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PubMed1991

Comparison of tidal ventilation and high-frequency jet ventilation before and after cardiopulmonary bypass in dogs using two-dimensional transesophageal echocardiography.

This study compared the use of high-frequency jet ventilation (HFJV) and tidal ventilation (TV) in a group of dogs with induced global myocardial ischemia before and after cardiopulmonary bypass. Transesophageal echocardiography was used to determine whether HFJV with its lower airway pressures could improve cardiac performance. The surgical procedure was separated into four study periods: closed chest before bypass, open chest before bypass, open chest after bypass, and closed chest after bypass. During each of these study periods, the dogs were randomly ventilated with alternate periods of TV and HFJV to maintain the PaCO2 at 34.3 +/- 3.3 mm Hg (mean +/- SEM). Cardiac output, stroke volume, systemic mean blood pressure, left ventricular ejection fraction, left ventricular end-diastolic volume, left ventricular dP/dt, left ventricular stroke work, and expiratory volumetric flows were higher during HFJV, whereas airway pressures and pulmonary vascular resistance were lower. Increases in cardiac output and stroke volume during HFJV were due to a combination of improved left ventricular contractility indicated by increased LV dP/dt and increased left ventricular end-diastolic volume accompanying decreased airway pressures. These data indicate that HFJV with its lower airway pressure is associated with significantly less impairment of cardiovascular function than TV in dogs with induced global myocardial ischemia.

Animals↗
PubMed2002

High frequency percussive ventilation and conventional ventilation after smoke inhalation: a randomised study.

Inhalation injury and bacterial pneumonia represent some of the most important causes of mortality in burn patients. Thirty-five severely burned patients were randomised on admission for conventional ventilation (CV; control group) versus high frequency percussive ventilation (HFPV; study group). HFPV is a ventilatory mode, introduced 10 years ago which combines the advantages of CV with some of those of high frequency ventilation. Arterial blood gases, ventilatory and hemodynamic variables were recorded for 5 days at 2h intervals. Incident complications were classically managed. A statistical analysis (Student's t-test and Wilcoxon signed rank test) demonstrated a significant higher PaO(2)/FiO(2) from days 0 to 3 in the HFPV group. No significant differences were observed for the other parameters. Our findings suggest that HFPV can improve blood oxygenation during the acute phase following inhalation injury allowing reduction of FiO(2). No significant differences were observed between groups for mortality nor incidence of infectious complications in this study.

Acute-Phase Reaction↗
PubMed2001

A comparison of surfactant delivery with conventional mechanical ventilation and partial liquid ventilation in meconium aspiration injury.

The objective of this study was to compare surfactant (SF) distribution and physiological effects after standard SF delivery during conventional mechanical ventilation (CMV) with that using partial liquid ventilation (PLV). A model of meconium aspiration syndrome (MAS) was developed using two groups of adult rats (n = 14). After meconium instillation of 2.5 ml kg(-1) (20% v/w), SF/CMV: (n = 7) CMV and SF/PLV: (n = 7) PLV, received 14C-labeled surfactant (4 ml kg(-1)) delivered intratracheally in four aliquots over 20 min in both groups. Sequential measurements of arterial blood chemistry and lung mechanics were performed in all animals. At the conclusion of experiments, lungs were inflated (30 cmH2O), dried, sectioned and evaluated for radioactivity in disintegrations per minute (DPM). Surfactant distribution was improved (P< 0.01) with PLV as compared to CMV with 48.8% of the pieces vs. 30.9% of the pieces receiving within 25% of the mean amount of surfactant, respectively. Further, regional distribution was also significantly more uniform with PLV than CMV: left vs right (P<0.01) lung and ventral vs. dorsal (P<0.01) regions. Finally, arterial PO2 and ventilation efficiency index were significantly (P<0.01) greater post-treatment in SF/PLV than SF/CMV. These data demonstrate surfactant delivery with PLV, as compared to CMV alone, to be an improved method of delivering surfactant in MAS and suggest the possible utility of SF/PLV combination therapy for its treatment of other etiologies of neonatal respiratory distress.

Analysis of Variance↗
PubMed1989

[Comparative studies of the circulatory system during high frequency inspiratory ventilation and inspiratory positive pressure ventilation].

The studies were carried out in 14 dogs in which two different ventilation techniques were used under the general anaesthesia: HFIV and IPPV. Functioning of the cardio-vascular system was evaluated, basing on the measurements of pulse rate, pressure in the peripheral vessels, pulmonary artery and central venous pressure and calculation of the stroke volume, cardiac index, and pulmonary vessels resistance index. It was found that both techniques of ventilation did not exert any effect on the functioning of cardio-vascular system. Stroke volume was lower during IPPV than that during HFIV ventilation.

Animals↗
PubMed1996

[Temporary use of chest negative pressure ventilation to facilitate closure of a tracheal stoma before domiciliary nasal intermittent positive pressure ventilation].

A 67-year-old patient with pulmonary tuberculosis sequela had undergone a tracheostomy. The patient was receiving nasal intermittent positive pressure ventilation and the stoma failed to close. Temporary use of chest negative pressure ventilation facilitated closure of the stoma and probably shortened the patient's hospital stay. Nasal intermittent positive pressure ventilation at home was begun safely and effectively.

Aged↗
PubMed1998

Patient-ventilator interaction: a general model for nonpassive mechanical ventilation.

A general mathematical model for the dynamic behaviour of a single-compartment respiratory system in response to an arbitrary applied inspiratory airway pressure and arbitrary respiratory muscle activity is investigated. The model is used to compute explicit expressions for ventilation and pressure variables of clinical interest for clinician-selected and impedance-determined inputs. The outcome variables include tidal volume, end-expiratory pressure, minute ventilation, mean alveolar pressure, average pleural pressure, as well as the work performed by the ventilator and the respiratory muscles. It is also demonstrated that under suitable conditions, there is a flow reversal that can occur during inspiration.

Computer Simulation↗
PubMed1989

Carbon dioxide mandatory ventilation (CO2MV): a new method for weaning from mechanical ventilation. Description and comparative clinical study with I.M.V. and T. tube method in COPD patient.

We describe a new technique specially designed for weaning from mechanical ventilation: carbon dioxide mandatory ventilation (CO2MV). CO2MV is based on feedback between end tidal expired partial pressure of carbon dioxide and ventilatory mode, controlled or spontaneous. In order to evaluate its real interest we performed a randomized prospective study, CO2MV vs Intermittent Mandatory Ventilation (IMV) and T. Tube Method (TTM). Fourty-two adult patients with chronic obstructive pulmonary disease entered this study at the end of acute respiratory failure requiring mechanical ventilatory support. We observed a better stability of arterial blood gas during weaning with CO2MV and an increase in success rate (CO2MV 13/14 - IMV 5/14 - TTM 10/14). From this study CO2MV seems available for weaning of COPD patients. Nevertheless, further studies are required to appreciate its real clinical interest.

Aged↗
PubMed1999

A prospective randomized comparison of conventional mechanical ventilation and very early high frequency oscillatory ventilation in extremely premature newborns with respiratory distress syndrome.

OBJECTIVE: To compare the effectiveness and safety of very early high-frequency oscillatory ventilation (HFOV) with conventional mechanical ventilation (CMV) in treatment of the respiratory distress syndrome (RDS) and to evaluate their impact on the incidence of chronic pulmonary disease and early and late morbidity of very low-birthweight neonates. DESIGN: A prospective randomized clinical trial. SETTING: Tertiary neonatal intensive care unit in the Perinatology Center in Prague. PATIENTS: 43 premature newborns, delivered in the Department of Obstetrics in the Perinatology Center, were randomly divided into two groups (HFOV and CMV) immediately after delivery; 2 patients in each group died, 2 fulfilled crossover criteria from CMV to HFOV, and 2 were excluded because of congenital malformations. Nineteen patients treated with HFOV were therefore compared with 18 infants in the CMV group. METHODS: The two contrasting modes of ventilation were introduced immediately after intubation. Maintenance of optimal lung volume in HFOV to optimize oxygenation and the therapeutic administration of surfactant after fulfilling defined criteria are important points of the strategy and design of the study. MEASUREMENTS AND MAIN RESULTS: Except for a higher proportion of males in the HFOV group (p<0.02), the basic clinical characteristics (gestational age, birthweight, Apgar score at 5 min, umbilical arterial pH), the two groups were similar. In the acute stage of RDS, infants treated with HFOV had higher proximal airway distending pressure with HFOV for 6 h after delivery (p<0.05). For a period of 12 h after delivery lower values for the alveolar-arterial oxygen difference (p<0.03) were noted. The number of patients who did not require surfactant treatment was higher in the HFOV group (11 vs. 1, p<0.001). In the HFOV group the authors found a lower roentgenographic score at 30 days of age (p<0.03) and a lower clinical score in the 36th postconceptional week (p<0.05), using these two scoring systems for assessing chronic lung disease according to Toce scale. The incidence of pneumothorax, pulmonary interstitial emphysema, intraventricular hemorrhage and retinopathy of prematurity in both groups was the same. CONCLUSIONS: HFOV, when applied early and when the clinical strategy of maintenance of optimal lung volume is used, improves oxygenation in the acute stage of RDS, reduces the need of surfactant administration, and can decrease the injury to lung tissue even in extremely immature newborns to whom surfactant is administered therapeutically.

Female↗
PubMed2001

Effect of ventilation mode on gas exchange during partial liquid ventilation at different perfluorocarbon doses in surfactant-depleted lung.

Although gas ventilation is an integral part of partial liquid ventilation (PLV), the role of ventilation mode during PLV is not established, especially at a varying perfluorocarbon dose. In 10 surfactant-depleted rabbits, PLV was performed at a low dose (10 ml/kg) and at a functional residual capacity (FRC) dose (30 ml/kg) of perfluorodecalin in pressure-control (PC) and volume-control (VC) modes in balanced sequence. In these four PLV trials, PC mode was adjusted to be identical to VC mode with regard to tidal volume and inspiratory-to-expiratory ratio. PaO2 during PLV in PC mode was higher than in VC mode at the Low dose (159 plus minus 93 mm Hg, 115 plus minus 75 mm Hg, respectively: p = 0.005) and at the FRC dose (228 +/- 114 mm Hg, 164 +/- 104 mm Hg, respectively: p = 0.002). PaCO2 during PLV in PC mode was lower than in VC mode at the Low dose (59 +/- 18 mm Hg, 72 +/- 20 mm Hg, respectively: p = 0.005), whereas PaCO2 at the FRC dose was not different between modes. Curves of inspiratory flow appeared least deformed with PLV in PC mode at the Low dose, whereas they were saw-tooth deformed with PLV in VC mode at both doses. Actual time for inspiratory gas flow during PLV was shorter in PC mode compared with VC mode at both doses. In conclusion, in surfactant-depleted rabbit, gas exchange during PLV was better with PC mode compared with VC mode, especially at a low perfluorocarbon dose. Given the same tidal volume, PC appeared to insufflate the perfluorocarbon-filled lung better than VC at both low and FRC doses of perfluorocarbon.

Animals↗
PubMed1987

Jet ventilation for laser laryngeal surgery in children. Modification of the Saunders jet ventilation technique.

In our clinical series, 40-50% O2 and 50-60% N2O (regulated by a blender and delivered by manual jet ventilation (MJV] and residual halothane from induction provided satisfactory supralaryngeal anesthesia. Fentanyl, N2O, atracurium, and lidocaine administered i.v. effectively blunted laryngeal stimulation, allowed control of respiration, and minimized vocal cord motion. Wide unobstructed surgical access to the entire endolarynx is provided. Atracurium (an intermediate-acting non-depolarizing muscle relaxant administered in a single bolus or by constant infusion) achieves the needed level of blockade and permits the anesthesiologist to focus on the pattern of respiration rather than the degree of neuromuscular blockade. Its duration of action seems to be well matched to the average duration of this surgical procedure. Because its reversal is prompt (35-45 min from i.v. injection to 25% recovery by neuromuscular transmission monitor) (Brandom et al., Clinical pharmacology of atracurium in paediatric patients, Br. J. Anaesth., 55 (1983) 117S-121S) children can be discharged safely from the recovery room to home after an appropriate period of observation in the short-stay unit. Our report confirms and extends another recent report supporting supraglottic jet ventilation (Scamman, F.L. and McCabe, B.F., Supraglottic jet ventilation for laser surgery of the larynx in children, Ann. Otol. Rhinol. Laryngol., 95 (1986) 142-145). We believe that the MJV technique is advantageous in children, particularly for outpatient surgery. Attention to detail and careful communication between a skilled anesthesiologist and surgeon are essential. Dangerous barotrauma can occur and skill and monitoring are essential.

Adolescent↗
PubMedDate not supplied

Advances in mechanical ventilation: high frequency ventilation.

High frequency oscillatory ventilation (HFOV) is a technique in which a small tidal volume of airway gas is vibrated by moving a piston at an extremely fast rate (15 Hz). By this technique infants are ventilated in less traumatic ways compared to the conventional mechanical ventilation (CMV). The control study performed in Japan showed the efficacy and safety of HFOV compared to CMV.

High-Frequency Ventilation↗
PubMed1991

Multicenter controlled trial comparing high-frequency jet ventilation and conventional mechanical ventilation in newborn infants with pulmonary interstitial emphysema.

One hundred forty-four newborn infants with pulmonary interstitial emphysema were stratified by weight and severity of illness, and randomly assigned to receive treatment with high-frequency jet ventilation (HFJV) or rapid-rate conventional mechanical ventilation (CV) with short inspiratory time. If criteria for treatment failure were met, crossover to the alternate ventilatory mode was permitted. Overall, 45 (61%) of 74 infants met treatment success criteria with HFJV compared with 26 (37%) of 70 treated with CV (p less than 0.01). Eighty-four percent of patients who crossed over from CV to HFJV initially responded to the new treatment, and 45% ultimately met success criteria on HFJV. In contrast, only 9% of those who crossed over from HFJV to CV responded well to CV (p less than 0.01), and the same 9% ultimately met success criteria (p less than 0.05). Therapy with HFJV resulted in improved ventilation at lower peak and mean airway pressures, as well as more rapid radiographic improvement of pulmonary interstitial emphysema, in comparison with rapid-rate CV. Survival by original assignment was identical. When survival resulting from rescue by the alternate therapy in crossover patients was excluded, the survival rate was 64.9% for HFJV, compared with 47.1% for CV (p less than 0.05). The incidence of chronic lung disease, intraventricular hemorrhage, patent ductus arteriosus, airway obstruction, and new air leak was similar in both groups. We conclude that HFJV, as used in this study, is safe and is more effective than rapid-rate CV in the treatment of newborn infants with pulmonary interstitial emphysema.

Bronchopulmonary Dysplasia↗
PubMed1987

Gas trapping with high-frequency ventilation: jet versus oscillatory ventilation.

Gas trapping was evaluated during high-frequency jet ventilation (HFJV) and high-frequency oscillatory ventilation (HFOV) in nine adult rabbits under basal conditions and after instillation of a mixture of 20% human meconium (2 mL/kg). The anesthetized animals underwent tracheostomy and were placed inside a body plethysmograph. Respiratory compliance and resistance were calculated from airway pressure and simultaneous flow, and volume was measured with a pneumotachograph. Gas trapping was measured as the change in volume observed in the plethysmograph after clamping the jet or the oscillatory line at respiratory rates of 10 and 15 Hz and tidal volumes of 1.0 and 2.0 mL/kg. Mean airway pressure was similar with both ventilators. Inspiratory/expiratory ratios were 1:4 at 10 Hz and 1:2 at 15 Hz with HFJV, and 1:1 during HFOV. Under all conditions, gas trapping was significantly greater with HFJV than with HFOV. More gas trapping was observed with higher tidal volume (2 mL/kg) and respiratory rate (15 Hz) during HFJV, before and after meconium instillation. After meconium instillation, gas trapping during HFJV at 15 Hz and tidal volume 2 mL/kg decreased significantly (32.7 +/- 10.4 to 24.9 +/- 10.3; P less than 0.05), compared with basal conditions. This finding may be explained by the shorter time constant of the respiratory system after meconium instillation (0.118 vs 0.083 seconds, P less than 0.01). Thus gas trapping was significantly greater with HFJV than with HFOV, a difference most likely related to the active expiratory phase of HFOV.

Airway Obstruction↗
PubMed2004

A prospective observational pilot study of synchronized nasal intermittent positive pressure ventilation (SNIPPV) as a primary mode of ventilation in infants > or = 28 weeks with respiratory distress syndrome (RDS).

OBJECTIVE: To compare the outcome of infants with respiratory distress syndrome (RDS) in the neonatal intensive care unit (NICU) who were extubated to synchronized nasal intermittent positive pressure ventilation (SNIPPV) or continued on conventional ventilation (CV), immediately postsurfactant. STUDY DESIGN: Prospective observational study of postsurfactant ventilatory management of consecutive infants (born between 10/99 and 12/02) of 28 to 34 weeks gestation. Extubation to SNIPPV was at the attending neonatologists' discretion. Babies in the CV group remained intubated, postsurfactant. RESULTS: There were no significant differences in the maternal demographics, antenatal steroid use, mode of delivery, birth weight (BW), gestational age (GA), gender, Apgar at 5 minutes, age at surfactant instillation, or oxygenation index (OI) prior to surfactant administration, between infants continued on CV (n=35) and those extubated to SNIPPV (n=24). The total duration of endotracheal intubation (mean+/-SEM; CV versus SNIPPV; 2.4+/-0.4 versus 0.3+/-0.0 days, p=0.001) and duration of supplemental oxygen exposure (15+/-3.2 versus 8.2+/-3.3 days, p=0.04) were significantly shorter in the SNIPPV group. Furthermore, the duration of parenteral nutrition (12.1+/-1.6 versus 8.4+/-0.8 days, p=0.02) and length of stay (37.5+/-3.0 versus 29.1+/-3.3 days, p=0.04) were also significantly shorter in the SNIPPV group. There were no differences between the two groups in blood gas or OI values postsurfactant (up to 48 hours). There was no statistical difference in the incidence of intraventricular hemorrhage grade I (three (9%) in the CV group and two infants (8%) in the SNIPPV group). No infant died in either group or had patent ductus arteriosus, air leaks, necrotizing enterocolitis, periventricular leukomalacia, retinopathy of prematurity or bronchopulmonary dysplasia. CONCLUSIONS: Infants of 28 to 34 weeks GA with RDS requiring surfactant with early extubation to SNIPPV had a shorter duration of intubation, and decreased need for oxygen as compared to CV. There was also a significant decrease in the duration of parenteral nutrition and hospitalization. SNIPPV is a safe and effective primary mode of ventilation in larger premature infants.

Blood Gas Analysis↗
PubMed2001

High-frequency oscillatory ventilation versus conventional mechanical ventilation in congenital diaphragmatic hernia.

AIMS: Newborns affected by congenital diaphragmatic hernia (CDH) are high-risk patients: today the mortality is still elevated and is essentially due to severe pulmonary hypoplasia, pulmonary hypertension and the absence of surfactant. High-Frequency Oscillatory Ventilation (HFOV) seems to be a good pre- and postoperative technique in cases of CDH. PATIENTS AND METHODS: We report our experience in the treatment of CDH; since 1987 we have followed 44 patients. We divided them into two different groups in accordance with the ventilation technique used: Group I (1987-1994): 25 patients treated with conventional mechanical ventilation (CMV); Group II (1994-1997): 19 patients treated with HFOV used since the first day of life until clinical stabilisation and also prolonged during surgery and in the postoperative period. RESULTS: 37 patients (84%) underwent surgery with closure of the diaphragmatic defect. We had a very good improvement in survival, rising from 67% (CMV) to 94% (HFOV) of the patients operated on, reaching an overall survival of 56% vs 79%. CONCLUSIONS: The use of HFOV for the treatment of CDH has proved to be a valuable technique for pre-operative stabilisation and for intra- and postoperative respiratory treatment, above all for newborns with CDH.

Female↗
PubMed2006

The role of cytokines during the pathogenesis of ventilator-associated and ventilator-induced lung injury.

Mortality rates from acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) range from 30 to 65%. Although mechanical ventilation (MV) may delay mortality in critically ill patients with ALI/ARDS, it may also cause a lung injury that further promotes and perpetuates ALI/ARDS and multiorgan dysfunction syndrome (MODS). Recent studies have demonstrated that lung protective strategies of MV, as compared with the injurious strategy of conventional MV (CMV) can reduce absolute mortality rates during ALI/ARDS. The protective strategies limit tidal volumes and peak/plateau pressures while maximizing positive end-expiratory pressure. The injury to the lung by CMV is characterized histologically by edema, leukocyte extravasation, and endothelial and epithelial damage. Both human and animal studies suggest that alveolar cell deformation from CMV leads to the release of cytokines/chemokines which orchestrate the extravasation, activation, and recruitment of leukocytes, causing ventilator-associated lung injury (VALI) and ventilator-induced lung injury (VILI). Moreover, VALI/VILI can perpetuate the chronic inflammatory response during ALI/ARDS and MODS. This article explores the role of cytokines/chemokines during the pathogenesis of VALI/VILI.

Animals↗