Measurement of pulmonary artery pressure in anesthetized rabbits and rats

Summary

This experiment is from the official website of the Fourth Military Medical University

Operation method

Measurement of pulmonary artery pressure in anesthetized rabbits and rats

Principle

Changes in pulmonary artery pressure (pulmonary artery pressure PAP) mainly reflect changes in pulmonary circulation and lung function, but also indirectly reflect changes in left heart function. For example, in the case of pulmonary disease, the pulmonary capillary pressure changes, causing changes in pulmonary artery pressure. In addition, the measurement of pulmonary artery capillary pressure, also known as pulmonary artery wedge pressure (PAWP), is also used to observe the left heart function. This method is based on the method of measuring the right ventricular pressure. A special plastic catheter is inserted into the right external jugular vein, into the superior vena cava, into the right atrium, into the right ventricle, and then into the pulmonary artery for pulmonary artery wedge pressure measurement. Because the cannula has to enter the right atrium, the right ventricle, and then the pulmonary artery, this measurement is somewhat difficult.

Materials and Instruments

Rabbit Rat
Ethyl carbamate Sodium pentobarbital Procaine injection Heparin
Animal laboratory bench Plastic catheter Water pressure meter Pressure transducer Multi-channel physiological signal acquisition and recording equipment

Move

1. Laboratory animals and equipmentRabbits, weighing about 2k g; rats, weighing about 200-250 g. 20% urethane injection or 1.5% pentobarbital sodium injection, 1% procaine injection, 0.3% heparin saline injection, a set of commonly used experimental instruments, a laboratory table for rabbits or rats, pressure transducer and its multi-channel physiological signal acquisition and recording equipment. Flexible plastic catheters for rabbits or rats (outer diameter of 2 mm, inner diameter of 1.5 mm for rabbits; outer diameter of 1 mm, inner diameter of 0.8 mm for rats) were specially processed so that the tip of the cannula had a certain degree of curvature.2. Experimental methods and procedures (in rats)One rat was taken, weighed about 200-250 g. It was anesthetized with 20% urethane injection 0.5 ml/100 g or 1.5% pentobarbital sodium injection 0.2 ml/100 g by intraperitoneal injection, and after the animal was anesthetized, it was fixed on the experimental table and the neck was clipped. The skin in the middle of the neck was cut with surgical scissors, and the right subcutaneous tissue was separated, i.e., the external jugular vein could be seen. The venous vessels of about 1 cm in length were gently separated with ophthalmic forceps, and two surgical threads were threaded at the distal and proximal ends respectively for backup. Before cannulation, the plastic catheter and pressure transducer were filled with 0.3% heparin saline injection, air bubbles were drained away, and the pressure range displayed on the recorder was adjusted to the range of 0-50 mmH g. The pressure range of the recorder was adjusted to the range of 0-50 mmH g, and the pressure range of the recorder was adjusted to the range of 0-50 mmH g. Then the distal end of the external jugular vein was ligated first, and the proximal surgical wire was gently lifted, and a cut was made with ophthalmic scissors at an angle of 45° in the wall of the vein at the distal end of the ligature, and the special plastic catheter was inserted into the external jugular vein, and the blood vessel and catheter were ligated with the proximal surgical wire but not too tightly, so that the catheter could be continued to be inserted, and the waveforms of the venous pressure were observed on the recorder. Continuing to feed the catheter slowly, the right atrium can be reached, and the waveform of the pressure within the right atrium is seen, with an amplitude of about 0 to 5 mmH g or so. Continuing to cannulate into the right ventricle, a waveform of intra-right ventricular pressure is seen, with an amplitude ranging from about 0 to 25 mmH g, as seen in Figure 1 (top). Continued intubation leads to the pulmonary artery, and a pulmonary artery pressure waveform appears, with a systolic pressure height that is the same as the height of the right intraventricular pressure, and a diastolic pressure height that ranges from about 10 to 15 mmH g, as seen in Figure 1 (lower panel).


Figure 1

Caveat

The proper curvature of the tip portion of the catheter remains a very important aspect of the method of pulmonary artery pressure measurement by cannulating from the right external jugular vein to reach the right atrium, enter the right ventricle, and then enter the pulmonary artery. With a small bend, the catheter tends to slip into the inferior vena cava within the right atrium, whereas with too large a bend, the catheter may circle within the right atrium or within the right ventricle without entering the pulmonary artery.

Common Problems

Changes in pulmonary artery pressure, mainly reflecting changes in pulmonary circulation and lung function, is an important indicator for evaluating lung function. Secondly, because the pulmonary circulation is closely related to the left atrium, clinically it is often used to monitor the change of the left atrial pressure by measuring the change of the pulmonary artery wedge pressure, indirectly reflecting the situation of the left heart function, and therefore it is also an important indicator for evaluating the left heart function.

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