动物造模,药效评价,颅内高压 z-bio 2024-08-21 607

　　1. Epidural balloon injection method

　　(1) Copy method: New Zealand rabbits, male or female, weighing 2.0-2.5kg. After intravenous injection of pentobarbital sodium (at a dose of 25-30mg/kg body weight) or 20% Uratan (at a dose of 5ml/kg body weight) through the ear vein, the animal was anesthetized and placed in a supine position. Left femoral artery catheterization was performed to measure the animal's blood pressure, heart rate, and record the animal's breathing. Then place the animal in a prone position, cut off the hair on the top of the head, and disinfect the skin in the surgical area. Make a longitudinal incision in the center of the skin to cut open the scalp, drill a hole in the top left corner, remove a circular bone flap with a diameter of about 1cm, place a water injection balloon and intracranial pressure fiber optic probe, connect a scalp needle plastic tube to the water injection balloon, and form a closed system with a 1ml water filled syringe; Drill a circular bone hole with a diameter of about 0.6cm at the top right, with the anterior edge reaching the coronal suture and the inner edge 0.3cm away from the midline (sagittal suture), to maintain the integrity of the dura mater. This hole is used to place a transcranial Doppler (TCD) probe to detect the middle cerebral artery (MCA), and is properly fixed after obtaining the best image.

　　Record intracranial pressure (ICP), TCD spectrum, heart rate, respiration, and mean arterial pressure once before the experiment. Subsequently, 0.05ml of water was uniformly injected into the balloon at different time points (once every 5 minutes). After the ICP stabilized, TCD spectra and various physiological indicators were recorded. The balloon was then refilled with water again, with a total volume of 0.45ml (halved to 0.025ml each time), until the rabbit ultimately died. Maintain animal body temperature at 37-38 ℃ during the experiment. Blood gas analysis can also be performed by collecting blood samples at different time points when intracranial pressure increases.

　　(2) The normal TCD spectrum of MCA in a complete cardiac cycle of New Zealand rabbits is similar in shape to the TCD spectrum of humans, resembling a right angled triangle. It is divided into two parts according to its shape: the first part is vertical and sharp, called the systolic wave; The second part is a low blunt triangular wave, called the relaxation period wave. There is a notch on the descending branch of the systolic wave, which gives the descending branch a stepped appearance. This notch divides the systolic wave into two parts, and the peak before the notch is called S1, hence the peak is called S1 peak. The trailing edge of the cut is approximately a platform, and its highest point is called S2. As water is injected into the balloon, intracranial pressure gradually increases, and its systolic peak becomes pointed and raised. S2 also gradually increases. As ICP continues to rise, the "S2 peak" gradually rises to a height similar to S1 peak, causing the entire systolic wave to evolve into a double peaked shape. Afterwards, ICP continued to rise to its peak, and the diastolic wave gradually decreased until it disappeared, resulting in a Cushing reaction of slowed heart rate and breathing, increased blood pressure, and ultimately death. The TCD spectrum also gradually decreased from a weak systolic peak to disappearance.

　　Monitor and analyze corresponding pathological indicators according to the needs of the experimental designer.

　　(3) The use of cranial Doppler detectors in comparative medicine can sensitively reflect changes in cerebral hemodynamics, especially when the TCD spectrum shows "double peaked waves", which may reflect the imminent failure of intracranial compliance. The analysis of TCD spectrum can reflect the severity of intracranial hypertension relatively early, bringing hope for clinical judgment, treatment of critical conditions, and saving patients' lives.

　　2. Epidural compression method

　　(1) Copy method: New Zealand rabbits, male or female, weighing 2.0-2.5kg. Anesthetize with pentobarbital sodium (at a dose of 25-30mg/kg body weight) or 20% Uratan (at a dose of 5ml/kg body weight) injected through the ear vein, and maintain airway patency with endotracheal intubation. Fix the rabbit head in a dorsal position using the Jiangwan-I stereotaxic device, remove hair from the top of the head, and disinfect the skin in the surgical area. Cut the scalp longitudinally along the midline to the posterior occipital region, and insert the puncture device (modified with a 9-gauge needle) of the continuous pressure gauge into the cerebellar medullary cistern through the meninges of the anterior occipital bone to measure normal intracranial pressure. Referring to the Sawyer diagram, locate the coordinate at APO · L4. Drill a small hole at the top of the skull, preferably just penetrating the skull. Under the control of a stereotaxic device, insert a puncture needle vertically downward into the ventricle (about H5 level). The end of the puncture needle is connected to a constant pressure infusion bottle containing artificial cerebrospinal fluid through a plastic tube, and the height of the constant pressure infusion bottle is gradually raised to apply pressure through the lateral ventricle. On the pressure gauge connected to the pressure measuring needle inserted from the cerebellomedullary cistern, it can be seen that the intracranial pressure increases accordingly. For every 20mmHg (2.67kPa) increase, if the height of the perfusion bottle is fixed, the intracranial pressure can remain relatively stable at the corresponding high level for more than 6 hours. When intracranial pressure increased by 80mmHg (10.64kPa), the vast majority of experimental animals died due to respiratory and circulatory arrest. Therefore, by adjusting the suspension height of the infusion bottle, different levels of intracranial pressure values required for different experimental values can be obtained.

　　(2) The normal intracranial pressure value of a rabbit model is around 0.09kPa. Considering that intracranial pressure may suddenly or gradually increase and the degree of increase may vary in clinical practice, stable intracranial pressure values with different gradients can be obtained by adjusting the height of the constant pressure perfusion bottle during the model making process. The compression needle inserted into the lateral ventricle can be quickly and firmly fixed to the skull with self consolidating dental support powder. The pressure measuring needle is only used for pressure measurement, and can be placed steadily after being inserted into the meninges without the need for additional fixation. During the experiment, maintain the animal's body temperature at 37-38 ℃.

　　(3) The comparative medical method of lateral ventricular compression and cerebellar medullary cistern pressure measurement involves the rapid diffusion of artificial cerebrospinal fluid dripped from the lateral ventricle through the third ventricle, midbrain aqueduct, fourth ventricle, and cerebellar medullary cistern to the entire subarachnoid space, resulting in diffuse intracranial hypertension. In clinical practice, subarachnoid hemorrhage and cerebral edema belong to this type of intracranial hypertension. Therefore, this model is similar to clinical intracranial hypertension and has the characteristics of simple operation, reliable effect, convenient observation, and stable intracranial hypertension, which can meet the needs of various acute animal experimental observations.