Serial Carboxyhemoglobin Levels and Its Relationship with Late Onset Sepsis in Preterm Infants: An Observational Cohort Study

Carboxyhemoglobin as biomarker of late-onset sepsis in preterm infants

Carboxyhemoglobin (COHb) is considered a biomarker of oxidative stress and previous studies reported an increase in COHb levels in preterm infants who develop late-onset sepsis (LOS). Our aim was to assess the correlation between COHb levels and the risk for LOS development. We retrospectively studied 100 preterm infants, 50 in the LOS and 50 in the no LOS group. COHb levels were measured on the day of diagnosis of the first episode of LOS, 3, 2, and 1 days before and 1 and 4 days after the onset of LOS. Logistic regression analysis showed that a higher level of COHb 2 days before the diagnosis of LOS increases the risk for LOS development (OR 12.150, 95% Cl 1.311-12.605; P = 0.028). A COHb level of 1.55% measured 2 days before the diagnosis of LOS is the best predictive threshold for LOS with a sensitivity of 70% and a specificity of 70%.    Conclusion: Increased levels of COHb may predict the diagnosis of LOS in very preterm infants with a good accuracy. If further studies confirm our findings, this easy-to-measure biomarker could provide neonatologists with another tool for monitoring and early diagnosis of sepsis in high-risk patients. What is Known: • Carboxyhemoglobin (COHb) is a biomarker of oxidative stress. • Previous studies reported an increase in COHb levels in preterm infants who develop late-onset sepsis (LOS). What is New: • COHb levels increased two days before the diagnosis of LOS and this increase was associated with the risk for developing LOS. • ROC curve analysis for COHb measured two days before the diagnosis of LOS showed that 1.55% is the best predictive threshold for LOS with a sensitivity of 70% and a specificity of 70%.

Carboxyhemoglobin as biomarker of prematurity complications

BACKGROUND

Carboxyhemoglobin (COHb) is considered a biomarker of oxidative stress and previous studies suggest a correlation between its blood level and prematurity complications. Our aim in this study was to assess the correlation between COHb levels and the risk for bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), and retinopathy of prematurity (ROP).

METHODS

We retrospectively studied 178 preterm infants with gestational age of 27.0 ± 1.5 weeks, among which 121 (68 %) had BPD, 43 (24 %) IVH, and 33 (19 %) ROP. COHb levels measured during the first seven days of life were recorded.

RESULTS

Logistic regression analysis showed that higher levels of COHb on the seventh day of life increases the risk for moderate-to-severe BPD (OR 4.552, 95 % Cl 1.220-16.997; P = 0.024), while higher levels of COHb on the fourth day of life increases the risk for grade 2-4 IVH (OR 5.537, 95 % Cl 1.602-19.134; P = 0.007).

CONCLUSIONS

COHb measured in the first week of life can contribute to predicting the risk for BPD and IVH, but not for ROP, in very preterm infants. Since COHb can be readily measured, its assessment can be useful in clinical practice for early identification of preterm infants at high risk for oxidative stress related complications.

Carboxyhemoglobin Levels in Preterm Neonatal Late-Onset Sepsis: to Predict or not to Predict

Background

In this study, we aimed to evaluate carboxyhemoglobin (COHb) levels in diagnosing late-onset sepsis (LOS) in preterm neonates.

Methods

The records of culture-positive LOS in preterm neonates hospitalized in NICU from January 2017 to July 2022 were reviewed. COHb levels, C-reactive protein, procalcitonin, and neutrophil to lymphocyte ratio of septic preterm infants were compared to controls. In addition, serial COHb levels measured within six hours before or 24h after blood culture sampling, three to seven days prior, and three to five days after starting antimicrobial therapy were retrieved from patient records.

Results

The study included 77 blood-culture-positive preterm infants and 77 non-septic controls. During the LOS episode, the COHb values were found to be significantly increased (median: 1.8, IQR: 1.4-2.5) when compared to the control group (median: 1.2, IQR: 0.8-1.6) (p < 0.001). ROC analysis yielded an AUC of 0.714 for COHb (95% CI: 0.631-0.796, p<0.001). At an optimal cut-off of >1.5%, the test's sensitivity was 64.94%, the specificity was 72.73%, the positive predictive value was 70.42%, and the negative predictive value was 67.47%. LOS led to a dramatic rise followed by a decrease after the initiation of the antimicrobial therapy [1.8 (1.4-2.5)] vs. [1.45 (0.2-4)] p<0.001.

Conclusion

COHb levels increased at the beginning of LOS, decreasing in response to antibiotics. When used in conjunction with other sepsis biomarkers, the variation of COHb can be important in evaluating late-onset sepsis episodes in preterm infants.

Higher ETCOc predicts longer phototherapy treatment in neonatal hyperbilirubinemia

Objective

This study aimed to evaluate the predictive performance of end-tidal carbon monoxide corrected to ambient carbon monoxide (ETCOc) values phototherapy in neonates with significant hyperbilirubinemia.

Methods

A prospective study was conducted on neonates with significant hyperbilirubinemia who received phototherapy between 3 and 7 days of life. The breath ETCOc and serum total bilirubin of the recruited infants were measured on admission.

Results

The mean ETCOc at admission in 103 neonates with significant hyperbilirubinemia was 1.70 ppm. The neonates were categorized into two groups: phototherapy duration ≤72 h (n = 87) and >72 h (n = 16) groups. Infants who received phototherapy for >72 h had significantly higher ETCOc (2.45 vs. 1.60, P = 0.001). The cutoff value of ETCOc on admission for predicting longer phototherapy duration was 2.4 ppm, with a sensitivity of 62.5% and specificity of 88.5%, yielding a 50% positive predictive value and a 92.7% negative predictive value.

Conclusion

ETCOc on admission can help predict the duration of phototherapy in neonates with hyperbilirubinemia, facilitate clinicians to judge disease severity, and make clinical communication easier and more efficient.

Retrospective evaluation of carboxyhemoglobin and methemoglobin levels in dogs and cats with respiratory disease

OBJECTIVE

To evaluate carboxyhemoglobin (COHb) and methemoglobin (MetHb) levels in dogs and cats with respiratory disease in the ICU.

DESIGN

Retrospective study.

SETTING

University veterinary teaching hospital.

ANIMALS

The ICU census was searched for dogs (n = 466) and cats (n = 97) hospitalized within the ICU between January 2016 and January 2019 in whom blood gas with co-oximetry was performed. Dogs and cats were stratified into those with primary respiratory and nonrespiratory categories; the underlying cause of the disease was also noted. Venous blood gas, co-oximeter, PaO₂ /FiO₂ (PF ratio), physical examination findings, and outcome were recorded.

MEASUREMENTS AND MAIN RESULTS

The median COHb and MetHb in dogs hospitalized in the ICU were 2.6% (0.1%-5.6%) and 1.1% (0.1%-2.9%), respectively. The median COHb and MetHb in cats hospitalized in the ICU were 2.2% (0.1%-5.4%) and 1.0% (0%-2.1%), respectively. Dogs with respiratory disease had a higher COHb than dogs without respiratory disease (median, 2.7% [range, 0.3%-5.0%] vs. 2.5% [0.1%-5.6%]; P = 0.0148). COHb was positively associated with survival in cats (median, 2.2% [range, 0.1%-5.4%] vs. 1.9% [0.1%-3.9%]; P = 0.0433). Both COHb and MetHb were higher in septic dogs than in nonseptic dogs (median COHb, 2.8% [range 0.3%-4.5%] vs. 2.6% [0.1%-5.6%]; P = 0.02 and median MetHb, 1.1% [0.1%-2.9%] vs. 1.1% [0.1%-2.4%]; P = 0.01, respectively).

CONCLUSIONS

There may be a positive association between COHb and respiratory disease in dogs; prospective studies are needed to evaluate this further. No association between COHb and respiratory disease in cats or MetHb and respiratory disease in either species was detected. Additional prospective studies are needed to determine whether COHb and MetHb are biomarkers for sepsis in dogs and whether COHb is an indicator of mortality in cats.

Carboxyhaemoglobin levels and free-radical-related diseases in prematurely born infants

BACKGROUND

Carboxyhaemoglobin (COHb) levels may reflect the level of early oxidative stress which plays a role in mediating free-radical-related diseases in prematurely born infants.

AIM

To assess the relationship of COHb levels in the first seven days of after birth to the development of bronchopulmonary dysplasia (BPD) and other free-radical-related diseases.

STUDY DESIGN

Retrospective analysis of routinely performed COHb via blood gas samples of infants born at less than 30 weeks of gestation admitted to a tertiary neonatal intensive care unit was undertaken.

SUBJECTS

One hundred and four infants were included with a median (range) gestational age of 27.4 (22.4-29.9) weeks and a birthweight of 865 (395-1710) grams.

OUTCOMES

The maximum COHb per infant per day was recorded for the first 28 days and BPD and other free-radical-related diseases including intraventricular haemorrhage (IVH) were noted. The severity of BPD, requirement for home oxygen on discharge and survival to discharge were also recorded.

RESULTS

Infants who developed BPD (n = 76) had significantly higher COHb levels in the first seven days [1.7% (0.3-6.8)] compared to those that did not develop BPD [1.6% (0.9-3.8); p = 0.001]. Higher COHb levels in the first seven days after birth were also observed in infants with grade three/four IVH [n = 20; 1.9% (1.0-6.8)] compared to those without [1.6% (0.3-5.6); p < 0.001]. COHb levels, however, were not associated with the duration of ventilation, BPD severity or survival to discharge.

CONCLUSION

Higher COHb levels in prematurely born infants were associated with the development of BPD and IVH.