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PubMed2003

A new method of inhalation anesthesia with nasopharyngeal insufflation in rat experiment.

We have established a new method of anesthesia with nasopharyngeal insufflation for intraoral procedure in rodents. Twelve male Wistar rats weighing 330-390 g were used in this study. Insertion of a feeding tube 1.0 mm in diameter coated with 2% xylocaine jelly was inserted into the nasal cavity approximately 25 mm from the naris, and anesthetization with mixed gas of 100% oxygen with 3-4% enflurane at 0.25-0.5 l/min flow rate was achieved. Using this anesthetic method, a chronic experiment comprising 1-h/day experimental procedure was carried out for 14 days. This method enabled, 1) simple and safe operation of the induction, emergence and anesthetic depth, 2) experimental procedures on the dental/oral region, 3) avoidance of the dyspnea and tachypnea, and 4) avoidance of cumulative effects in daily anesthesia.

Anesthesia, Inhalation↗
PubMed1999

New tools in ventilatory support: high frequency ventilation, nitric oxide, tracheal gas insufflation, non-invasive ventilation.

Protection of the lungs against ventilator-induced lung injury is becoming one of the main concerns in pediatric and neonatal intensive care. High frequency ventilation using a constant distending pressure with small variations during respiratory cycles allows adequate recruitment. High frequency oscillation is the most promising HFV mode especially in premature neonates but clinical studies are contradictory. Nitric oxide, an inhaled gas with specific pulmonary vasodilating effects, has become a powerful tool in the treatment of pulmonary arterial hypertension alone or in combination with HFO, but studies have failed to show improvement in survival in neonates as well as in children with ARDS. Tracheal gas insufflation, in addition to conventional ventilation, by washing dead space during exhalation, improves gas exchange while lowering tidal volume. It is however still experimental. Maintenance of spontaneous ventilation during conventional ventilation improves gas exchange, hemodynamic functions, mobilization, active coughing, and avoids prolonged muscle weakness. Non invasive modes of ventilation like BiPAP have certain indications in pediatrics but need to become more familiar to the pediatric intensivist.

Child↗
PubMed1999

[Continuous flow apnoeic ventilation via intratracheal oxygen insufflation].

BACKGROUND: In patients with disturbed gas-exchange (e.g. COPD) intratracheal oxygen insufflation (ITO2) improves oxygenation and reduces the minute ventilation. We use a bronchoscopic technique of intratracheal catheter placement in unintubated patients. In a patient with a pink-puffer emphysema after endoscopical insertion of the catheter ITO2 induced a "continuous flow apnoeic ventilation" (CFAV). CASE REPORT: A patient (female, 58 years) with a pink-puffer emphysema was admitted to the ICU with acute on chronic respiratory failure due to acute laryngitis. Because of laryngitis associated upper airway obstruction a non-invasive mechanical ventilation could not be performed. The ensuing high flow ITO2 (10 l/min) induced a CFAV characterized by no chest wall movement and adequate ventilation as reflected by stable, elevated PaCO2 (between 118 and 125 mm Hg), which could be maintained for 4 hours. After an ensuing short-term invasive mechanical ventilation and the administration of high dose glucocorticoids the patient was successfully extubated and the clinical status improved continuously. CONCLUSION: In a patient with an acute on chronic respiratory failure due to end-stage emphysema ITO2 induced CFAV and stabilized the clinical status. Especially in patients with end-stage emphysema, who are likely to be difficult to be weaned from the respirator ITO2 may be a feasible technique in order to bridge an emergency situation.

Emphysema↗
PubMed2001

Clinical studies of tracheal gas insufflation.

Tracheal gas insufflation (TGI) is an adjunct to mechanical ventilation that allows ventilation with small tidal volumes while carbon dioxide (CO2) is satisfactorily cleared. Pioneering studies in healthy animals and in humans suffering respiratory failure showed that the expiratory flushing of proximal dead space decreased minute ventilation with no change in arterial partial pressure of carbon dioxide (PaCO2). Recent work indicates that conventional mechanical ventilation aided by TGI may represent a novel ventilatory strategy that succeeds in limiting both the distending forces acting on the lungs and the PaCO2 elevation of permissive hypercapnia. Furthermore, some studies suggest that weaning aided by TGI may allow a reduction in minute ventilation, PaCO2, physiologic dead space, and the patient's respiratory demands. Clinical use of TGI requires careful monitoring of delivered volumes and pressures to ensure safe clinical application and to evaluate the effect on lung function. Finally, routine use of TGI in intensive care warrants further investigation to solve some technical problems and randomized clinical trials to confirm the beneficial effects in the absence of complications.

Animals↗
PubMed2001

Complications of tracheal gas insufflation.

Numerous reports of patient, lung model, and animal use of tracheal gas insufflation (TGI) have appeared in the literature over the past 10 years. However, no commercial TGI system is available. As a result, extreme care must be exercised if attempts are made to provide TGI. Numerous problems with noncommercial systems have been identified. Continuous-flow TGI results in an increase in peak pressure and delivered tidal volume. The use of a flow-limiting or pressure relief valve or a ventilator with an exhalation valve active during exhalation minimizes these problems. Ideally, TGI should only be activated during the expiratory phase. However, this requires that the TGI system be integrated with the mechanical ventilator. In addition, appropriate system monitoring should be available, including measurement of total positive end-expiratory pressure, peak inspiratory pressure, and tidal volume, and there should be a method of identifying increased carinal pressure and deactivating the TGI system if an obstruction occurs proximal to the point of TGI injection. As a result of the potential complications of TGI, this technique cannot be recommended for routine use until commercial systems are available.

Humans↗
PubMed2001

Catheters for tracheal gas insufflation.

As an adjunct to mechanical ventilation, tracheal gas insufflation (TGI) injects gas flow into the trachea to flush carbon dioxide (CO2) from the anatomical and mechanical dead space, but the addition of TGI flow from a catheter may cause problems related to increased flow velocity at the catheter tip. Forward momentum and turbulence beyond the tip oppose expiratory flow and may cause or increase intrinsic positive end-expiratory pressure. If the catheter is placed within the endotracheal tube (ETT), the catheter itself acts as a resistive element to exhalation. Effects of the catheter presence (contact on or whipping against the airway) or local rapid gas flow effects on the tracheal mucosa are possible. Thus far, TGI has been delivered through a range of catheter sizes and styles. Two general design modifications have been incorporated in TGI systems to address the possible problems: embedding the catheter flow channel within the ETT, and directing the TGI flow cephalad. The LaBrune-Boussignac tube was designed with 6 or 8 channels embedded within the ETT, from which TGI flow exits laterally within the ETT at 1.5 cm from its tip. This avoids the use of a catheter and thus avoids local traumatic effects. A reverse-thrust catheter has been designed to direct flow within a sheath around the catheter tip; flow exits cephalad from a gap between the sheath and the catheter shaft. As part of a proposed ventilatory mode (intratracheal pulmonary ventilation) the reverse-thrust catheter delivers the tidal breath and, additionally, flushes CO2 and accelerates secretion removal during exhalation. A reverse-flow design ETT has been developed with two channels, one for tidal volume delivery and the other for TGI flow. The TGI channel is relatively large and flow is directed cephalad by a nozzle at the catheter tip. A recently developed bidirectional catheter allows the option of delivering TGI flow cephalad, towards the lungs or in both directions. Unfortunately, to be convenient, the use of specially designed catheters or ETTs requires the anticipation of TGI use. A complete system for the safe and convenient use of TGI in ventilated patients is not as yet available, but concerns about the safety and convenience of TGI delivery have been addressed with recent advances in catheter/tube design.

Catheterization↗
PubMed2001

Effects of continuous, expiratory, reverse, and bi-directional tracheal gas insufflation in conjunction with a flow relief valve on delivered tidal volume, total positive end-expiratory pressure, and carbon dioxide elimination: a bench study.

INTRODUCTION: Tracheal gas insufflation (TGI) can increase total positive end-expiratory pressure (total-PEEP) when flow is delivered in a forward direction, necessitating adjustments to maintain total-PEEP constant. When TGI is delivered throughout the respiratory cycle, additional adjustments are needed to maintain tidal volume (V(T)) constant. OBJECTIVE: Determine if bi-directional TGI (bi-TGI) (simultaneous flows toward the lungs and upper airway) in combination with a flow relief valve eliminates the increase in total-PEEP and maintains a constant V(T), thus simplifying TGI administration. METHODS: Using an artificial lung model and pressure control ventilation, we studied the effect of TGI at 10 L/min on inspired V(T), total-PEEP, and CO(2) elimination during 6 conditions: (1) control (no TGI, no catheter in the airway), (2) baseline (catheter in the airway but no TGI), (3) continuous TGI, (4) expiratory TGI, (5) reverse TGI, and (6) bi-TGI. Each condition was studied under 3 inspiration-expiration ratios (1:1, 1:2, and 2:1). A preset flow relief valve was inserted into the ventilator circuit during all TGI conditions with continuous flow. SETTING: University research laboratory. RESULTS: CO(2) elimination efficiency was similar under all conditions. Total-PEEP increased with continuous TGI and expiratory TGI, decreased during reverse TGI, and was unchanged during bi-TGI. With the flow relief valve in place, and no adjustment in mechanical ventilation, the change in minute ventilation ranged from 0% to 10%, with the least change during bi-TGI (0-5%). During bi-TGI, gas flow was equivalent in both directions during dynamic conditions and the flow relief valve consistently removed gas at 10 L/min under various pressures. CONCLUSIONS: Our data from an artificial lung model support that continuous bi-TGI minimizes the change in total-PEEP seen during other TGI modalities. The flow relief valve compensated for the extra gas volume delivered by the TGI catheter, thereby eliminating the need to make ventilator adjustments. Used in combination with a flow relief valve, bi-TGI appears to offer unique advantages by providing a simpler method to deliver TGI. Further testing is indicated to determine if similar benefits occur in the clinical setting.

Airway Resistance↗
PubMed1999

[Effects of tracheal gas insufflation on blood gases and respiratory mechanics in acute hypercapnia rabbits].

OBJECTIVE: To evaluate the effects of tracheal gas insufflation (TGI) on elimination of CO2 and improvement of ventilation efficiency. METHODS: Using self-designed TGI device, physiological parameters such as PaCO2, Ppeak, Ppause, end expiratory carbondioxide pressure (PetCO2), lung statistic compliance(Cst), respiratory resistance(Re) and expiratory lung volume(VE) in the two animal groups of conventional mechanical ventilation (CMV) and hypercapnia (HC) by applying two different TGI flow(0.2 L/min and 0.4 L/min) were observed. RESULTS: TGI can significantly decrease the PaCO2 level, enhance CO2 elimination and maintain PaCO2 in the normal range while decreasing VT by 30%, the eliminating effect of CO2 is flow dependent. TGI can elevate airway pressure in both animal groups, but the level of Ppeak, Ppause in HC group are significantly lower than those of CMV group. PetCO2 levels are significantly decreased after TGI while Re and VE increased significantly after TGI. TGI shows no obvious influence on Cst, mean arterial pressure and heart rate. CONCLUSIONS: Our results reveals that TGI is a simple and practical adjunct method to mechanical ventilation, it can effectively decrease PaCO2, and maintain low airway pressure.

Animals↗
PubMed1999

[Continuous tracheal gas insufflation during pressure control ventilation with a pressure relief valve].

OBJECTIVE: To establish the method of continuous tracheal gas insufflation (CTGI) and investigate the role of pressure relief valve (PRV) in limiting high peak airway pressure induced by CTGI. METHODS: CTGI device was made by authors. Nine healthy mongrel dogs were mechanically ventilated by using Evita 2 (Drager Inc.). PRV was inserted into the ventilatory circuit for selected experiment steps and adjusted a threshold pressure equal to the preset inspiratory pressure. PCV, PCV + CTGI (TGI group) and PCV + CTGI + PRV (PRV group) were conducted in different inspiration/expiration (I/E) ratio of 1:2 and 2:1. Gas exchange, lung mechanics and hemodynamics status were monitored at the constant set inspiratory pressure of PCV. RESULTS: At the same I/E ratio, peak airway pressure in TGI group was higher than that of PRV and PCV group (P < 0.01), whereas PRV group maintained the preset inspiratory pressure as PCV group. At the different I/E ratio, peak airway pressure in TGI (2:1) group was higher than that of TGI (1:2) group(P < 0.01). PaCO2 in TGI and PRV group decreased significantly than that of PCV, TGI group was more lower than PRV group, PaO2, hemodynamics and oxygenation remained unchanged in all groups. CONCLUSIONS: The CTGI device is effective in improving alveolar ventilation with no significant influence on hemodynamics and oxygenation; A pressure relief valve is necessary to ensure the safe use of CTGI.

Animals↗
PubMed2001

Efficacy of continuous tracheal gas insufflation in spontaneously breathing canine with acute lung injury.

OBJECTIVE: To investigate the effects of continuous tracheal gas insufflation (CTGI) combined with biphasic intermittent positive airway pressure (BIPAP) ventilation on dogs with spontaneous breathing. METHODS: Eight canine models with oleic acid induced lung injury and spontaneous breathing were ventilated in a random order by Evita 2 (Drager Inc., Germany) in modes of BIPAP (BIPAP group) and BIPAP with CTGI flow rate of 3, 6 and 9 L/min (T3, T6 and T9 groups), respectively. The setting parameters of BIPAP were fiction of inspired oxygen 60%, inspiratory to expiratory ratio 1:1, respiratory rate 20 and positive end expiratory pressure 5 cm H2O. Arterial and mixed venous blood gas, lung mechanics, systemic and pulmonary hemodynamics status were monitored at the same level of PaCO2 obtained by adjusting peak inspiratory pressure of BIPAP. RESULTS: Peak inspiratory pressure in the T6 group (14 +/- 4 cm H2O) and in the T9 group (11 +/- 3 cm H2O) were significantly lower than that of BIPAP (20 +/- 5 cm H2O, P < 0.01), but there was no significant difference among the T3, T6 and T9 groups or between the T3 and BIPAP groups. PaO2, mean artery blood pressure, mean pulmonary artery pressure, pulmonary artery wedge pressure, cardiac output, oxygen delivery and oxygen consumption all remained unchanged in four different conditions. CONCLUSIONS: Using BIPAP combined with CTGI does not cause asynchrony between ventilator and spontaneous breathing, but significantly decreases airway pressure with no influence on hemodynamics and oxygenation. Therefore, BIPAP with CTGI may be a useful support technique, especially in cases where the airway pressure should be limited.

Animals↗
PubMed2000

[Effects of continuous tracheal gas insufflation during biphasic intermittent positive airway pressure ventilation on canine model of acute lung injury with spontaneous breathing].

OBJECTIVE: To study the possibility of using continuous tracheal gas insufflation (CTGI) in dogs with spontaneous breathing. METHODS: Eight canine with oleic acid induced lung injury which had spontaneous breathing were ventilated by Evita 2 (Drager Inc). The setting parameters were FiO(2) (60%), I/E (1:1), RR (20) and PEEP (5 cm H(2)O) in four different conditions: BIPAP (BIPAP group) and BIPAP with different CTGI flow rates (3, 6 and 9 L/min, T3, T6 and T9 group). Gas exchange, lung mechanics and hemodynamic status were monitored at the same level of PaCO(2) obtained by adjusting the high pressure (P high) of BIPAP. RESULTS: The peak inspiratory pressures in the T6 group (14 cm H(2)O +/- 4 cm H(2)O) and T9 group (11 cm H(2)O +/- 3 cm H(2)O) were significantly lower than that of BIPAP group (20 cm H(2)O +/- 5 cm H(2)O, P < 0.01), but significant differences were not found neither among T3, T6 and T9 groups, nor between T3 and BIPAP groups. PaO(2), hemodynamics and oxygenation remained unchanged in the four different conditions. CONCLUSION: BIPAP combined with CTGI in canine with spontaneous breathing could significantly decrease the airway pressure, with no influence on hemodynamics and oxygenation. Thus BIPAP with CTGI may be a useful support technique, especially for cases whose airway pressure should be limited.

Animals↗
PubMed2003

Safe laparoscopic entry guided by Veress needle CO2 insufflation pressure.

Laparoscopy was performed in 259 women. Under general anesthesia, after administering muscle relaxants, and with the patient in stirrups and horizontal position, a nondisposable Veress needle was inserted at the umbilicus or left upper quadrant site with carbon dioxide (CO2) flowing at 1 L/minute. We measured initial intraabdominal pressure in the first 52 women (group 1), pneumoperitoneum pressure (up to 15 mm Hg) at 1-L intervals in the next 102 women (group 2), and CO2 volume required for pressures of 10, 15, 20, and 25 mm Hg in the final 102 women (group 3). In three patients the procedure was abandoned. The primary trocar and laparoscope were introduced at pressure of 25 mm Hg and the entry site and abdominal contents were inspected before desufflation to 15 mm Hg and Trendelenburg position. Medians and means of initial intraabdominal pressure were 4 and 4.09 mm Hg (SD 1.34 mm Hg, range 2-8 mm Hg). This was always below interstitial pressures measured in the abdominal wall and during inadvertent insertion into omentum (5) and colon (2). Correlation between initial intraperitoneal pressure and patients' parity, weight, and body mass index was minimal. Mean CO2 volumes at 10, 15, 20, and 25 mm Hg were 3.7, 5.1, 5.9, and 6.5 L, respectively. No major complications were encountered. An initial intraabdominal pressure of 8 mm Hg or below always indicates correct placement of the Veress needle regardless of the patient's body habitus. Pressures greater than 8 mm Hg indicate interstitial placement including colon. Adequate pneumoperitoneum is determined by CO2 insufflation to a pressure of 25 mm Hg and not by a preconceived volume of CO2.

Abdominal Wall↗
PubMed2006

Effects of continuous tracheal gas insufflation during pressure limited ventilation on pulmonary surfactant in rabbits with acute lung injury.

BACKGROUND: Pulmonary surfactant dysfunction may contribute to the development of ventilator induced lung injury (VILI). Tracheal gas insufflation (TGI) is a technique in which fresh gas is introduced into the trachea and augment ventilation by reducing the dead space of ventilatory system, reducing ventilatory pressures and tidal volume (V(T)) while maintaining constant partial arterial CO2 pressure (PaCO(2)). We hypothesised that TGI limited peak inspiratory pressure (PIP) and V(T) and would minimize conventional mechanical ventilation (CMV) induced pulmonary surfactant dysfunction and thereby attenuate VILI in rabbits with acute lung injury (ALI). METHODS: ALI was induced by intratracheal administration of lipopolysaccharide in anaesthetized, ventilated healthy adult rabbits randomly assigned to continuous TGI at 0.5 L/min (TGI group) or CMV group (n = 8 for each group), and subsequently ventilated with limited PIP and V(T) to maintain PaCO(2) within 35 to 45 mmHg for 4 hours. Physiological dead space to V(T) ratio (V(D)/V(T)), dynamic respiratory compliance (Cdyn) and partial arterial O(2) pressure (PaO(2)) were monitored. After ventilation, lungs were analysed for total phospholipids (TPL), total proteins (TP), pulmonary surfactant small to large aggregates ratio (SA/LA) in bronchoalveolar lavage fluid (BALF) and for determination of alveolar volume density (V(V)), myeloperoxidase and interleukin (IL)-8. RESULTS: TGI resulted in significant (P < 0.05 or P < 0.01) decrease in PIP [(22.4 +/- 1.8) cmH2O vs (29.5 +/- 1.1) cmH2O], V(T) [(6.9 +/- 1.3) ml/kg vs (9.8 +/- 1.11) ml/kg], V(D)/V(T) [(32 +/- 5)% vs (46 +/- 2)%], TP [(109 +/- 22) mg/kg vs (187 +/- 25) mg/kg], SA/LA (2.5 +/- 0.4 vs 5.4 +/- 0.7), myeloperoxidase [(6.2 +/- 0.5) U/g tissue vs (12.3 +/- 0.8) U/g tissue] and IL-8 [(987 +/- 106) ng/g tissue vs (24 +/- 3) mN/m] of BALF, and significant (P < 0.05) increase in Cdyn [(0.47 +/- 0.02) ml.cmH2O(-1).kg(-1) vs (0.31 +/- 0.02) ml.cmH2O(-1).kg(-1)], PaO(2) [(175 +/- 24) mmHg vs (135 +/- 26) mmHg], TPL/TP (52 +/- 8 vs 33 +/- 11) and Vv (0.65 +/- 0.05 vs 0.44 +/- 0.07) as compared with CMV. CONCLUSIONS: In this animal model of ALI, TGI decreased ventilatory requirements (PIP, V(T) and V(D)/V(T)), resulted in more favourable alveolar pulmonary surfactant composition and function and less severity of lung injury than CMV. TGI in combination with pressure limited ventilation may be a lung protective strategy for ALI.

Animals↗
PubMedDate not supplied

Cocaine disposition in humans after intravenous injection, nasal insufflation (snorting), or smoking.

The disposition of radiolabeled cocaine in humans has been studied after three routes of administration: iv injection, nasal insufflation (ni, snorting), and smoke inhalation (si). Metabolism, followed by urinary excretion of metabolites, proved to be the major route of elimination in all cases. Hydrolytic products (benzoylecgonine, ecgonine methyl ester) were the major excretion products. Benzoyl ecgonine was generally most prevalent, but after smoking two subjects excreted larger amounts of ecgonine methyl ester and the ratio of the two compounds averaged lower in subjects who smoked cocaine. Low binding of cocaine to plasma proteins was observed and blood to plasma ratios were essentially unity. The volume of distribution of cocaine is low (2.70 liter/kg for V beta). Absorption of smoked cocaine was rapid (half-time of 1.1 min). Absorption after ni was slower (half-time of 11.7 min). After iv injection, a rapid distribution phase was observed (half-life of 11 min) and the elimination half-life was 78 min. In 16 subjects divided into three groups based on routes, the half-life based on the average rate constant was 69 min. Bioavailability was good after ni (80%). Undecomposed cocaine from si was well absorbed, but observed bioavailability was diminished by degradation from heating.

Administration, Intranasal↗
PubMed1989

[Pneumothorax: indications for thoracoscopic talc insufflation].

Recurrent spontaneous pneumothorax and a persistent air-leakage after three days of suction therapy are two major indications for thoracoscopy. This procedure allows coagulation of blebs and cutting of pleural adhesions as well as identification of patients with large emphysematous bullae which should be treated surgically pleurectomy. Insufflation of talcum is safe and effective in achieving definitive pleurodesis.

Humans↗
PubMed1988

Cardiopulmonary effects of direct venous CO2 insufflation in ewes. A model for CO2 hysteroscopy.

In order to mimic the delivery of CO2 into the pelvic circulation during sustained hysteroscopic surgery, direct insufflation of CO2 was done into the femoral vein of six anesthetized ewes. Following the establishment of baseline values in each animal, cardiac output, pulmonary arterial pressure (Ppa), pulmonary arterial wedge pressure (Ppw), arterial pH and gas levels, and ECG changes were recorded at ten-minute intervals. CO2 was delivered into the femoral circulation for 30 minutes. Following the experiment, measurements were repeated during a 20-minute recovery period. Ppa and Ppw increased significantly during the experiment but returned to baseline values after 70 minutes. Cardiac output, which increased significantly, remained high after the same period and was paralleled by cardiac rate. There was no significant change in systemic blood pressure or arterial oxygenation. Only at the highest flow rate were there observable changes in PCO2, accompanied by mild acidosis. One of the six animals displayed premature ventricular contractions at the inception of the highest flow rate. Since the delivery rate of CO2 per kilogram of body weight clearly exceeded that generally used in human hysteroscopic surgery (35-100 mL/min), these experimental results suggest that CO2, when employed as a distension modality in hysteroscopic surgery, displays a wide margin of safety.

Animals↗
PubMed1994

[Insufflators for endoscopy].

Operative laparoscopy needs a space to be made inside the abdominal cavity. This can only be achieved by suspension or by positive pressure. The endoscopic insufflator makes it possible to create this positive pressure, and does indeed enable the operating space to remain open. But it would be too limiting to consider these devices from the visibility point of view only, for they can also be exploited for their action on hemostasis and dissection. With this in mind we feel that the endoscopic surgeon ought to be perfectly familiar with his apparatus and not simply limit himself to adjusting the pressure and flowrate at the beginning of the operation. This hyper pressure in the abdomen is not without consequences for the patients' homeostasis and can indeed require an operation to be halted or converted to laparotomy. So knowledge of the biomedical aspects of his equipment will also enable the surgeon to increase the safety of his operations.

Endoscopes↗
PubMed1993

Effect of tracheal insufflation of deferoxamine on acute ozone toxicity in rats.

To test the hypothesis that deferoxamine (DFO) may protect the lung against the acute toxicity of ozone (O3), male Sprague-Dawley rats (250 to 300 gm) were tracheally insufflated before exposure to O3 (2 ppm for 4 hours) with DFO (25 mg/kg), ferric-DFO, or sterile water. Measurements of bronchoalveolar lavage fluid (BALF) protein, ascorbate, hydrogen peroxide, and lipid hydroperoxides were made immediately after O3 exposure and 12 and 24 hours later. DFO (25 mg/kg) decreased BALF protein concentration (p < 0.05) and was associated with higher BALF ascorbate concentrations (p < 0.01) in O3-exposed animals. Ferric-DFO did not show these protective effects. No peroxides were found in BALF from any control or O3-exposed animals (detection limit: H2O2, 1 pmol; lipid hydroperoxides, 0.3 pmol). Higher DFO doses (50 mg/kg and 100 mg/kg) did not decrease BALF protein concentration immediately after O3 exposure or 12 hours later. Indeed, the highest dose was toxic to O3-exposed animals. Although DFO is able to protect against O3-induced lung damage in rats, apparently by chelating iron, its effect dose range appears to be narrow.

Animals↗