Why do we say that Jesus shed blood to the last drop on the Cross?

We read in Jn 19:33-34( KJV): > But when they came to Jesus, and saw that he was dead already, they brake not his legs: But one of the soldiers with a spear pierced his side, and forthwith came there out blood and water. Possible physiological reasons for the flow of blood and water include the phenomenon where the physical toll of the crucifixion and scourging caused a buildup of fluid around Jesus' heart and lungs. Going back to OT, we see in Lev 5:9: > And he shall sprinkle of the blood of the sin offering upon the side of the altar; and the rest of the blood shall be wrung out at the bottom of the altar: it is a sin offering. Traditionally, the water from Jesus' pierced heart is taken as an indication that he had no blood left in the body . (A number of prayers contain the statement that Jesus shed blood to the last drop in order to atone for the sins of mankind ). In fact, John the Evangelist's narration appears to have been made with the purpose of substantiating that Jesus in deed was dead on the cross. Traditional teachings perhaps put together both the Leviticus instructions on draining of the sacrificial animal/ bird of all its blood, as well as Jn 19:34 to conclude that Jesus had shed blood to the last drop on the cross. My question is: How do Bible scholars interpret Jn 19:34 ? Inputs from experts of any denomination are welcome.