Discussions
In this study, we investigated the effect of preoperative
hospitalization periods on early POCD development and the associated
risk factors in adult patients undergoing total hip placement surgery
under regional anesthesia. We observed a higher POCD incidence rate in
patients with prolonged preoperative hospitalization period, advanced
age, high ASA score, present comorbidities, extended operation periods
and low post-op hematocrit levels.
Mean MMT scores of the patients were significantly lower when compared
MMT scores at 24 hours after the operation and initial admission MMT
scores, which demonstrated us cognitive dysfunction. In our study, at
24-hour POCD after surgery incidence rate was 43.8%. Our results were
similar with the previous studies.
In previous studies reported orthopedic surgeries on elderly patients
had a high risk of developing POCD and incidence was reported as 15-60%
among especially elderly patients after hip fracture surgery (5, 8).
Advanced age is reported the most important risk factor for developing
POCD (9). Elderly patients were reported to have a higher risk of
developing POCD compared to younger patients (10, 11). In the study of
Salazar including 150 patients reported that POCD incidence rate in
patients over 65 was 12% at 4th day after knee
replacement surgery (12). In ISPOCD1 study including 1218 patients over
60 who underwent non-cardiac surgery reported POCD incidence rate was
25.8% (13).
We revealed statistical significance between age and POCD development.
Mean age of the patients who did not develop POCD in 24 hours was
50.6±21.9 years, while patients who developed POCD, the mean age was
79.0±10.0 years.
The previous studies in the literature also report the ASA risk
classification may play an important role on cognitive functions. A
study which included 118 patients over 75 who underwent major abdominal
surgery reported postoperative delirium in 28 (24%) of the patients and
ASA 3 score is one of the risk factors for the development of POCD (14).
In our study, Although 46.4% of patients who developed POCD had ASA 1-2
score, 53.6% of had ASA 3 score. Our results are similar with the
previous studies which reported a significant association between POCD
development and high ASA scores.
Presence of comorbidity, which is one of the most important factors in
the assessment of ASA scores, is also reported to be a risk factor in
POCD development in various studies (15). In addition, several studies
reported association between not only with diabetes and hypertension,
but also with coronary artery disease (CAD), congestive heart failure
(CHF), respiratory diseases and POCD development (16). In this study, we
also found a significant association between presence of comorbidities
and POCD development. When comorbidities were classified and evaluated
separately, HT and CAD were found to be a risk factor for POCD
development. We consider that association between presence of
comorbidities and POCD development may be depend on the level of
systemic effects of the comorbid disease and duration.
The effect of prolonged preoperative hospitalization period on POCD
development was evaluated in this study regardless of the factors such
comorbidities and high ASA scores, which might affect the preoperative
hospitalization period. Our results showed us that the preoperative
hospitalization period is significantly longer in patients who developed
POCD compared to other patients, regardless of comorbidity presence and
high ASA score factors. Patients without POCD had a lower mean
preoperative hospitalization period compared to patients who developed
POCD.
There are limited studies in the literature investigating the effect of
preoperative hospitalization period on POCD development. In a study
including 54 patients reported that even an increase in hospitalization
periods from 14 hours to 32 hours could be attributed to delirium
development in postoperative period (17). Although POCD and delirium
could be clinically similar, they are different diagnoses that should be
differentiated properly. Another study performed on elderly patients
operated for hip fractures also reported that increased preoperative
hospitalization periods could also increase postoperative
hospitalization and might cause POCD development in those cases (5).
Most of the important risk factors for POCD development are
patient-related and could not be changed. Especially elderly patients
with comorbidities and high ASA scores are under a high risk for POCD
development. Moreover, POCD could be seen even in postoperative
3rd month in 14% of those patients (18). Since
prolonged preoperative hospitalization periods could affect POCD
development after surgery, regardless of other factors, we suggest
preoperative hospitalization period should be minimized in patients have
risk factors for developing POCD.
In the study of Bitsch including 100 operated hip fracture patients
reported a severe cognitive dysfunction in 32% of patients. According
to this study, age is a risk factor for POCD, in addition to low
postoperative hematocrit (Htc) and perioperative transfusion volume (5).
According to our study results, postoperative Htc levels had a
significant effect on postoperative MMT values similar to Bitsch’ study.
Although blood loss volume and postoperative Htc values might be related
with POCD, in our study, we could not observed a significant association
between POCD development and total transfused erythrocyte suspension
volume, crystalloid and colloid replacement. Erythrocyte and liquid
transfusion must be planned according to preoperative Htc values of the
patient and his comorbidities which may be related and cause different
outcomes among patients with POCD.
In our study, we found a significant association between POCD
development and ephedrine administration. Although there are no studies
investigating association between ephedrine administration and POCD in
such surgeries, we consider that this is probably due to
ephedrine-induced hypotension, not ephedrine administration.
There are some studies reported increased POCD incidence rates with
prolonged surgery periods (19). In our study, we also observed that the
POCD group had a longer operation time compared to the non-POCD group,
in accordance with the literature.
Some of the limitations of this study are its low patient population and
short-term evaluation of postoperative cognitive functions. Longer
follow-up periods in patients with cognitive function assessment will be
beneficial for long-term results.