Association Between Physiological Homeostasis and Early Recovery After Stroke
To the Editor:
Stroke patients who are managed in an organized (stroke unit) setting are more likely to make a good recovery than those who receive conventional care in general wards, an effect that has been attributed to the coordinated rehabilitation input.1 However, recent descriptive information from 2 Norwegian trials2 3 now indicates that some of the benefits of stroke unit care may also be due to acute medical interventions. In particular, these units employed early mobilization and the routine use of intravenous saline, plus selective use of antipyretic and antibiotic medication, oxygen, and insulin.2 3 4 We therefore wished to test the hypothesis that stroke patients who manage to maintain key physiological variables (osmolarity, temperature, oxygen saturation, blood glucose) within a narrow physiological range are more likely to enjoy an early recovery and better functional outcome.
We carried out a case-control study, recruiting consecutive individuals admitted to a large, urban teaching hospital with a clinical diagnosis of stroke in the previous 24 hours that was confirmed on CT scan. Patients were assessed on admission, day 3, and day 7 after stroke with the Scandinavian Stroke Scale, Barthel Index, and modified Rankin scale.5 Physiological variables were recorded up to 4 times daily as part of routine clinical care.
We compared the characteristics of patients who showed no major deviation from normal physiological values during the first 3 days (defined as a peak calculated serum osmolarity <300 mOsm/kg, peak temperature ≤37.5°C, peak blood glucose ≤10 mmol/L, minimum oxygen saturation ≥93%) compared with those who showed abnormalities of at least 1 of those variables. We controlled for the key predictors of stroke outcome by using a frequency-matching schedule, matching for age, prestroke disability (Rankin scale score) and initial stroke severity (Scandinavian Stroke Scale score). Matching of cases and controls was conducted blinded to the outcome data.
During a 3-month period, 102 eligible patients were admitted, of whom 35 showed no major physiological homeostatic upset in the first 3 days after stroke; we were able to match 28 of those patients (group A) with 28 who showed 1 or more physiological abnormalities (group B). The main results are outlined in the Table⇓. The 2 patient groups were well balanced for age, gender, prestroke independence, initial stroke severity and stroke subtype, and the prevalence of comorbidities. Patients who maintained physiological homeostasis (group A) showed improved outcomes across a range of measures.
These results lend support to the concept that some of the neurological impairment occurring in the acute phase of stroke is reversible and may be exacerbated by physiological abnormalities.6 7 In particular, hyperglycemia may be neurotoxic through the promotion of lactic acidosis,6 dehydration and hypotension may impair cerebral perfusion to ischemic brain tissue,6 and pyrexia appears to be neurotoxic.7 The recent descriptions of some stroke unit practices2 3 suggest that intervening to maintain key physiological variables within narrow limits (in particular, avoiding extremes of blood glucose concentration, pyrexia, dehydration, and oxygen desaturation) may assist neurological recovery after stroke. We believe that further clinical trials of physiological control in acute stroke are justifiable and could focus on hydration, pyrexia control, blood glucose control, and prevention of hypoxia.
Funded by Chest, Heart and Stroke, Scotland.
- Copyright © 2000 by American Heart Association
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Indredavik B, Bakke F, Slordahl SA, Rokseth, Haheim LL. Treatment in a combined acute and rehabilitation stroke unit: which aspects are most important? Stroke.. 1999;30:917–923.
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Reith J, Jorgensen HS, Pedersen PM, Nakayama H, Raaschou HO, Jeppesen LL, Olsen TS. Body temperature in acute stroke: relation to stroke severity, infarct size, mortality and outcome. Lancet.. 1996;347:422–425.
It is of great interest for us that Langhorne and coworkers have tried to confirm our observations about the importance of optimizing physiological variables in acute stroke patients.
In univariate analyses in our trial,R1 we found that control of glucose level, temperature, and blood pressure were associated with a better outcome. There is growing evidence to indicate that such physiological variables are of importance for the prognosis.R2 R3 R4 R5 R6 The intervention on hydration, blood pressure (avoiding low blood pressure), temperature, and glucose level in our trial have until now, however, been one of the few indications of beneficial effects of intervention on these factors. It is therefore important that Langhorne and coworkers have been able to achieve similar results. We think this is an important area for more research because control of such physiological variables may be the most important neuroprotective options in acute stroke patients. However, in traditional acute care or intensive care, control of physiological variables has very often been associated with intensive monitoring while the patient has been immobilized in bed.R7 It is worth noting that in our trial early mobilization was even more important for a better outcome than control of physiological variables.R1 Hence, control of these physiological variables should probably occur simultaneously with an early mobilization and start of rehabilitation. That advanced monitoring is not necessarily beneficial was shown for cardiological patients several years ago.R8 If prolonged bedrest occurs, the beneficial effect may disappear. In our stroke unit we now perform studies to look at the effects of our very early mobilization on physiological variables. Our hypothesis is that early mobilization may not only reduce bed-associated complications and enhance recovery but may also contribute to more optimal control of some of the physiological variables.
Until more data are accumulated, we will continue the approach to acute stroke care that we developed during our stroke unit trial.R1 Our approach can be summarized in the following way: Acute stroke patients need acute medical care in order to control physiological variables, and they need acute mobilization/training to reduce complications and enhance recovery. One reason that stroke units which combine acute care and acute rehabilitation are very beneficial might be that such units are able to offer both acute care and acute rehabilitation and that they are able to offer these options simultaneously. We think the results in the letter from Langhorne and coworkers support our approach, but we agree that more research is needed in this important field to achieve more knowledge and to improve acute care of stroke.
Indredavik B, Bakke F, Slørdahl SA, Rokseth R, Haaheim LL. Treatment in a combined acute and rehabilitation stroke unit: which aspects are most important? Stroke. 1999;30;917–923.
Oppenheimer S, Hachinski V. Complications of acute stroke. Lancet. 1992;339:721–724.
Reith J, Jørgensen HS, Pedersen PM, Nakayama H, Raaschou HO, Jeppesen LL, Olsen TS. Body temperature in acute stroke: relation to stroke severity, infarction size, mortality and outcome. Lancet. 1996;347:422–425.
Hajat C, Hajat S, Sharma P. Effects of poststroke pyrexia on stroke outcome: a meta-analyses of studies in patients. Stroke. 2000;31:410–414.
Jørgensen HS, Nakayama H, Raaschou HO, Olsen TS. Effect of blood pressure and diabetes on stroke in progression. Lancet. 1994;344:156–159.
Pulsinelli WA, Levy DE, Sigsbee B, Scherer P, Plum F. Increased damage after ischemic stroke in patients with hyperglycemia with or without established diabetes mellitus. Am J Med. 1983;74:540–544.
Hacke W, Scwab S, DeGeorgia M,. Intensive care of acute ischemic stroke. Cerebrovasc Dis. 1995;5:385–392.
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