Table 2 |
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|
Evidence for altered patterns of variability in illness states |
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| Variability analysis |
Cardiac |
Respiratory |
Neurological |
Miscellaneous |
Critical care |
|
|
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| Time domain |
?HRV ??mortality risk in elderly, CAD, post-MI, CHF and dilated cardiomyopathy [14–24] |
Altered frequency distribution of airway impedance in asthma [5] Altered respiratory variability (?kurtosis) in sleep apnoea [148] |
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| Frequency domain |
Altered spectral HRV analysis?illness severity in cardiac disease (CHF [50–52], hypertension
[53,54], CAD [55,56], angina [57], MI [58]) and noncardiac disease (hypovolaemia [49],
chronic renal failure [59], diabetes mellitus [60], anaesthesia [61]) |
?Total HRV, ?LF and ?LF/HF HRV following trauma [149], sepsis and septic shock in
the ICU [62,64,68,150,151] and in ER patients [63] |
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| Power law analysis |
Altered HRV power law (?HRV left shift and steeper slope) with age [84], CAD [85]
and post-MI [86] |
?Respiratory variability (right shift) in patients with asthma [7] ?Variability of
foetal breathing with maternal alcohol intake [152] |
Altered variability in gait analysis [153–155] and postural control [156] with ageing
and neurological disease Altered variability of mood?psychiatric illness [157–159] |
Haematological: altered leucocyte dynamics [160,161] observed in haematological disorders
(e.g. cyclic neutropenia) |
Altered HRV power law (?HRV left shift)??mortality risk in paediatric ICU patients
[33] |
| DFA |
Altered DFA scaling exponent?age [92], heart disease [93–96], post-ACBP [100], prearrhythmias
[97], patients with sleep apnoea [98], and ?mortality risk post-MI [99] |
Altered respiratory variability (?DFA scaling exponent)?age[101] |
Temperature: altered temperature measurements?age[103] |
?Heart rate DFA scaling exponent?septic shock[162] and procedures[61] in paediatric
ICU patients |
|
| Entropy |
?HR ApEn?age [118], ventricular dysfunction [123], occurs prior to arrhythmias [119–121] |
Greater respiratory irregularity in patients with panic disorder [136] |
Altered EEG entropy with anaesthesia[132,163,164] |
Endocrine: ?ApEn of GH [125,126], insulin [127,128], ACTH, GH, PRL [129,130], PTH
[131]?age and/or illness |
?HR ApEn?healthy individuals infused with endotoxin [124] ?TV ApEn in respiratory
failure [135] |
|
|
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|
?, decreased; ?, increased; ?, is associated with; ACBP, aorto–coronary bypass procedure; ACTH, adrenocorticotrophic hormone; ApEn, approximate entropy; CAD, coronary artery disease; CHF, congestive heart failure; DFA, detrended fluctuation analysis; EEG, electroencephalogram; ER, emergency room; GH, growth hormone; HF, high frequency; HRV, heart rate variability; ICU, intensive care unit; LF, low frequency; MI, myocardial infarction; PRL, prolactin; PTH, parathyroid hormone; TV, tidal volume. |
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Seely and Macklem Critical Care 2004 8:R367 doi:10.1186/cc2948 |
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