Unbeknownst to the new arrivals, Leonard had planted explosives under the panels of the D.H.D., which detonated when Kagan attempted to dial. Kagan's injuries were severe, with penetrating abdominal trauma. Dr. Carson Beckett, who only had his medical kit, insisted he needed complicated surgery and blood transfusions.
Upon locating the cave where unusual electromagnetic distortions were emanating, Dr. Beckett began operating. Rodney McKay eventually discovered the source of the interference -- a Wraith mind manipulator, which affected the entire team.
Beckett visualized Barroso as living, long after he had died, and perceived Kagan as dying, but returning to life repeatedly with his aid. McKay, who came to see for himself, found Kagan dead once. The fictional Barroso continued to haunt Beckett, forcing him to operate on Kagan until his heart began beating once again.
Colonel Sheppard managed to deactivate the mind manipulator. Beckett, his mind clear, discovered that, even through his hallucinations, he had managed to keep Kagan alive.
Phantoms - Kagan is continually revived by Dr. Carson Beckett, who is susceptible to the false perceptions of a Wraith mind manipulator.