MANAGING THE CAST - CONCEPTUAL FRAMEWORKS

CONCEPTUAL FRAMEWORKS

7.3 MANAGING THE CAST

Left ACA 105.5 ± 29.9 71.8± 12.5 18.4 < 0.001*

Mean TAMMV 131.5 ± 21.3 87.2 ± 10.7 32.9 < 0.001*

Keys:

*: Statistically significant

ICA: internal carotid artery ICA: internal carotid artery MCA: middle cerebral artery MCA: middle cerebral artery

ACA: anterior cerebral artery ACA: anterior cerebral artery Mean TAMMV: mean Time Averaged Mean of the Maximum Velocities

Cerebral Blood Flow Velocities Values According To Age, Socioeconomic

age groups from 24-59 months up until 167-196 months when it declined in both controls and subjects. The highest TAMMV across the different age groups were those within 60-95 months and lowest at 167-196 months in all the intracranial arteries assessed in both controls and subjects (See figure 2 )

Table X: Comparison of Cerebral Blood Flow Velocities among Different Age Groups of HbSS patients

Age groups (Months) Artery

assessed

24 – 59 n = 134 Mean ± SD

60 – 95 n= 74 Mean ± SD

96 – 131 n=53 Mean ± SD

132 –167 n=48 Mean ± SD

168 – 196 n=6

Mean ± SD

F p value

Right ICA

142.1 ± 25.3

154.8 ± 26.6 150.0 ± 39.1 137.7 ± 33.48

128.3 ± 30.4

3.631 0.007^* Left ICA 143.3 ±

30.2

143.3 ± 26.5 150.12 ± 29.9

146.4 ± 33.7 137.6 ± 27.9

1.534 0.192 Right

MCA

144.3 ± 29.1

151.7 ± 27.7 140.4 ± 39.6 137.7 ± 33.56

135.7 ± 24.6

1.862 0.117

61 Left

MCA

145.3 ± 28.5

151 ± 29.5 145.4 ± 32.8 134.7 ± 29.4 124.3 ± 19.8

2.718 0.030*

Right ACA

103.1 ± 26.9

112.5 ± 34.4 105.7 ± 30.8 98.6 ± 28.7 103.7 ± 37.1

1.871 0.115 Left

ACA

107.1 ± 28.5

109.7 ± 33.4 98.8 ± 27.7 102.6 ± 30.2 99.8 ± 24.1 1.296 0.271 Mean

TAMMV

130.9 ± 20.5

138.1 ± 22.7 130.8 ± 20.3 124.8 ± 20.1 122.1±

20.2

3.420 0.009*

Keys:*: Statistically significant

RTICA: right internal carotid artery LTICA: left internal carotid artery RTMCA: right middle cerebral artery LTMCA: left middle cerebral

RTACA: right anterior cerebral artery LTACA: left anterior cerebral artery Mean TAMMV: mean Time Averaged Mean of the Maximum Velocities

Table XI. Comparison of Cerebral Blood Flow Velocities among Different Age Groups of HbAA

Age groups (Months) Artery

assessed

24 – 59 n=136 Mean± SD

60 – 95 n=74 Mean± SD

96 – 131 n=54 Mean ± SD

132 –167 n=45 Mean ± SD

168 – 196 n=6

Mean ± SD

F p value

RT ICA 91.9± 11.4 102.1±

14.0

95.9± 15.6 84.5± 12.9 83.5± 19.7 14.752 < 0.001^* LTICA 95.6± 12.0 99.9±10.7 96.4± 11.9 87.7± 12.0 91.3± 22.2 7.534 < 0.001*

62 RTMCA 93.5± 12.2 102.8±

14.3

98.8± 11.7 87.7± 12.6 90.6± 17.9 12.001 < 0.001*

LT MCA 97.32±

13.6

102.5±

11.5

101.6± 16.4 90.8± 11.1 88.6± 13.5 7.152 < 0.001*

RTACA 68.3± 13.3 74.2± 13.0 69.4± 14.0 59.9± 10.3 54.3± 7.2 10.370 < 0.001*

LT ACA 72.3± 13.9 76.3± 9.8 71.9± 10.8 64.8 ± 10.1 62.6± 10.5 8.181 < 0.001*

Mean TAMMV

86.5± 10.6 93.0± 8.1 89.0± 9.6 79.2± 9.6 78.5± 12.9 15.841 < 0.001*

Keys:*: Statistically significant

RTICA: right internal carotid artery LTICA: left internal carotid artery RTMCA: right middle cerebral artery LTMCA: left middle cerebral

RTACA: right anterior cerebral artery LTACA: left anterior cerebral artery Mean TAMMV: mean Time Averaged Mean of the Maximum Velocities

Pattern of changes in cerebral blood flow velocities according to age in subjects and controls

Children in the HBSS group showed a steady rise in TAMMV with a peak at age 60-95 months followed by a progressive decline from age 96-131months till age 168-196 months and a similar pattern was observed for the controls as shown in figure 7

Figure 2: Mean Cerebral Blood Flow Velocities in Different Age Groups in Subjects and Controls

Cerebral blood flow velocities and socio-economic status in subjects and controls

There was not statistically significant difference in the cerebral blood flow velocities between lower and upper socio-economic class in the subjects (P > 0.05) as depicted in Table XII. In contrast to the subjects, those in HbAA group who had lower socioeconomic status had higher

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0

24-59 months

60-95 months

96-131 months

132-167 months

168-196 months

Mean TAMMV subjects Mean TAMMV controls

cerebral blood flow velocities in all the arteries measured except left ACA (P < 0.001) as shown in Table XIII.

Table XII. Comparison of Cerebral Blood Flow Velocities of Subjects in the High Socioeconomic Class with Values in those from Lower Socioeconomic Class

Intracranial artery assessed

Socio-economic class

T p value

Lower n=226 Mean ± SD

Upper n=89 Mean ± SD

Right ICA 144.6± 28.6 146.4 ± 33.9 0.4 0.635

Left ICA 145.2 ± 27.6 142.6 ± 32.1 0.7 0.466

Right MCA 144.1 ± 30.4 144.4 ± 34.5 0.1 0.942

Left MCA 144.5± 28.4 143.9 ± 33.1 0.2 0.857

Right ACA 104.9± 29.5 105.5 ± 31.5 0.2 0.880

Left ACA 104.8 ± 30.4 107.1 ± 28.4 0.6 0.544

Mean TAMMV 131.4 ± 21.0 131.7 ± 21.9 0.1 0.921

Keys:

*: Statistically significant

ICA: internal carotid artery ICA: internal carotid artery MCA: middle cerebral artery MCA: middle cerebral artery

ACA: anterior cerebral artery ACA: anterior cerebral artery Mean TAMMV: mean time averaged mean of the maximal velocities

Table XIII. Comparison of Cerebral Blood Flow Velocities of Controls in the High Socioeconomic Class with Values in those from Lower Socioeconomic Class

65 Intracranial

artery assessed

Socio-economic class

T P value

Lower n=204 Mean ± SD

Upper n=111 Mean ± SD

Right ICA 97.5± 15.3 86.9 ± 8.9 6.6 < 0.001^* Left ICA 96.9 ± 13.4 93.1 ± 9.8 2.6 0.009*

Right MCA 99.5 ± 14.6 88.7 ± 8.1 7.2 < 0.001*

Left MCA 99.3 ± 15.6 96.0 ± 9.7 2.0 0.046*

Right ACA 71.7 ± 14.3 62.4 ± 10.0 6.0 < 0.001*

Left ACA 72.6 ± 13.1 70.4 ± 11.2 1.4 0.144 Mean TAMMV 89.6 ± 11.0 83.0 ± 8.5 5.5 < 0.001*

Keys:

*: Statistically significant

ICA: internal carotid artery ICA: internal carotid artery MCA: middle cerebral artery MCA: middle cerebral artery

ACA: anterior cerebral artery ACA: anterior cerebral artery Mean TAMMV: mean time averaged mean of the maximal velocities

Comparison of mean cerebral blood flow velocities between males and females in subjects and controls

The mean cerebral blood flow velocities in males were compared with those of females in both subjects and controls. There were not statistically significant differences in the mean TAMMV in males and female subjects (See Table XIV). However the females in the control group had statistically higher mean TAMMV than the male in the same group (See Table XV).

Table XIV. Comparison of Mean Cerebral Blood Flow Velocities between Males and Females in Subjects and Controls

Artery assessed

Male n=314 Mean ± SD

Female n=316 Mean ± SD

T P value

Right ICA 144.9 ± 29.4 145.3 ± 31.0 0.1 0.895

Left ICA 142.8 ± 27.1 146.1 ± 30.5 1.0 0.306

Right MCA 143.2 ± 30.2 145.2 ± 32.9 0.5 0.574

Left MCA 145.2 ± 27.7 143.5 ± 31.7 0.5 0.606

Right ACA 105.9 ± 30.3 104.2 ± 29.9 0.5 0.615

Left ACA 108.4 ± 32.8 102.5 ± 26.4 1.7 0.077

Mean TAMMV

131.8 ± 21.4 131.2 ± 21.2 0.3 0.803

Keys:

*: Statistically significant

ICA: internal carotid artery ICA: internal carotid artery MCA: middle cerebral artery MCA: middle cerebral artery

ACA: anterior cerebral artery ACA: anterior cerebral artery Mean TAMMV: mean Time Averaged Mean of the Maximum Velocities

Table XV. Comparison of Mean Cerebral Blood Flow Velocities between Male and Female Controls

67 Intracranial artery

assessed

Male n=314 Mean ± SD

Female n=316 Mean ± SD

T P value

Right ICA 90.6 ± 12.8 96.9 ± 15.0 3.9 < 0.001^*

Left ICA 94.3 ± 12.2 96.8 ± 12.5 1.7 0.074

Right MCA 91.5 ± 12.2 99.8 ± 13.9 5.6 < 0.001*

Left MCA 95.5 ± 10.3 100.9 ± 16.9 3.4 0.001*

Right ACA 64.7 ± 13.3 72.1 ± 13.1 4.9 < 0.00*1

Left ACA 69.0 ± 11.6 74.5 ± 12.7 4.0 < 0.001*

mean TAMMV 84.3 ± 9.9 90.2 ± 10.6 5.1 < 0.001*

Keys:

*: Statistically significant

ICA: internal carotid artery ICA: internal carotid artery MCA: middle cerebral artery MCA: middle cerebral artery

ACA: anterior cerebral artery ACA: anterior cerebral artery Mean TAMMV: Time Averaged Mean of the Maximum Velocities

Comparison of cerebral blood flow velocities with respect to presence and absence history of acute chest syndrome in the study population

The Table XVI shows that there is a statistically significant difference in the mean cerebral blood flow velocities between those with and those without history of acute chest syndrome in HbSS group but not in all arteries (left ICA, left MCA, right and ACA). Thus those with history of acute chest syndrome had higher cerebral blood velocities and the intracranial vessels that were mostly involved were right ICA and right MCA. However, the mean TAMMV was significantly higher in those without history of acute chest syndrome.

Table XVI: Comparison of Cerebral Blood Flow Velocities with Respect to Presence or Absence History of Acute Chest Syndrome in the Study Population

Intracranial artery assessed

History of acute chest syndrome

T P value

Yes n =31 Mean ± SD

No n=284 Mean ± SD

Right ICA 165.5 ± 42.4 142.9 ± 27.7 4.0 < 0.001^*

Left ICA 149.4 ± 40.1 143.9 ± 27.4 0.9 0.321

Right MCA 167.2 ± 49.4 141.7 ± 27.9 4.4 < 0.001*

Left MCA 153.2 ± 38.0 143.4 ± 28.6 1.7 0.080

Right ACA 106.6 ± 40.3 104.9 ± 28.8 0.2 0.773

Left ACA 111.7 ± 31.1 104.7 ± 29.7 1.2 0.217

Mean TAMMV

130.3 ± 20.6 142.32 ± 24.15

2.7 0.012*

Keys:

*: Statistically significant

ICA: internal carotid artery ICA: internal carotid artery MCA: middle cerebral artery MCA: middle cerebral artery

ACA: anterior cerebral artery ACA: anterior cerebral artery Mean TAMMV: mean time averaged mean of the maximal velocities

Relationship between some clinical and haematological variables and cerebral blood flow velocities in the individual major intracranial vessels among HbSS

Relationship between some clinical, haematological variables and cerebral blood flow velocities: in ICA; MCA; ACA; and mean TAMMV among the subjects are shown in Table XVII. The table show significant relationship between haemoglobin, white cell count, platelet, SaO2 and cerebral blood flow velocities [TAMMV] (P <0.05). The correlation coefficient (R) indicates negative but weak relationship between haemoglobin, SaO2 and CBFV. While there were positive but weak relationships between white cell count, platelet and the cerebral blood flow velocities. The coefficient of determination (R²) indicates that less than half the variation in the cerebral blood flow velocities can be attributed to the independent variables. However the TAMMV in the right ACA (B = 0.060, P= 0.222) and that in the left ACA (B = 0.072, P = 0.139) do not have a significant relationship with white cell count.

A multiple linear regression was done with variables noted to have statistically significant relationship with cerebral blood flow velocity. The independent variables: haemoglobin, and SaO2 for the HBSS were noted to retain their statistical significance with standardized beta coefficient of -3.746 and -4,949 respectively as depicted in Table XVIII. The multiple regression model shows a positive strong relationship between CBFV and independent variables which include haemoglobin and SaO2 (R = 0.0.648) and they all accounted for 42.0%

of the changes in the cerebral blood flow velocities (R² = 0.420) depicted in Table XVIII.

Table XVII. Relationship between some Haematological Variables and Cerebral Blood Flow Velocities among HbSS

R R² B P value

RTICA

HB -0.396 0.156 -9.640 < 0.001*

WBC 0.127 0.016 0.111 0.024*

Platelet 0.303 0.092 0.059 < 0.001*

SPO2 -0.486 0.236 -6.811 < 0.001*

LTICA

HB -0.332 0.110 -7.753 < 0.001*

WBC 0.151 0.023 0.127 0.007*

Platelet 0.285 0.081 0.053 < 0.001*

SPO2 -0.485 0.235 -6.509 < 0.001*

RTMCA

HB -0.410 0.168 -10.440 < 0.001*

WBC 0.144 0.021 0.132 0.010*

Platelet 0.357 0.127 0.073 < 0.001*

SPO2 -0.548 0.300 -8.026 < 0.001*

LTMCA

HB -0.366 0.134 -8.795 < 0.001*

WBC 0.160 0.026 0.138 0.004^*

Platelet 0.290 0.084 0.056 < 0.00*1

SPO2 -0.488 0.238 -6.754 < 0.001*

Table XVII (cont’d). Relationship between some Haematological Variables and Cerebral Blood Flow Velocities among HbSS

R R² B P value

RTACA

HB -0.215 0.046 -5.208 < 0.001*

WBC 0.069 0.005 0.060 0.222

Platelet 0.142 0.020 0.028 0.012*

SPO2 -0.267 0.071 -3.728 < 0.001*

LTACA

HB -0.243 0.059 -5.853 < 0.001*

WBC 0.084 0.007 0.072 0.139

Platelet 0.149 0.022 0.029 0.008*

SPO2 -0.348 0.121 -4.827 < 0.001*

Mean TAMMV

HB -0.463 0.215 -7.948 < 0.001*

WBC 0.173 0.030 0.107 0.002*

Platelet 0.361 0.130 0.049 < 0.001*

SPO2 -0.619 0.383 -6.109 < 0.001*

Keys: *: Statistically significant R: Correlation of coefficient R^2: coefficient of determination B: Regression coefficient Mean TAMMV: mean time averaged mean of the maximal velocities

Table XVIII. Multivariate Linear Regression Results showing the Determinants of Changes of Cerebral Blood Flow Velocities in the Study Population

R R² B P value

TAMMV

HB -3.746 0.002*

WBC 0.054 0.050

Platelet 0.648 0.420 0.007 0.322

SPO2 -4.949 < 0.001*

PCV 0.390 0.353

Keys:

*: Statistically significant R: Correlation of coefficient R^2: coefficient of determination B: Regression coefficient Mean TAMMV: mean time averaged mean of the maximal velocities.

Relationship between some haematological variables and cerebral blood flow velocities in the individual major intracranial vessels among HbAA

The table XIX shows the relationship between clinical, haematological variables and cerebral blood flow velocities: ICA; MCA; ACA; and mean TAMMV among the controls. It shows a significant negative but weak correlation between haemoglobin and right internal carotid artery (P <0.001, R = -0.306, R²= 0.094, B = -3.309). Similarly total white cell count had significant negative but weak relationship with left internal carotid artery (P <0.001, R = -0.267, R²= 0.071, B = -1.483). Other predictors include: platelet on right middle carotid artery (B = 0.035, p = 0.05); total white cell count on left middle carotid artery (B = -0.833, p < 0.001); total white cell count (B = 1.089, p < 0.001)and platelet (B = 0.038, p < 0.001) on right anterior carotid artery; haemoglobin and RTICA (B = -2.750, p <0.001); total white cell count on LTACA(B = -0.642, p < 0.001). Furthermore, there was significant relationships between haemoglobin (p <

0.001) and mean TAMMV in HBAA group. Similarly there was a statistically significant difference between platelet (P = 0.029) and mean TAMMV. When these two significant independent variables were included in a multiple regression model, only haemoglobin retained its statistical significance for the HBAA children with standardized beta coefficient of -2.261 as shown in table XX. The model accounted for just 7.3% of the changes in the cerebral blood flow velocities (R²= 0.073).

Table XIX. Relationship between some Haematological Variables and Cerebral Blood Flow Velocities among HbAA Group

R R² B P value

RTICA

HB -0.306 0.094 -3.309 < 0.001^*

WBC 0.041 0.002 -0.264 0.466

Platelet 0.059 0.004 0.014 0.294

SPO2 0.041 0.002 0.305 0.470

LTICA

HB 0.099 0.010 0.926 0.079

WBC -0.267 0.071 -1.483 < 0.001*

Platelet 0.015 0.000 0.003 0.790

SPO2 0.105 0.011 0.679 0.062

RTMCA

HB 0.409 0.167 4.222 0.533

WBC 0.026 0.001 0.159 0.647

Platelet 0.157 0.025 0.035 0.005*

SPO2 0.012 0.000 -0.087 0.829

LTMCA

HB 0.083 0.007 0.872 0.140

WBC -0.134 0.018 -0.833 0.017*

Platelet 0.089 0.008 0.020 0.115

SPO2 0.036 0.001 0.258 0.527

Keys:

*: Statistically significant R: Correlation of coefficient R^2: coefficient of determination B: Regression coefficient Mean TAMMV: mean time averaged mean of the maximal velocities

Table XIX (Cont’d.) Relationship between some Haematological Variables and Cerebral Blood Flow Velocities among HbAA Group

R R² B P value

RTACA

HB -0.267 0.071 -2.750 < 0.001*

WBC 0.178 0.032 1.089 0.002*

Platelet 0.171 0.029 0.038 0.002*

SPO2 0.052 0.003 -0.367 0.362

LTACA

HB 0.103 0.011 0.973 0.067

WBC 0.115 0.013 -0.642 0.042*

Platelet 0.089 0.008 0.018 0.113

SPO2 0.035 0.001 0.226 0.538

Mean TAMMV

HB -0.270 0.073 -2.176 < 0.001*

WBC 0.069 0.005 -0.329 0.223

Platelet 0.123 0.015 0.022 0.029*

SPO2 0.030 0.001 0.169 0.591

Keys:

*: Statistically significant R: Correlation of coefficient R^2: coefficient of determination B: Regression coefficient Mean TAMMV: mean time averaged mean of the maximal velocities

Table XX. Multivariate Linear Regression Results Showing the Determinants of Changes of Cerebral Blood Flow Velocities in the Controls

R R² B p value

TAMMV

HB 0.271 0.073 -2.261 < 0.001^*

Platelet 0.004 0.745

Keys:

*: Statistically significant R: Correlation of coefficient R^2: coefficient of determination B: Regression coefficient TAMMV: Time averaged mean of the maximal velocities Hb: Haemoglobin

The association between categories of cerebral blood flow velocity and some variables among the subjects

The pattern of cerebral flow velocities was categorized into standard or normal, conditional and high velocities according to Adams’s criteria¹⁶ and was thus compared with some variables [gender, age, socio-economic class platelet, SaO2 and history of acute chest] as shown in table XXI.

The table shows that 81(46.8%), 64(55.7%) and 12(44.4%) of the male subjects were classified in the standard, conditional and high risk categories respectively; while the female subjects had 92(53.2%), 51(44.3%) and 15(55.6%) respectively in those categories. These proportions were not statistical significant. Additionally, there was no significant association between age groups, socio-economic class and the category of flow velocities (𝜒²= 13.413, P = 0.098; 𝜒²= 0.646, P = 0.724). Platelet, SPO2 and acute chest were significantly associated with category of flow velocities (P< 0.001). Abnormal platelet and acute chest syndrome were more associated with conditional and high risk patterns of flow velocities. All the subjects with normal SPO2 were in the standard risk category while 115(100%) and 27(100%) subjects with abnormal SPO2 were in the conditional and high risk categories respectively.

Table XXI. Association between Categories of Cerebral Blood Flow Velocity and some Variables among the Subjects

Standard risk n (%)

Conditional risk n (%)

High risk n (%)

𝜒² p value

Sex

Male 81 (46.8) 64 (55.7) 12 (44.4) 2.499 0.287

Female 92 (53.2) 51 (44.3) 15 (55.6)

Age (months)

24 – 59 80 (59.7) 47 (35.1) 7 (5.2) 13.413 0.098

60 – 95 30 (40.5) 36 (48.6) 8 (10.8)

96– 131 29 (54.7) 17 (32.1) 7 (13.2)

132 – 168 29 (60.4) 14 (29.2) 14 (29.2)

169 – 196 5 (83.3) 1 (16.7) 1 (16.7)

SEC

Lower 123 (71.1) 85 (73.9) 18 (66.7) 0.646 0.724

Upper 50 (28.9) 30 (26.1) 9 (33.3)

Platelet group

Normal 104 (60.1) 17 (14.8) 5 (18.5) 64.830 < 0.001^*

Abnormal 69 (39.9) 98 (85.2) 22 (81.5)

SPO2

Normal 91 (52.6) 0 (0.0) 0 (0.0) 105.038 < 0.001*

Abnormal 82 (47.4) 115 (100.0) 27 (100.0) History of

Acute chest syndrome

Yes 8 (4.6) 13 (11.3) 10 (37.0) 28.091 < 0.001*

No 165 (95.4) 102 (88.7) 17 (63.0)

*: Statistically significant

Correlation of Blood Pressure with Cerebral Blood Flow Velocities in Subjects and Controls

There was a significant positive correlation between the systolic (P<0.001; r =0.400) and diastolic blood pressure (P<0.001; r =0.397) and TAMMV in the subjects as shown in table XXII below.

However there was no statistical significant difference between the systolic (P= 0.332; r= -0.055) and diastolic blood pressures (P =0.106; r = -0.091) among the controls as depicted below.

Table XXII: Correlation of Blood Pressure with Cerebral Blood Flow Velocities in Subjects and Controls

TAMMV

P value Pearson correlation coefficient (r) Subject

Systolic BP < 0.001* 0.400

Diastolic BP < 0.001* 0.397

Control

Systolic BP 0.332 -0.055

Diastolic BP 0.106 -0.091

Keys: *: Statistically significant BP: Blood pressure

Correlation of Blood Pressure with Cerebral Blood Flow Velocities between Male and Female in Subjects

The table XXIII below depicts that there was a significant positive correlation of blood pressure (both systolic and diastolic) with TAMMV between the male and female among subjects (P>0.05).

Thus as the systolic and diastolic blood pressure increases, the cerebral blood flow velocities increases in both male and female subjects as shown in the table XXIII below.

Table XXIII: Correlation of Blood Pressure with Cerebral Blood Flow Velocities between Male and Female in Subjects

Subjects

TAMMV

P value Pearson correlation coefficient (r) Male

Systolic BP < 0.001* 0.289

Diastolic BP < 0.001* 0.316

Female

Systolic BP < 0.001* 0.520

Diastolic BP < 0.001* 0.502

Keys: *: Statistically significant BP: Blood pressure

Correlation of Blood Pressure with Cerebral Blood Flow Velocities between Male and Females in Controls

The table XXIV below depicts that there was no statistical significant difference in the correlation of blood pressure (both systolic and diastolic) with TAMMV between the male and female among controls except in the males who has significant positive correlation (P>0.05).

Table XXIV: Correlation of Blood Pressure with Cerebral Blood Flow Velocities between Male and Females in Controls

Controls

TAMMV

P value Pearson correlation coefficient (r) Male

Systolic BP 0.052 -0.155

Diastolic BP 0.024* -0.180

Female

Systolic BP 0.354 0.074

Diastolic BP 0.574 0.045

Keys: *: Statistically significant BP: Blood pressure

Correlation of Blood Pressure with Cerebral Blood Flow Velocities among Different Age Groups in Subjects

There was a significant positive correlation of blood pressure (systolic and diastolic) with TAMMV among the different age groups in the subjects except for those within 167-196 months(P<0.05) as shown in table XXV. Thus as the blood pressure increases, the cerebral blood flow velocities increases across the different age groups except for the age group of 167-196 months.

Table XXV: Correlation of Blood Pressure with Cerebral Blood Flow Velocities among Different Age Groups in Subjects

Subjects (age groups in months)

TAMMV

P value Pearson correlation coefficient (r)

24-59

Systolic BP < 0.001* 0.590

Diastolic BP < 0.001* 0.487

60-95

Systolic BP < 0.001* 0.520

Diastolic BP < 0.001* 0.416

96-131

Systolic BP < 0.001* 0.491

Diastolic BP < 0.001* 0.610

132-167

Systolic BP < 0.004* 0.413

Diastolic BP < 0.001* 0.532

168-196

Systolic BP 0.182 0.628

Diastolic BP 0.573 0.293

Keys: *: Statistically significant BP: Blood pressure

Correlation of Blood Pressure with Cerebral Blood Flow Velocities among Different Age Groups in Controls

There was a significant positive correlation of systolic and diastolic blood pressure with TAMMV among the age group of 24-59 months [(P=0.001; r=0.0527): (P=0.001; r=0.414) respectively] and only systolic blood pressure among those within 132-167 months (P=0.020;r=0.0347) as shown in table XVI below.

Table XVI: Correlation of Blood Pressure with Cerebral Blood Flow Velocities among Different Age Groups in Controls

Controls (age groups in months)

TAMMV

P value Pearson correlation coefficient (r)

24-59

Systolic BP < 0.001* 0.527

Diastolic BP < 0.001* 0.414

60-95

Systolic BP 0.332 -0.115

Diastolic BP 0.759 -0.037

96-131

Systolic BP 0.093 -0.231

Diastolic BP 0.100 -0.226

132-167

Systolic BP 0.020* 0.347

Diastolic BP 0.955 -0.009

168-196

Systolic BP 0.201 0.607

Diastolic BP 0.800 -0.134

Keys: *: Statistically significant BP: Blood pressure

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