Systemic hypothermia to decrease morbidity of hypoxic-ischemic brain injury

Genetic Polymorphisms, Gene-Gene Interactions and Neurologic Sequelae at Two Years Follow-Up in Newborns with Hypoxic-Ischemic Encephalopathy Treated with Hypothermia

Inflammation and oxidative stress after hypoxic-ischemic brain injury may be modified by genetic variability in addition to therapeutic hypothermia. The aim of our study was to evaluate the association between the polymorphisms in genes of antioxidant and inflammatory pathways in newborns treated with therapeutic hypothermia and the development of epilepsy or CP at two years follow-up. The DNA of 55 subjects was isolated from buccal swabs. Genotyping using competitive allele-specific PCR was performed for polymorphisms in antioxidant (SOD2 rs4880, CAT rs1001179, GPX1 rs1050450) and inflammatory (NLRP3 rs35829419, CARD8 rs2043211, IL1B rs1143623, IL1B rs16944, IL1B rs10716 76, TNF rs1800629) pathways. Polymorphic CARD8 rs2043211 T allele was less frequent in patients with epilepsy, but the association was not statistically significant. The interaction between CARD8 rs2043211 and IL1B rs16944 was associated with epilepsy after HIE: CARD8 rs2043211 was associated with lower epilepsy risk, but only in carriers of two normal IL1B rs16944 alleles (OR_adj = 0.03 95% CI = 0.00–0.55; p_adj = 0.019). Additionally, IL1B rs16944 was associated with higher epilepsy risk only in carriers of at least one polymorphic CARD8 rs2043211 (OR_adj = 13.33 95% CI = 1.07–166.37; p_adj = 0.044). Our results suggest that gene–gene interaction in inflammation pathways might contribute to the severity of brain injury in newborns with HIE treated with therapeutic hypothermia.

Immediate Remote Ischemic Postconditioning Reduces Brain Nitrotyrosine Formation in a Piglet Asphyxia Model

Remote ischemic postconditioning (RIPostC) is a promising therapeutic intervention that could be administered as an alternative to cooling in cases of perinatal hypoxia-ischemia (HI). In the current study we hypothesized that RIPostC in the piglet model of birth asphyxia confers protection by reducing nitrosative stress and subsequent nitrotyrosine formation, as well as having an effect on glial immunoreactivity. Postnatal day 1 (P1) piglets underwent HI brain injury and were randomised to HI (control) or HI + RIPostC. Immunohistochemistry assessment 48 hours after HI revealed a significant decrease in brain nitrotyrosine deposits in the RIPostC-treated group (p = 0.02). This was accompanied by a significant increase in eNOS expression (p < 0.0001) and decrease in iNOS (p = 0.010), with no alteration in nNOS activity. Interestingly, RIPostC treatment was associated with a significant increase in GFAP (p = 0.002) and IBA1 (p = 0.006), markers of astroglial and microglial activity, respectively. The current study demonstrates a beneficial effect of RIPostC therapy in the preclinical piglet model of neonatal asphyxia, which appears to be mediated by modulation of nitrosative stress, despite glial activation.

Effects of therapeutic hypothermia on multiorgan dysfunction in asphyxiated newborns: whole-body cooling versus selective head cooling

OBJECTIVE

Multiorgan dysfunction in asphyxiated newborns receiving therapeutic hypothermia achieved by either selective head cooling (SHC) or whole-body cooling (WBC) has not been well characterized. The beneficial effect of SHC in organs other than the brain may potentially be limited because unlike WBC, SHC aims to achieve effective brain cooling with less-systemic hypothermia. However, the relative effects of SHC and WBC with currently available cooling protocols on multiorgan dysfunction are unknown.The aim of this study was to compare the multiorgan dysfunction in infants receiving therapeutic hypothermia induced by either SHC or WBC.

STUDY DESIGN

In 59 asphyxiated newborns who received therapeutic hypothermia by either SHC (n=31) or WBC (n=28), the severity of pulmonary, hepatic and renal dysfunction and coagulopathy and electrolyte disturbances were assessed before the start of cooling (baseline), and at specific time intervals (24, 48 and 72 h) throughout cooling. Enrollment criteria, clinical monitoring and treatment during cooling, whether SHC or WBC, were similar, as reported earlier.

RESULT

The presence of clinical respiratory distress, along with the need for ventilatory support for varying duration during cooling, was similar in both the WBC and SHC groups (100 vs 94%, P=0.49, OR 1.9, 95% CI 1.5-2.5). The use of fresh frozen plasma and platelet transfusion to treat coagulopathy and thrombocytopenia was similar (WBC 48% vs SHC 58%, P=0.59, OR 0.7, 95% CI 0.2-1.9, and WBC 41% vs SHC 32%, P=0.58, OR 1.4, 95% CI 0.5-4.2, respectively), and equivalent numbers of infants from both groups were treated with vasopressors for >24 h (WBC 59% vs SHC 55%, P=0.79, OR 1.2, 95% CI 0.4-3.4). The incidence of oliguria (urine output <0.5 ml kg(-1) h(-1) for >24 h after birth) and rising serum creatinine (with maximum serum creatinine >0.9 mg dl(-1)) was also similar (WBC 18% vs SHC 39%, P=0.15, OR 0.4, 95% CI 0.1-1.3, and WBC 48% vs SHC 58%, P=0.59, OR 0.7, 95% CI 0.2-1.9, respectively). Laboratory parameters to assess the differential effect of WBC versus SHC on multiorgan dysfunction during 72 h of cooling, which include serum transaminases (serum aspartate aminotransferase and alanine aminotransferase), prothrombin time, partial thromboplastin time, INR, platelet counts, serum creatinine, serum sodium, serum potassium and serum calcium, were similar between the groups at the initiation of cooling and did not differ with the method of cooling.

CONCLUSION

Multiorgan system dysfunction in asphyxiated newborns during cooling remains similar for both cooling methods. Concerns regarding a differential effect of WBC versus SHC on multiorgan dysfunction, other than of the brain, should not be a consideration in selecting a method to produce therapeutic hypothermia.