Hemorrhagic shock is responsible for 2 million deaths worldwide every year. We are studying the pathophysiological mechanism of hemorrhagic shock with the aim of identifying new target and thus proposing innovative therapeutic strategies. Hemorrhagic shock is a difficult condition in its own right, hemodynamic alteration with metabolic damage and organ dysfunction.
The variety of experiments protocol make its study even more complex. In this study, we proposed to develop a reproductive, standardized, and clinically relevant rat model of hemorrhagic shock. We hope that this model of hemorrhagic shock can become one of the standard model for future study.
The use of a standard model would facilitate advance in the field, and at least because it would make it possible to compare results between differences in working on hemorrhagic shock. To begin, insert a lubricated rectal probe to control the temperature of the anesthetized rat during surgery. After locating the jugular region in the lower right neck region of the anesthetized rat above the clavicle, use DeBakey atraumatic forceps to gently grasp the skin and make a precise incision with fine sharp scissors or a scalpel.
Gently slash the tissue with standard pattern forceps. Locate and gently liberate the jugular vein from its muscular compartment. Place a 4-0 silk suture thread to securely ligate the distal side of the jugular vein.
Use the suture with the needle holders to tension the jugular vein. Place a 4-0 suture on the proximal side of the jugular vein and prepare a surgeon knot without tightening it. Using Vannas micro dissecting scissors, make a small incision in the jugular vein.
After carefully grasping the vein wall with small forceps, insert the PE50 catheter in the jugular vein. Slightly advance the catheter and to confirm its correct placement in the vein, draw a small amount of blood and re-inject it. Tighten the previously prepared knot to secure the catheter.
Apply a drop of lidocaine to the incised area. Cover the incision with a moist sterile gauze pad. Use DeBakey atraumatic forceps to grasp the skin of the Scarpa triangle on the left leg, and make an incision with fine sharp scissors or a scalpel.
Gently dilacerate tissue with standard pattern forceps. Locate the femoral triad and place one forceps under the triad. Then with a second standard pattern forceps, carefully separate the artery from the nerve and femoral vein.
Place a 4-0 suture the femoral artery distally and take the suture with the needle holders to put the femoral artery in tension. Now, place a 4-0 suture on the proximal side of the femoral artery and prepare a surgeon knot without closing it. After clamping the artery, use Vannas micro dissecting scissors to make a transverse incision in the femoral artery.
Grasp the artery wall with standard pattern forceps and cannulate the femoral artery with the catheter, holding it with forceps. Gently unclamp the artery and ensure that the blood is not flowing back into the catheter. If the signal is good, advance the catheter slightly into the artery and tighten the previously prepared surgeon knot.
Administer heparin into the rat and place a moistened sterile gauze pad over the incised area. After 10 minutes of stabilization, record the basal hemodynamic values for five minutes. To induce hemorrhagic shock, use a 1 mL syringe to draw 5 mL of blood from the femoral artery over five minutes.
Prepare a mix of 50%lactated Ringer's solution and 50%collected blood at room temperature. Place a 2 mL syringe filled with the mix at the end of the jugular vein cannula. For hemorrhagic shock maintenance, when mean arterial pressure exceeds 38 mmHg, withdraw 200 L of blood from the femoral artery.
If pressure drops below 32 mmHg, inject 200 microliters of the 50%blood, 50%lactated Ringer's mixture through the jugular vein. After sterile preparation of the tail with a gauze pad, use the tip of the needle to draw a blood drop from the end of the tail to measure peripheral blood lactate. Finally, resuscitate the rat with a lactated Ringer's solution using a 20 mL syringe through the jugular catheter with a syringe pump.
After hemorrhagic shock treatment, clamp the jugular vein of the anesthetized rat. Remove the catheter from the veins. Upon ligation, ensure that there is no blood leakage from the vessels.
Now, use a 5-0 sterile suture to close incised areas with subcutaneous and cutaneous stitches. Disinfect the surgical area with 10%povidone iodine solution. Using a 1 mL syringe fitted with a 26-gauge needle, subcutaneously inject buprenorphine.
Upon awakening, place the rat on the heating mat in its cage. After 16 hours of hemorrhagic shock induction, draw a blood drop from the end of the tail to measure blood lactate. Place the anesthetized rat on the surgical table and insert the rectal probe.
For carotid artery cannulation, use DeBakey atraumatic forceps to grasp the skin and make an incision in the middle of the neck with fine and sharp scissors, or a scalpel. With standard pattern forceps, gently dilacerate tissue. Separate the salivary glands and open the tracheal muscle to reveal the tracheal rings.
Isolate the left carotid artery from the nerve with standard pattern forceps and ligate it distally with a 4-0 silk thread. Now, place the suture thread on the proximal side of the artery and prepare a surgeon's knot without closing it. After clamping, use Vannas micro dissecting scissors to incise the carotid artery.
With standard operating forceps, gently grasp the artery wall to enlarge the opening and cannulate the artery with the catheter provided, holding it using forceps. Gently unclamp the artery and ensure that the blood is not flowing back into the catheter. After confirming the correct blood pressure signal, advance the catheter slightly into the artery and tighten the previously prepared surgeon knot.
Basal mean arterial pressure was similar between sham and hemorrhagic shock groups. 24 hours post-hemorrhagic shock induction, the mean arterial pressure significantly decreased in the hemorrhagic shock group due to a reduction in diastolic blood pressure. No changes were observed in systolic blood pressure, pulse pressure, and heart rate across groups.
While the shock index remained unchanged, the modified shock index exhibited a notable increase in the hemorrhagic shock group. Lactatemia, indicative of global metabolic impairment, showed a significant increase following hemorrhagic shock, further elevating after 16 hours of hemorrhagic shock. Temperature, and respiration rate, markers of systemic inflammatory response syndrome, remained unchanged between groups 16 hours after hemorrhagic shock induction.
Behavioral assessments demonstrated an increased behavioral score in the hemorrhagic shock group, suggesting altered postures and activities.
