Unreliable Early Neuroprognostication After Severe Carbon Monoxide Poisoning Is Likely Due to Cytopathic Hypoxia: A Case Report and Discussion

A 17-year-old girl was found unconscious in a running vehicle. She developed very severe acute respiratory distress syndrome (which was treated with rescue high-frequency oscillation), hemodynamic instability, acute kidney injury, rhabdomyolysis, and remained comatose with a Glasgow Coma Scale score of 3 and gasping respirations for 67 hours (when the Glasgow Coma Scale score improved to 6, with tachypnea to Paco ₂ 28 and pH 7.5). By 92 hours, she was obeying commands, and she was extubated at 96 hours, shortly after which she was conversing with family and texting on her phone. A magnetic resonance imaging (MRI) scan 6 days after being found showed subacute infarctions affecting the medial aspect of the globus pallidus bilaterally as well as a small cortical/subcortical infarction in the right parietal lobe. At a 7-week follow-up, she had no delayed-onset signs of brain injury. This case demonstrated that neurologic prognostication after carbon monoxide poisoning may be unreliable for more than 72 hours after injury. We discuss that it is possible that the mitochondrial dysfunction induced by carbon monoxide was responsible for a functional coma without irreversible brain injury, similar to the mechanism of cytopathic hypoxia in multiple-organ dysfunction that allows some other organ recovery without necrosis in survivors.

Nutritional support for critically ill children

BACKGROUND

Nutritional support in the critically ill child has not been well investigated and is a controversial topic within paediatric intensive care. There are no clear guidelines as to the best form or timing of nutrition in critically ill infants and children. This is an update of a review that was originally published in 2009. .

OBJECTIVES

The objective of this review was to assess the impact of enteral and parenteral nutrition given in the first week of illness on clinically important outcomes in critically ill children. There were two primary hypotheses:1. the mortality rate of critically ill children fed enterally or parenterally is different to that of children who are given no nutrition;2. the mortality rate of critically ill children fed enterally is different to that of children fed parenterally.We planned to conduct subgroup analyses, pending available data, to examine whether the treatment effect was altered by:a. age (infants less than one year versus children greater than or equal to one year old);b. type of patient (medical, where purpose of admission to intensive care unit (ICU) is for medical illness (without surgical intervention immediately prior to admission), versus surgical, where purpose of admission to ICU is for postoperative care or care after trauma).We also proposed the following secondary hypotheses (a priori), pending other clinical trials becoming available, to examine nutrition more distinctly:3. the mortality rate is different in children who are given enteral nutrition alone versus enteral and parenteral combined;4. the mortality rate is different in children who are given both enteral feeds and parenteral nutrition versus no nutrition.

SEARCH METHODS

In this updated review we searched: the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 2); Ovid MEDLINE (1966 to February 2016); Ovid EMBASE (1988 to February 2016); OVID Evidence-Based Medicine Reviews; ISI Web of Science - Science Citation Index Expanded (1965 to February 2016); WebSPIRS Biological Abstracts (1969 to February 2016); and WebSPIRS CAB Abstracts (1972 to February 2016). We also searched trial registries, reviewed reference lists of all potentially relevant studies, handsearched relevant conference proceedings, and contacted experts in the area and manufacturers of enteral and parenteral nutrition products. We did not limit the search by language or publication status.

SELECTION CRITERIA

We included studies if they were randomized controlled trials; involved paediatric patients, aged one day to 18 years of age, who were cared for in a paediatric intensive care unit setting (PICU) and had received nutrition within the first seven days of admission; and reported data for at least one of the pre-specified outcomes (30-day or PICU mortality; length of stay in PICU or hospital; number of ventilator days; and morbid complications, such as nosocomial infections). We excluded studies if they only reported nutritional outcomes, quality of life assessments, or economic implications. Furthermore, we did not address other areas of paediatric nutrition, such as immunonutrition and different routes of delivering enteral nutrition, in this review.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the searches, applied the inclusion criteria, and performed 'Risk of bias' assessments. We resolved discrepancies through discussion and consensus. One author extracted data and a second checked data for accuracy and completeness. We graded the evidence based on the following domains: study limitations, consistency of effect, imprecision, indirectness, and publication bias.

MAIN RESULTS

We identified only one trial as relevant. Seventy-seven children in intensive care with burns involving more than 25% of the total body surface area were randomized to either enteral nutrition within 24 hours or after at least 48 hours. No statistically significant differences were observed for mortality, sepsis, ventilator days, length of stay, unexpected adverse events, resting energy expenditure, nitrogen balance, or albumin levels. We assessed the trial as having unclear risk of bias. We consider the quality of the evidence to be very low due to there being only one small trial. In the most recent search update we identified a protocol for a relevant randomized controlled trial examining the impact of withholding early parenteral nutrition completing enteral nutrition in pediatric critically ill patients; no results have been published.

AUTHORS' CONCLUSIONS

There was only one randomized trial relevant to the review question. Research is urgently needed to identify best practices regarding the timing and forms of nutrition for critically ill infants and children.

An evaluation of enteral feeding practices in critically ill children

BACKGROUND

Establishing and sustaining enteral feeding in critically ill children is challenging and has met with many problems.

AIMS AND OBJECTIVES

The aim of this study was to investigate (a) how actual calorie intake compared with estimated caloric requirements and (b) whether feeding guideline adherence resulted in improved nutritional intake.

DESIGN AND METHODS

A prospective observational study was undertaken over 1 month in a tertiary referral paediatric intensive care unit (PICU) in the northwest of England.

RESULTS

Forty-seven children were studied, with a wide range of diagnoses in a 1-month period. Only 47% of the children had enteral feeds started within our 6 h post-admission target. Over half (55%) of the children received less than half of their estimated calorie requirements, but if feeding guidelines were followed, this resulted in a significantly higher (p = 0.004) delivery of the child's estimated requirements.

CONCLUSIONS

This study found that many children are not receiving adequate nutrition in PICU and that the use of feeding guidelines significantly improves calorie delivery in PICU patients.

RELEVANCE TO CLINICAL PRACTICE

This paper highlights the dearth of research related to enteral feeding in critically ill children. We found that the use of feeding guidelines improved calorie delivery and so units should be encouraged to develop their own guidelines based on the best evidence available.

Nutritional support for critically ill children

BACKGROUND

Nutritional support in the critically ill child has not been well investigated and is a controversial topic within paediatric intensive care. There are no clear guidelines as to the best form or timing of nutrition in critically ill infants and children.

OBJECTIVES

To assess the impact of enteral and total parenteral nutrition on clinically important outcomes for critically ill children.

SEARCH STRATEGY

We searched: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 1); Ovid MEDLINE (1966 to February 2007); Ovid EMBASE (1988 to February 2007); OVID Evidence-Based Medicine Reviews; ISI Web of Science - Science Citation Index Expanded (1965 to February 2007); WebSPIRS Biological Abstracts (1969 to February 2007); and WebSPIRS CAB Abstracts (1972 to February 2007). We also searched trial registries; reviewed reference lists of all potentially relevant studies; handsearched relevant conference proceedings; and contacted experts in the area and manufacturers of enteral and parenteral nutrition products. We did not limit the search by language or publication status.

SELECTION CRITERIA

We included studies if they were randomized controlled trials; involved paediatric patients, aged one day to 18 years of age, cared for in a paediatric intensive care unit setting (PICU) and received nutrition within the first seven days of admission; and reported data for at least one of the pre-specified outcomes (30-day or PICU mortality; length of stay in PICU or hospital; number of ventilator days; and morbid complications, such as nosocomial infections). We excluded studies if they only reported nutritional outcomes, quality of life assessments, or economic implications. Furthermore, other areas of paediatric nutrition, such as immunonutrition and different routes of delivering enteral nutrition, were not addressed in this review.

DATA COLLECTION AND ANALYSIS

Two authors independently screened searches, applied inclusion criteria, and performed quality assessments. We resolved discrepancies through discussion and consensus. One author extracted data and a second checked data for accuracy and completeness.

MAIN RESULTS

Only one trial was identified as relevant. Seventy-seven children in intensive care with burns involving > 25% of the total body surface area were randomized to either enteral nutrition within 24 hours or after at least 48 hours. No statistically significant differences were observed for mortality, sepsis, ventilator days, length of stay, unexpected adverse events, resting energy expenditure, nitrogen balance, or albumin levels. The trial was assessed as of low methodological quality (based on the Jadad scale) with an unclear risk of bias.

AUTHORS' CONCLUSIONS

There was only one randomized trial relevant to the review question. Research is urgently needed to identify best practices regarding the timing and forms of nutrition for critically ill infants and children.

Mortality after neonatal cardiac surgery: Prediction from mean arterial pressure after rewarming in the operating room

OBJECTIVE

To examine the predictive contribution of mean arterial pressure after rewarming to > or =34 degrees C in the operating room to mortality after cardiac surgery in infants < or =6 weeks old.

METHODS

In this prospective inception cohort study, 70 consecutive infants who had open cardiac surgery with deep hypothermic circulatory arrest when < or =6 weeks old in the years 1996 to 1999 had follow-up to 5 years of age. Demographic, preoperative, operative, and postoperative variables were recorded prospectively. The previously unexplored variables of lowest mean arterial pressure in the operating room after rewarming to 34 degrees C were recorded retrospectively from anesthesia records. Predictor variables for death were examined using univariate and multivariate analyses.

RESULTS

Deep hypothermic circulatory arrest time, re-cardiopulmonary bypass in the operating room, duration of mean arterial pressure below 40, 35, 30, and 25 mm Hg after rewarming in the operating room, time for lactate to return to < or =2 mmol/L postoperatively, and cardiopulmonary resuscitation were significantly associated with death at 1 and 5 years of age on univariate analysis. Multivariate stepwise forward logistic regression analysis found the duration of mean arterial pressure after rewarming below 30 mm Hg (odds ratio 1.094; 95% confidence interval 1.033-1.158) and cardiopulmonary resuscitation (odds ratio 13.800, 95% CI 3.062-62.194) were significant predictors of death by 5 years of age. Stepwise multiple regression using pre- and intraoperative variables accounted for 30.1% of the variability related to mean arterial pressure < or =30 mm Hg after rewarming.

CONCLUSION

In these infants, low mean arterial pressure after rewarming in the operating room, even for brief times, is significantly associated with death.

Abnormal permeability of inner and outer mitochondrial membranes contributes independently to mitochondrial dysfunction in the liver during acute endotoxemia*

OBJECTIVE

This study was designed to determine the role played by the mitochondrial permeability transition in the pathogenesis of mitochondrial damage and dysfunction in a representative systemic organ during the acute phase of endotoxemia.

DESIGN

A well-established, normotensive feline model was employed to determine whether pretreatment with cyclosporine A, a potent inhibitor of the mitochondrial permeability transition, normalizes mitochondrial ultrastructural injury and dysfunction in the liver during acute endotoxemia.

SETTING

The Ohio State University Medical Center research laboratory.

SUBJECTS

Random source, adult, male conditioned cats.

INTERVENTIONS

Hemodynamic resuscitation and maintenance of acid-base balance and tissue oxygen availability were provided, as needed, to minimize the potentially confounding effects of tissue hypoxia and/or acidosis on the experimental results. Treatment groups received isotonic saline vehicle (control; n = 6), lipopolysaccharide (3.0 mg/kg, intravenously; n = 8), or cyclosporine A (6.0 mg/kg, intravenously; n = 6) or tacrolimus (FK506, 0.1 mg/kg, intravenously; n = 4) followed in 30 mins by lipopolysaccharide (3.0 mg/kg, intravenously). Liver samples were obtained 4 hrs posttreatment, and mitochondrial ultrastructure, function, and cytochrome c, Bax, and ceramide contents were assessed.

MEASUREMENTS AND MAIN RESULTS

As expected, significant mitochondrial injury was apparent in the liver 4 hrs after lipopolysaccharide treatment, despite maintenance of regional tissue oxygen availability. Namely, mitochondria demonstrated high-amplitude swelling and exhibited altered respiratory function. Cyclosporine A pretreatment attenuated lipopolysaccharide-induced mitochondrial ultrastructural abnormalities and normalized mitochondrial respiratory control, reflecting protection against inner mitochondrial membrane damage. However, an abnormal permeability of outer mitochondrial membranes to cytochrome c was observed in all lipopolysaccharide-treated groups and was associated with increased mitochondrial concentrations of Bax and ceramide.

CONCLUSIONS

These studies confirm that liver mitochondria are early targets of injury during endotoxemia and that inner and outer mitochondrial membrane damage occurs through different mechanisms. Inner mitochondrial membrane damage appears to relate to the mitochondrial permeability transition, whereas outer mitochondrial membrane damage can occur independent of the mitochondrial permeability transition. Preliminary evidence suggests that Bax may participate in lipopolysaccharide-induced outer mitochondrial membrane damage, but further investigations are needed to confirm this.