During transfer to the PICU, one of the lines that Odim had constructed fell apart and had to be repaired. Marietess's condition never significantly improved, once she was transferred to the PICU at 2020 hours. She was cyanotic, air entry to her lungs was poor and she had a severe respiratory and metabolic acidosis. Her head and neck remained swollen. While the pressure in her left external jugular decreased for a period of time, it remained high. As a result, the flow of blood to her lungs and heart remained poor. This lack of blood flow played a major role in the heart failure that led to Marietess's death.

Dr. Ellsabete Doyle, who admitted Marietess to the PICU, indicated in her notes that Marietess was at risk of impaired blood flow to her brain and her lungs and also at risk for heart rhythm problems. In his testimony, however, Giddins said that Marietess's condition was normal for a child following this procedure.

Odim wanted to have Marietess treated with vasodilators and nitroglycerin as soon as possible in the PICU, in an attempt to dilate her vein and lower her pressures. Swartz had ordered nitroglycerin while the team was in the OR; however, treatment with this drug was not started until 2047 hours, almost half an hour after her arrival in the ICU. No satisfactory explanation has been offered for this delay.

The pressures in the left external jugular vein dropped to the mid-twenties once Marietess was in the PICU. Giddins concluded that: "It appeared that the measures that we had planned on starting in the operating room during transfer were working." (Evidence, page 4,004) Odim felt that during the first few hours in the PICU, Marietess's condition was "moving slowly in what appeared to be the right direction." (Evidence, page 25,548)

However, Marietess's perfusion remained poor, and while the pressure in the left external jugular did drop, it never approached an acceptable reading. After approximately three hours in the PICU, those readings began to increase once more. Between 2100 and 2130 hours, the pressure in her left jugular vein ranged between 29 and 33 millimetres of mercury.

A chest X-ray taken in the PICU showed how seriously Marietess's heart was failing: both her lungs were collapsing and the X-ray report described them as airless. The team undertook a variety of steps to try to improve her condition, including using hand ventilation. However, her oxygen saturation continued to fall, while the amount of carbon dioxide in her blood increased. Marietess was treated with vasodilators, at their maximum doses.

Odim and Giddins felt that, given Marietess's fragile condition, they could not perform a line-a-gram. As time passed, the pressures on the right side of her body began to rise.

Marietess also experienced an abnormally fast heart rhythm, called junctional ectopic tachycardia (or JET), which reduced her cardiac output. Attempts were made to slow the heart rate by cooling Marietess and treating her with digoxin. At 0110 hours, Marietess had her first cardiac arrest. The team in the PICU began cardiac compressions, which were continued intermittently until 0313 hours, when Marietess died.