Tetradecafluorohexane

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2005-2006

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Comparative Effects of Vaporized Perfluorohexane and Partial Liquid Ventilation in Oleic Acid– induced Lung Injury

Author:

Marcelo Gama de Abreu
Andre´ Domingues Quelhas
Peter Spieth
Thea Koch

Year:

2006

Bibliographic source:

Anesthesiology 2006; 104:278–89

Materials and methods

Principles of method if other than guideline:

Methods: Lung injury was induced in 30 anesthetized and
mechanically ventilated pigs by means of central venous infusion
of oleic acid. Animals were assigned to one of the following
groups: (1) control or gas ventilation (GV), (2) 2.5% perfluorohexane
vapor, (3) 5% perfluorohexane vapor, (4) 10% perfluorohexane
vapor, or (5) PLV with perfluorooctane (30 ml/kg).
Two hours after randomization, lungs were recruited and positive
end-expiratory pressure was adjusted to obtain minimal
elastance. Ventilation was continued during 4 additional hours,
when animals were killed for lung histologic examination

GLP compliance:

not specified

Test type:

other: Trial to assess benefits in using tetradecafluorohexane in injured lungs

Test material

Test material information

Constituent 1

Reference substance name:

Tetradecafluorohexane

EC Number:

206-585-0

EC Name:

Tetradecafluorohexane

Cas Number:

355-42-0

Molecular formula:

C6F14

IUPAC Name:

tetradecafluorohexane

Test material form:

liquid

Test animals

Species:

pig

Strain:

not specified

Sex:

female

Details on test animals or test system and environmental conditions:

All animal procedures were approved by the Institutional
Animal Care Committee and the Government of
the State of Saxony, Germany, and conformed to the
Guide for the Care and Use of Laboratory Animals.
15
Anesthesia
Thirty female pigs weighing 31.1 3.5 kg (range,
25–37 kg) were premedicated with ketamine (2–3
mg/kg intramuscular) and brought to the experimental
operation room, where an ear vein was punctured. After
that, the trachea was intubated with a cuffed endotracheal
tube (7.5 ID), and an esophageal catheter (Erich
Jaeger GmbH, Ho¨chberg, Germany) was placed and advanced
into the mid chest until optimization of the
position was performed (see Instrumentation and Measurement
Devices section). Thereafter, anesthesia was
deepened and maintained with midazolam (0.5- to
1-mg/kg bolus plus 1–3 mg kg1 h1 intravenous) and
ketamine (3- to 4-mg/kg bolus plus 5–10 mg kg1 h1
intravenous). Paralysis was achieved with 2 mg pancuronium
bromide administered intravenously every hour.
Volume status was maintained by means of the administration
of a crystalloid solution (E153; Serumwerk Bernburg
AG, Bernburg, Germany) at a rate of 10–15 mg
kg1 h1
, with a colloid solution (10% hydroxyethyl
starch; Fresenius Kabi Deutschland GmbH, Bad Homburg,
Germany) being given as necessary to keep the
hemoglobin concentration in blood approximately constant
(normovolemia).

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

head only

Vehicle:

air

Details on inhalation exposure:

Volume-controlled ventilation was initiated using an
anesthesia machine with a semiclosed circle system
(Cato®; Dra¨gerwerk AG, Lu¨beck, Germany). Ventilator
settings were as follows: fraction of inspired oxygen
(FIO2) of 1.0 (fresh gas flow of 4 l/min), PEEP of 5 cm
H2O, and inspiratory:expiratory ratio of 1:1.7, which
corresponds approximately to the physiologic value. We
also used tidal volumes (VT) of 9 ml/kg, which corresponds to an intermediary value between protective (6
ml/kg) and conventional ventilation (12 ml/kg). The reason
for choosing this value was that in our experience,
carbon dioxide elimination is easier to achieve while
keeping inspiratory plateau pressures lower than 35 cm
H2O. Respiratory rates were adjusted to an arterial carbon
dioxide tension (PaCO2) of 35–45 mmHg. Except for
PEEP, which was readjusted later (see Protocol for Measurements
section), all settings of the mechanical ventilator
were kept constant throughout the experiments.

Analytical verification of test atmosphere concentrations:

not specified

Duration of exposure:

6 h

Concentrations:

2.5%
5%
10%

No. of animals per sex per dose:

6

Control animals:

yes

Remarks:

Vehicle

Details on study design:

Protocol for Measurements
Figure 1 shows the time course of events. After instrumentation,
a period of 30 min was allowed for animals to
stabilize. Baseline measurements were then obtained
and injury was performed in 30 animals, as previously
described. After injury (time 0), animals were assigned to
one of the five therapy groups after opening sealed
envelopes (n 6/group): (1) control—no therapy with
perfluorocarbon or gas ventilation (GV), (2) therapy
with 2.5% perfluorohexane, (3) therapy with 5% perfluorohexane,
(4) therapy with 10% perfluorohexane, and
(5) PLV with perfluorooctane (30 ml/kg) (see Partial
Liquid Ventilation section). Two hours thereafter, measurements were repeated (time 2), and the lungs were
recruited by means of a continuous pressure of 40 cm
H2O during 30 s. To avoid derecruitment and stabilize
the lungs thereafter, PEEP was set at 20 cm H2O while
other respiratory parameters remained unchanged. After
that, PEEP was reduced in steps of 5 cm H2O up to the
start value, with periods of 3 min being allowed at each
level (20, 15, 10, and 5 cm H2O). Measurements of total
respiratory elastance (ERS EL ECW) and PaO2 were
taken at each step. After this procedure, recruitment was
repeated in the same manner, and PEEP was set at the
level corresponding to the lowest ERS level. If ERS values
were comparable between two steps (difference 5 cm
H2O/l), the higher PaO2 level was used to set PEEP.
Measurements were repeated 4 and 6 h after injury
(times 4 and 6, respectively). Except for PEEP, mechanical
ventilator settings were the same as before lung
injury. Finally, animals were killed by means of the intravenous
injection of 2 g thiopental and 50 ml KCl, 1 M.
Administration of Vaporized Perfluorohexane
Perfluorohexane (C6F14; ABCR, Karlsruhe, Germany)
with a purity of 95% was used in this work. This compound
was chosen because of its relatively low molecular
weight (338 amu) and unique physicochemical properties
among the perfluorocarbons, particularly the
relatively high vapor pressure (273 mmHg at 30°C),
which permits its administration in vapor form.22 Accordingly,
administration of perfluorohexane vapor was
accomplished by means of two standard bypass vaporizers,
type 19 n (Dra¨gerwerk AG, Lu¨beck, Germany),
which were modified by a scaled opening of the dosage
control cone. Vaporizers were connected in series in the
inspiratory limb of the anesthesia machine and opened
to permit mixing of perfluorohexane with the fresh gas
flow. Inspiratory and expiratory concentrations of per-
fluorohexane were measured continuously by the mass
spectrometer, ensuring a controlled application

Statistics:

Statistical Analysis
Values are given as mean SD. Paired Student t tests
were used to assess the effects of lung injury. Comparability
among groups at baseline and time 0, total amounts
of OA per group, PEEP levels after lung recruitment, and
histologic findings were tested with one-way analysis of
variance. Repeated-measures two-way analysis of variance
was used to determine the effects of therapies on
time course of variables (time, group, and time * group
effects). When significance was achieved, it was followed
by post hoc analysis (Student-Newman-Keuls test).
Statistical analysis was performed using SPSS, version
11.5 (SPSS, Chicago, IL), and significance was accepted
at P 0.05.

Results and discussion

Effect levels

Key result

Sex:

female

Dose descriptor:

LC50

Effect level:

>= 100 000 ppm

Based on:

test mat. (total fraction)

Exp. duration:

6 h

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

No lethal event occured

Clinical signs:

other: No alteration

Body weight:

Not adressed

Gross pathology:

No alteration

Other findings:

Improved function of previously injured lung.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

No toxicity reported after 6h exposure to tetradecafluorohexane by inhalation.

Executive summary:

This study aimed to assess wether administration of perfluorocarbons as liquid during acute lung injury is beneficial.

Although this study was not designed to assess toxicity, as no toxic effect was reported in any treatment group, whereas animals where closely monitored, the conclusion can reasonably be derived from this study that 6h acute exposure to 10% tetradecafluorohexane by inhalation has no toxic potential in pigs.