The Management of Blood Pressure After Stroke

Acute but not delayed amphetamine treatment improves behavioral outcome in a rat embolic stroke model

OBJECTIVES

The objective of this study was to examine the effects of d-amphetamine (amph) upon recovery after embolic stroke in rats.

METHODS

Ninety-three rats were embolized in the right middle cerebral artery and assigned to: (1) controls; (2) combination (acute amph and later amph-facilitated retraining); (3) late amph (later amph-facilitated retraining alone); and (4) acute amph (acute amph alone). Animals in the combination and in the acute amph groups received a high dose of amph immediately after embolization, while later amph-facilitated retraining in the combination and late amph groups was done by administering a low dose of amph on post-stroke days 2, 5, 8, and 11 followed by retraining in Montoya's Staircase Test.

RESULTS

Rats receiving acute amph immediately after embolization achieved an 11% increase in median blood pressure (P<0.05). An investigation of performances with the ipsilateral paws during days 14-21 showed that the acute amph group performed better than the control group (P<0.02). Infarct volumes were lower among animals in the acute amph group than in both the combination and the late amph groups (P<0.05), while the controls did not differ from any group.

DISCUSSION

In conclusion, results showed that the acute amph group performed the best, while the late amph and the combination groups performed the worst. Amphetamine treatment in acute stroke may be warranted due to reduced detrimental effects of hypotension and improved brain plasticity.

The Effect of Transdermal Glyceryl Trinitrate on 24 h Ambulatory Blood Pressure in Acute/Subacute Stroke

Background

High blood pressure is a common complication in acute stroke and is associated with a poor outcome.

Aims

This study assesses the effects of transdermal glyceryl trinitrate on 24 h ambulatory blood pressure in patients with recent stroke.

Methods

One hundred and seven patients with acute ischaemic or haemorrhagic stroke were included. The patients had been enrolled in one of two trials of transdermal glyceryl trinitrate (5 mg daily) or placebo/control, and underwent 24 h ambulatory blood pressure monitoring (56 glyceryl trinitrate, 51 control). Ambulatory blood pressure data were analysed using area under the curve for the entire 24 h, and day and night periods. Nocturnal dipping was defined as a decline in systolic blood pressure >10%. Comparisons of blood pressure between groups were performed by analysis of covariance (ANCOVA) with adjustments for trial and baseline measure.

Results

In comparison with control, glyceryl trinitrate significantly lowered 24 h blood pressure (systolic blood pressure/ diastolic blood pressure 9·4/4·8 mmHg, P < 0·001/0·001, n = 104), daytime blood pressure (8·7/4·2, P < 0·001/ < 0·001, n = 103) and night-time blood pressure (6·9/1·7, P = 0·008/0·458, n = 86). Only 86 patients (glyceryl trinitrate 45, placebo/control 41) had sufficient night blood pressure measurements to assign dipping status; 28 were dippers (12 glyceryl trinitrate, 16 control) and 58 were nondippers (33 glyceryl trinitrate, 25 control); glyceryl trinitrate significantly lowered systolic but not diastolic blood pressure in both dippers and nondippers. Treatment with glyceryl trinitrate increased the daytime heart rate (4·8 beats/min) but not the night-time heart rate. Patients whose blood pressure did not dip at night had a worse functional outcome at three-months.

Conclusions

Transdermal glyceryl trinitrate (5 mg) significantly lowered 24 h blood pressure by 9/5 mmHg (equivalent to a 6% reduction) in both dipping and nondipping patients with acute/subacute stroke. This reduction in blood pressure is clinically relevant and is unlikely to be excessive.

Influence of acute blood pressure on short- and mid-term outcome of ischemic and hemorrhagic stroke

The optimal management of blood pressure (BP) during acute stroke is controversial. We aimed to investigate whether (1) acute BP has differential impact on clinical outcome of ischemic stroke (IS) and spontaneous intracerebral hemorrhage (ICH), and (2) the magnitude of such an effect varies from the very acute phase to the postacute phase of the two diseases. BP values were automatically recorded at 15-min intervals within the first 48 h in consecutive patients with stroke onset less than 24 h before Stroke Unit admission. Growth mixture models were applied to evaluate the association between binary outcome measures [(1) early neurological deterioration (defined as a ≥4-point increase in 48-h National Institutes of Health Stroke Scale [NIHSS] score), (2) 90-day unfavorable functional status (modified Rankin Scale [mRS] 3-6), and (3) 90-day mortality] and the latent heterogeneity of maximum BP trajectories over time, expressed by two (high/low) BP latent classes within stroke groups. After exclusions, 264 patients (198 IS, 66 ICH) were included. High systolic BP (sBP) class was associated with (1) a direct ~15% increased risk of early neurological deterioration [risk difference (RD), +0.151; 95% confidence interval (CI) +0.039 to +0.263] and ~4% worse 48-h outcome for ICH with respect to IS (RD, +0.038; 95% CI +0.005 to +0.071), (2) a ~28% increased risk of 90-day unfavorable outcome in the group of patients with ICH with respect to IS [IRD = RD(ICH) - RD(IS), +0.289; 95% CI +0.010 to +0.571], and (3) no significant effect on 90-day mortality. The influence of acute BP values on mid-term stroke outcome varies depending on the stroke subtype.

Hypocapnia enhances the pressor effect of phenylephrine during isoflurane anesthesia in monkeys

Phenylephrine was administered to increase arterial blood pressure in 6 monkeys anesthetized with isoflurane during both normocapnia (arterial partial pressure of CO2 35 to 44 mm Hg) and hypocapnia (arterial partial pressure of CO2 23 to 29 mm Hg). The doses of phenylephrine required to increase mean blood pressure to 33% and 66% above control pressure during hypocapnia [1.7+/-0.9 and 3.1+/-1.7 microg/kg/min (mean+/-SD), respectively] were significantly less than the doses required to achieve the same changes in blood pressure during normocapnia (2.4+/-0.9 and 4.9+/-2.4 microg/kg/min, respectively, P<0.05). In patients with intracranial pathology, for whom hypocapnia is frequently induced, phenylephrine dosage may need to be appropriately reduced.

Blood pressure lowering and stroke

Hypertension is the most prevalent of the modifiable risk factors for stroke. The benefits of blood pressure (BP) lowering on primary and secondary prevention of stroke are undeniable. Despite this, BP control in hypertensive individuals and patients with prior cerebrovascular events is suboptimal. Noncompliance, inappropriate antihypertensive usage and under-utilization of medications contribute significantly to inadequate BP control. Recently, elegantly designed studies that assessed the preventive role of BP lowering in patients with cerebrovascular disease have helped clarify management issues in terms of BP targets and effective antihypertensive regimens. Current evidence suggests that BP targets for primary and secondary prevention are suboptimal and need reassessment. The effect of BP modulation in acute stroke is still not completely understood. Although the thresholds for BP treatment in acute stroke have been recommended, BP targets are as yet ill-defined. The available evidence supports early lowering of blood pressure following stroke. This review discusses the impact of blood pressure on stroke incidence and outcomes, outlines the recommendations for blood pressure lowering in stroke and delineates questions that still need to be addressed.

Ambulatory blood pressure monitoring in stroke survivors: do we really control our patients?

BACKGROUND

We aim to evaluate prospectively the long-term changes of blood pressure (BP) in stroke survivors using ambulatory BP monitoring (ABPM) and compare them with the clinic conventional measurements.

METHODS

We studied 101 patients who were admitted within 24h after stroke onset. To study the circadian rhythm of BP a continuous BP monitor (Spacelab 90207) was used. After six and twelve months follow-up a new ABPM was undertaken. Data were analyzed using the SSPS 12.0.

RESULTS

We studied 62 males and 39 females, mean age: 70.9+/-10.7 years. We included 88 ischemic strokes and 13 hemorrhagic strokes. In the acute phase mean 24 h BPs were 136+/-19/78.6+/-11.4 mm Hg. The normal diurnal variation in BP was abolished in 88 (87.1%) patients. After six months, 74 patients were assessed. Mean office readings were 137.5+/-23.8/76.4+/-11.4 mm Hg, and high systolic BPs and diastolic BPs were found in 37% and 11% of the subjects respectively. ABPM revealed a mean BP of 118.5+/-20.1/70.3+/-8.6 (p<0.0001). In 57 (76.9%), the normal BP pattern remained abolished (p<0.001). After one year, 63 patients were assessed. Mean office readings were 130.8+/-26.3/77.6+/-9.3 mm Hg, and high systolic BPs and diastolic BPs were found in 23.8% and 10% of the subjects respectively. Mean 24 h BPs were 117+/-12.5/69.7+/-7.2 (p<0.001). The normal diurnal variation in BP was now abolished in 47 (74.6%) patients (p<0.001).

CONCLUSION

Survivors of stroke, both hypertensive and non-hypertensive patients, present a chronic disruption of circadian rhythm of BP. Conventional clinical recordings are an unreliable method of controlling these patients and ABPM should be routinely performed in this population.

Abnormal Blood Pressure Circadian Rhythm in Acute Ischaemic Stroke: are Lacunar Strokes Really Different?

Background

A pathologically reduced or abolished circadian blood pressure variation has been described in acute stroke. However, studies on alterations of circadian blood pressure patterns after stroke and stroke subtypes are scarce. The objective of this study was to evaluate the changes in circadian blood pressure patterns in patients with acute ischaemic stroke and their relation to the stroke subtype.

Aims

We studied 98 consecutive patients who were admitted within 24 h after ischaemic stroke onset. All patients had a detailed clinical examination, laboratory studies and a CT scan study of the brain on admission. To study the circadian rhythm of blood pressure, a continuous blood pressure monitor (Spacelab 90217) was used. Patients were classified according to the percentage fall in the mean systolic blood pressure or diastolic blood pressure at night compared with during the day as: dippers (fall ≥ 10–20%); extreme dippers (≥20%); nondipper (<10%); and reverse dippers (<0%, that is, an increase in the mean nocturnal blood pressure compared with the mean daytime blood pressure). Data were separated and analysed in two groups: lacunar and nonlacunar infarctions. Statistical testing was conducted using the SSPS 12.0.

Methods

We studied 60 males and 38 females, mean age: 70·5 ± 11 years. The patient population consisted of 62 (63·2%) lacunar strokes and 36 (36·8%) nonlacunar strokes. Hypertension was the most common risk factor (67 patients, 68·3%). Other risk factors included hypercholesterolaemia (44 patients, 44·8%), diabetes mellitus (38 patients, 38·7%), smoking (24 patients, 24·8%) and atrial fibrillation (19 patients, 19·3%). The patients with lacunar strokes were predominantly men ( P = 0·037) and had a lower frequency of atrial fibrillation ( P = 0·016) as compared with nonlacunar stroke patients. In the acute phase, the mean systolic blood pressure was 136±20 mmHg and diastolic blood pressure was 78·7 ± 11·8. Comparing stroke subtypes, there were no differences in 24·h systolic blood pressure and 24-h diastolic blood pressure between patients with lacunar and nonlacunar infarction. However, patients with lacunar infarction showed a mean decline in day–night systolic blood pressure and diastolic blood pressure of approximately 4 mmHg [systolic blood pressure: 3·9 (SD 10) mmHg, P = 0·003; diastolic blood pressure 3·7 (SD 7) mmHg, P = 0·0001] compared with nonlacunar strokes. Nonlacunar strokes showed a lack of 24-h nocturnal systolic blood pressure and diastolic blood pressure fall. The normal diurnal variation in systolic blood pressure was abolished in 87 (88·9%) patients, and the variation in diastolic blood pressure was abolished in 76 (77·5%) patients. On comparing lacunar and nonlacunar strokes, we found that the normal diurnal variation in systolic blood pressure was abolished in 53 (85·4%) lacunar strokes and in 34 (94·4%) nonlacunar strokes ( P = nonsignificant). In terms of diurnal variation in diastolic blood pressure, it was abolished in 43 (69·3%) lacunar strokes and in 33 (91·6%) nonlacunar strokes ( P = 0·026).

Conclusions

Our results show clear differences in the blood pressure circadian rhythm of acute ischaemic stroke between lacunar and nonlacunar infarctions by means of 24-h blood pressure monitoring. The magnitude of nocturnal systolic and diastolic blood pressure dip was significantly higher in lacunar strokes. Besides, patients with lacunar strokes presented a higher percentage of dipping patterns in the diastolic blood pressure circadian rhythm. Therefore, one should consider the ischaemic stroke subtype when deciding on the management of blood pressure in acute stroke.

Early changes in physiological variables after stroke

Several aspects of physiology, notably blood pressure, body temperature, blood glucose, and blood oxygen saturation, may be altered after an ischemic stroke and intracerebral hemorrhage. Generally, blood pressure and temperature rise acutely after a stroke, before returning to normal. Blood glucose and oxygen levels may be abnormal in individuals, but they do not follow a set pattern. Several aspects of these physiological alterations remain unclear, including their principal determinants - whether they genuinely affect prognosis (as opposed to merely representing underlying processes such as inflammation or a stress response), whether these effects are adaptive or maladaptive, whether the effects are specific to certain subgroups (e.g. lacunar stroke) and whether modifying physiology also modifies its prognostic effect. Hypertension and hyperglycemia may be helpful or harmful, depending on the perfusion status after an ischemic stroke; the therapeutic response to their lowering may be correspondingly variable. Hypothermia may provide benefits, in addition to preventing harm through protection from hyperthermia. Hypoxia is harmful, but normobaric hyperoxia is unhelpful or even harmful in normoxic patients. Hyperbaric hyperoxia, however, may be beneficial, though this remains unproven. The above-mentioned uncertainties necessitate generally conservative measures for physiology management, although there are notably specific recommendations for thrombolysis-eligible patients. Stroke unit care is associated with better outcome, possibly through better management of poststroke physiology. Stroke units can also facilitate research to clarify the relationship between physiology and prognosis, and to subsequently clarify management guidelines.