Noninvasive Neuromonitoring Modalities in Children Part I: Pupillometry, Near-Infrared Spectroscopy, and Transcranial Doppler Ultrasonography

BACKGROUND

Noninvasive neuromonitoring in critically ill children includes multiple modalities that all intend to improve our understanding of acute and ongoing brain injury.

METHODS

In this article, we review basic methods and devices, applications in clinical care and research, and explore potential future directions for three noninvasive neuromonitoring modalities in the pediatric intensive care unit: automated pupillometry, near-infrared spectroscopy, and transcranial Doppler ultrasonography.

RESULTS

All three technologies are noninvasive, portable, and easily repeatable to allow for serial measurements and trending of data over time. However, a paucity of high-quality data supporting the clinical utility of any of these technologies in critically ill children is currently a major limitation to their widespread application in the pediatric intensive care unit.

CONCLUSIONS

Future prospective multicenter work addressing major knowledge gaps is necessary to advance the field of pediatric noninvasive neuromonitoring.

Ketamine for Management of Neonatal and Pediatric Refractory Status Epilepticus

BACKGROUND AND OBJECTIVES

Few data are available regarding the use of anesthetic infusions for refractory status epilepticus (RSE) in children and neonates, and ketamine use is increasing despite limited data. We aimed to describe the impact of ketamine for RSE in children and neonates.

METHODS

Retrospective single-center cohort study of consecutive patients admitted to the intensive care units of a quaternary care children's hospital treated with ketamine infusion for RSE.

RESULTS

Sixty-nine patients were treated with a ketamine infusion for RSE. The median age at onset of RSE was 0.7 years (interquartile range 0.15-7.2), and the cohort included 13 (19%) neonates. Three patients (4%) had adverse events requiring intervention during or within 12 hours of ketamine administration, including hypertension in 2 patients and delirium in 1 patient. Ketamine infusion was followed by seizure termination in 32 patients (46%), seizure reduction in 19 patients (28%), and no change in 18 patients (26%).

DISCUSSION

Ketamine administration was associated with few adverse events, and seizures often terminated or improved after ketamine administration. Further data are needed comparing first-line and subsequent anesthetic medications for treatment of pediatric and neonatal RSE.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence on the therapeutic utility of ketamine for treatment of RSE in children and neonates.

Near-infrared spectroscopy during cardiopulmonary resuscitation for pediatric cardiac arrest: a prospective, observational study

AIM

Cerebral oxygenation (rSO2) is not routinely measured during pediatric cardiopulmonary resuscitation (CPR). We aimed to determine whether higher intra-arrest rSO2 was associated with return of spontaneous circulation (ROSC) and survival to hospital discharge.

METHODS

Prospective, single-center observational study of cerebral oximetry using near-infrared spectroscopy (NIRS) during pediatric cardiac arrest from 2016 to 2020. Eligible patients had ≥30 s of rSO2 data recorded during CPR. We compared median rSO2 and percentage of rSO2 measurements above a priori thresholds for the entire event and the final five minutes of the CPR event between patients with and without ROSC and survival to discharge.

RESULTS

Twenty-one patients with 23 CPR events were analyzed. ROSC was achieved in 17/23 (73.9%) events and five/21 (23.8%) patients survived to discharge. The median rSO2 was higher for events with ROSC vs. no ROSC for the overall event (62% [56%, 70%] vs. 45% [35%, 51%], p = 0.025) and for the final 5 minutes of the event (66% [55%, 72%] vs. 43% [35%, 44%], p = 0.01). Patients with ROSC had a higher percentage of measurements above 50% during the final five minutes of CPR (100% [100%, 100%] vs. 0% [0%, 29%], p = 0.01). There was no association between rSO2 and survival to discharge.

CONCLUSIONS

Higher cerebral rSO2 during CPR for pediatric cardiac arrest was associated with higher rates of ROSC but not with survival to discharge.

Variability in Pediatric Brain Death Determination Protocols in the United States

OBJECTIVE

To determine the variability in pediatric death by neurologic criteria (DNC) protocols between US pediatric institutions and compared to the 2011 DNC guidelines.

METHODS

In this cross-sectional study of DNC protocols obtained from pediatric institutions in the United States via regional organ procurement organizations, protocols were evaluated across 5 domains: general DNC procedures, prerequisites, neurologic examination, apnea testing, and ancillary testing. Descriptive statistics compared protocols to each other and the 2011 guidelines.

RESULTS

A total of 130 protocols were analyzed with 118 dated after publication of the 2011 guidelines. Of those 118 protocols, identification of a mechanism of irreversible brain injury was required in 97%, while 67% required an observation period after acute brain injury before DNC evaluation. Most protocols required guideline-based prerequisites such as exclusion of hypotension (94%), hypothermia (97%), and metabolic derangements (92%). On neurologic examination, 91% required a lack of responsiveness, 93% no response to noxious stimuli, and 99% loss of brainstem reflexes. A total of 84% of protocols required the guideline-recommended 2 apnea tests. CO2 targets were consistent with guidelines in 64%. Contrary to guidelines, 15% required ancillary testing for all patients and 15% permitted ancillary studies that are not validated in pediatrics.

CONCLUSION

Variability exists between pediatric institutional DNC protocols in all domains of DNC determination, especially with respect to apnea and ancillary testing. Better alignment of DNC protocols with national guidelines may improve the consistency and accuracy of DNC determination.

dSarm/Sarm1 is required for activation of an injury-induced axon death pathway

Axonal and synaptic degeneration is a hallmark of peripheral neuropathy, brain injury, and neurodegenerative disease. Axonal degeneration has been proposed to be mediated by an active autodestruction program, akin to apoptotic cell death; however, loss-of-function mutations capable of potently blocking axon self-destruction have not been described. Here, we show that loss of the Drosophila Toll receptor adaptor dSarm (sterile α/Armadillo/Toll-Interleukin receptor homology domain protein) cell-autonomously suppresses Wallerian degeneration for weeks after axotomy. Severed mouse Sarm1 null axons exhibit remarkable long-term survival both in vivo and in vitro, indicating that Sarm1 prodegenerative signaling is conserved in mammals. Our results provide direct evidence that axons actively promote their own destruction after injury and identify dSarm/Sarm1 as a member of an ancient axon death signaling pathway.

The Drosophila cell corpse engulfment receptor Draper mediates glial clearance of severed axons

Neuron-glia communication is central to all nervous system responses to trauma, yet neural injury signaling pathways remain poorly understood. Here we explore cellular and molecular aspects of neural injury signaling in Drosophila. We show that transected Drosophila axons undergo injury-induced degeneration that is morphologically similar to Wallerian degeneration in mammals and can be suppressed by the neuroprotective mouse Wlds protein. Axonal injury elicits potent morphological and molecular responses from Drosophila glia: glia upregulate expression of the engulfment receptor Draper, undergo dramatic changes in morphology, and rapidly recruit cellular processes toward severed axons. In draper mutants, glia fail to respond morphologically to axon injury, and severed axons are not cleared from the CNS. Thus Draper appears to act as a glial receptor for severed axon-derived molecular cues that drive recruitment of glial processes to injured axons for engulfment.

Higher level practice in community nursing: part two

AIM

To establish whether or not community nurse practitioners were able to achieve a 'higher level of practice', as articulated by the United Kingdom Central Council.

METHOD

Grounded theory was used as a framework for the research. Data were gathered using primary observation with some participation, and by interviewing community nurse practitioners and clinical managers.

FINDINGS

'Negotiation for autonomy' is the core category at the centre of the overall theoretical framework that emerged from the research data. Those working at a higher level of practice had the ability to negotiate for autonomy with GPs and other doctors. This ability gave them the opportunity to practise with the autonomy required to hold consultations, as first point of access, with patients with undifferentiated diagnoses, providing care through to discharge or referral to others.

CONCLUSION

The research highlights that unless community nurse practitioners can negotiate their role with GPs and hospital doctors, they are unable to achieve a 'higher level of practice'.

Effect of flow configuration and membrane characteristics on membrane fouling in a novel multicoaxial hollow-fiber bioartificial liver

A novel "multicoaxial hollow fiber bioreactor" has been developed consisting of four concentric tubes, the two innermost tubes are called hollow fibers. Bioartificial livers are created by culturing liver progenitors in the space between the two innermost hollow fibers and with culture media contained in the two compartments (intracapillary and extracapillary) sandwiching the cell compartment. The outermost compartment is used for gas exchange. A hydrodynamic model has recently been established to predict the optimum hydraulic permeability and bioreactor operational parameters to create the physicochemical environment found in the liver acinus. However, perfusion with serum-free hormonally-defined media and inoculation of cells introduces membrane fouling into the equation, and this parameter must be incorporated into the model. Using commercially available semipermeable hollow fibers (1 mm [0.65 microm pores] and 3 mm [0.1 microm pores] outer diameters [o.d]), the primary cause of resistance is the middle hollow fiber. Preliminary studies using bioreactors inoculated with isolated rat hepatocytes and perfused with serum-containing culture media demonstrated that the middle hollow fiber is the primary site of fouling, and this fouling ultimately causes cell mortality by blocking the transfer of nutrients. Experiments were performed to determine the best commercially available middle hollow fiber for construction of bioreactors and two 3-mm outer-diameter middle hollow fibers were compared: polypropylene and polysulfone, with 0.2 microm and 0.1 microm pore sizes, respectively. Dead-ended and cross flow configurations were compared for their effectiveness at reducing membrane fouling in the middle hollow fiber by determining the change in resistance with time. The results demonstrate that the 0.2-microm pore size polypropylene hollow fiber is the best choice for construction of the multicoaxial hollow-fiber bioreactor, and that cross flow results in two orders of magnitude lower resistance than dead-ended flow after 36 h.

Effects of Stachybotrys chartarum (atra) conidia and isolated toxin on lung surfactant production and homeostasis

This study evaluated the effects of Stachybotrys chartarum conidia and a trichothecene, isosatratoxin-F, on choline incorporation into DSPC by fetal rabbit alveolar type II cells and on alveolar surfactant subtypes in mice. Exposure of fetal rabbit type II cells to S. chartarum conidia at concentrations of 10(3) to 10(6) conidia ml(-1) significantly depressed [3H] choline incorporation after 24 h of exposure. Exposure of the rabbit cells to 10(5) to 10(6) conidia ml(-1) also resulted in significantly depressed [3H] choline uptake after 48 h. Additionally, fetal rabbit alveolar type II cells exposed to isosatratoxin-F in concentrations ranging from 10(-9) to 10(-4) M showed a significant reduction in [3H] choline incorporation into DSPC. Alveolar surfactant phospholipid concentrations in the different metabolic subfractions of lung lavage fluid of mice intratracheally exposed to either 50 microl of 10(7) ml(-1) S. chartarum conidia or 50 microl 10(-7) M isosatratoxin-F showed some significant changes at 12, 24, 48, and 72 h post-exposure, compared to the surfactant subfractions of control mice which were either untreated, exposed to saline or to 50 microl of 10(-7) ml(-1) Cladosporium cladosporioides conidia. In both the S. chartarum- and the isosatratoxin-F-treated mice, exposure significantly increased P10, P100, and S100 phospholipid concentrations, while the P60 phospholipid concentrations were depressed. In contrast, C. cladosporioides-treated mice showed only one significant change in subfraction phospholipid concentration: P60 was depressed at 48 h post-exposure. These results reveal that alveolar type II cells are sensitive to exposure to S. chartarum conidia and to isosatratoxin F. Sensitivity is manifest by alterations in the normal metabolic processing of alveolar surfactant. In exposed mice, this effect appears to involve a significant increase in newly secreted surfactant and an accumulation of the used surfactant forms.

Effect of endotoxin on hormonal responses to thyrotropin and thyrotropin-releasing hormone in dogs

OBJECTIVE

To determine whether administration of endotoxin affects thyroid gland function in dogs.

ANIMALS

24 Beagles.

PROCEDURE

Dogs were given thyrotropin (TSH) or thyrotropin-releasing hormone (TRH) on 2 occasions. Twenty-four hours before the second challenge with TSH or TRH, all dogs were given 5 micrograms of endotoxin/kg of body weight. Serum concentrations of thyroxine (T4), free T4 (fT4), 3,3',5-triiodothyronine (T3), reverse T3, autoantibodies to T3, and plasma concentrations of ACTH and cortisol were determined.

RESULTS

Treatment with endotoxin was associated with reduced baseline concentration of serum T3 and increased baseline concentration of reverse T3 and free T4. Endotoxin treatment resulted in reduced peak serum concentration of T4 after TSH and TRH. However, peak serum concentration of fT4 after TSH and TRH were not affected by endotoxin.

CONCLUSIONS

A single dose of endotoxin affects several aspects of thyroid gland function in dogs, including T4 binding, deiodinase activity, and the thyroidal response to TSH and TRH.

CLINICAL RELEVANCE

Acute or chronic nonthyroidal illness may affect thyroid gland function in dogs. Determination of fT4 concentration may provide a means of differentiating the effects of nonthyroidal illness from those of thyroid dysfunction, because endotoxin treatment was associated with increased baseline serum free T4 concentration and unchanged peak serum fT4 concentration after administration of TSH or TRH.

Citrate as an in vivo marker to discriminate prostate cancer from benign prostatic hyperplasia and normal prostate peripheral zone: detection via localized proton spectroscopy

OBJECTIVES

This study was designed to determine whether citrate levels detected by localized 1H spectroscopy could reliably discriminate regions of prostate adenocarcinoma from surrounding regions of normal peripheral zone and benign prostatic hyperplasia (BPH).

METHODS

In 28 patients and 5 volunteers stimulated echo proton spectroscopy was used in conjunction with endorectal surface coils to obtain water-suppressed 1H spectra from regions of normal prostate peripheral zone, BPH, and prostate cancer. 1H spectra from prostate cancer patients were correlated with pathologic areas identified on T2-weighted endorectal coil magnetic resonance (MR) images and histologic study of the step-sectioned gland after surgery.

RESULTS

The major finding of in vivo studies was consistently lower citrate levels in prostate cancer compared with BPH and normal prostate peripheral zone. This was reflected by significantly (P < 0.05) lower mean citrate/(creatine plus choline) peak area ratio observed for regions of cancer (0.67 +/- 0.17) compared with BPH (1.21 +/- 0.29) and normal peripheral zone (1.46 +/- 0.28). Moreover, there was no overlap of individual cancer and normal peripheral zone citrate ratios and no significant difference between citrate ratios in regions of normal peripheral zone in young volunteers (1.28 +/- 0.14) and age-matched patients (1.46 +/- 0.28). The observed alterations in vivo citrate levels were supported by citrate concentration data obtained from extracts of histologically proven samples of normal, benign, and malignant prostatic tissues removed at surgery. In vitro citrate levels in the normal peripheral zone (30.9 +/- 8.5 mumol/g wet weight) and BPH (46.3 +/- 5.4 mumol/g wet weight) were significantly higher than those for prostate cancer (3.74 +/- 0.54 mumol/g wet weight).

CONCLUSIONS

These studies further demonstrate the potential of citrate as an in vivo marker for discriminating prostate cancer from surrounding regions of normal peripheral zone and BPH.

Effects of smoke inhalation on alveolar surfactant subtypes in mice

The effects of smoke inhalation on alveolar surfactant subtypes were examined in mice exposed for 30 minutes to smoke generated from the burning of a flexible polyurethane foam. At 4 or 12 hours after the exposure, three surfactant pellets, P10, P60, and P100, and a supernatant, S100, were prepared by sequential centrifugation of lavage fluids at 10,000 g for 30 minutes (P10), 60,000 g for 60 minutes (P60), and 100,000 g for 15 hours (P100 and S100). Phospholipid analysis and electron microscopy were performed on each fraction. Smoke exposure dramatically altered the normal distributions of these fractions: it significantly increased the phospholipid content of the heavier subtype, P10, which is thought to represent newly secreted surfactant; had no effect on the intermediate form, P60; and dramatically increased the phospholipid content (approximately fivefold) of the lighter subtypes, P100 and S100, which are believed to represent catabolic end-products of alveolar surfactant. Only P100 was structurally altered by the smoke. These results represent alterations of the normal metabolic processing of alveolar surfactant. Whereas the mechanism is yet to be defined, it seems to involve a small but significant increase in the newly secreted surfactant, as well as an excessively high accumulation of the structurally altered catabolic forms of the secreted surfactant.

Adenomatous polyps of the duodenum in cats: 18 cases (1985-1990)

Medical records were reviewed for 18 cats with adenomatous polyps of the proximal portion of the duodenum. Cats of Asian ancestry were over represented (8/18), and male castrated cats were common (15/18). The median age was 11.8 years. Common clinical signs were acute and chronic vomiting and hematemesis. Nine cats were anemic. Contrast radiography was performed in 12 cats, and a mass of the proximal portion of the duodenum was identified in 10 cats. Endoscopy was used to confirm existence of the mass in 3 cats. Complete excision of the duodenal mass was performed in 17 cats. One cat died before abdominal exploratory surgery, and a duodenal adenomatous polyp was identified at necropsy. Fifteen cats survived the immediate postoperative period, with 13 of 15 having complete resolution of clinical signs. Five cats had concurrent disease, which caused 4 of them to die between 3 and 26 months after surgery. Redevelopment of adenomatous polyps was not detected in any cat during the follow-up period of 1 to 49 months. Results of the study indicated that benign, adenomatous polyps of the duodenum in cats can be safely excised and that the prognosis for return to normal function is excellent.

Treatment of Forelimb Growth Plate Deformity in 11 Dogs by Radial Dome Osteotomy and External Coaptation

Radial dome osteotomy and external coaptation were used to correct forelimb growth deformities with carpal valgus angles of 15 to 43 degrees in 11 dogs (12 forelimbs). Osteotomy sites were clinically healed by week 4. Appearance and function in 10 limbs was good to excellent. The angular deformity recurred in one dog by week 4 due to partial closure of the distal radial growth plate. Carpal valgus recurred in one dog by week 2 because the ulnar osteotomy healed before radial growth ceased.

Efficacy of cefadroxil in the treatment of bacterial dermatitis in dogs

Cefadroxil was found to be an effective antibiotic for the treatment of canine bacterial pyoderma. Bacterial pyoderma was diagnosed in 30 dogs, which were treated with cefadroxil administered orally at 22 mg/kg of body weight, q 12 h, for 21 to 30 days. Dogs were reexamined at the conclusion of antibiotic treatment, and 29 were found to have good to excellent response. On the basis of this study, cefadroxil is a good choice in the treatment of canine pyoderma when cephalosporins are necessary. Efficacy, frequency of administration, cost, and veterinary approval are the major advantages.