Among all the witnessed arrests, close to 1 in 2 patients were able to be resuscitated, 1 in 3 survived to 24 hours (data not shown), 1 in 4 survived to discharge, and 1 in 5 were able to return home (). Of all the discharged patients, about 1 in 7 did not return home because of decreased function following the arrest. The discrepancy between initial resuscitation and likelihood of recovering independence emphasizes the need to discuss both when deciding upon resuscitation wishes. The particularly low survival following pulseless EA/ASY arrests and unwitnessed arrests also illustrates the need to consider these eventualities separately. Although 1 in 5 patients with an unwitnessed cardiac arrest were initially resuscitated, none of them survived to discharge. However, the degree of collinearity between whether an arrest was witnessed and the type of arrest indicates that both parameters are effectively measuring a similar construct, namely the degree of “irreversibility” of the arrest, with pulseless EA/ASY being the most refractory to attempted treatment.
Our survival data do not differ greatly from those in American and Canadian studies from the 1960s to 1980s.7,8,9,10,11,12,13,14,15
In the 1990s, however, 3 American studies reported survival to discharge that was 2–3 times greater than our results.2,3,4
This difference may be because those patients typically had witnessed arrests and had single-organ cardiac disease, rather than cardiac arrest in addition to non-cardiac illness.4
Our study may be a more accurate prediction of survival in the general hospital population. If so, survival has not improved in 40 years.
Our results showed no significant association between age and outcome. The combined results of previous studies have not conclusively found a relation between age and outcome.2,3,4,7,8,11,12,13,14,15,16
Consistent with findings from other studies,17,18
our results did not show a statistically significant effect of sex on survival (). Overall, there are insufficient data to recommend refusal of resuscitation on the basis of age or sex. This study confirms that the type of arrest has a far stronger influence on outcome.
Although some researchers have argued that resuscitation is not beneficial for cardiac arrest patients,7,8
our data show that this is not the case for patients who have primary respiratory arrests. The belief that this is due to stopping an arrest in its earlier stage before full cardiorespiratory collapse occurs is supported by our finding that 93% of the respiratory arrests were witnessed, as compared with only 45% of the pulseless EA/ASY arrests. Regardless, for some patients, it may be appropriate to discuss offering ventilatory support alone instead of full CPR.
In our study, patients who had a cardiac arrest, particularly those who had a pulseless EA/ASY arrest, were significantly less likely to survive than were patients who had a primary respiratory arrest (p
< 0.001). The low survival rate after pulseless EA/ASY is consistent with the findings of many studies,7,8,12,15
including the 3 from the 1990s that showed encouraging survival rates after other types of arrests.2,3,4
If we assume that pulseless EA/ASY is typically a terminal arrest, then survival following asystole may never be significantly improved upon.
Several large trials have reported an early morning peak and late night nadir for out-of-hospital arrests.19,20,21,22
The data have been less clear for in-hospital arrests, where circadian influences may be lessened. However, we observed significantly higher odds of not being able to return home for patients whose arrest occurred between 2301 and 0700, and there were more unwitnessed and pulseless EA/ASY arrests during this period. Typically, the greatest proportion of arrests in hospital occur when the least number of staff are available who might otherwise be able to witness an arrest during its early, potentially salvageable period.
Data from the 3 hospitals in our study, which encompass tertiary care, inner-city health care and community health care, should provide survival rates generalizable to most adult inpatients. However, all 3 hospitals have resuscitation teams and resources that exceed those of rural hospitals. Therefore, these results may represent a “best-case scenario,” which re-emphasizes the need to discuss the realities of resuscitation. Other limitations of our study include possible inaccuracies with charting and how competently resuscitation was performed. To examine comorbidity would require predefined standardized criteria, which are not possible with a retrospective study. Chart review is also an imperfect way to establish definitively whether arrests were unwitnessed. Despite these limitations, families must still decide on the utility of resuscitation, and therefore these crude survival data are important. Furthermore, our results are intended as objective data to facilitate informed dialogue rather than to dictate who should, or should not, be resuscitated.
In an ingenious review of television medical dramas, Diem and colleagues23
found that the initial survival rate following CPR was 75%, with 67% survival to discharge. Except for respiratory arrests, these rates are 2–6 times higher than those in any reported study. However, these figures may represent public expectations. The onus is therefore on physicians to discuss the reality and enquire about the expectations of families.
Resuscitation was never originally recommended for all patients,1
and its goal should be to “reverse premature death not prolong inevitable death.”24
The current situation is often to attempt CPR unless it is explicitly refused. Although this may be due to increased patient autonomy or litigation, it is inconsistent with an age of evidence-based treatment and resource concerns. Given the complexity and importance of resuscitation issues, vigorous debate and study are essential.