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106 PART 1: An Overview of the Approach to and Organization of Critical Care

with neurocognitive sequelae had worse quality of life than individuals 1.0 1.0
without neuropsychological dysfunction. Decreased HRQoL has also
30
been associated with psychiatric morbidities such as posttraumatic stress 0.8 0.8
disorder (PTSD), which may represent yet another important contribu-
tor to subsequent disability and loss of employment. 15,31,32 A more ful- 0.6 0.6
some discussion of neuropsychological morbidities will follow later in Proportion alive
this chapter. 0.4 0.4
There is clear evidence that HRQoL in ARDS survivors is adversely
influenced by physical and neuropsychological morbidities. These 0.2 0.2
observations have helped to elevate awareness about the important 0.0 0.0
consequences of critical illness in the critical care community, but an
important limitation that remains is the lack of generalizability of the 500 % Predicted
ARDS outcomes literature to all ICU survivors. Rapidly accruing out- 75.0
comes data from international cohorts, evaluating both functional and
neurocognitive long-term outcomes, has helped us begin to understand 400 62.5
the heterogeneous nature of reported morbidity and the complexity of Distance walked (m) 450 Distance Percent predicted
350
interaction among physical, emotional, and neurocognitive domains in
individual patients (Fig. 15-2). 300 50.0
250
37.5
NEUROMUSCULAR DYSFUNCTION 200

Recent research work has highlighted the concept of a continuum of
weakness that begins with muscle injury documented within hours of 50 MCS Norm
mechanical ventilation, is evident with bedside testing using clinical
33
strength measures (MRC scoring system) within 1 week of ICU admis- 40 Norm-1SD
sion, and may persist with incomplete recovery for years after ICU dis- SF-36 subscale score
34
charge (Fig. 15-1B). Muscle weakness and impaired function constitute PCS
2
an important morbidity of severe critical illness. 30
ICUAW appears to be ubiquitous in severe lung injury and also with
other complex critical illnesses. Regardless of disease process, muscles
and nerves are injured and this manifests as prolonged mechanical 20 0.0 1.0 2.0 3.0 4.0 5.0
ventilation and poor functional outcomes. However, ICUAW does not Year of study
completely explain functional impairment since this is influenced by N at risk 109 92 86 79 77 74 69 64
many factors. In 2009, a Round Table Conference was held in Brussels, N for 6 min walk 80 78 81 60 64 64 57 54
which produced a series of publications that serve as a good review N for SF-36 67 74 74 56 57 57 49 50
on this topic including a framework for classification of ICUAW. An
13
overview of the findings was included in a summary by Griffiths and
Hall. ICUAW comprised a nerve or muscle lesion or a combination
35
of each as outlined below and recently reviewed in detail by Latronico
and Bolton. 36

CRITICAL ILLNESS POLYNEUROPATHY
■ BACKGROUND AND INCIDENCE

Bolton and colleagues first described critical illness polyneuropathy
(CIP) in 1984 and reported on five critically ill patients who were
37
having difficulties with liberation from mechanical ventilation. On
electrophysiological testing, these patients had a primary axonopathy,
which manifested clinically as a mixed sensorimotor neuropathy.
Since this initial publication, it has become clear that CIP is very com-
mon in patients with the systemic inflammatory response syndrome
12 Months
3 Months
(SIRS) and sepsis, with an occurrence of 70% to 100% of longer stay 3 Months 12 Months
ICU patients. It affects the limb and respiratory muscles and facial
muscles are typically spared. Limb involvement is symmetrical, most
prominent in the proximal muscle groups and in the lower extremi- FIGURE 15-1. A. Survival, 6-minute walk distance and quality of life to 5 years after ICU
ties. Detection of the true incidence of CIP is complicated by lack of discharge. Exact survival times were used for these analyses whereas deaths indicated in the consort
consensus on surveillance, timing and nature of testing, limitations to diagram were included between scheduled follow-up visits. Top panel: Kaplan-Meier curve to 5 years.
testing because of patient sedation or poor cooperation, formal defi- Dashed lines represent the 95% confidence interval. middle panel: Distance walked in 6 minutes
nition, and diagnostic criteria. When patients were evaluated strictly (meters and % predicted); distance in meters is a solid line and % predicted is a dashed line. BoTTom
on clinical grounds for weakness, studies have reported an incidence panel: SF-36 Subscale scores for Physical Component Score (PCS) and Mental Component Score (MCS).
of 25% to 36%. 34,38 A systematic review on 1421 critically ill patients, (Reproduced with permission from Herridge MS, Tansey CM, Matte A, et al. Functional disability
reported an incidence of ICUAW of 46% (95% confidence interval 5 years after acute respiratory distress syndrome. N Engl J Med. April 7, 2011;364(14):1293-1304.)
43%-49%). They defined patients as having ICUAW if they were B. Improvement but incomplete resolution of muscle weakness at 1 year after ICU discharge.
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