 7 and 10 mL/kg. During the study the peak inspiratory pressure was adjusted to maintain the target PaCO2. Arterial blood gases were taken pre-lavage, immediately post-lavage (time = 0) and then hourly for 5 hours. Pulmonary mechanics were estimated by measuring compliance and resistance. Pulmonary function was measured pre-lavage, immediately post-lavage and at 1 and 5 hours. At 5 hours the rabbits were killed and the lungs were removed for histological examination. RESULTS: Baseline PaO2, compliance and resistance were not significantly different between groups. The partial liquid ventilation group had a higher PaO2 and a significantly better oxygenation index one hour after commencing partial liquid ventilation and a significantly higher PaO2 averaged over the three hours post-treatment. There were no significant differences in compliance, resistance or lung damage scores. CONCLUSIONS: In this experimental model of acute lung injury, partial liquid ventilation resulted in immediate and sustained increase in PaO2 over 3 hours without significant change in lung mechanics or histological lung damage.

Journal Article↗
PubMed1982

Comparison of venous admixture during high-frequency ventilation and conventional ventilation in oleic acid-induced pulmonary edema in dogs.

High-frequency jet ventilation (HFJV) was compared with conventional ventilation ventilation during oleic acid-induced pulmonary edema in dogs. HFJV, when combined with positive end-expiratory pressure (PEEP), returned arterial PO2 (PAO2) and venous admixture to preoleic acid levels, even with tidal volumes as low as 4.8 ml/kg and rates of 300 min-1. When HFJV was compared with conventional (low-frequency, high tidal volume) ventilation at the same Flo2 and level of PEEP, Pao2 was lower and venous admixture higher with HFJV. However, venous admixture was lower with HFJV when comparisons were made at the same peak airway pressure, because of a higher level of PEEP compared with conventional ventilation. At each level of PEEP, cardiac and stroke indices were not different between the two methods of ventilation. The ability to eliminate CO2 with lower peak airway pressures or to increase PEEP without further increases in peak airway pressure are the primary advantages of HFJV during severe lung injury. Oxygenation is as efficient during HFJV as during conventional ventilation in this model of pulmonary edema when comparisons are made at the same peak airway pressure, but less efficient at the same PEEP.

Airway Resistance↗
PubMed2003

Elimination of ventilator dead space during synchronized ventilation in premature infants.

BACKGROUND: Mainstream airflow sensors used in neonatal ventilators to synchronize mechanical breaths with spontaneous inspiration and measure ventilation increase dead space and may impair carbon dioxide (CO(2)) elimination. OBJECTIVE: To evaluate a technique consisting of a continuous gas leakage at the endotracheal tube (ETT) adapter to wash out the airflow sensor for synchronization and ventilation monitoring without CO(2) rebreathing in preterm infants. DESIGN: Minute ventilation (V'(E)) by respiratory inductance plethysmography, end-inspiratory and end-expiratory CO(2) by side-stream microcapnography, and transcutaneous CO(2) tension (TcPCO(2)) were measured in 10 infants (body weight, 835+/-244 g; gestational age, 26+/-2 weeks; age, 19+/-9 days; weight, 856+/-206 g; ventilator rate, 21+/-6 beats/min; PIP, 16+/-1 centimeters of water (cmH(2)O); PEEP, 4.2+/-0.4 cmH(2)O; fraction of inspired oxygen (FIo(2)), 0.26+/-0.6). The measurements were made during four 30-minute periods in random order: IMV (without airflow sensor), IMV+Sensor, SIMV (with airflow sensor), and SIMV+Leak (ETT adapter continuous leakage). RESULTS: Airflow sensor presence during SIMV and IMV+Sensor periods resulted in higher end-inspiratory and end-expiratory CO(2), Tcpco(2), and spontaneous V'(E) compared with IMV. These effects were not observed during SIMV+Leak. CONCLUSIONS: The significant physiologic effects of airflow sensor dead space during synchronized ventilation in preterm infants can be effectively prevented by the ETT adapter continuous leakage technique.

Blood Gas Analysis↗
PubMed2000

Pressure control ventilation: three anesthesia ventilators compared using an infant lung model.

UNLABELLED: We compared three ventilators-Servo 900C (Siemens Medical Systems, Danvers, MA), Aestiva 3000 (Datex-Ohmeda, Madison, WI), and NAD 6000 (North American Dräger, Telford, PA)-set to deliver pressure control ventilation using an infant test lung model. Ventilator settings were selected to test "near-maximum" settings that would be used for a neonatal patient (peak inspiratory pressure [PIP] 30 cm H(2)O) or older child (PIP 60 cm H(2)O). When adjusted for set inspiratory pressure and compliance, the average tidal volume (V(t)) produced by the NAD 6000 was 5.8 mL less than the Servo 900C (P: = 0. 103), and the average V(t) produced by the Aestiva 3000 was 18.9 mL less than the Servo 900C (P: < 0.001). The Servo 900C generated increased peak pressures, tending to overshoot the set maximum inflating pressures, especially during rapid respiratory rates with decreased inspiratory times. The Aestiva 3000 did not achieve the set PIP during testing conditions of decreased inspiratory times, and the NAD 6000 was not greatly affected by changes in inspiratory time. All three ventilators measured expiratory V(t) to be larger than the actual V(t) delivered to the lung; however, the NAD 6000 was more accurate. IMPLICATIONS: There are differences in performance of ventilators when set to deliver pressure control ventilation to an infant test lung model.

Anesthesia↗
PubMed2002

Partial liquid ventilation and positive end-expiratory pressure reduce ventilator-induced lung injury in an ovine model of acute respiratory failure.

OBJECTIVE: To examine the isolated and combined effects of positive end-expiratory pressure (PEEP) and partial liquid ventilation (PLV) on the development of ventilator-induced lung injury in an ovine model. DESIGN: Prospective controlled animal study. SETTING: University-based cardiovascular animal physiology laboratory. SUBJECTS: Thirty-eight anesthetized supine sheep weighing 22.3 +/- 2.2 kg. INTERVENTIONS: Animals were ventilated for 6 hrs (respiratory rate, 15; FIO2, 1.0, inspiratory/expiratory ratio, 1:1) with one of five pressure-controlled strategies, expressed as peak inspiratory pressure (PIP)/PEEP: low-PIP, 25/5 cm H2O (n = 8); high-PIP, 50/5 cm H2O (n = 8); high-PIP-PLV, 50/5 cm H2O-PLV (n = 8); high-PEEP, 50/20 cm H2O (n = 7); and high-PEEP-PLV, 50/20 cm H2O-PLV (n = 7). MEASUREMENTS AND MAIN RESULTS: Compared with the low-PIP control, high-PIP ventilation increased airleak, shunt, histologic evidence of lung injury, neutrophil infiltrates, and wet lung weight. Maintaining PEEP at 20 cm H2O or adding PLV reduced the development of physiologic shunt and dependent histologic injury indexes. Neither higher PEEP nor PLV reduced the high incidence of barotrauma observed in high-PIP animals. CONCLUSIONS: We conclude that application of PLV or PEEP at 20 cm H2O may improve gas exchange and afford lung protection from ventilator-induced lung injury during high-pressure mechanical ventilation in this model.

Acute Disease↗
PubMed1987

Comparison of the haemodynamic effects of intermittent positive pressure ventilation with high frequency jet ventilation. Studies following valvular heart surgery.

The cardiorespiratory effects of intermittent positive pressure ventilation and high frequency jet ventilation with and without positive end expiratory pressure were compared in patients following valvular heart surgery (mitral and/or aortic). Twenty patients received intermittent positive pressure ventilation and high frequency jet ventilation with 0, 0.5 and 1.0 kPa positive end expiratory pressure. High frequency jet ventilation was well tolerated. The addition of 1.0 kPa positive end expiratory pressure was associated with preservation of the arterial oxygen tension without any increase in shunt or significant adverse haemodynamic effect. The results are discussed and compared with a previous study of high frequency jet ventilation following aortocoronary bypass graft surgery.

Adult↗
PubMed1997

Shunt and ventilation-perfusion distribution during partial liquid ventilation in healthy piglets.

Replacing gas in the lung with perfluorocarbon fluids (PFC) and periodically ventilating with a gas [partial liquid ventilation (PLV)] has been shown to improve oxygenation in models of respiratory distress syndrome. We hypothesized that the addition of PFC to healthy lungs would result in shunt, diffusion impairment, and increased ventilation-perfusion (VA/Q) heterogeneity. Previously, Mates et al. showed that O2 shunt and arterial-alveolar CO2 difference increased linearly with dose in piglets given graded intratracheal doses of PFC (10, 20, and 30 ml/kg followed by mechanical ventilation with 100% O2) (E.A. Mates, J. C. Jackson, J. Hildebrandt, W. E. Truog, T. A. Standaert, and M. P. Hlastala. In: Oxygen Transport to Tissue XVI, 1994, p. 427-435). Here we report VA/Q distribution in the same animals, showing a 50% increase in VA/Q heterogeneity during PLV independent of PFC dose. Ventilation heterogeneity was the major factor in this increase, and there was no significant change in dead space ventilation. We also report on five animals given a single 20 ml/kg dose of PFC and followed for 3 h. They showed an increase in shunt during PLV but no change in arterial-alveolar CO2 difference.

Animals↗
PubMed2002

Effects of intermittent negative pressure ventilation on effective ventilation in normal awake subjects.

RATIONALE: Previous studies have shown that an increase in inspiratory pressure during nasal intermittent positive pressure ventilation (IPPV) does not result in increased effective minute ventilation (E) due to glottic interference. STUDY OBJECTIVES: To test the consequences of increases in negative pressure ventilation (NPV) on V(E). MATERIAL AND METHODS: Eight healthy awake subjects underwent NPV delivered by an iron lung. First, NPV was started at a respirator frequency (f) of 15 cycles per minute with an inspiratory negative pressure (INP) of - 15 cm H(2)O (F15-P15). Then, f was increased to 20 cycles per minute and INP was kept at - 15 cm H(2)O. Next, f was kept at 20 cycles per minute and INP was reduced to - 30 cm H(2)O (F20-P30). Finally, f was decreased to 15 cycles per minute and INP was kept at - 30 cm H(2)O. At each step and for each breath, effective tidal volume (VT), V(E), and end-tidal carbon dioxide pressure were measured. In three subjects, the glottis width was assessed using fiberoptic bronchoscopy. RESULTS: From spontaneous breathing to the first step of NPV (F15-P15), we observed an inhibition of the phasic inspiratory diaphragmatic electromyogram concomitant to a significant increase in V(E) (p < 0.0005). For the group as a whole, the increase in mechanical ventilation (from F15-P15 to F20-P30) resulted in significant increases in VT and V(E) leading to hypocapnia (p < 0.0005). Moreover, the glottis width did not decrease with the increase in mechanical ventilation. CONCLUSIONS: We conclude that in normal awake subjects, NPV allowed a significant increase in V(E). These results differ from those previously obtained with nasal IPPV in which the glottic width interferes with the delivered mechanical ventilation.

Adult↗
PubMed1990

[Functional scintigraphic studies of perfusion and ventilation during high frequency jet ventilation (HFJV)].

In a controlled study, functional-scintigraphic investigations into perfusion and ventilation were performed on 10 dogs with non-damaged and extremely severely damaged lungs. The pulmonary damage was produced by injecting oleic acid (OA) into the right atrium of the heart under controlled ventilation (IPPV). The scintigraphic examinations were carried out using 133Xenon. The study compared HFJV (HFJV100, HFJV300) with IPPV in the non-damaged lung as well as HFJV300 with IPPV and CPPV (PEEP 1 kPa) after damage by OA. With the aid of the present radionuclide investigations, new insights can be gained into the largely unclear regional conditions of the gas exchange under HFJV in both the healthy and the damaged lung. Results from controlled studies on the distribution of ventilation and perfusion under HFJV have not been reported to date. The functional-scintigraphic examination with 133Xe on dogs shows, based on specific conditions of the gas exchange and special anatomic conditions of the lungs, a ventilation distribution that differs fundamentally from all other forms of ventilation, including HFOV, preference being given to apical pulmonary segments. This refers to the normal and the damaged lungs alike. However, ventilation-specific changes in pulmonary perfusion do not occur. The resulting deviating regional VA/Q relationship are obviously not of crucial influence upon the gas exchange. Rather, it is influenced and determined by damage-induced intraregional functional-structural alterations in the lung.

Animals↗