Experimental Pulmonary Edema in Rabbits

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GoalsGoals1. Replicate the animal model of

experimental pulmonary edema.

2. Understand the manifestations

and mechanisms of pulmonary

edema.2

① Capillary hydrostatic pressure (17 mmHg)

② Interstitial hydrostatic pressure (-6.5 mmHg)

③ Plasma colloidal osmotic pressure (28 mmHg)

④ Interstitial colloidal osmotic pressure (5 mmHg)

The normal interchange of body fluid between plasma and interstitial fluid

(17 - (-6.5)) - (28 - 5) = 0.5 mmHg

①

②

③④

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Accumulation of excessive fluid in the interstitium or alveoli of the lungs.

Pulmonary Edema

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Gross view

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Pulmonary EdemaMicroscopic view

Normal

Edema

Rapid infusion of large amount of fluidEffect of epinephrine

Mechanisms of Pulmonary Edema in This Experiment

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Animals: Rabbits Drugs:

Normal salineProcaine (1%)Epinephrine (1 mg/ml)

Supplies:

Trachea cannula, venous catheter, intravenous infusion device, surgical instruments, balances, stethoscope, fixing table, syringes, suture, gauze, filter paper, beaker

Lab Supplies

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Normal saline + Epinephrine

4 animals

Normal saline

2 animals

Groups

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1. Weigh the rabbit; Fix the rabbit on the fixing table;- fix the limbs;- fix the front tooth to the table;

Procedure

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2. Cut the hair in the center of the neck;3. Inject procaine (1%) (locally under the skin, 2-

3 ml/animal) for anesthesia;4. Cut a 5-7cm excision on the center of the neck

(from the edge of thyroid cartilage to sternum) .

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5. Dissect the trachea and the jugular vein; 6. Apply one suture under the trachea and two

sutures under the vein;7. Cut an inverted “T”-shape excision 3-4 cartilage

rings below the thyroid cartilage;

118. Insert the trachea cannula and ligate.

9. Connect the venous catheter to the infusion device, put in NS (500 ml) and remove the air in the tubing;

10. Ligate the vein at the distal end;

11. Cut a 45 º “V”-shape opening;• Insert the venous catheter and ligate at the

proximal end;

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12. Slowly start infusion of normal saline, 5-10 drops/min;

• Observe the respiratory frequency and listen to the breathing sound of the lungs using stethoscope;

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生

理水盐

13. Quickly infuse normal saline, 150-180 drops/min;

14. After infusion for 2/3 of the total volume, add Epinephrine (0.5 mg/kg) (NS + EP group);

(no Epinephrine added to the NS only group).

Continue infusion at a lower speed (5-10 drops/min).

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EP

15. Watch if there is any change in respiration, listen to the appearance of moist rales of the lungs; and watch if there is any pink frothy fluid coming out;

16. When the frothy fluid appears, clamp the trachea immediately using the forceps - to avoid the leakage of the edema fluid;- to let the animal die;

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17. Open the chest and ligate at the branching of the bronchus;

• Cut the trachea between the forceps and the suture and take out the whole lungs;

• Do not damage the pleura;

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18. Wipe off the moist on the surface of the lungs using filter paper and weigh the lungs, and calculate the lung ratio:

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Lung ratio = Lung weight （ g ）

Body weight （ kg ）

（ Normal value ： 4 ～5 ）

19. Watch the gross changes of the lungs (volume, surface, edge, color, texture, etc) ;

• Cut open the lungs and note the existence of frothy fluid.

Dissect using the glass hook or forceps (not the scissors);

Firmly fix the trachea cannula and the venous catheter (notice the orientation of the insertion);

Remove the air in the infusion device; Do not infuse too fast or too slow (150-180 drops/min)

for edema induction; Remove the lungs completely together with the trachea; Care should be taken in order not to damage and press

the lungs to avoid the leakage of the edema fluid.

Points for Attention

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Observational Index

Animal No.1 2 3 4 5 6

Amplitude and frequency of breathing Cyanosis

Moist rales Frothy fluid

Gross changes

Color Volume Texture

Lung ratio

Results

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Lab Report Requirements

1. The name of the experiment, the experimenters, the date.

2. The experimental purpose.3. The experimental animal and its sex, weight and

health conditions.4. Medicine and main equipment.5. Main experimental methods and steps.

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6. The result: the presentation generally can be in the following two formats:

(1)Descriptive type: Description in words.

(2) Chart type: A table or diagram giving more clear reflection of observation and comparison.

In order to make experimental results more clear and comprehensive, the above two ways can be combined.

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7. Discussion: By applying the theory of known knowledge, explain the experimental phenomena observed in the experiment, as well as the existing problems and deficiency, and anomalies in the experiment.

• Discussion should be based on the experimental results.

8. Conclusion: according to the experimental purpose and the results, summarize in general terms.

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