Indirect Calorimetry in Spontaneously Breathing, Mechanically Ventilated and Extracorporeally Oxygenated Patients: An Engineering Review

Indirect calorimetry (IC) is considered the gold standard for measuring resting energy expenditure (REE). This review presents an overview of the different techniques to assess REE with special regard to the use of IC in critically ill patients on extracorporeal membrane oxygenation (ECMO), as well as to the sensors used in commercially available indirect calorimeters. The theoretical and technical aspects of IC in spontaneously breathing subjects and critically ill patients on mechanical ventilation and/or ECMO are covered and a critical review and comparison of the different techniques and sensors is provided. This review also aims to accurately present the physical quantities and mathematical concepts regarding IC to reduce errors and promote consistency in further research. By studying IC on ECMO from an engineering point of view rather than a medical point of view, new problem definitions come into play to further advance these techniques.

Pharmacological Management of Paroxysmal Sympathetic Hyperactivity: A Scoping Review

Paroxysmal sympathetic hyperactivity (PSH) occurs in ∼10% of patients following acute severe brain injury. While PSH is associated with worse outcomes, there are no clinical practice guidelines to inform treatment. We aimed to systematically review the literature on the pharmacological management of PSH. MEDLINE, Embase, and Cochrane library databases were searched from inception to August 2020. Eligible studies met the following criteria: 1) randomized controlled trials, non-randomized controlled trials (case control or controlled cohort), observational studies, case series, and case reports; 2) study population of adult and pediatric patients; 3) exposure to an acute neurological insult complicated by PSH (or historic synonym); 4) description of pharmacological treatment of PSH. Our search retrieved 2729 citations with 83 articles assessed for inclusion. After full text extraction, 56 manuscripts inclusive of 459 patients met eligibility criteria. We identified 31 case reports, 15 case series (152 patients), seven retrospective case control or cohort studies (212 patients), and three prospective observational studies (52 patients). Traumatic brain injury was the most common precipitating insult (407 patients), followed by hypoxic encephalopathy (72 patients) and intracranial hemorrhage (10 patients). There were 48 drugs from 22 classes prescribed for the management of PSH. The most frequently prescribed agents were benzodiazepines, β-blockers, opioids, α-2 agonists, and baclofen. However, route and dose of drug and subsequent outcome were inconsistently reported, such that no summary was possible. While a wide variety of drugs have been reported to treat PSH, there is a lack of even moderate-quality evidence to inform clinical decision making.

Sample Preparation for High-Throughput Urine Proteomics Using 96-Well Polyvinylidene Fluoride (PVDF) Membranes

Proteomics analysis of urine samples allows for studying the impact of system perturbation. However, meaningful proteomics-based biomarker discovery projects often require the analysis of large patient cohorts with hundreds of samples to describe the biological variability. Thus, robust high-throughput sample processing methods are a prerequisite for clinical proteomics pipelines that minimize experimental bias due to individual sample processing methods. Herein we describe a high-throughput method for parallel 96-well plate-based processing of urine samples for subsequent LC/MS-based proteomic analyses. Protein digestion and subsequent sample processing steps are efficiently performed in 96-well polyvinylidene fluoride (PVDF) membrane plate allowing for the use of vacuum manifolds for rapid liquid transfer, and multichannel pipettes and/or liquid handing robots. In this chapter we make available a detailed step-by-step protocol for our 'MStern blotting' sample processing strategy applied to patient urine samples followed by mass spectrometry-based proteomics analysis. Subsequently, we provide an example application using minimal volume of urine samples (e.g. 150 μL) collected from children pre and post thoracotomy to identify the predominant sites of protein catabolism and aid in the design of therapies to ameliorate protein catabolism and breakdown during critical illness. Furthermore, we demonstrate how the systemic state is reflected in the urine as an easily obtainable, stable, and safe biofluid.

Utility of Serum Procalcitonin in Diagnosing Paroxysmal Sympathetic Hyperactivity in Patients with Traumatic Brain Injury

Background

Paroxysmal sympathetic hyperactivity (PSH) is a grave entity affecting patients following traumatic brain injury (TBI). It presents with cyclic and simultaneous fever, posturing, and other symptoms of sympathetic hyperactivity. Lack of diagnostic tests or biochemical markers and its propensity to mimic other common causes of fever in the neurotrauma intensive care unit (ICU) result in clinical dilemmas and management delay.

Case Descriptions

We present a case series of four patients (two adults and two pediatrics) with TBI who developed PSH during ICU stay. These patients presented with fever along with variable symptoms of sympathetic hyperactivity. However, the value of serum procalcitonin (PCT) was not elevated, and management of PSH was started. Serial monitoring of PCT helped in differentiating fever due to PSH from sepsis and thus the institution of appropriate and timely treatment of PSH and also helped to use antibiotics rationally.

Conclusion

The use of serum PCT in differentiating sepsis from systemic inflammatory reaction and its role in the initiation and titration of antibiotics are well described. PSH is a common entity after TBI, causing episodic fever and sympathetic hyperactivity, often confused with infectious pathology. Our report proposes the role of serum PCT in differentiating PSH from infectious etiology and management of two different clinical entities.

How to cite this article

Bindra A, Chowdhary V, Dube SK, Goyal K, Mathur P. Utility of Serum Procalcitonin in Diagnosing Paroxysmal Sympathetic Hyperactivity in Patients with Traumatic Brain Injury. Indian J Crit Care Med 2021;25(5):580–583.

Testosterone replacement in hypogonadal men during inpatient rehabilitation following traumatic brain injury: Results from a double-blind, placebo-controlled clinical pilot study

BACKGROUND

Endocrinopathy, including hypogonadism, is common following traumatic brain injury (TBI). Prior evidence suggests hypogonadism is associated with poorer function.

OBJECTIVE

Determine the feasibility, safety, and efficacy of testosterone (T) therapy in hypogonadal men following TBI in acute rehabilitation.

DESIGN

Randomized, double blind, placebo-controlled pilot trial.

SETTING

Inpatient rehabilitation brain injury unit.

PARTICIPANTS

Men ages 18 -65, post moderate to severe TBI receiving inpatient rehabilitation.

INTERVENTIONS

Transdermal T gel or placebo.

MAIN OUTCOME MEASURES

Revised FIM™ score, strength, adverse events.

RESULTS

Of 498 screened, 70 participants were enrolled, and 22 meeting all criteria were randomized into placebo (n = 10) or physiologic T therapy (n = 12). There was no significant difference between groups in rate of improvement on the FIM™ (intercepts t = -0.31, p = 0.7593, or slopes t = 0.61, p = 0.5472). The Treatment group demonstrated the greatest absolute improvement in FIM™ scores and grip strength compared to Placebo or Normal T groups. There was no difference in adverse events between groups. Percentage of time with agitation or aggression was highest in the Placebo group.

CONCLUSIONS

Although there were no significant differences in rates of recovery, treatment group subjects showed greater absolute functional and strength improvement compared to the Placebo or Normal T groups.

Paroxysmal Sympathetic Hyperactivity

Paroxysmal sympathetic hyperactivity (PSH) is a relatively common, but often unrecognized, complication of acute diffuse or multifocal brain diseases, most frequently encountered in young comatose patients with severe traumatic brain injury. It is presumed to be caused by loss of cortical inhibitory modulation of diencephalic and brain stem centers and possible additional maladaptive changes in the spinal cord that combine to produce exaggerated sympathetic responses to stimulation. The syndrome consists of repeated sudden episodes of tachycardia, tachypnea, hypertension, sweating, and sometimes fever and dystonic posturing. The diagnosis is clinical. Treatment includes reducing any external stimulation that can trigger the episodes, and starting abortive (e.g., intravenous morphine) and preventive medications (e.g., gabapentin, propranolol, clonidine). Prompt and adequate treatment of PSH may reduce the likelihood of secondary complications, such as dehydration, weight loss and malnutrition, and muscle contractures.

Identification and Management of Paroxysmal Sympathetic Hyperactivity After Traumatic Brain Injury

Paroxysmal sympathetic hyperactivity (PSH) has predominantly been described after traumatic brain injury (TBI), which is associated with hyperthermia, hypertension, tachycardia, tachypnea, diaphoresis, dystonia (hypertonia or spasticity), and even motor features such as extensor/flexion posturing. Despite the pathophysiology of PSH not being completely understood, most researchers gradually agree that PSH is driven by the loss of the inhibition of excitation in the sympathetic nervous system without parasympathetic involvement. Recently, advances in the clinical and diagnostic features of PSH in TBI patients have reached a broad clinical consensus in many neurology departments. These advances should provide a more unanimous foundation for the systematic research on this clinical syndrome and its clear management. Clinically, a great deal of attention has been paid to the definition and diagnostic criteria, epidemiology and pathophysiology, symptomatic treatment, and prevention and control of secondary brain injury of PSH in TBI patients. Potential benefits of treatment for PSH may result from the three main goals: eliminating predisposing causes, mitigating excessive sympathetic outflow, and supportive therapy. However, individual pathophysiological differences, therapeutic responses and outcomes, and precision medicine approaches to PSH management are varied and inconsistent between studies. Further, many potential therapeutic drugs might suppress manifestations of PSH in the process of TBI treatment. The purpose of this review is to present current and comprehensive studies of the identification of PSH after TBI in the early stage and provide a framework for symptomatic management of TBI patients with PSH.

Feeding Intolerance in Children with Severe Impairment of the Central Nervous System: Strategies for Treatment and Prevention

Children with severe impairment of the central nervous system (CNS) experience gastrointestinal (GI) symptoms at a high rate and severity, including retching, vomiting, GI tract pain, and feeding intolerance. Commonly recognized sources of symptoms include constipation and gastroesophageal reflux disease. There is growing awareness of sources due to the impaired nervous system, including visceral hyperalgesia due to sensitization of sensory neurons in the enteric nervous system and central neuropathic pain due to alterations in the thalamus. Challenging the management of these symptoms is the lack of tests to confirm alterations in the nervous system as a cause of symptom generation, requiring empirical trials directed at such sources. It is also common to have multiple reasons for the observed symptoms, further challenging management. Recurrent emesis and GI tract pain can often be improved, though in some not completely eliminated. In some, this can progress to intractable feeding intolerance. This comprehensive review provides an evidence-based approach to care, a framework for recurrent symptoms, and language strategies when symptoms remain intractable to available interventions. This summary is intended to balance optimal management with a sensitive palliative care approach to persistent GI symptoms in children with severe impairment of the CNS.

Paroxysmal sympathetic hyperactivity: the storm after acute brain injury

A substantial minority of patients who survive an acquired brain injury develop a state of sympathetic hyperactivity that can persist for weeks or months, consisting of periodic episodes of increased heart rate and blood pressure, sweating, hyperthermia, and motor posturing, often in response to external stimuli. The unifying term for the syndrome-paroxysmal sympathetic hyperactivity (PSH)-and clear diagnostic criteria defined by expert consensus were only recently established. PSH has predominantly been described after traumatic brain injury (TBI), in which it is associated with worse outcomes. The pathophysiology of the condition is not completely understood, although most researchers consider it to be a disconnection syndrome with paroxysms driven by a loss of inhibitory control over excitatory autonomic centres. Although therapeutic strategies to alleviate sympathetic outbursts have been proposed, their effects on PSH are inconsistent between patients and their influence on outcome is unknown. Combinations of drugs are frequently used and are chosen on the basis of local custom, rather than on objective evidence. New rigorous tools for diagnosis could allow better characterisation of PSH to enable stratification of patients for future therapeutic trials.

Calming the Storm: Dysautonomia for the Pediatrician

Dysautonomia is a potentially life-threatening syndrome seen in many different types of brain injuries. It involves paroxysmal sympathetic hyperactivity and typically includes a constellation of symptoms, including: tachycardia, tachypnea, hyperthermia, hypertension, diaphoresis, hypertonia, and/or decerebrate or decorticate posturing. It is a clinical diagnosis of exclusion. A multimodal treatment approach is necessary including environmental modifications along with pharmacotherapy. Early management can help prevent comorbidities including secondary brain injury while also improving patient outcomes. This discussion serves as an overview of dysautonomia with a focus on management in the pediatric population including an example of a clinical algorithm and a review of the commonly used medications.

[Factors affecting recovery of consciousness in patients with disorders of consciousness following brain trauma: a logistic regression analysis]

OBJECTIVE

To explore the factors that affect the recovery of consciousness in patients with disorders of consciousness following brain trauma.

METHODS

We analyzed the data of 114 patients with disorders of consciousness following brain trauma admitted for rehabilitation. Bilateral logistic regression analysis was used to explore the factors that affected the recovery of the patients' consciousness. A logistic regression model was established and the ROC curve was drawn to obtain the optimal threshold of the prognostic model.

RESULTS

Univariate analysis showed that vegetative state duration (P<0.001), CRS-R scores (P<0.001), hydrocephalus (P=0.037), hypertonia (P=0.034), central fever (P=0.035), paroxysmal sympathetic hyperactivity (PSH) (P=0.004), and epilepsy seizures were correlated with the recovery of consciousness. Logistic multivariate analysis showed that central fever (OR=3.493, P=0.044), vegetative state duration (OR=1.016, P=0.008), PSH (OR=4.223, P=0.034) and CRS-R scores (OR=0.640, P=0.002) all significantly affected the recovery of consciousness. The χ² value of the Hosmer-Lemeshow test was 10.214 (P=0.250), and the goodness of fit of this model indicated an outstanding fitting (c=0.91).

CONCLUSIONS

The presence of PSH is the one of the most important factor followed by centric fever to affect the outcome of patients with disorders of consciousness. A lower CRS-R score and a longer duration of vegetative state also predict a poor recovery of consciousness in these patients.

The preventive effect of dexmedetomidine on paroxysmal sympathetic hyperactivity in severe traumatic brain injury patients who have undergone surgery: a retrospective study

Background

Paroxysmal sympathetic hyperactivity (PSH) results and aggravates in secondary brain injury, which seriously affects the prognosis of severe traumatic brain injury patients. Although several studies have focused on the treatment of PSH, few have concentrated on its prevention.

Methods

Ninety post-operation (post-op) severe traumatic brain injury (sTBI) patients admitted from October 2014 to April 2016 were chosen to participate in this study. Fifty of the post-op sTBI patients were sedated with dexmedetomidine and were referred as the “dexmedetomidine group” (admitted from May 2015 to April 2016). The other 40 patients (admitted from October 2014 to May 2015) received other sedations and were referred as the “control group.” The two groups were then compared based on their PSH scores and the scores and ratios of those patients who met the criteria of “probable,” “possible” and “unlikely” using the PSH assessment measure (PSH-AM) designed by Baguley et al. (2014). The durations of the neurosurgery intensive care unit (NICU) and hospital stays and the Glasgow outcome scale (GOS) values for the two groups were also compared to evaluate the therapeutic effects and the patients’ prognosis.

Results

The overall PSH score for the dexmedetomidine group was 5.26 ± 4.66, compared with 8.58 ± 8.09 for the control group. The difference between the two groups’ PSH scores was significant (P = 0.017). The score of the patients who met the criterion of “probable” was 18.33 ± 1.53 in the dexmedetomidine group and 22.63 ± 2.97 in the control group, and the difference was statistically significant (P = 0.045). The ratio of patients who were classified as “unlikely” between the two groups was statistically significant (P = 0.028); that is, 42 (84%) in the dexmedetomidine group and 25 (62.5%) in the control group. The differences in NICU, hospital stays and GOS values between the two groups were not significant.

Conclusion

Dexmedetomidine has a preventive effect on PSH in sTBI patients who have undergone surgery.

Paroxysmal sympathetic hyperactivity in brainstem-compressing huge benign tumors: clinical experiences and literature review

Severe paroxysmal sympathetic overactivity occurs in a subgroup of patients with acquired brain injuries including traumatic brain injury, hypoxia, infection and tumor-related complications. This condition is characterized by sudden increase of heart rate, respiratory rate, blood pressure, body temperature and excessive diaphoresis. The episodes may be induced by external stimulation or may occur spontaneously. Frequent occurrence of this condition could result in secondary morbidities, therefore, should be diagnosed and managed insightfully. These symptoms could be confused with seizures or other medical conditions, leading to unnecessary treatment. Despite clinical significance of paroxysmal sympathetic hyperactivity (PSH), brain tumor-induced PSH has not been studied nearly. In this report, two cases of the PSH in patients with brainstem-compressing benign tumors were introduced. The most useful pharmacologic agents were opioid (e.g., fentanyl patch) in preventing PSH attack, and nonselective β-blocker (e.g., propranolol) in relieving the symptoms. Clinical experiences of the rare cases of benign tumor-induced PSH can be helpful as an essential basis for further research.

Morphine: An Effective Abortive Therapy for Pediatric Paroxysmal Sympathetic Hyperactivity After Hypoxic Brain Injury

Paroxysmal sympathetic hyperactivity (PSH) is a life-threatening condition characterized by hyperadrenergic activity and autonomic dysfunction. Also termed autonomic storms, PSH can occur after a variety of cerebral insults, most commonly traumatic brain injury. Limited pediatric literature is available, especially in patients with brain injury from hypoxia. No consensus exists for the terminology, diagnostic criteria, or treatment algorithm for PSH. Thus, the optimal management, including medication selection and dosing, remains unclear. We present the detailed treatment of a 9-year-old, African American male with hypoxic brain injury after pulseless arrest following status asthmaticus, who subsequently developed PSH. The patient began to experience episodes of tachycardia, hypertension, tachypnea, diaphoresis, rigidity, and dystonic posturing on hospital day 5. After ruling out other potential causes, a diagnosis of PSH was made. Episodes of PSH failed to respond to lorazepam or labetalol but were aborted successfully with morphine. Management of PSH after hypoxic brain injury required medications for acute treatment as well as for prevention of PSH. Morphine was found to be highly effective and safe for aborting the autonomic crises. Other agents more commonly described in the literature did not result in an adequate response and were associated with significant adverse effects. A combination of clonazepam, baclofen, and either propranolol or clonidine aided in reducing the frequency of episodes of PSH. We suggest using morphine for aborting severe episodes of PSH that do not respond to antihypertensive agents or benzodiazepines.

Paroxysmal sympathetic hyperactivity in pediatric traumatic brain injury: A case series of four patients

Paroxysmal sympathetic hyperactivity (PSH) is a condition in which there is extreme autonomic dysregulation leading to multiple episodes of sympathetic hyperactivity. Its occurrence after traumatic brain injury (TBI) in pediatric population is a neglected scenario. In our series, all pediatric patients with moderate and severe head injuries were studied and those patients who developed PSH were monitored for the PSH episodes. Four children out of 36 cases of pediatric severe traumatic brain injury developed features of PSH. Admission GCS of 3 children were 4/15 and 1 child was 6/15 and each of them had an ICU stay of more than 2 weeks and a poor DRS score at discharge. The presence of PSH is known to produce poorer outcome in terms of overall mortality, time needed for recovery, chances of developing infections, etc. which was also seen in these cases presented here. Though some studies have provided guidelines for the management of PSH like symptomatic management and use of drugs like clonidine, bromocriptine, benzodiazepines, and gabapentin, strict management guidelines are not established and exact incidence in pediatric population is not determined.

Fulfilling caloric demands according to indirect calorimetry may be beneficial for post cardiac arrest patients under therapeutic hypothermia

INTRODUCTION

We sought to investigate the energy requirements for patients under therapeutic hypothermia, and the relationship of energy fulfillment to patient outcome.

PATIENTS AND METHODS

Adult patients admitted to our ICU after successful resuscitation from cardiac arrest for post resuscitation therapeutic hypothermia from April, 2012 to March, 2014 were enrolled. Body temperature was managed using the surface cooling device (Arctic Sun(®), IMI). Calorimeter module on the ventilator (Engström carestation(®), GE) was used for indirect calorimetry. Energy expenditure (EE) and respiratory quotient (RQ) were recorded continuously, as the average of the recent 2h. Measurements were started at the hypothermic phase and continued until the rewarming was completed. Cumulative energy deficit was calculated as the sum of difference between EE and daily energy provision for the 4 days during hypothermia therapy.

RESULTS

Seven patients were eligible for analysis. Median EE for the hypothermic phase (day 1) was 1557.0kcald(-1). EE was elevated according with the rise in body temperature, reaching 2375kcald(-1) at normothermic phase. There was significant association between cumulative energy deficit and the length of ICU stay, among patients with good neurologic recovery (cerebral performance category (CPC): 1-3).

CONCLUSION

The EE for patients under therapeutic hypothermia was higher than expected. Meeting the energy demand may improve patient outcome, as observed in the length of ICU stay for the present study. A larger, prospective study is awaited to validate the results of our study.

Current applications of metabolic monitoring in the pediatric intensive care unit

Delivery of adequate nutrients during illness to counteract the metabolic stress response and facilitate healing and tissue repair is an important goal in the care of critically ill children. With recent advances in technology, accurate minute-to-minute gas exchange and energy expenditure measurements are now available in intensive care units. The bedside availability of these devices may allow a titrated approach to energy delivery for patients, ushering in a new era of individualized nutrition therapy. Basic concepts, available monitoring devices, indications, pitfalls, and bedside application of metabolic monitoring are discussed in this article.

Nutritional practices and their relationship to clinical outcomes in critically ill children--an international multicenter cohort study*

OBJECTIVES

To examine factors influencing the adequacy of energy and protein intake in the pediatric intensive care unit and to describe their relationship to clinical outcomes in mechanically ventilated children.

DESIGN, SETTING, PATIENTS

We conducted an international prospective cohort study of consecutive children (ages 1 month to 18 yrs) requiring mechanical ventilation longer than 48 hrs in the pediatric intensive care unit. Nutritional practices were recorded during the pediatric intensive care unit stay for a maximum of 10 days, and patients were followed up for 60 days or until hospital discharge. Multivariate analysis, accounting for pediatric intensive care unit clustering and important confounding variables, was used to examine the impact of nutritional variables and pediatric intensive care unit characteristics on 60-day mortality and the prevalence of acquired infections.

MAIN RESULTS

31 pediatric intensive care units in academic hospitals in eight countries participated in this study. Five hundred patients with mean (SD) age 4.5 (5.1) yrs were enrolled and included in the analysis. Mortality at 60 days was 8.4%, and 107 of 500 (22%) patients acquired at least one infection during their pediatric intensive care unit stay. Over 30% of patients had severe malnutrition on admission, with body mass index z-score >2 (13.2%) or <-2 (17.1%) on admission. Mean prescribed goals for daily energy and protein intake were 64 kcals/kg and 1.7 g/kg respectively. Enteral nutrition was used in 67% of the patients and was initiated within 48 hrs of admission in the majority of patients. Enteral nutrition was subsequently interrupted on average for at least 2 days in 357 of 500 (71%) patients. Mean (SD) percentage daily nutritional intake (enteral nutrition) compared to prescribed goals was 38% for energy and 43% (44) for protein. A higher percentage of goal energy intake via enteral nutrition route was significantly associated with lower 60-day mortality (Odds ratio for increasing energy intake from 33.3% to 66.6% is 0.27 [0.11, 0.67], p = .002). Mortality was higher in patients who received parenteral nutrition (odds ratio 2.61 [1.3, 5.3], p = .008). Patients admitted to units that utilized a feeding protocol had a lower prevalence of acquired infections (odds ratio 0.18 [0.05, 0.64], p = .008), and this association was independent of the amount of energy or protein intake.

CONCLUSIONS

Nutrition delivery is generally inadequate in mechanically ventilated children across the world. Intake of a higher percentage of prescribed dietary energy goal via enteral route was associated with improved 60-day survival; conversely, parenteral nutrition use was associated with higher mortality. Pediatric intensive care units that utilized protocols for the initiation and advancement of enteral nutrient intake had a lower prevalence of acquired infections. Optimizing nutrition therapy is a potential avenue for improving clinical outcomes in critically ill children.

Dysautonomia after pediatric brain injury

AIM

Dysautonomia after brain injury is a diagnosis based on fever, tachypnea, hypertension, tachycardia, diaphoresis, and/or dystonia. It occurs in 8 to 33% of adults with brain injury and is associated with poor outcome. We hypothesized that children with brain injury with dysautonomia have worse outcomes and prolonged rehabilitation, and sought to determine the prevalence of dysautonomia in children and to characterize its clinical features.

METHOD

We developed a database of children (n = 249, 154 males, 95 females; mean [SD] age 11 years 10 months [5 y 7 mo]) with traumatic brain injury, cardiac arrest, stroke, infection of the central nervous system, or brain neoplasm admitted for rehabilitation to The Children's Institute of Pittsburgh between 2002 and 2009. Dysautonomia diagnosis, injury type, clinical signs, length of stay, and Functional Independence Measure for Children (WeeFIM) testing were extracted from medical records, and analysed for differences between groups with and without dysautonomia.

RESULTS

Dysautonomia occurred in 13% of children with brain injury (95% confidence interval 9.3-18.0%), occurring in 10% after traumatic brain injury and 31% after cardiac arrest. The combination of hypertension, diaphoresis, and dystonia best predicted a diagnosis of dysautonomia (area under the curve = 0.92). Children with dysautonomia had longer stays, worse WeeFIM scores, and improved less on the score's motor component (all p ≤ 0.001).

INTERPRETATION

Dysautonomia is common in children with brain injury and is associated with prolonged rehabilitation. Prospective study and standardized diagnostic approaches are needed to maximize outcomes.

Accuracy of abbreviated indirect calorimetry protocols for energy expenditure measurement in critically ill children

BACKGROUND

Accurate measurement of resting energy expenditure (REE) using indirect calorimetry (IC) facilitates optimal energy prescription. Steady-state (SS) REE obtained using a 5-minute protocol (SS5) has been used as a surrogate for 24-hour REE measurement. However, SS5 conditions are difficult to achieve in critically ill children on mechanical ventilatory support.

METHODS

The authors prospectively examined factors associated with successful IC testing using the standard SS5 protocol in mechanically ventilated children. They examined the agreement of REE between SS5 and 2 abbreviated SS protocols: 4-minute (SS4) and 3-minute (SS3) protocols as well as the Schofield prediction equation, using Bland-Altman analysis.

RESULTS

IC testing (n = 45) was completed in 34 children. SS was achieved during 25 (56%), 31 (69%), and 42 (93%) tests, using the SS5, SS4, and SS3 protocols, respectively. Intratest variability in respiratory rate, endotracheal tube leak, and inspiratory time was associated with failed IC by the SS5 protocol. The mean bias (limits of agreement) for REE was 2.8 (-47 to 65), 5.8 (-71 to 72), and -127 (-418 to 1176) kcal/d using SS4, SS3, and Schofield, respectively. A stronger agreement was observed when means of all abbreviated SS REE values during a 30-minute test were used.

CONCLUSION

In mechanically ventilated children, 4-minute and 3-minute SS protocols allowed REE measurements to be obtained in most patients with reasonable accuracy. Abbreviated protocols may decrease the need to rely on inaccurate equations when assessing energy expenditure in children who fail IC testing by standard SS criteria.

Energy imbalance and the risk of overfeeding in critically ill children

OBJECTIVE

To examine the role of targeted indirect calorimetry in detecting the adequacy of energy intake and the risk of cumulative energy imbalance in a subgroup of critically ill children suspected to have alterations in resting energy expenditure. We examined the accuracy of standard equations used for estimating resting energy expenditure in relation to measured resting energy expenditure in relation to measured resting energy expenditure and cumulative energy balance over 1 week in this cohort.

DESIGN

A prospective cohort study.

SETTING

Pediatric intensive care unit in a tertiary academic center.

INTERVENTIONS

A subgroup of critically ill children in the pediatric intensive care unit was selected using a set of criteria for targeted indirect calorimetry.

MEASUREMENTS

Measured resting energy expenditure from indirect calorimetry and estimated resting energy expenditure from standard equations were obtained. The metabolic state of each patient was assigned as hypermetabolic (measured resting energy expenditure/estimated resting energy expenditure >110%), hypometabolic (measured resting energy expenditure/estimated resting energy expenditure <90%), or normal (measured resting energy expenditure/estimated resting energy expenditure = 90-110%). Clinical variables associated with metabolic state and factors influencing the adequacy of energy intake were examined.

MAIN RESULTS

Children identified by criteria for targeted indirect calorimetry, had a median length of stay of 44 days, a high incidence (72%) of metabolic instability and alterations in resting energy expenditure with a predominance of hypometabolism in those admitted to the medical service. Physicians failed to accurately predict the true metabolic state in a majority (62%) of patients. Standard equations overestimated the energy expenditure and a high incidence of overfeeding (83%) with cumulative energy excess of up to 8000 kcal/week was observed, especially in children <1 yr of age. We did not find a correlation between energy balance and respiratory quotient (RQ) in our study.

CONCLUSIONS

We detected a high incidence of overfeeding in a subgroup of critically ill children using targeted indirect calorimetry The predominance of hypometabolism, failure of physicians to correctly predict metabolic state, use of stress factors, and inaccuracy of standard equations all contributed to overfeeding in this cohort. Critically ill children, especially those with a longer stay in the PICU, are at a risk of unintended overfeeding with cumulative energy excess.

A review of paroxysmal sympathetic hyperactivity after acquired brain injury

Severe excessive autonomic overactivity occurs in a subgroup of people surviving acquired brain injury, the majority of whom show paroxysmal sympathetic and motor overactivity. Delayed recognition of paroxysmal sympathetic hyperactivity (PSH) after brain injury may increase morbidity and long-term disability. Despite its significant clinical impact, the scientific literature on this syndrome is confusing; there is no consensus on nomenclature, etiological information for diagnoses preceding the condition is poorly understood, and the evidence base underpinning our knowledge of the pathophysiology and management strategies is largely anecdotal. This systematic literature review identified 2 separate categories of paroxysmal autonomic overactivity, 1 characterized by relatively pure sympathetic overactivity and another group of disorders with mixed parasympathetic/sympathetic features. The PSH group comprised 349 reported cases, with 79.4% resulting from traumatic brain injury (TBI), 9.7% from hypoxia, and 5.4% from cerebrovascular accident. Although TBI is the dominant causative etiology, there was some suggestion that the true incidence of the condition is highest following cerebral hypoxia. In total, 31 different terms were identified for the condition. Although the most common term in the literature was dysautonomia, the consistency of sympathetic clinical features suggests that a more specific term should be used. The findings of this review suggest that PSH be adopted as a more clinically relevant and appropriate term. The review highlights major problems regarding conceptual definitions, diagnostic criteria, and nomenclature. Consensus on these issues is recommended as an essential basis for further research in the area.

Is Energy Expenditure of Infants Predictable After Surgery?

Infants undergoing surgery have unique metabolic demands. The stress of an operation and recovery combined with expectations for growth and development imply elevations in energy expenditure beyond that of healthy, free-living infants. In contrast, surgery may trigger a diversion of energy utilization from tissue accumulation and growth toward the catabolic stress response and cytokine production. Predictive equations are commonly used in clinical settings to estimate basal or resting energy expenditure because measurement techniques such as indirect calorimetry may not be feasible or available. Investigations of measured energy expenditure in surgical infants have portrayed mixed results, however, and estimation equations may not consistently lead to accurate assessment of actual energy needs. Studies are limited in number and quality and often involve a heterogeneous, small population. Grouped outcomes may conceal the wide variability frequently observed in these studies. Measurement of energy expenditure is therefore preferable to the use of predictive equations to customize nutrition intervention for individual infants undergoing surgery.

Challenges to optimal enteral nutrition in a multidisciplinary pediatric intensive care unit

OBJECTIVE

To describe nutrient intake in critically ill children, identify risk factors associated with avoidable interruptions to enteral nutrition (EN), and highlight opportunities to improve enteral nutrient delivery in a busy tertiary pediatric intensive care unit (PICU). Design, Setting, and Measurements: Daily nutrient intake and factors responsible for avoidable interruptions to EN were recorded in patients admitted to a 29-bed medical and surgical PICU over 4 weeks. Clinical characteristics, time to reach caloric goal, and parenteral nutrition (PN) use were compared between patients with and without avoidable interruptions to EN.

RESULTS

Daily record of nutrient intake was obtained in 117 consecutive patients (median age, 7 years). Eighty (68%) patients received EN (20% postpyloric) for a total of 381 EN days (median, 2 days). Median time to EN initiation was less than 1 day. However, EN was subsequently interrupted in 24 (30%) patients at an average of 3.7 +/- 3.1 times per patient (range, 1-13), for a total of 88 episodes accounting for 1,483 hours of EN deprivation in this cohort. Of the 88 episodes of EN interruption, 51 (58%) were deemed as avoidable. Mechanically ventilated subjects were at the highest risk of EN interruptions. Avoidable EN interruption was associated with increased reliance on PN and impaired ability to reach caloric goal.

CONCLUSIONS

EN interruption is common and frequently avoidable in critically ill children. Knowledge of existing barriers to EN such as those identified in this study will allow appropriate interventions to optimize nutrition provision in the PICU.

Nutritional deficiencies during critical illness

A significant proportion of critically ill children admitted to the pediatric intensive care unit (PICU) present with nutritional deficiencies. Malnourished hospitalized patients have a higher rate of complications, increased mortality, longer length of hospital stay, and increased hospital costs. Critical illness may further contribute to nutritional deteriorate with poor outcomes. Younger age, longer duration of PICU stay, congenital heart disease, burn injury, and need for mechanical ventilation support are some of the factors that are associated with worse nutritional deficiencies. Failure to estimate energy requirements accurately, barriers to bedside delivery of nutrients, and reluctance to perform regular nutritional assessments are responsible for the persistence and delayed detection of malnutrition in this cohort.

Cumulative energy imbalance in the pediatric intensive care unit: role of targeted indirect calorimetry

INTRODUCTION

Failure to accurately estimate energy requirements may result in underfeeding or overfeeding. In this study, a dedicated multidisciplinary nutrition team measured energy expenditure in critically ill children.

METHODS

Steady-state indirect calorimetry was used to obtain measured resting energy expenditure, which was compared with equation-estimated energy expenditure and the total energy intake for each subject. The children's metabolic status was examined in relation to standard clinical characteristics.

RESULTS

Sixteen measurements were performed in 14 patients admitted to the multidisciplinary pediatric intensive care unit over a period of 12 months. Mean age of subjects in this cohort was 11.2 years (range 1.6 months to 32 years) and included 7 males and 7 postoperative patients. Altered metabolism was detected in 13 of 14 subjects and in 15 of 16 (94%) measurements. There was no correlation between the metabolic status of subjects and their clinical characteristics. Average daily energy balance was 200 kcal/d (range -518 to +859 kcal/d). Agreement between measured resting energy expenditure and equation-estimated energy expenditure was poor, with mean bias of 72.3 +/- 446 kcal/d (limits of agreement -801.9 to + 946.5 kcal/d).

CONCLUSIONS

A disparity was observed between equation-estimated energy expenditure, measured resting energy expenditure, and total energy intake, with a high incidence of underfeeding or overfeeding. A wide range of metabolic alterations were recorded, which could not be accurately predicted using standard clinical characteristics. Targeted indirect calorimetry on high-risk patients selected by a dedicated nutrition team may prevent cumulative excesses and deficits in energy balance.