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PubMed1996

Tracheal gas insufflation: catheter effectiveness determined by expiratory flush volume.

Used adjunctively during mechanical ventilation, tracheal gas insufflation (TGI) improves CO2 elimination, principally by decreasing effective anatomic dead space. Continuing lung deflation at end- expiration raises the end-expiratory C02 concentration within the proximal airway, and could theoretically reduce the efficiency of a given catheter flow. To test this possibility, we designed a series of experiments that examined the influence of TGI delivery patterns on the efficiency of CO2 elimination. Using a gating device, catheter flow was delivered selectively during desired portions of expiration. Paralyzed, ventilated dogs were studied at short and extended inspiratory time fractions (TI/TT) with inspiratory tidal volume and ventilator frequency held constant. The expiratory flush volume, not the pattern of gas delivery, determined the observed decline in PaCO2, provided that the end-expiratory period was included in the catheter flush period. Despite continuing end-expiratory lung deflation (extended TI/TT), catheter effectiveness remained the same at matched expiratory flush volumes. To determine if enhanced distal mixing at the higher catheter flows required during the extended TI/TT (to match expiratory flush volume) masked a decrease in efficiency, we repeated the experiment with a tip-inverted catheter. We again found that matched catheter delivered expiratory volumes were similarly effective. With or without ongoing lung deflation, the volume of gas flushed during the expiratory period determined the effectiveness of TGI, provided that inspired minute ventilation remains unchanged and end-expiration is included in the catheter flush period.

Analysis of Variance↗
PubMed1996

Efficacy of tracheal gas insufflation in acute respiratory distress syndrome with permissive hypercapnia.

This study was conducted to assess the CO2-elimination efficiency of tracheal gas insufflation (TGI) in 20 patients with acute respiratory distress syndrome and to compare its efficacy during volume-controlled (VCV) and pressure-controlled ventilation (PCV). TGI was initially applied as an adjunct to VCV, with continuous flows (Vcath) of 4 and 6 L/min delivered through a catheter positioned 2 cm above the carina. Total effective tidal volume (VTeff) was held constant. The percent reductions in PaCO2 (% delta PaCO2) were 13.3 +/- 2.1 and 16.7 +/- 2.7% at Vcath 4 and 6 L/min, respectively, which correlated well with the percent reduction in the end-tidal PCO2 from baseline (% delta PETCO2) (r = 0.75, p < 0.001). An inverse relationship (r = -0.65, p < 0.001 and r = -0.59, p < 0.01 at Vcath 4 and 6 L/min, respectively) was found between the % delta PaCO2 and the baseline ratio of artery to PETCO2 difference to PaCO2, which was determined as the fraction of alveolar dead space (VDalv) relative to total alveolar ventilation. Twelve patients were subsequently switched to PCV combined with Vcath 6 L/min, which provided a % delta PaCO2 of 16.1 +/- 3.0% (p = NS versus 17.1 +/- 2.6% during VCV). These data suggest that in patients with ARDS the change in PETCO2 may be helpful in predicting the decrement in PaCO2 during TGI, and the existence of a high VDalv tends to limit its effectiveness. Further, the efficacy of TGI with VCV is equivalent to that with PCV.

Adult↗
PubMed1996

Efficacy of cardiopulmonary resuscitation using intratracheal insufflation.

The effects of constant-flow insufflation (CFI) of air in the trachea at the distal end of a modified endotracheal tube as the sole mode of ventilation during cardiopulmonary resuscitation (CPR) were studied in pigs. The ventilatory effect of CFI (15 +/- 2 L/min) generating a positive pressure of about 10 cm H2O with concomitant chest compression was studied first. In nine sedated, paralyzed animals disconnected from the ventilator, CFI alone did not significantly alter the decrease in PaO2 and the rise in PaCO2 observed during apnea. By contrast, the combination of precordial compression and CFI (CFI-CPR) maintained arterial blood gases over a 4-min period at the level obtained during mechanical ventilation. In the second part of the study, ventricular fibrillation was induced and CFI-CPR was compared with standard CPR using conventional mechanical ventilation during two successive 4-min periods, in random order. Ventilatory parameters were identical in the two situations, whereas hemodynamic parameters were similar or better with CFI-CPR than with standard CPR. Significant differences were observed between standard CPR and CFI-CPR for systolic aortic pressure (72 +/- 22 versus 82 +/- 27 mm Hg, respectively; p < 0.02) and for systolic (322 +/- 216 versus 431 +/- 237 ml/s; p < 0.01) and mean (116 +/- 106 versus 143 +/- 108 ml/s; p < 0.01) common carotid blood flows. The ease of use of CFI together with its beneficial hemodynamic effects suggests that CFI deserves to be investigated further as a mode of ventilation during CPR.

Animals↗
PubMed1999

Pressure-release tracheal gas insufflation reduces airway pressures in lung-injured sheep maintaining eucapnia.

Although tracheal gas insufflation (TGI) has proved to be a useful adjunct to mechanical ventilation, end-inspiratory as well as end-expiratory pressures may increase. We investigated the ability of continuous-flow TGI to maintain eucapnia while reducing airway pressure (Paw) and tidal volume (VT). Seven sheep (36 +/- 2 kg) were ventilated using the Dräger Evita 4 in the pressure control plus mode where flow is released via the expiratory valve to maintain constant inspiratory pressure. To avoid TGI-generated positive end-expiratory pressure (PEEP), a prototype reverse flow TGI tube was used. Two TGI flows (5 and 10 L/min) were investigated pre- and postsaline lavage-induced lung injury. Inspiratory pressures and VT were significantly reduced as TGI flow increased. At 10 L/min TGI flow the carinal pressures (Pcar) and VT were reduced pre- and postinjury by 15% and 20%, and by 28% and 34%, respectively. Tidal volume to dead space ratio (VD/VT) decreased preinjury from 0.49 +/- 0.1 to 0.18 +/- 0.2 and postinjury from 0.62 +/- 0.1 to 0.33 +/- 0.1 at a TGI flow of 10 L/min. The combination of the reverse flow TGI tube and a ventilator with an inspiratory pressure relief mechanism kept set end-inspiratory and end-expiratory pressures constant. This TGI system effectively reduced set Paw and VT while maintaining eucapnia.

Airway Resistance↗
PubMed2000

Tracheal gas insufflation. Limits of efficacy in adults with acute respiratory distress syndrome.

In mechanically ventilated adults with acute respiratory distress syndrome (ARDS), peak airway pressures (Paw(peak)) above 35 cm H(2)O may increase the risk of barotrauma or volutrauma. Tracheal gas insufflation (TGI), an adjunctive ventilatory technique, may facilitate a reduction in set inspiratory pressure in these patients, and thereby in the tidal volume (VT) and Paw(peak) used in their ventilation, without a consequent increase in arterial carbon dioxide tension (PaCO(2)). The purpose of this study was to: (1) assess the limits of efficacy of continuous TGI at two levels of decreased mechanical ventilatory support; and (2) determine an appropriate time interval after initiation of TGI at which to evaluate response. We prospectively studied eight adults with ARDS and increased airway pressures (40.2 +/- 2.7 cm H(2)O) who were managed with pressure-control ventilation (PCV). After obtaining baseline ventilatory and hemodynamic measures, we initiated TGI at 10 L/min, adjusting ventilator positive-end expiratory pressure (PEEP) to maintain baseline VT, and decreased the set inspiratory pressure by 5 cm H(2)O. Data were obtained after 30 and 60 min. Set inspiratory pressure was then decreased by an additional 5 cm H(2)O (total: 10 cm H(2)O), and data were again obtained after 30 min. Baseline (zero TGI) measures were then again recorded. Thirty minutes after decreasing the set inspiratory pressure by 5 cm H(2)O with TGI at 10 L/min, there was a 15% decrease in Paw(peak) and a 16% decrease in VT as compared with their baseline values. However, Pa(CO(2)) remained constant (59 +/- 10 mm Hg versus 57 +/- 6 mm Hg) (p = NS). There was no change in Pa(O(2)) or in hemodynamic variables, and no differences between variables, at 30 min versus 60 min in seven subjects. The remaining subject did not tolerate the reduction in set inspiratory pressure for 60 min. Thirty minutes after the set inspiratory pressure was decreased by 10 cm H(2)O with TGI at 10 L/min, there was a 26% decrease in Paw(peak) and a 26% decrease in VT. However, Pa(CO(2)) increased by 19% and Pa(O(2)) decreased by 13%. Six subjects completed this phase of the protocol for 30 min, and one subject completed it for 60 min. TGI can be used to rapidly facilitate a 5 cm H(2)O reduction in set inspiratory pressure without an increase in Pa(CO(2)). The ability to achieve a 5 cm H(2)O reduction in set inspiratory pressure without adverse physiologic effects was evident within 30 min. Attempts to further reduce set inspiratory pressure were not successful.

Acute Disease↗
PubMed2000

Continuous tracheal gas insufflation in preterm infants with hyaline membrane disease. A prospective randomized trial.

In mechanically ventilated neonates, the instrumental dead space is a major determinant of total minute ventilation. By flushing this dead space, continuous tracheal gas insufflation (CTGI) may allow reduction of the risk of overinflation. We conducted a randomized trial to evaluate the efficacy of CTGI in reducing airway pressure over the entire period of mechanical ventilation while maintaining oxygenation. A total of 34 preterm newborns, ventilated in conventional pressure-limited mode, were enrolled in two study arms, to receive or not receive CTGI. Transcutaneous Pa(CO(2)) (tcPa(CO(2))) was maintained at 40 to 46 mm Hg in both groups to ensure comparable alveolar ventilation. Respiratory data were collected several times during the first day and daily until Day 28. Both groups were similar at the time of inclusion. During the first 4 d of the study, the difference between peak pressure and positive end-expiratory pressure was significantly lower in the CTGI group by 18% to 35%, with the same tcPa(CO(2)) level and with no difference in the ratio of tcPa(O(2)) to fraction of inspired oxygen (245 +/- 29 versus 261 +/- 46 mm Hg [mean +/- SD] over the first 4 d). Extubation occurred sooner in the CTGI group (p < 0.05), and the duration of mechanical ventilation was shorter (median: 3.6 d; 25th to 75th quartiles: 1.5 to 12.0 d; versus median: 15.6 d; 25th to 75th quartiles: 7.9 to 22.2; p < 0.05) than in the non-CTGI group. CTGI allows the use of low-volume ventilation over a prolonged period and reduces the duration of mechanical ventilation.

Blood Gas Monitoring, Transcutaneous↗
PubMed2001

Application of tracheal gas insufflation to acute unilateral lung injury in an experimental model.

In unilateral lung injury, application of global positive end-expiratory pressure (PEEP) may cause overdistension of normal alveoli and redistribution of blood flow to diseased lung areas, thereby worsening oxygenation. We hypothesized that selective application of tracheal gas insufflation (TGI) will recruit the injured lung without causing overdistension of the normal lung. In eight anesthetized dogs, left lung saline lavage was performed until Pa(O(2))/FI(O(2)) fell below 100 mm Hg. Then, the dogs were reintubated with a Univent single lumen endotracheal tube that incorporates an internal catheter to provide TGI. After injury, increasing PEEP from 3 to 10 cm H(2)O did not change gas exchange, hemodynamics, or lung compliance. Selective TGI, while keeping end-expiratory lung volume (EELV) constant, improved Pa(O(2))/FI(O(2)) from 212 +/- 43 to 301 +/- 38 mm Hg (p < 0.01) while Pa(CO(2)) and airway pressures decreased (p < 0.01). During selective TGI, reducing tidal volume to 5.2 ml/kg while keeping EELV constant, normalized Pa(CO(2)), did not affect Pa(O(2))/FI(O(2)), and decreased end-inspiratory plateau pressure from 16.6 +/- 1.0 to 11.9 +/- 0.5 cm H(2)O (p < 0.01). In unilateral lung injury, we conclude that selective TGI (1) improves oxygenation at a lower pressure cost as compared with conventional mechanical ventilation, (2) allows reduction in tidal volume without a change in alveolar ventilation, and (3) may be a useful adjunct to limit ventilator-associated lung injury.

Animals↗
PubMed1991

Constant-flow insufflation prevents arterial oxygen desaturation during endotracheal suctioning.

In mechanically ventilated patients, disconnection from the ventilator and endotracheal suctioning can induce major arterial oxygen desaturation resulting from apnea, changes in inspired oxygen fraction, and decrease in lung volume. The aim of this study was to test the efficacy of a simple method of delivering oxygen and maintaining lung volume during this process. Our study was conducted in two parts. In the first part, constant-flow insufflation of oxygen (CFI) was used in seven patients ventilated for acute respiratory failure (PaO2/FlO2 = 347 +/- 33 mm Hg) as a means of maintaining arterial oxygenation during apnea and disconnection from the ventilator. CFI was administered via a modified endotracheal tube in which small capillaries allowed delivery of a high-velocity jet flow near the tracheal end of the tube during disconnection from the ventilator. In comparison to apnea alone, CFI prevented a fall in arterial oxygen tension (16 +/- 7 mm Hg during CFI versus 117 +/- 27 during apnea, after 90 s of disconnection in the two situations, p less than 0.001), whereas it did not reduce the development of hypercapnia. The efficacy of CFI resulted both from the injection of oxygen into the trachea and from the maintenance of positive alveolar pressure induced by air entrainment (mean 10.4 +/- 1.1 cm H2O), preventing a fall in lung volume usually occurring after disconnection (+338 +/- 88 ml during CFI versus -344 +/- 64 ml during apnea, p less than 0.01). In the second part of the study CFI was used to prevent arterial oxygen desaturation induced by endotracheal suctioning.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Airway insufflation. Increasing flow rates progressively reduce dead space in respiratory failure.

We have previously shown that airway insufflation (AI) reduces dead space (VD) and minute ventilation (VL) in patients with respiratory failure, and when used chronically leads to lowered and more stable arterial PCO2. The present study was designed to measure the effect of increasing AI flow rate on VD and other aspects of gas exchange in respiratory failure in order to examine the hypothesis that AI exerts its main physiologic effect by progressive reductions of VD. Five patients with varying degrees of respiratory failure caused by either restrictive or obstructive lung disease were studied by means of the specialized techniques we developed to analyze gas exchange during AI. At 1 L/min (as in transtracheal oxygenation), at 5 L/min, and 8 L/min, AI produced progressive reductions in VD, tidal volume, and VL. Contrary to our previous study, some of these patients accompanied the decrease in VD with not only decreases in VL but with slight rises in alveolar ventilation (VA) and decrements in arterial PCO2. The greatest percentile decreases in VD and VL occurred in those with the smallest initial control values for each of these parameters. In summary, AI exerts its main effects on gas exchange through the reductions in VD that it produces, and the accompanying decreases in VL and/or slight increases in VA seem to stem from the latter.

Aged↗
PubMed1992

Gas exchange by intratracheal insufflation in a ventilatory failure dog model.

Respiratory insufficiency patients who need only partial ventilatory support are, nevertheless, intubated and connected to a respirator. In search of a partial respiratory assistance method we evaluated the gas exchange, mechanisms, and hemodynamic effects of intratracheal insufflation (ITI) via a narrow (0.2-cm) catheter. The effects of flow rate (0.05-0.2 liter/min per kg), catheter tip position (carina, bronchus, and trachea), and superimposed chest vibration at 22 Hz were studied in seven anesthetized and partially paralyzed dogs. ITI in the carina induced CO2 removal (VCO2) of 48 +/- 16 ml/min in the periods between breaths, which was 39% of the control VCO2. CO2 removal rates between breaths with ITI in a bronchus and in the trachea were 63 and 28% of control, respectively (P < 0.05). ITI at 0.15-0.2 liter/min per kg augmented total VCO2 by > 50% over control (P < 0.05) and decreased PaCO2 by 10% (P < 0.05) despite a 28% fall in VE and 32% lower work of breathing (P < 0.05). Adding vibration to ITI at 0.15 liter/min per kg induced VCO2 of 162 +/- 34 ml/min, which was significantly greater than control, while PaCO2 fell from 69 +/- 24 to 47 +/- 6 mmHg (P < 0.05), despite complete cessation of spontaneous breathing. ITI with or without vibration did not cause any hemodynamic changes, except for a fall in the shunt fraction from 14.6 +/- 9.9% to 5.8 +/- 2.8% with vibration. Thus, ITI at low flow rates can support respiration with no hemodynamic side effects. Adding chest vibration further enhances gas exchange and can provide total ventilation.

Animals↗
PubMed1995

Bronchoscopic insufflation of room air for the treatment of lobar atelectasis in mechanically ventilated patients.

Segmental and lobar pulmonary atelectasis is a common occurrence in mechanically ventilated patients. Standard therapy for atelectasis relies on positive pressure ventilation, positive and expiratory pressure (PEEP), tracheobronchial toilet and regular chest physiotherapy. Various adjuncts to physiotherapy such as bronchoscopic clearance of secretions have not proved to be of additional benefit. Bronchoscopic clearance of secretions followed by insufflation of room air at 30 cm H2O into the atelectatic segment was employed on ten occasions in mechanically ventilated patients. Rapid re-expansion of the collapsed segment or lobe occurred in seven out of the ten treatments.

APACHE↗
PubMed1990

Tracheal insufflation of oxygen at low flow: capabilities and limitations.

Tracheal insufflation of oxygen (TRIO) may provide temporary oxygenation for patients or sustain life in apneic mass casualties when conventional ventilatory techniques are not available or feasible. Logistically, minimum flows of TRIO (Vmin) are desirable for field use and to reduce barotrauma should airway obstruction occur. We carried out a feasibility study to determine the efficacy of Vmin of TRIO delivered within 1 cm of the carina, in nine anesthetized and paralyzed dogs. Minimum flows of TRIO for these dogs of average weight (12 kg) was 91 mL/min. In six of the dogs Vmin TRIO was continued and provided oxygenation for an average of 1.5 h compatible with subsequent resuscitation with conventional ventilation. However, PaCO2 levels increased to mean values of 256 mm Hg in the 90 min. To determine what the effect of increased gas mixing was on gas exchange, we repeated Vmin TRIO for 10 min in six of the dogs with and without high frequency oscillations superimposed on the TRIO flow. The oscillations (60 mL at 16.3 Hz) increased carbon dioxide excretion but significantly impaired oxygenation. In completely apneic animals, TRIO at low flow delivered by cricothyroidotomy may be useful as an emergency procedure when upper airway obstruction limits the use of other airway management techniques. However, enhancement of gas mixing during low-flow TRIO impairs oxygenation, so that higher flows would be required when respiratory efforts occur.

Animals↗
PubMed2006

Cardiac function during intraperitoneal CO2 insufflation for aortic surgery: a transesophageal echocardiographic study.

The effect of laparoscopy on cardiac function is controversial. We hypothesized that cardiac dysfunction related to increased afterload could be predominant in patients undergoing elective abdominal aortic repair. To test this hypothesis, we conducted a transesophageal echocardiographic study in 15 patients during laparoscopic aortic surgery. We systematically assessed left ventricular (LV) and right ventricular (RV) functions. Measurements were obtained in the supine position without pneumoperitoneum and with an intraabdominal pressure of 14 mm Hg. Then, patients were turned to the right lateral position without pneumoperitoneum and intraabdominal pressure was increased to 7 mm Hg and to 14 mm Hg. Pneumoperitoneum induced a 25% arterial blood pressure increase and a 38% increase in LV systolic wall stress. A 25% decrease in LV ejection fraction and an 18% decrease in LV stroke volume were observed, associated with an increase in LV end-systolic volume. LV diastolic function impairment was observed without change in LV end-diastolic volume. Respiratory alterations in superior vena cava diameter were never observed, suggesting that volume status remained optimal. Respiratory changes in RV stroke volume were increased according to intraabdominal pressure and body position, reflecting an increase in RV afterload. In conclusion, peritoneal CO2 insufflation in patients scheduled for laparoscopic aortic surgery could impair LV and RV systolic functions as a consequence of increased afterload.

Adult↗
PubMed2006

The effect of tracheal gas insufflation on gas exchange efficiency.

Transtracheal gas insufflation (TGI) improves gas exchange efficiency, but is associated with hyperinflation, and usually requires ventilator adjustment to compensate for the increased gas flow. Although bidirectional TGI (Bi-TGI) minimizes hyperinflation, it does not preclude the need to reduce tidal volumes to prevent hyperinflation. A flow-compensation system was developed by Respironics (Murrysville, PA) to match TGI flows; however, neither that nor the efficacy of Bi-TGI have been tested in vivo. We tested the hypotheses that flow compensation allows for a constant minute ventilation; Bi-TGI produces less hyperinflation than does unidirectional TGI (Uni-TGI), and endotracheal tube size influences the degree of hyperinflation during TGI. Seven anesthetized intact dogs were studied during positive-pressure ventilation using the Respironics flow compensation system. Measurements were made during steady-state conditions at constant and measured levels of CO(2) production. Gas exchange efficiency (assessed by expired gas analysis for dead space) and hyperinflation (measured as an increase in pleural pressure) were compared during Bi- and Uni-TGI and for endotracheal tube sizes varying from 7 to 10F. Bi- and Uni-TGI could be delivered at constant minute ventilation without adjusting ventilatory setting when the flow compensation circuit was present. Uni-TGI produced more hyperinflation than did Bi-TGI with all sizes of endotracheal tube, and hyperinflation was universally present as tube size decreased to 7.5F. We conclude that this new flow compensation system allows for the delivery of TGI without the need for adjustments to the ventilator settings, and that Bi-TGI produces less hyperinflation than does Uni-TGI, even with small diameter endotracheal tubes.

Animals↗
PubMed1995

Is tracheal gas insufflation an alternative to extrapulmonary gas exchangers in severe ARDS?

Tracheal gas insufflation (TGI) of pure oxygen combined with mechanical ventilation decreases dead space and increases CO2 clearance. In the present study, TGI was used in six patients with ARDS who met extracorporeal membrane oxygenation criteria and who were severely hypoxemic and hypercapnic despite optimal pressure-controlled ventilation. This open clinical study aimed to investigate the effects of 4 L/min continuous flow of oxygen given via an intratracheal catheter. PaCO2 decreased from 108 +/- 32 to 84 +/- 26 mm Hg (p < 0.05), and no significant change in PaO2 (68 +/- 18 vs 96 +/- 43, p = 0.06). There was no change in airway pressures and hemodynamic variables. A slight increase in end-expiratory and end-inspiratory volumes with TGI possibly occurred, as seen on tracings from respiratory inductive plethysmography (Respitrace). We conclude that TGI improves tolerance of limited pressure ventilation by removing CO2, but it may induce changes in lung volumes that are not detected by ventilator measurements.

Adult↗
PubMed1996

Effect of tracheal gas insufflation on demand valve triggering and total work during continuous positive airway pressure ventilation.

Tracheal gas insufflation (TGI) improves CO2 clearance and may reduce work of breathing by lowering the required minute ventilation (VE). However, TGI might also impair the ability to trigger the ventilator, because to lower external circuit pressures, inspiratory effort must outstrip catheter flow rate (Vc) and overcome the dynamic hyperinflation caused by TGI. We studied these effects using a two-chamber lung model of the respiratory muscles (RM) and lungs (L). The RM-chamber was ventilated using a sinusoidal flow pattern with a tidal volume (VT) of 0.5 L at various peak inspiratory flow rates (Vpk) to simulate differences in effort intensity. The L-chamber was connected to a 60-L/min continuous flow circuit with a 10 cm H2O positive end-expiratory pressure valve and to 3 different ventilatory demand valve circuits, each set at continuous positive airway pressure (CPAP) of 10 cm H2O. We used continuous TGI at 0, 2.5, 5, 10, and 15 L/min. The work of triggering (W-trig) increased with increasing Vc and decreased with increasing Vpk. The L-ventilator failed to trigger when Vc was 15 L/min and Vpk was 20 L/min. At a fixed VE, the effect of TGI on total mechanical inspiratory work (W-tot) was relatively small and varied among the different CPAP systems used. We conclude that weak patients may fail to open the demand valve of the CPAP system during TGI at high catheter flow rates. The net effect of TGI on the effort made by ventilated patients would depend not only on the interactions between TGI and the ventilator, but also on the efficiency of TGI in decreasing dead-space and lowering the VE requirement.

Humans↗
PubMed2002

Ventilating with tracheal gas insufflation and periodic tracheal occlusion during sleep and wakefulness.

INTRODUCTION: The current invasive and noninvasive methods for delivering long-term ventilatory support rely on cumbersome patient interfaces that may interfere with upper airway function. To overcome these limitations, a novel system was developed to ventilate conscious, spontaneously breathing dogs through a self-contained cuffed cannula that was used for tracheal gas insufflation (TGI) and periodic tracheal occlusion (PTO). We hypothesized that TGI + PTO would provide greater ventilatory support than would TGI alone and that its effect would be more pronounced during sleep than wakefulness. METHODS: Chronically tracheostomized dogs were monitored for sleep (ie, EEG, electro- oculogram, and nuchal electromyogram) and breathing (ie, tracheal pressure [Ptr] and upper airway flow via snout mask). A thin transtracheal cannula housed within a cuffed tracheostomy tube was used for TGI and PTO monitoring. E, gas exchange, and breathing patterns were examined during sleep and wakefulness at baseline (ie, no TGI) and during the application of TGI alone (at 5, 10, and 15 L/min) and the application of TGI + PTO. RESULTS: Compared to baseline breathing without TGI, TGI at 5, 10, and 15 L/min decreased minute ventilation without influencing PaCO(2). In contrast, TGI + PTO led to progressive increases in ventilation, positive Ptr swings, and decreases in PaCO(2) as the flow rate was increased during sleep and wakefulness. Moreover, spontaneous breathing efforts ceased during TGI + PTO at flow rates of 10 and 15 L/min during wakefulness, and at all flow rates during sleep. CONCLUSIONS: The findings indicate that TGI + PTO can fully support ventilation in a spontaneously breathing canine model during sleep and wakefulness. Its streamlined interface could ultimately prove to be clinically significant, once technical concerns are addressed.

Animals↗
PubMed1990

Treatment for collapsed lung in critically ill patients. Selective intrabronchial air insufflation using the fiberoptic bronchoscope.

A new, simpler method to re-expand collapsed lungs was introduced in 14 procedures in 12 critically ill patients. To close the bronchus, we wedge the fiberoptic bronchoscope into each segment or subsegment of the collapsed lung instead of using a balloon cuff. Room air was then insufflated into the atelectatic alveoli after repetitive sputum suctioning and bronchial washing with normal saline solution. Complete re-expansion was achieved in 12 of the 14 procedures and partial in two. The average alveolar-arterial oxygen pressure difference (P[A-a]O2) declined from 217.5 before the procedure to 200.3, 150.0 and 152.2, respectively at 30 minutes, 12 hours and 24 hours after. There were no complications.

Adolescent↗