Hypermetabolism in the acute stage of hemorrhagic cerebrovascular disease

High-Protein Supplementation and Neuromuscular Electric Stimulation after Aneurysmal Subarachnoid Hemorrhage Increases Systemic Amino Acid and Oxidative Metabolism: A Plasma Metabolomics Approach

Background The INSPIRE randomized clinical trial demonstrated that a high protein diet (HPRO) combined with neuromuscular electrical stimulation (NMES) attenuates muscle atrophy and may improve functional outcomes after aSAH. Using an untargeted metabolomics approach, we sought to identify specific metabolites mediating these effects. Methods Blood samples were collected from subjects on admission prior to randomization to either standard of care (SOC; N=12) or HPRO+NMES (N=12) and at 7 days as part of the INSPIRE protocol. Untargeted metabolomics were performed for each plasma sample. Paired fold changes were calculated for each metabolite among subjects in the HPRO+NMES group at baseline and 7 days after intervention. Changes in metabolites from baseline to 7 days were compared for the HPRO+NMES and SOC groups. Sparse partial least squared discriminant analysis (sPLS-DA) identified metabolites discriminating each group. Pearson's correlation coefficients were calculated between each metabolite and total protein per day, nitrogen balance, and muscle volume Multivariable models were developed to determine associations between each metabolite and muscle volume. Results A total of 18 unique metabolites were identified including pre and post treatment and differentiating SOC vs HPRO+NMES. Of these, 9 had significant positive correlations with protein intake: N-acetylserine (ρ=0.61, P =1.56x10 -3 ), N-acetylleucine (ρ=0.58, P =2.97x10 -3 ), β-hydroxyisovaleroylcarnitine (ρ=0.53, P =8.35x10 -3 ), tiglyl carnitine (ρ=0.48, P =0.0168), N-acetylisoleucine (ρ=0.48, P =0.0183), N-acetylthreonine (ρ=0.47, P =0.0218), N-acetylkynurenine (ρ=0.45, P =0.0263), N-acetylvaline (ρ=0.44, P =0.0306), and urea (ρ=0.43, P =0.0381). In multivariable regression models, N-acetylleucine was significantly associated with preserved temporalis [OR 1.08 (95%CI 1.01, 1.16)] and quadricep [OR 1.08 (95%CI 1.02, 1.15)] muscle volume. Quinolinate was also significantly associated with preserved temporalis [OR 1.05 (95%CI 1.01, 1.09)] and quadricep [OR 1.04 (95%CI 1.00, 1.07)] muscle volume. N-acetylserine, N-acetylcitrulline, and b-hydroxyisovaleroylcarnitine were also associated with preserved temporalis or quadricep volume. Conclusions Metabolites defining the HPRO+NMES intervention mainly consisted of amino acid derivatives. These metabolites had strong correlations with protein intake and were associated with preserved muscle volume.

Plasma Amino Acids May Improve Prediction Accuracy of Cerebral Vasospasm after Aneurysmal Subarachnoid Haemorrhage

Aneurysmal subarachnoid haemorrhages (aSAH) account for 5% of strokes and continues to place a great burden on patients and their families. Cerebral vasospasm (CVS) is one of the main causes of death after aSAH, and is usually diagnosed between day 3 and 14 after bleeding. Its pathogenesis remains poorly understood. To verify whether plasma concentration of amino acids have prognostic value in predicting CVS, we analysed data from 35 patients after aSAH (median age 55 years, IQR 39-62; 20 females, 57.1%), and 37 healthy volunteers (median age 50 years, IQR 38-56; 19 females, 51.4%). Fasting peripheral blood samples were collected on postoperative day one and seven. High performance liquid chromatography-mass spectrometry (HPLC-MS) analysis was performed. The results showed that plasma from patients after aSAH featured a distinctive amino acids concentration which was presented in both principal component analysis and direct comparison. No significant differences were noted between postoperative day one and seven. A total of 18 patients from the study group (51.4%) developed CVS. Hydroxyproline (AUC = 0.7042, 95%CI 0.5259-0.8826, p = 0.0248) and phenylalanine (AUC = 0.6944, 95%CI 0.5119-0.877, p = 0.0368) presented significant CVS prediction potential. Combining the Hunt-Hess Scale and plasma levels of hydroxyproline and phenylalanine provided the model with the best predictive performance and the lowest leave-one-out cross-validation of performance error. Our results suggest that plasma amino acids may improve sensitivity and specificity of Hunt-Hess scale in predicting CVS.

Indirect Calorimetry Measurements Compared With Guideline Weight-Based Energy Calculations in Critically Ill Stroke Patients

BACKGROUND

Perturbations in resting energy expenditure (REE) among critically ill stroke patients are ill defined, and guidelines recommend weight-based dosing when indirect calorimetry (IC) is not feasible to estimate daily energy requirements. We aimed to determine whether guideline-recommended weight-based dosing provides adequate energy requirements compared with guidelines recommended IC target.

METHODS

IC data was collected on stroke patients admitted to a neurocritical care unit. We compared low-weight-based dosing (25 kcal/kg) and high (30 kcal/kg) with the IC REE target. Subsequently, we analyzed the effect of stroke subtype on the differences among these measurements.

RESULTS

Seventy-two metabolic studies were performed (45.1% intracerebral hemorrhage [ICH], 18.3% aneurysmal subarachnoid hemorrhage [aSAH], and 36.6% acute ischemic stroke [AIS]). Energy needs, estimated using low-weight-based group, were significantly lower than IC REE target (1496 kcal/day [IQR, 1224-1850] vs 1770 kcal/day [IQR, 1400-2150]; P = .003). High weight-based group energy measurements were similar to IC REE target (1806 kcal/day [IQR, 1530-2236] vs 1770 kcal/day; P = .343). Subgroup analysis showed that low-weight-based calculations were significantly lower than those of IC in ICH and aSAH, but they were similar in AIS (P ≤ .001, .016, and .078, respectively). Linear regression analysis showed that weight, height, and hemorrhagic stroke subtype were associated with IC (P ≤ .001, .024, and .051, respectively).

CONCLUSION

Important differences between weight-based estimation of energy needs and guideline-recommended IC estimation exist for critically ill stroke patients. Low-weight-based calculations of REE underestimate energy needs in ICH and aSAH patients.

Systematic review of factors associated with energy expenditure in the critically ill

BACKGROUND AND AIMS

Indirect calorimetry is the reference standard for energy expenditure measurement. Predictive formulae that replace it are inaccurate. Our aim was to review the patient and clinical factors associated with energy expenditure in critically ill patients.

METHODS

We conducted a systematic review of the literature. Eligible studies were those reporting an evaluation of factors and energy expenditure. Energy expenditure and factor associations with p-values were extracted from each study, and each factor was classified as either significantly, indeterminantly, or not associated with energy expenditure. Regression coefficients were summarized as measures of central tendency and spread. Metanalysis was performed on correlations.

RESULTS

The search strategy yielded 8521 unique articles, 307 underwent full text review, and 103 articles were included. Most studies were in adults. There were 95 factors with 352 evaluations. Minute volume, weight, age, % body surface area burn, sedation, post burn day, and caloric intake were significantly associated with energy expenditure. Heart rate, fraction of inspired oxygen, respiratory rate, respiratory disease diagnosis, positive end expiratory pressure, intensive care unit days, C- reactive protein, and size were not associated with energy expenditure. Multiple factors (n = 37) were identified with an unclear relationship with energy expenditure and require further evaluation.

CONCLUSIONS

An important interval step in the development of accurate formulae for energy expenditure estimation is a better understanding of relationships between patient and clinical factors and energy expenditure. The review highlights the limitations of currently available data, and identifies important factors that are not included in current prediction formulae of the critically ill.

Systemic metabolism and energy consumption after microsurgical clipping and endovascular coiling for aneurysmal subarachnoid hemorrhage

BACKGROUND

The postoperative metabolic states of subarachnoid hemorrhage (SAH) patients were investigated using indirect calorimetry (IDC) and various nutritional evaluations to establish any difference in perioperative metabolic and nutritional states between microsurgical and endovascular treatment.

METHODS

This study included 30 acute aneurysmal SAH patients with ruptured intracranial aneurysms treated by surgical clipping (n = 16) or coil embolization (n = 14) at a single institute. The resting energy expenditure (REE) and respiratory quotient were measured using IDC on days 1, 4, 7, 10, 14, and 17-21 after the operation. Various blood tests, including C-reactive protein (CRP) and prealbumin, were evaluated on the same days.

RESULTS

The clipping group showed a significant increase in REE/basal energy expenditure (BEE) compared with the coiling group on days 1 and 4 (p = 0.04 and 0.03, respectively). No significant differences were found on days 7, 10, 14, and 17-21. The mean REE/BEE on days 1-14 and 1-21 showed no significant differences between the groups with repeated measures analysis of variance. The clipping group showed a significant decrease of prealbumin on day 4 and significant increase in CRP on days 1, 4, and 7.

CONCLUSIONS

The clipping group was in the hypermetabolic state compared with the coiling group during the very early postoperative period. However, the difference associated with the treatment modality was relatively small compared to the effects of the SAH and of the sequelae.

Increased Resting Energy Expenditure after Endovascular Coiling for Subarachnoid Hemorrhage

BACKGROUND

Appropriate nutritional care from the acute stage is essential for improved functional outcomes and reduced mortality in patients with subarachnoid hemorrhage (SAH). Although endovascular coiling is increasingly being used as an alternative to neurosurgical clipping and craniotomy for ruptured aneurysms, the resting energy expenditure (REE) of patients treated with this new technique has not been systemically evaluated.

METHODS

We measured REE values by indirect calorimetry in 12 SAH patients treated with endovascular coiling. We averaged the REE measurements obtained on days 1 and 7 after endovascular coiling, and then we statistically compared the mean REE values with those in 30 patients with acute cerebral infarction (ACI) by the Wilcoxon rank-sum test (P <.05). Next, we calculated the ratio of measured REE values to the values estimated using the Harris-Benedict equation to adjust for demographic differences in sex, weight, height, and age between the groups.

RESULTS

The ratios were significantly higher in SAH patients (median value, 1.12; interquartile range, 1.05-1.23) than in ACI patients (median value, 1.02; interquartile range, .97-1.09).

CONCLUSIONS

Because endovascular coiling is less invasive than neurosurgical clipping, the observed increase in REE was attributed to metabolic changes after SAH. To provide optimal nutritional care to SAH patients from the acute stage, clinicians should be aware of this change in REE.

Supplementation of essential amino acids may reduce the occurrence of infections in rehabilitation patients with brain injury

BACKGROUND

To investigate whether supplementation with oral essential amino acids (EAAs) may reduce the occurrence of nosocomial infection among patients with brain injury (BI: stroke, trauma, anoxic coma).

METHODS

Patients (n = 125; 77 men, 48 women; mean age 63 ± 15 years) with stroke (68.8%), subarachnoid hemorrhage (17.6%), traumatic BI (7.2%), and anoxic BI (6.4%) 88 ± 15 days after the index event. Patients were randomly assigned to 2 months of oral EAAs (n = 63; 8 g/d) or placebo (n = 62).

RESULTS

Over the first month of rehabilitation, there were 60 infections in the whole population of 125 patients (48%); however, the rate was 23.2% lower in the EAA group (23 episodes/63 patients; 36.5%) than in the placebo group (37 episodes/62 patients; 59.7%) (P < .01). The types of infection were similarly distributed between the 2 groups. Serum levels of prealbumin <20 mg/dL and C-reactive protein (CRP) >0.3 mg/dL were the best predictors of future infection (prealbumin: odds ratio [OR] = 4.17, confidence interval [CI] 1.84-9.45, P < .001; CRP: OR = 3.8, CI 1.71-8.44, P < .001).

CONCLUSION

Supplementary EAAs may reduce the occurrence of nosocomial infections in rehabilitation patients with BI. Prealbumin and CRP are the best predictors of future infections.

The ratio of energy expenditure to nitrogen loss in diverse patient groups--a systematic review

BACKGROUND & AIMS

The ratio of energy expenditure to nitrogen loss respectively of energy to nitrogen provision (E/N) is considered a valuable tool in the creation of an enteral or parenteral formulation. Specific E/N ratios for parenteral nutrition (PN) have not yet been clearly defined. To determine the range of energy expenditure, nitrogen (protein) losses, and E/N ratios for various patient groups, we performed a systematic review of the literature.

METHODS

Medline 1950-2011 was searched for all studies on patients or healthy controls reporting energy expenditure and nitrogen loss at the same time.

RESULTS

We identified 53 studies with 91 cohorts which comprised 1107 subjects. Mean TEE ± standard deviation (SD) was 31.2 ± 7.2 kcal/kg BW/day in patients (n = 881) and 35.6 ± 4.3 kcal/kg BW/day in healthy controls (n = 266). Mean total protein loss (TPL) was 1.50 ± 0.57 g/kg BW/day in patients and 0.94 ± 0.24 g/kg BW/day in healthy controls. A non-linear significant correlation was found between TPL and the E/N ratio.

CONCLUSION

The E/N ratio is not a constant value but decreases continuously with increasing protein loss. These variations should be considered in the nutritional support of patients.

Relationship between C-reactive protein, systemic oxygen consumption, and delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Subarachnoid hemorrhage (SAH) is known to result in elevated systemic oxygen consumption (Vo(2)) and increases in high-sensitivity C-reactive protein (hsCRP), although the relationship among hsCRP, Vo(2), and delayed cerebral ischemia (DCI) after SAH remains unknown. We hypothesized that hsCRP is directly associated with Vo(2) and that elevated Vo(2) is a predictor of DCI after SAH.

METHODS

Prospective serial assessments of Vo(2) and hsCRP over 4 prespecified time periods during the first 14 days after bleed in consecutive SAH patients admitted to a single academic medical center for a 2-year period.

RESULTS

One hundred ten SAH patients met study criteria (mean age, 55±16 years; 62% women), with a median admission Hunt Hess grade of 3 (interquartile range, 2-4). In multivariate generalized estimating equation model of the first 14 days after bleed, Vo(2) was associated with younger age (P=0.01), male gender (P=0.01), and hsCRP levels (P=0.03). Twenty-four (22%) patients had DCI develop, with a median onset on day 7 after bleed (interquartile range, 5-11). The mean Vo(2) (291±65 mL/min versus 226±55 mL/min; P=0.003) was higher in DCI patients. In a multivariable Cox proportional hazards model, younger age (hazard ratio, 1.2 per 5 years; 95% CI, 1.1-1.3), a higher modified Fisher scale score (hazard ratio, 3.4 per 1-point increase; 95% CI, 1.7-6.9), and higher Vo(2) (HR, 1.2 per 50-mL/min increase; 95% CI, 1.1-1.3) were predictive of DCI.

CONCLUSIONS

Systemic oxygen consumption is associated with hsCRP levels in the first 14 days after SAH and is an independent predictor of DCI.

Effect of targeted deletion of the heme oxygenase-2 gene on hemoglobin toxicity in the striatum

The heme oxygenase (HO) enzymes catalyze the rate-limiting step in the breakdown of heme to iron, carbon monoxide, and biliverdin. A prior cell culture study demonstrated that deletion of HO-2, the isoform constitutively expressed in neurons, attenuated hemoglobin (Hb) neurotoxicity. The present study tested the hypothesis that HO-2 gene deletion is cytoprotective in a model of Hb toxicity in vivo. Stereotactic injection of 6 microL stroma-free Hb (SFHb) into the striatum significantly increased protein oxidation in wild-type mice at 24 to 72 h, as detected by an assay for carbonyl groups. At 72 h, carbonylation was increased 2.5-fold compared with that in the contralateral striatum. In HO-2 knockout mice, protein oxidation was not increased at 24 h, and was increased by only 1.7-fold at 72 h. Similarly, striatal lipid peroxidation, as detected by the malondialdehyde assay, was significantly greater in the SFHb-injected striata of wild-type mice than in knockout mice. Striatal cell viability, determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, was 45.0%+/-6.3% of that in contralateral striata in wild-type mice at 72 h; it was increased to 85%+/-8% in knockouts. Heme oxygenase-2 gene deletion did not alter weight loss or mortality after SFHb injection. Baseline striatal HO-1 expression was similar in knockout and wild-type mice; induction after SFHb injection occurred more rapidly in the latter. These results suggest that HO-2 gene deletion protects striatal cells from the oxidative toxicity of Hb in vivo. Pharmacologic or genetic strategies that target HO-2 may be beneficial after central nervous system hemorrhage, and warrant further investigation.

Metabolic profiles of patients with subarachnoid hemorrhage treated by early surgery

OBJECTIVE

This study was conducted to evaluate the metabolic response of patients with subarachnoid hemorrhage (SAH) and to determine whether the severity of hemorrhage influenced the response.

METHODS

Resting energy expenditure, nitrogen balance, and serum rapid-turnover proteins were studied for 3-day periods at Day 4, Day 10, and before discharge in patients with SAH who underwent surgical clipping within 2 days after the onset. The patients were divided into two groups according to the Hunt and Hess classification system; there were 17 patients with Grade I or II (mild group) and 19 patients with Grade III, IV, or V (severe group).

RESULTS

The mean resting energy expenditures (mean+/-standard deviation) were highest on Day 10, which were 146+/-24% and 198+/-78% of basal energy expenditure in the mild and severe groups, respectively. The nitrogen balance levels of the mild group on Days 4 and 10 were -3.0+/-3.5 g per day and -4.5+/-2.9 g per day, and those of the severe group were -7.5+/-3.2 g per day and -9.2+/-4.1 g per day, respectively. There was a significant difference in the nitrogen balance over time between the two groups (P=0.0037). Serum transferrin, prealbumin, and retinol-binding protein levels were lowest on Day 4 and gradually increased. There were no significant differences in these parameters between the two groups.

CONCLUSION

SAH treated by surgery induces a profound stress response. A significant difference of increased catabolism but not decreased anabolism between the mild and severe groups was noted.

Complications and outcome after acute stroke. Does dysphagia matter?

BACKGROUND AND PURPOSE

The published data on the relationship between dysphagia and both outcome and complications after acute stroke have been inconclusive. We examined the relationship between these, using bedside assessment and videofluoroscopic examination.

METHODS

We prospectively studied 121 consecutive patients admitted with acute stroke. A standardized bedside assessment was performed by a physician. We performed videofluoroscopy blinded to this assessment within 3 days of stroke onset and within a median time of 24 hours of the bedside evaluations. The presence of aspiration was recorded. Mortality, functional outcome, lengthy of stay, place of discharge, occurrence of chest infection, nutritional status, and hydration were the main outcome measures.

RESULTS

Patients with an abnormal swallow (dysphagia) on bedside assessment had a higher risk of chest infection (P=.05) and a poor nutritional state (P=.001). The presence of dysphagia was associated with an increased risk of death (P=.001), disability (P=.02), length of hospital stay (P<.001), and institutional care (P<.05). When other factors were taken into account, dysphagia remained as an independent predictor of outcome only with regard to mortality. The use of videofluoroscopy in detecting aspiration did not add to the value of bedside assessment.

CONCLUSIONS

Bedside assessment of swallowing is of use in identifying patients at risk of developing complications. The value of routine screening with videofluoroscopy to detect aspiration is questioned.