The Lazarus phenomenon
Lazarus syndrome (autoresuscitation after failed cardiopulmonary resuscitation) is the ROSC after failed resuscitation. Its has been noted in medical literature at least 38 times since 1982. The name comes from Lazarus who was raised from the dead by Jesus, as described in the New Testament of The Bible.
Even though Lazarus phenomenon is rare, it may have been under reported. There is no doubt that Lazarus phenomenon is real, but so far the scientific explanations have been inadequate. As far the plausible explanation we have, at least in some cases is auto-PEEP and impaired venous return. In patients with asystole or PEA, dynamic hyperinflation can be considered as a cause and a short period of apnoea (30-60 seconds) should be tried before stopping resuscitation. Since ROSC occurred within 10 minutes in most of the cases, patients should be passively monitored for at least 10 minutes after the cessation of CPR before confirming death.
The Lazarus phenomenon is described as delayed return of spontaneous circulation (ROSC) after cessation of cardiopulmonary resuscitation (CPR). This was first reported in the medical literature in 1982, and the term Lazarus phenomenon was first used by Bray in 1993. The term was coined from the story of Lazarus, who was resurrected by Christ four days after his death.
The mechanism of delayed ROSC is unclear and it is possible that more than one mechanism is involved.
Positive end expiratory pressure
Rapid manual ventilation without adequate time for exhalation during CPR can lead to dynamic hyperinflation. Dynamic hyperinflation leads to gas trapping and increases the end-expiratory pressure (auto-PEEP) delaying venous return, leading to low cardiac output and even cardiac arrest in patients with obstructive airways disease.
The physiology of severe auto-PEEP is similar to pericardial tamponade, where circulation can only be restored after removing the obstacle to cardiac filling. Auto-PEEP is a possible cause of pulseless electrical activity (PEA), and rapid ventilation during CPR should be avoided.
Rapid ventilation during CPR should be avoided!
Hypovolaemia and decreased myocardial contractility could exaggerate its effect on venous return and cardiac output. Some recommend stopping ventilation transiently (10 to 30 seconds) in PEA to allow venous return.
Even that auto-PEEP due to dynamic hyperinflation seems most plausible and has evidence in patients with obstructive airways disease, this alone can not explain all cases of delayed ROSC.
Delayed action of drugs
It is possible, drugs injected through a peripheral vein to be inadequately delivered centrally due to impaired venous return, and when venous return improves after stopping the dynamic hyperinflation, delivery of drugs can contribute to return of circulation.
There are some reports of delayed ROSC in the presence of hyperkalaemia. It is a fact that intracellular hyperkalaemia could persist longer, contributing for the myocardium to be retractile for long periods of time.
Prolonged myocardial dysfunction can follow myocardial ischaemia, taking up to several hours before normal function returns.