One hundred and seventeen preterm infants < 33 weeks GA who had significant hypotension were enrolled in the study; 38 (32.5%) died and 79 (67.5%) survived. Table 1 showed comparison of the descriptive data between both groups. The groups had similar birth weights and gestational ages. Nine infants presented initially with lactic acidosis, 4 with oliguria and 8 with both, and 96 infants presented initially with hypotension. Infants who died have developed shock at an earlier postnatal age day 2 (1–8) vs. day 4 (1–14) (p < 0.05), and had a significantly higher VIS (median, IQR): 28 (12, 37) vs. 10(7, 18) (p < 0.0001) compared to those who recovered. Infant who died also had a higher fraction of inspired oxygen (FIO2) at the time of the highest recorded VIS 0.45(0.36–0.65) vs. 0.4(0.3–0.5) (p < 0.05) and lower serum cortisol level 294(196–739) vs. 1640(383–1750) (p < 0.05). VIS value had an area under the curve of 0.73 (95% CI 0.85–0.98, p < 0.001). A VIS value cut off of ≥ 25 has sensitivity and specificity of 66% and 92%, and positive and negative predictive values of 78.5% and 83%, respectively, Fig. 1 shows the receiver operator curve.
Table 1
Descriptive data of the studied groups presented as median (IQR) and percentages, p-value is bold when significant
| Hypotension in survivals N = 79(67.5%) | Hypotensive shock with death N = 38(32.5%) | p value |
GA (wk) | 26 (25–29) | 25(24–27) | 0.07 |
Birth Weight (g) | 860(740–1200) | 856(766–1056) | 0.2 |
Male Sex | 45(57%) | 26(68%) | 0.5 |
Antenatal steroids | 51(64%) | 23(60%) | 0.6 |
Age at presentation (days) | 4(1–14) | 2(1–8) | < 0.05 |
Systolic blood pressure (mmHg) | 33(29–37) | 34(30–38) | 0.3 |
Mean blood pressure (mmHg) | 25(22–27) | 24(21–25) | 0.07 |
Diastolic blood pressure (mmHg) | 18(17–22) | 17(15–19) | 0.12 |
Urine output hours (ml/kg/hr) | 2.6(1.3–4.2) | 3(1.7-4) | 0.1 |
Lactic acid hours (mmol/l) | 1.9(1.2–3.4) | 2.6(1.2–5.1) | 0.7 |
Confirmed Infection | 26(32%) | 13(34%) | 0.6 |
Vasoactive inotropic score (Highest) | 10(7–18) | 28(12–37) | < 0.0001 |
Cumulative exposure to CVS medications VISct | 312(116–912) | 388(172–2088) | < 0.01 |
Cumulative time of CSC (hours) | 72(24–120) | 62(24–121 | 0.9 |
Serum cortisol level | 1640(383–1750) | 294(196–739) | < 0.05 |
Fraction of inspired oxygen | 0.4(0.3–0.5) | 0.45(0.36–0.65) | < 0.05 |
IVH (any grade) | 47 (59%) | 24 (63%) | 0.3 |
A multivariate analysis was conducted and shows significant difference between survivors and infants who died before discharge on variables GA, VIS, hours of CSC, confirmed infection and VISct with Wilk’s Lambda = 0.75, F (4-112) = 9.3 p = 0.0001 partial ŋ2 =0.25. A separate ANOVA was conducted for each dependent variable, with each ANOVA evaluated at an alpha level of 0.05, both VIS and VISct were significantly higher in the non survivors (M of VISct = 1827), (M of VIS = 46) compared to survivors (M of VISct = 850), (M of VIS = 12), p < 0.05, partial ŋ2=0.04 for VISct and p < 0.0001, partial ŋ2=0.18 for VIS. There was no significat difference in GA (p = 0.13, partial ŋ2=0.02), there was no significant difference in hours with CSC between survival and non survival group (p = 0.9, partial ŋ2=0.0001). Figure 2 shows Cox proportional of death of infants with VIS ≥ 25 compared to infants with VIS < 25 and in relation to exposure time to cardiovasculr drugs. Table 2 and Fig. 3 show the assoctation beween infants with VIS who either dead or survived with the following variables:, lactic acid, urine output, systolic blood pressure, diastolic blood pressure, mean blood pressures, serum cortisol levels, gestational age, and Apgar scores, there was signifcant correlation with lactic acid, urine output, systolic blood pressure, gestaional age, and serum cortisol level. Higher percent of cases underwent delayed cord claming was assocaited with VIS < 25, which was not the case with the percent of cases with confirmed infection Fig. 4.
Table 2
Correlation between duration of VIS ≥ 25 in infants who dead, and physiologic parameters:
parameters | CORRELATION |
R | p-value |
Lactic acid | 0.68 | 0.008** |
Unrine output | 0.64 | 0.041* |
SYSTOLIC BLOOD PRESSURE | 0.59 | 0.043* |
DIASTOLIC BLOOD PRESSURE | 0.79 | 0.022* |
MEAN BLOOD PRESSURE | 0.54 | 0.068 |
SERUM CORTISOL LEVEL | 0.71 | 0.032* |