Intratracheal Pulmonary Ventilation Research Articles

The Ventilatory Effect of Intratracheal Pulmonary Ventilation in Rabbits with Acute Respiratory Failure

The Ventilatory Effect of Intratracheal Pulmonary Ventilation in Rabbits with Acute Respiratory Failure

Intratracheal pulmonary ventilation versus conventional ventilation in a model of meconium aspiration

Intratracheal pulmonary ventilation versus conventional ventilation in a model of meconium aspiration

Intratracheal Pulmonary Ventilation and Continuous Positive Airway Pressure in a Sheep Model of Severe Acute Respiratory Failure

Previously we have shown that optimal pulmonary gas exchange can be sustained at normal airway pressures in a model of severe acute respiratory failure (ARF), using intratracheal pulmonary ventilation (ITPV), with weaning to room air. In an identical model of ARF, we have now explored whether ITPV, combined with continuous positive airway pressure (CPAP), can sustain adequate ventilation, with weaning to room air. Randomized study in sheep. Animal research laboratory at the National Institutes of Health. ARF was induced in 12 sheep, using mechanical ventilation at peak inspiratory pressure of 50 cm H2O, but excluding 5 to 8% of lungs. Sheep were then randomized into two groups: the CPAP-ITPV group (n=6), in which ITPV was combined with a novel CPAP system; and a control group (n=6) in which the same CPAP circuit was used, but without ITPV. All sheep in the CPAP-ITPV group were weaned to room air in 38.7+/-14 h. PaO2/fraction of inspired oxygen (FIO2) progressively increased from 108.8+/-43 to 355.7+/-93.1; PaCO2 remained within normal range; respiratory rate (RR) ranged from 18 to 120 breaths/min, and tidal volume (VT) was as low as 1.1 mL/kg. All sheep in the control group (CPAP alone) developed severe respiratory acidosis and hypoxemia after 4.8+/-4 h. PaO2/FIO2 decreased from 126.6+/-58.2 to 107.2+/-52.5 mm Hg, with a final PaCO2 of 166.8+/-73.3 mm Hg. All sheep treated with CPAP-ITPV maintained good gas exchange without hypercapnia at high RR and at low VT, with weaning to room air. All control animals treated with CPAP alone developed severe hypercapnia, respiratory acidosis, and severe hypoxemia, and were killed.

Clearance of mucus from endotracheal tubes during intratracheal pulmonary ventilation.

Intratracheal pulmonary ventilation (ITPV) is a form of tracheal gas insufflation in which all gas emerges in a cephalad direction from the tip of a reverse-thrust catheter positioned within an endotracheal tube. In vitro experiments have shown that this rapid gas flow, with 5 ml/h of normal saline added to the gas flow, continuously removes tracheal secretions from within the endotracheal tube. The authors evaluated its effectiveness to remove mucus in long-term studies in sheep. Fourteen healthy sheep were tracheally intubated and ventilated for 3 days with ITPV or with volume-controlled ventilation. Measurements were made of the total amount of secretions within the endotracheal tubes (weight gain), the protein content within the endotracheal tubes, and the increase in resistance to constant air flow. The structure of the airways was examined grossly and histologically. Three additional sheep were ventilated for 24 h with ITPV, and Evans Blue dye was added to the saline to assess the distribution of the infused saline. There was significantly less mucus in endotracheal tubes of sheep ventilated with ITPV than with conventional ventilation, as shown by minimal weight gain (0.70 +/- 0.14 g vs. 2.44 +/- 0.81 g; P < 0.001), lower protein content (14.09 +/- 10.79 mg vs. 294.99 +/- 153.06 mg; P < 0.001), and lower resistance to constant air flow (6.15 +/- 0.54 cm H2O x 1(-1) x s(-1) vs. 15.34 +/- 5.28 cm H2O x 1(-1) x s(-1); P < 0.001). Results of gross and histological examinations of the tracheas of animals in both groups were similar, and the tracheas were well preserved. More than 95% of the instilled saline was recovered during ITPV. Only traces of Evans Blue dye were found near the tip of the endotracheal tubes. Intratracheal pulmonary ventilation makes it possible to keep the endotracheal tubes of sheep ventilated for 3 days free of mucus without suctioning.

High-frequency intratracheal pulmonary ventilation: Improved gas exchange at lower airway pressures

Purpose: Conventional ventilation in the neonatal intensive care unit causes iatrogenic injury to fragile newborn lungs, especially those with preexisting pathology or prematurity. Intratracheal pulmonary ventilation (ITPV), developed by Dr Theodor Kolobow and associates at the National Institutes of Health (NIH), incorporates a continuous flow of humidified gas through a reverse thrust catheter positioned at the distal end of the endotracheal tube. In animal studies ITPV was shown to facilitate gas exchange at low peak pressures by reducing physiological dead space, facilitating exhalation, and enhancing CO 2 elimination. The specific aims of this project were (1) to invent a new ITPV-specific ventilator; (2) to optimize gas exchange in a newborn animal model at low airway pressures using higher frequency ITPV; and (3) to demonstrate efficacy and improved ventilation at lower airway pressures in a prematurity model. Methods: (1) A new ventilator had to be constructed. The first prototype is microprocessor driven, incorporating controls for flow, pressures, and concentrations of gases. The ventilator has the capability to vary F io 2, respiratory rate (0 to 15 Hz), and inspiratory-expiratory I:E ratio. (2) Prototype testing was performed. Newborn lambs (n = 3, 6 to 7 kg) underwent tracheotomy and placement of arterial and venous lines. Lambs were initially supported on conventional mechanical ventilation (CMV). Animals were allowed to achieve steady state with measurements of baseline vital signs, arterial blood gases, and ventilatory settings. ITPV was instituted at a rate of 100 breaths per minute and flow adjusted to achieve lower peak carinal pressures than obtainable on conventional ventilation. In a stepwise fashion, respiratory rate, I:E ratio, and ITPV flows were varied while initially maintaining Pa co 2 constant, and then allowing improvement. (3) These experiments were repeated in preterm lambs (n = 6, 1.8 to 3.6 kg). Results: At the time of transition from CMV to ITPV (rate, 100, I:E, 1:3), gas exchange was maintained despite a documented drop in average peak carinal pressure for the newborn lambs from 28.3 cm H 2O on CMV to 10.3 cm H 2O on ITPV ( P = .028). The average peak carinal pressure fell even further at higher ITPV rates with adjustments in I:E ratio. For the premature lambs, peak carinal pressures also fell significantly on ITPV (44 to 32 cm H 2O, P = .002) with corresponding significant improvement in ventilation (Pa co 2 from 52.2 to 31.9 mm Hg, P = .029). Conclusions: (1) Our new ITPV ventilator operates at rates and I:E ratios previously unobtainable. (2) In newborn and premature lambs ITPV functions most effectively at higher rates with higher gas flow rates and with longer exhalation, providing significantly improved gas exchange at significantly lower peak carinal pressures. (3) ITPV may prove beneficial in achieving gas exchange in newborns while avoiding barotrauma. Based on these data, we have initiated human clinical studies of ITPV in newborns with congenital diaphragmatic hernia or prematurity to improve gas exchange and reduce barotrauma in the neonatal intensive care unit.

The Effect of Intratracheal Pulmonary Ventilation on Dead Space and Airway Pressures in Rabbits with Acute Respiratory Failure Induced by Oleic Acid Injection

Background : Intratracheal pulmonary ventilation (ITPV) was developed to allow a decrease in physiological dead space during mechanical ventilation. To reduce anatomic dead space, a reverse thrust catheter (RTC) is introduced into an endotracheal tube (ETT) through an adapter and positioned just above the carina inside the ETT. ITPV can be combined with pressure control mode of mechanical ventilation to make hybrid ventilation(HV). The effect of HV on the reduction of dead space was compared with that of conventional mechanical ventilation(CMV) in rabbits with acute respiratory failure. Methods : Oleic acid of 0.06 ml/kg was injected to induce acute respiratory failure in 7 rabbits. PaO2 and PaCO2 were measured 30 minutes after the injection. Oleic acid was injected in another 7 rabbits to compare CMV with HV while increasing the respiratory rate(RR). Tidal volume, dead space(VD) and peak inspiratory pressure(PIP) were measured at the same RR. Results : PaO2 decreased significantly from 467± 68 mmHg to 156 ±26 mmHg at FIO2 1.0 after the injection of oleic acid. In another 7 rabbits, the VD''s of CMV were 34± 10 ml, 27 ±10 ml, 20± 6 ml, and 18± 3 ml at respiratory rate of 20/min, 40/min, 80/min and 120/min, respectively. The VD''s of HV were 28 ±11 ml, 16± 8 ml, 9± 4 ml, and 7± 3 ml at the same respiratory rates as in CMV. The VD''s of HV were lower than those of CMV. The PIP''s were lower in HV than in CMV. Conclusion: We conclude that HV, as the modification of ITPV, can be applied to acute respiratory failure to minimize the airway pressures and dead space of CMV. (Korean J Anesthesiol 1997; 32: 360∼365)

THE USE OF ITPV VS CONVENTIONAL VENTILATION IN MECONIUM ASPIRATION SYNDROME IN A NEWBORN PIG MODEL. ▴ 1988

Intratracheal Pulmonary Ventilation (ITPV) uses a venturi (reverse thrust) catheter to introduce gas exchange at the level of the carina. This method reduces anatomic dead space and enhances oxygenation and carbon dioxide elimination, which allows gas exchange with lower levels of ventilatory support and reduces the incidence of barotrauma. To test this hypothesis we compared ITPV to conventional ventilation in a newborn pig model of MAS. Piglets (n=17), 2-7 days of age, 1.8-2.8 kg were anesthetized, paralyzed, intubated, and ventilated. Femoral arterial and venous catheters were placed for IV fluids, medications, and physiologic and blood gas monitoring. 5 ml/kg of 20% meconium in normal saline was instilled into the endotracheal tube. Animals were randomized to either ITPV or conventional ventilation and settings were adjusted to maintain ideal blood gases, i.e. pH=7.35-7.45, PaCO2=40-45, PaO2=70-90, and SaO2≥90%. Ventilator settings were increased as needed until maximum settings of: FiO2=1.00, PIP=40, Peep=5, and IMV=80. Arterial blood gases and physiologic measurements were taken every 30 minutes for four hours and ventilator settings were adjusted to maintain optimal blood gases. At the end of the experiment animals were sacrificed with a KCL/pentobarbital overdose and the lungs were examined both grossly and histologically for evidence of barotrauma. Results are shown in the table. Conclusion: ITPV is as effective as conventional ventilation and allows for lower mean airway pressure and PIP to effectively support piglets with MAS. The lungs of animals treated with ITPV were less hemorrhagic and had less evidence of pneumothoraces when compared with the conventional group.

Intratracheal pulmonary ventilation provides effective ventilation in a near-drowning model

Overdistension of the lungs from high inspiratory pressure is increasingly recognized as a major contributor to lung injury and worsening respiratory failure in the child who requires prolonged mechanical ventilation. Many modes of ventilation (such as high-frequency ventilation) have been introduced in an attempt to decrease this lung injury. Recently, a new mode of tracheal ventilation, intratracheal pulmonary ventilation (ITPV), has been described. By using a catheter positioned at the carina with continuous gas flow, it is possible to achieve effective ventilation at very low pressures. The purpose of this study was to evaluate the usefulness of ITPV in a near-drowning model. Ten domestic Yorkshire swine underwent arterial, venous, and pulmonary arterial catheter as well as tracheotomy placement. All animals received 13 mL/kg of fresh water intratracheally to induce a pulmonary injury. Six pigs were ventilated for 4 hours using ITPV; the other four pigs received conventional mechanical ventilation (CMV). Circulatory and ventilatory pressures, hemodynamic variables, arterial blood gases, and end-tidal CO 2 were measured before lung injury and every 30 minutes thereafter. Both proximal and distal peak and mean airway pressures were measured. The animals were ventilated as needed to maintain the arterial blood gases in the normal range. The authors found the expected changes in pulmonary compliance, oxygen requirement, and airway pressure after inducement of lung injury. The six animals treated with ITPV had significantly lower airway pressures than those of controls. Peak inspiratory pressures with ITPV were 8.2 ± 1.9 cm H 2O versus 17.8 ± 3.7 with CMV ( P <.001). Distal mean airway pressures using ITPV were 2.3 ± 0.1 cm H 2O versus 9.0 ± 3.2 with CMV ( P < .01). With respect to hemodynamic variables, there were no differences between experimental and control animals. In conclusion, ITPV can afford effective ventilation in a near-drowning model of lung injury at airway pressures significantly lower than those required with CMV. ITPV could be a very valuable addition to the currently available methods of mechanical ventilation.

The Current Status of Intratracheal-Pulmonary Ventilation (ITPV)

The Current Status of Intratracheal-Pulmonary Ventilation (ITPV)

Intratracheal Pulmonary Ventilation (ITPV)

A new mode of pulmonary ventilation called intratracheal pulmonary ventilation (ITPV) was studied. Briefly, a continuous flow of air/oxygen is introduced through a small catheter, the tip of which is positioned at the carina, with a diffuser mounted at its distal end. A timed expiration valve, when closed, provides for inspiration; when open, it provides for expiration. The system as first described had a potential for significant back pressure at the level of the carina, which was more at rapid gas flows and with smaller endotracheal tubes. We have now mounted a venturi on the tip of the catheter (reverse thrust catheter [RTC]) that avoids back pressure, and which facilitates expiration. At respiratory rates from 10 to 120/min, the ITPV system with the RTC maintained end-expiratory pressure at the level of the carina at, or near 0 cm H2O. Compared to conventional mechanical ventilation, at identical respiratory rates, this system reduced tidal volume by one half at the lowest respiratory rates, and by as much as two thirds at the highest respiratory rates, with a proportional decrease in peak inspiratory pressure. ITPV has the smallest minute volume ventilation of any conventional or nonconventional mode of pulmonary ventilation.

Intratracheal Pulmonary Ventilation and Congenital Diaphragmatic Hernia

Previous studies from our institution have shown that neonates with congenital diaphragmatic hernia (CDH), whose best postductal PaO2 (BPDPO2) was less than 100 mm Hg while on maximal conventional mechanical ventilation (CMV), had a mortality exceeding 90%. When combined with extracorporeal membrane oxygenation (ECMO), the mortality rose to 100% in those infants who developed hypercarbia following decannulation. Historically, those patients have required increasing ventilator support, leading to iatrogenic lung damage, and eventual death. Intratracheal pulmonary ventilation (ITPV) using the reverse thrust catheter (RTC) developed by Kolobow incorporates a continuous flow of humidified gas through a reverse Venturi catheter positioned at the distal end of the endotracheal tube. In animal studies, ITPV was shown to result in a reduced physiological dead-space (VD), to facilitate expiration, and to enhance CO2 elimination. In our current study, we have applied ITPV in two neonates with CDH who could not be weaned from ECMO because of uncontrollable hypercapnia, and who met above criteria for 100% mortality. In both cases, ITPV restored normal PaCO2 at low peak inspiratory pressure (PIP) with a substantial decrease in VD. We believe ITPV is suited to ventilating newborns with CDH in whom barotrauma is known to be common. Beyond its present use, ITPV may be useful to ventilate children with other forms of respiratory failure, and should be so considered along with other now available methods of mechanical pulmonary ventilation.

How to ventilate lungs as small as 12.5% of normal: the new technique of intratracheal pulmonary ventilation.

We wished to determine in a laboratory animal model how much residual lung was needed to sustain total gas exchange. In a series of young, healthy lambs weighing approximately 10 kg that were sedated and paralyzed, we progressively excluded from gas exchange all the left lung (a total of 43%), plus the right lower and cardiac lobes (81%), plus the right middle lobe (87.5%). In some studies, the respective lobes were surgically removed; in others, the bronchi and the pulmonary arteries to the respective lobes were ligated. We provided pulmonary ventilation using the pressure control mode (Servo 900 C) at a tidal volume of 20 mL/kg multiplied by the fraction of the remaining lungs, a respiratory rate up to 120/min, a peak inspiratory pressure of 12-15 cm H2O, and a positive end-expiratory pressure of 3 cm H2O. Those lambs with at least both the right upper lobe (RUL) and right middle lobe remaining (19% of total lungs) were weaned to room air on mechanical ventilation within 48 h. Ventilating RUL (12.5% of remaining lung) with the same ventilator required a substantially higher tidal volume and peak inspiratory pressure to result in adequate alveolar ventilation but led to respiratory failure and death within 8 h. We then applied a newly developed system of intratracheal pulmonary ventilation to ventilate the RUL (12.5% of remaining lung) alone. A continuous flow of humidified mixture of air and oxygen was directly passed into the trachea at the level of the carina through a diffuser at a tidal volume of 2.5 mL/kg. A single valve controlled expiration and respiratory rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Rescue from Pediatric ECMO with Prolonged Hybrid Intratracheal Pulmonary Ventilation

Rescue from Pediatric ECMO with Prolonged Hybrid Intratracheal Pulmonary Ventilation

Rescue from Pediatric ECMO with Prolonged Hybrid Intratracheal Pulmonary Ventilation

Hybrid intratracheal pulmonary ventilation (h-ITPV) is a continuous flow ventilatory technique that uses a "reverse thruster" catheter to redirect the flow of gas away from the carina. We report here the use of h-ITPV in a pediatric patient with acute sickle cell chest syndrome who required venoarterial ECMO support because of refractory hypoxemic respiratory failure. Her ECMO course was complicated by air leaks, coagulopathy, cardiac tamponade, and necrotizing tracheobronchitis. She could be weaned from ECMO only by maintaining high pressure conventional ventilatory support. To prevent ventilator induced barotrauma, we initiated h-ITPV and weaned her from ECMO bypass. After 12 days of h-ITPV, with tidal volumes of 2-3 ml/kg at carinal peak inspiratory pressures of 25-30 cm H2O, the air leaks ceased and h-ITPV was discontinued. Dead space ventilation fraction (VD/VT) as low as 0.29 was achieved with this technique. Post-h-ITPV bronchoscopy displayed a dramatic resolution of the necrotizing tracheobronchitis. The patient survived and was discharged from the hospital. We conclude that the use of hybrid ITPV may facilitate weaning from ECMO to low pressure conventional ventilation and prevent the development of pulmonary barotrauma.

Intratracheal pulmonary ventilation and congenital diaphragmatic hernia: A report of two cases

Previous studies from our institution have shown that neonates with congenital diaphragmatic hernia (CDH), whose best postductal PaO 2 (BPDPO 2) was less than 100 mm Hg while on maximal conventional mechanical ventilation (CMV), had a mortality exceeding 90%. When combined with extracorporeal membrane oxygenation (ECMO), the mortality rose to 100% in those infants who developed hypercarbia following decannulation. Historically, those patients have required increasing ventilator support, leading to iatrogenic lung damage, and eventual death. Intratracheal pulmonary ventilation (ITPV) using the reverse thrust catheter (RTC) developed by Kolobow incorporates a continuous flow of humidified gas through a reverse Venturi catheter positioned at the distal end of the endotracheal tube. In animal studies, ITPV was shown to result in a reduced physiological dead-space (V D), to facilitate expiration, and to enhance CO 2 elimination. In our current study, we have applied ITPV in two neonates with CDH who could not be weaned from ECMO because of uncontrollable hypercapnia, and who met above criteria for 100% mortality. In both cases, ITPV restored normal PaCO 2 at low peak inspiratory pressure (PIP) with a substantial decrease in V D. We believe ITPV is suited to ventilating newborns with CDH in whom barotrauma is known to be common. Beyond its present use, ITPV may be useful to ventilate children with other forms of respiratory failure, and should be so considered along with other now available methods of mechanical pulmonary ventilation.