Download Intensive care monitoring after total joint replacement

 HIP REPLACEMENT: AVOIDING AND MANAGING PROBLEMS
Intensive care monitoring after total joint
replacement
A. F. Kamath,
C. L. McAuliffe,
J. T. Gutsche,
L. M. Kosseim,
E. L. Hume,
K. D. Baldwin,
Z. Kornfield,
C. L. Israelite
Patient safety is a critical issue in elective total joint replacement surgery. Identifying risk
factors that might predict complications and intensive care unit (ICU) admission proves
instrumental in reducing morbidity and mortality. The institution’s experience with risk
stratification and pre-operative ICU triage has resulted in a reduction in unplanned ICU
admissions and post-operative complications after total hip replacement. The application of
the prediction tools to total knee replacement has proven less robust so far. This work also
reviews areas for future research in patient safety and cost containment.
From University of
Pennsylvania,
Philadelphia,
Pennsylvania, United
States
Patient safety has come to the forefront of both
government and lay scrutiny.1 At a time when
the nation’s agenda has focused on health care
reform, several key issues are closely connected
including patient safety, risk stratification, and
cost. Apart from internal institutional pressures
to be accountable, orthopaedic surgeons face
numerous public, governmental, and external
pressures. In a changing politico-economic climate, finite resources strain the balance
between cost containment and the infrastructure needed in order to reduce the risks, both in
terms of morbidity and mortality inherent in
total joint replacement (TJR) surgery. Broadening surgical indications, increased medical comorbidities, and case complexity all challenge
the available resources in hospitals.
A number of studies have explored these
issues in order to understand the peri-operative
morbidity and mortality associated with TJR,
which is being performed in older and sicker
patients.2 Increasing case complexity is compounded by the high prevalence of patient comorbidities.3 The reported rates of major
adverse4,5 or life-threatening6 events, as well as
direct surgical related complications,7 are high
after elective lower limb TJR. Memtsoudis et
al4 indicate there is a need for critical care services in nearly one-third of TJR patients, and
this in turn prompts a discussion of resource
allocation and screening methods.
Surgeons must look closely at how patients
are assessed after TJR. In a study by Parvizi et
al,8 58% of patients who had a post-operative
life-threatening complication after TJR surgery
did not exhibit obvious risk factors during preoperative assessment. It is therefore urgent to
 A. F. Kamath, MD, Attending
Surgeon
 E. L. Hume, MD, Attending
Surgeon
 K. D. Baldwin, MD, MSPT, MPH,
Attending Surgeon
 C. L. Israelite, MD, Attending
Surgeon
University of Pennsylvania,
Department of Orthopaedic
Surgery, Hospital of the
University of Pennsylvania,
Philadelphia, Pennsylvania,
19104, USA.
 C. L. McAuliffe, BS, Candidate
for Doctor of Medicine
University of Pennsylvania,
Perelman School of Medicine,
University of Pennsylvania,
Philadelphia, Pennsylvania 19104,
USA.
 J. T. Gutsche, MD, Assistant
Professor; Medical Director
Intensive Care Unit Presbyterian
Hospital
 Z. Kornfield, MD, Resident
University of Pennsylvania,
Department of Anesthesia and
Critical Care, Hospital of the
University of Pennsylvania,
Philadelphia, Pennsylvania 19104,
USA.
 L. M. Kosseim, MD, Associate
Professor
University of Pennsylvania,
Department of Internal Medicine,
Hospital of the University of
Pennsylvania, Philadelphia,
Pennsylvania 19104, USA.
Correspondence should be sent
to A. F. Kamath; e-mail:
[email protected]
©2013 The British Editorial
Society of Bone & Joint Surgery
doi:10.1302/0301-620X.95B11.
33093 $2.00
Bone Joint J
2013;95-B, Supple A:74–6.
Received 7 September 2013;
Accepted after revision 8
September 2013
74
Cite this article: Bone Joint J 2013;95-B, Supple A:74–6.
develop accurate and timeous risk stratification models in order to increase patient safety,
which ideally, should be accomplished prior to
the patient’s admission to hospital.
Retrospective9 and prospective10 studies were
conducted at the authors’ institution in order to
examine the morbidity and mortality after total
hip replacement (THR). The study looked to
establish a clinically useful risk model for prospective testing. Work has now extended to
total knee replacement (TKR) patients, and this
is the most recent evaluation of risk factors
associated with unplanned admission to the
intensive care unit (ICU) after TKR.
Triage at joint replacement centres
Post-operative triage to the ICU remains a complex, frequent clinical decision. The authors
have looked at factors that might guide postoperative admission to the ICU and thus
develop a predictive model of risk for
unplanned ICU admission. This might be
analogous to a TJR Apgar score, used to assess
new born babies,11,12 and other work predicting
post-operative risks after hip fracture surgery.13
Undertaking any safety study involves a
multi-disciplinary effort (Fig. 1). Input must be
obtained from critical care specialists, hospital
administration, and biostatistics. Nursing and
nurse management is critical, as resource allocation and nurse staffing has been related to
mortality.14
Previous risk studies in THR patients
Results of the authors’ retrospective study in
THR were published in 2012.9 The study looked
at certain pre-operative and intra-operative
CCJR SUPPLEMENT TO THE BONE & JOINT JOURNAL
INTENSIVE CARE MONITORING AFTER TOTAL JOINT REPLACEMENT
Fig. 1
Diagram showing the interdisciplinary team approach.
variables, as well as post-operative factors associated with
those patients admitted unplanned to an ICU from a series
of 1259 THR patients. In comparing unplanned ICU
admissions with the control group, regression analysis demonstrated that age > 75 years, body mass index > 35 kg/m2,
creatinine clearance < 60 mL/min, revision surgery, and
prior myocardial infarction were independent risk factors
for ICU admission. If a patient possessed several risk factors, the risk of unplanned admission to the ICU accordingly rose.
This risk model was then applied in a prospective series
of consecutive THR patients.10 All were assigned to either
the ICU or a ward based on these multivariate risk factors.
These triage criteria aimed to establish a threshold for
planned ICU admission. The primary goal in this pilot
study was to influence unplanned admission rates, as well
as any major complications. Secondary outcomes included
rapid response interventions and any medical or surgical
events requiring acute attention. The authors found, with
only a modest total increase in the number of planned ICU
admissions that our pre-operative assessment resulted in a
reduction in both unplanned ICU admissions and major
complications in general. The mean number of ICU days
for those who were admitted decreased from 2.5 days to
1.7 (2 to 11). This was statistically, as well as clinically significant, both for the institution and model performance
characteristics worked in practice.
Prediction of intensive care need for knee
replacement patients
TKR patients were analysed in a separate retrospective
review. This study compared 55 patients who required
admission to the ICU post-operatively with 164 patients
who did not. The mean age of the ICU patients was
68 years (48 to 90), and the mean age for ward patients was
62 years (35 to 85). Of the intensive care admissions, 60%
(33 of 55) were female, and 67% (111 of 164) of ward
patients were female.
VOL. 95-B, No. 11, NOVEMBER 2013
75
Univariate analysis was performed to identify factors
that might be associated with a statistically significant risk
of ICU admission. Revision surgery, creatinine clearance
less than 60 mL/min, history of previous myocardial infarction, and American Society of Anesthesiologists (ASA)
Class 3 or greater were potential risk factors.15 The first
multivariate model focused on factors that might be known
at the time of scheduling a patient for surgery. Pre-operative
variables predictive of unplanned ICU admission were age
> 75 years, revision surgery, history of obstructive sleep
apnea, creatinine clearance less than 60 mL/min, history
of previous myocardial infarction and a prior venous
thromboembolism. Of these, creatinine clearance less than
60 mL/min and history of previous myocardial infarction
were the strongest predictors. The second multivariate
model focused on variables known at initial assessment
plus the ASA score obtained pre-operatively during the
anaesthesia assessment. Out of the variables examined, the
strongest individual predictors of ICU admission were previous myocardial infarction and ASA Class 3 or greater.
In planning for a prospective trial for THR,10 one must
consider the performance characteristics of the model.
Choosing an appropriate threshold for planned ICU admission in a controlled trial might identify patients with two or
more risk factors in addition to an ASA Class > 2. Applying
this to the patients in the TKR, one would correctly identify
53 out of the 55 patients admitted to the ICU. However,
this triage model would also have identified 85 patients
who ultimately did not require intensive care, accounting
for a high false positive rate. The strength of the model
for TKR patients lies in its negative predictive value
(0.93 (0.91 to 0.96)).
Future study
This work has inspired ideas for several future projects
looking into the issues concerning patient safety, including
examination of the costs attributable to ICU intervention.
While the authors demonstrated only a modest increase in
the total number of ICU admissions in the prospective arm
of the THR study, it is unclear without formal cost analysis
whether the increased costs of ICU monitoring are offset by
the savings associated with reduced morbidity and mortality. Another study could look at the outcomes of patients
referred from other institutions. Re-admission rates and
longer-term clinical follow-up may offer insight into a lasting benefit, if any, to earlier peri-operative ICU care. Future
work may also look at the influence of these safety measures on public and governmental perceptions of orthopaedic care. Of course, more data should allow us to define
better the costs involved and resource use associated with
tertiary/referral care of TJR patients; i.e. similar work in
other fields of orthopaedic surgery has provided insight
into ICU triage. 16
Yet the triage model established may not be applicable to
other institutions due to its relevance to the authors’ institution; and it equally may not be as applicable to those that
76
A. F. KAMATH, C. L. MCAULIFFE, J. T. GUTSCHE, L. M. KOSSEIM, E. L. HUME, K. D. BALDWIN, Z. KORNFIELD, C. L. ISRAELITE
perform less TJR surgery. The costs of ICU admission will
be significant, and it is reasonable to assume that those
patients with the highest medical risk may be most suitable
for planned admission and monitoring. An internal analysis
of patient characteristics may inform the decision to apply
either this or a modified version of the risk model and triage
criteria. Multi-centre data and harnessing of large clinical
data sets may provide more generalised risk stratification
and cost-benefit models.
Conclusion
Patient safety is intimately tied to the balance between risk
reduction and cost containment. Safety has a direct relationship with the costs of care, reimbursement issues, public policy, patient perceptions and satisfaction with care.
Work will need to be continued if patient safety in TJR is to
be improved and to reconcile this with cost containment
and reduced risk.
According to selected risk factors, pre-operative triage to
the ICU affects the reduction in post-operative unplanned
ICU admissions as well as major complications, after elective THR. It validates a pre-operative risk stratification
model in the authors’ institution, which is a useful decision
making tool that facilitates the booking of a THR patient
for an ICU admission at the time of pre-operative assessment. However, this area of work is an interdisciplinary
effort. The issue of patient safety must bring together different parties across the spectrum of clinical care, and offers
an opportunity for synergy.
A study of risk factors that may predict unplanned ICU
admission after TKR procedures was not as effective. Further work in larger patient populations, as well as the prospective validation of prediction tools, will allow for the
creation of a more robust model for TKR.
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
This paper is based on a study which was presented at the 29th Annual Winter
2012 Current Concepts in Joint Replacement® meeting held in Orlando, Florida,
12th – 15th December.
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