Emergence delirium in children: a randomized trial to compare total intravenous anesthesia with propofol and remifentanil to inhalational sevoflurane anesthesia

BACKGROUND

Emergence delirium (ED) refers to a variety of behavioral disturbances commonly seen in children following emergence from anesthesia. Vapor-based anesthesia with sevoflurane, the most common pediatric anesthetic technique, is associated with the highest incidence of ED. Propofol has been shown to reduce ED, but these studies have been methodologically limited.

OBJECTIVE

To conduct a randomized-controlled trial comparing the incidence of ED in children following sevoflurane (SEVO) anesthesia and propofol-remifentanil total intravenous anesthesia (TIVA).

METHODS

One hundred and twelve children, ASA I-II, aged ≥ 2 and ≤ 6 years, undergoing strabismus repair, were assigned to receive TIVA (intravenous induction and maintenance of anesthesia with propofol and remifentanil) or SEVO (inhalational induction and maintenance of anesthesia with sevoflurane). Parent-child induction behavior was scored using the Perioperative Adult Child Behavior Interaction Scale (PACBIS). Postoperatively, ED was assessed by a masked investigator using the Pediatric Anesthesia Emergence Delirium (PAED) Scale and pain using the Face, Legs, Activity, Cry, Consolability (FLACC) Scale every 5 min.

RESULTS

Data are reported for 94 subjects. Incidence of ED was higher with SEVO (38.3% vs 14.9%, P = 0.018). There was no difference in the median PACBIS score. A higher FLACC score was seen with SEVO (median 3 vs 1, P = 0.033). Subjects experiencing ED had higher FLACC scores vs those unaffected by ED (median 7 vs 1, P < 0.0001).

CONCLUSION

There was a lower incidence of ED after TIVA. Both intravenous and inhalational inductions were similarly well-tolerated. The use of TIVA was associated with reduced postoperative pain as measured using FLACC scores.

Real-time cardiorespiratory coherence is blind to changes in respiration during general anesthesia

PURPOSE

A novel real-time cardiorespiratory coherence (CRC) algorithm has been developed to monitor nociception during general anesthesia. CRC uses custom designed filters to track and analyze the respiratory sinus arrhythmia (RSA) as it moves in time and frequency. CRC is a form of sensor fusion between heart rate and respiration, estimating the strength of linear coupling between the two signals. The aim of this study was to estimate the effect of changes in respiration rate (RR) and peak airway pressure (PPaw) on CRC. The response of CRC was compared to a prior offline wavelet-based algorithm (WTCRC) as well as traditional univariate heart rate variability (HRV) measures. A nociception index was created for each algorithm, ranging from 0 (no nociception) to 100 (strong nociception).

METHODS

Following ethics approval and informed consent, data were collected from 48 children receiving general anesthesia during dental surgery. The times of change in RR and PPaw events were noted in real-time. A total of 43 RR and 35 PPaw change events were analyzed post hoc in pseudo real-time. The nociception index averages were compared between a baseline period and a response period around each event. A Wilcoxon rank-sum test was used to compare changes.

RESULTS

The change in RR changed the CRC nociception index by an average of -2.2 [95% CI from -10 to 4.7] (P > 0.3), and the change in PPaw changed the CRC nociception index by an average of 5.4 [-1.0 to 11] (P > 0.1). The changes were smaller than those of many traditional HRV measures.

CONCLUSIONS

Real-time CRC was blind to the changes in respiration, and was less sensitive than many of the traditional HRV measures. A nociception index based on CRC can thus function across a wider range of respiratory conditions than can many traditional univariate HRV measures. The real-time CRC algorithm shows promise for monitoring nociception during general anesthesia.

Wavelet transform cardiorespiratory coherence detects patient movement during general anesthesia

Heart rate variability (HRV) may provide anesthesiologists with a noninvasive tool for monitoring nociception during general anesthesia. A novel wavelet transform cardiorespiratory coherence (WTCRC) algorithm has been developed to calculate estimates of the linear coupling between heart rate and respiration. WTCRC values range from 1 (high coherence, no nociception) to 0 (low coherence, strong nociception). We have assessed the algorithm's ability to detect movement events (indicative of patient response to nociception) in 39 pediatric patients receiving general anesthesia. Sixty movement events were recorded during the 39 surgical procedures. Minimum and average WTCRC were calculated in a 30 second window surrounding each movement event. We used a 95% significance level as the threshold for detecting nociception during patient movement. The 95% significance level was calculated relative to a red noise background, using Monte Carlo simulations. It was calculated to be 0.7. Values below this threshold were treated as successful detection. The algorithm was found to detect movement with sensitivity ranging from 95% (minimum WTCRC) to 65% (average WTCRC). The WTCRC algorithm thus shows promise for noninvasively monitoring nociception during general anesthesia, using only heart rate and respiration.

An allometric model to estimate fluid requirements in children following burn injury

OBJECTIVES

To evaluate the ability of an allometric 3/4 Power Model combined with the Galveston Formula (Galveston-3/4 PM Formula) to predict fluid resuscitation requirements in children suffering burn injuries in comparison with the frequently used Parkland Formula and Galveston Formula using the Du Bois formula for surface area estimation (Galveston-DB Formula).

AIM

To demonstrate that the Galveston-3/4 PM Formula is clinically equivalent to the Galveston-DB Formula for the estimation of fluid requirements in pediatric burn injury cases.

BACKGROUND

Fluid resuscitation requirements differ in children suffering burn injuries when compared to adults. The Parkland Formula works well for normal weight adults but underestimates fluid requirements when indiscriminately applied to pediatric burn patients. The Galveston-DB Formula accounts for the change in body composition with age by using a body surface area (BSA) model but requires the measurement of height. The allometric model, using an exponent of 3/4, accounts for the dependence of a physiological variable on body mass without requiring height measurement and can be applied to estimate fluid requirements after burn injury in children.

METHODS

Comparisons were performed between the hourly calculated fluid requirements for the first 8 h following 20%, 40%, and 60% BSA burns using the Parkland Formula, the Galveston-DB Formula and Galveston-3/4 PM Formula for children 2-23 kg.

RESULTS

In children less than 23 kg, the fluid requirements predicted by the Galveston-3/4 PM Formula are well correlated with those predicted by the Galveston-DB Formula (R2 = 0.997, P < 0.0001) and are much better than of the predictions made with the Parkland Formula, especially for children <10 kg.

CONCLUSIONS

For the purposes of clinical estimation of fluid requirements, the Galveston-3/4 PM Formula is indistinguishable from the Galveston-DB Formula in children 23 kg or less.

Estimates of historical exposures by phase contrast and transmission electron microscopy in North Carolina USA asbestos textile plants

OBJECTIVES

To develop a job-exposure matrix (JEM) for fibre exposures in three asbestos textile plants and to develop estimates of fibre size-specific exposures.

METHODS

Historical dust samples from three North Carolina, USA asbestos textile plants were obtained. Plant specific samples were used to express impinger dust concentrations as fibre concentrations by phase contract microscopy (PCM). Mixed models were used to estimate PCM exposures by plant, department, job and calendar time. Archived membrane filter samples were analysed by transmission electron microscopy (TEM) to determine the bivariate diameter/length distribution of airborne fibres by plant and operation.

RESULTS

PCM fibre levels estimated from the models were very high in the 1930s, with some operations having in excess of 200 fibres/ml, and decreased appreciably over time. TEM results for 77 airborne dust samples found that only a small proportion of airborne fibres were measured by PCM (>0.25 microm in diameter and >5 microm in length) and the proportion varied considerably by plant and operation (range 2.9% to 10.0%). The bivariate diameter/length distribution of airborne fibres demonstrated a relatively high degree of variability by plant and operation. PCM adjustment factors also varied substantially across plants and operations.

CONCLUSIONS

These data provide new information concerning airborne fibre levels and characteristics in three historically important asbestos textile plants. PCM concentrations were high in the early years and TEM data demonstrate that the vast majority of airborne fibres inhaled by the workers were shorter than 5 microm in length, and thus not included in the PCM-based fibre counts.

The anatomy of category-specific object naming in neurodegenerative diseases

Neuropsychological studies suggest that knowledge about living and nonliving objects is processed in separate brain regions. However, lesion and functional neuroimaging studies have implicated different areas. To address this issue, we used voxel-based morphometry to correlate accuracy in naming line drawings of living and nonliving objects with gray matter volumes in 152 patients with various neurodegenerative diseases. The results showed a significant positive correlation between gray matter volumes in bilateral temporal cortices and total naming accuracy regardless of category. Naming scores for living stimuli correlated with gray matter volume in the medial portion of the right anterior temporal pole, whereas naming accuracy for familiarity-matched nonliving items correlated with the volume of the left posterior middle temporal gyrus. A previous behavioral study showed that the living stimuli used here also had in common the characteristic that they were defined by shared sensory semantic features, whereas items in the nonliving group were defined by their action-related semantic features. We propose that the anatomical segregation of living and nonliving categories is the result of their defining semantic features and the distinct neural subsystems used to process them.

Advanced Merkel cell cancer and the elderly

BACKGROUND

Merkel cell cancer (MCC) is an uncommon neuroendocrine skin cancer occurring predominantly in elderly Caucasians. It tends to metastasize to regional lymph nodes and viscera and is sensitive to chemotherapy but recurs rapidly.

AIM

To report one such case, its response to chemotherapy and briefly review the literature.

METHODS

A 73-year-old male with a fungating primary lesion on his left knee and ulcerated inguinal lymph nodes was diagnosed with MCC and treated with chemotherapy. The two largest case series and reviews of case reports were summarised.

RESULTS

His ulcer healed after two cycles of carboplatin and etoposide with improvement in quality of life. Overall response rates of nearly 60% to chemotherapy are reported but median survival is only nine months with metastatic disease.

CONCLUSIONS

Chemotherapy should be considered for fit elderly patients with MCC who have recurrent or advanced disease.

High-salt diet and responses of the pressurized mesenteric artery of the dog to noradrenaline and acetylcholine

A high-salt diet in rats has been shown to result in enhanced vasoconstrictor and/or reduced vasodilator responses of isolated arteries to agonists. The present experiments were designed to investigate the effects of dietary salt on the responses of the pressurized mesenteric resistance artery of the dog to constrictor and dilator agents. Dogs were fed diets containing three different levels of salt with sodium concentrations (in mmol/kg per day) of 0.4 (low salt; LS), 3.0 (intermediate salt; IS) and 6.0 (high salt; HS) for a period of 4 weeks. At the end of the feeding period, animals were killed and lengths of third-order mesenteric artery were obtained and mounted in a perfusion myograph and changes in internal diameter were measured using a microscope and video-tracking device. The responses to noradrenaline (NA), acetylcholine (ACh) and sodium nitroprusside (SNP) were then determined. The vasoconstrictor responses to NA were identical in the three groups. However, the relaxation response of the vessels to ACh was attenuated in HS dogs compared with LS dogs (P < 0.05), but not with IS dogs. The application of N(G)-nitro-l-arginine methyl ester, an inhibitor of nitric oxide synthase, reduced the relaxation responses to ACh comparably in all three groups. The relaxation responses of the vessels to SNP were similar in all groups. These results indicate that, in the dog mesenteric resistance artery, a high-salt diet does not affect vasoconstrictor responses to NA, but does attenuate the vasorelaxant action of ACh, largely by inhibiting the production of endothelium-derived relaxing factor.

Growth in overcrowded housing: a comparison of the states

"The present article reports on a research project that is seeking greater understanding of the prevalence of overcrowding [in the United States] and its causes. First we review the definition of overcrowding and describe differences between renters and owners. Next we document the state-by-state variation in crowding levels among renters. Then we explore some of the factors that may explain this variation."

Triplex ultrasound: elasticity imaging to age deep venous thrombosis

Deep venous thrombosis (DVT), and its sequela, pulmonary embolism (PE), is the leading cause of preventable in-hospital mortality in the USA and other developed countries. After it is detected, acute clots must be differentiated from chronic DVT for appropriate treatment. However, there are no reliable thrombus staging methods presently available in clinical practice. In this study, we tested the hypothesis that blood clots can be detected and staged using a triplex ultrasound (US) test. Triplex US is based on a "gold standard" duplex US technique augmented by US-based reconstructive elasticity imaging. Fibrin-composed blood clots harden with development and organization. By imaging clot elasticity, it may be possible to both detect and differentiate clots and, therefore, provide an urgently needed noninvasive means of DVT staging.

A preliminary evaluation of a prospective study of pulmonary function studies and symptoms of hypoventilation in ALS/MND patients

There is still no consensus as to which physiologic marker should be used as a trigger for the initiation of non-invasive positive pressure ventilation (NPPV) in patients with amyotrophic lateral sclerosis (ALS). Current practice parameters recommend that the decision to begin treatment be based upon forced vital capacity (FVC) measurements. A prospective, randomized study was performed in 20 ALS patients who had an FVC of 70-100%. Patients received baseline assessments including: ALS functional rating scale-respiratory version (ALSFRS-R), pulmonary symptom scale, Short form 36 (SF-36), FVC%, maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and nocturnal oximetry. Patients were randomized to receive NPPV based upon nocturnal oximetry studies suggesting oxygen desaturation <90% for one cumulative minute ("early intervention") or a FVC <50% ("standard of care"). At enrollment, there was no significant correlation between FVC% and the ALSFRS-R, symptom score, MEP, MIP, or duration of nocturnal desaturation <90%. An increase in the vitality subscale of the SF-36 was demonstrated in 5/6 patients randomized to "early intervention" with NPPV. Our data indicate that FVC% correlates poorly with respiratory symptoms and suggests that MIP and nocturnal oximetry may be more sensitive measures of early respiratory insufficiency. In addition, intervention with NPPV earlier than our current standard of care may result in improved quality of life.

Near-infrared and nuclear magnetic resonance spectroscopic assessment of tissue energetics in an isolated, perfused canine hind limb model of dysoxia

This controlled laboratory study examined the efficacy of near-infrared spectroscopy (NIRS) and 31P-nuclear magnetic resonance (NMR) spectroscopy in measuring regional tissue oxygenation in a isolated, perfused hind limb model of tissue dysoxia. Isolated hind limb perfusion was carried out in 20 mongrel dogs and oxygen delivery was varied by manipulating either hemoglobin concentration, oxygen saturation, or flow. Hind limbs from anesthetized mongrel dogs (n = 20) were separated and isolated perfusion performed. NIRS probes for recording relative O2 saturation of tissue hemoglobin (HbO2) and cytochrome a,a3 and NMR probes for measuring 31P-high energy phosphates were placed over the limb. Measurements of physiologic parameters, blood gases, lactate, NIRS values for HbO2 and cytochrome a,a3 redox state, and 31P-phosphate levels were recorded at set intervals throughout the experiment. Measures of tissue oxygen consumption (VO2) correlated with tissue oxygenation as measured by HbO2 and cytochrome a,a3 redox state (NIRS), as well as by 31P-high energy phosphate levels (NMR) throughout the experiment. Delivery-dependent tissue oxygenation was detected at a higher DO2 by NIRS than by VO2 or NMR. Tissue oxygenation as measured by NIRS and NMR shows excellent correlation with oxygen delivery in an isolated, perfused model of shock. NIRS may allow early detection of tissue dysoxia using rapid non-invasive techniques.

Identification of a mutant bovine herpesvirus-1 (BHV-1) in post-arrival outbreaks of IBR in feedlot calves and protection with conventional vaccination

Outbreaks of infectious bovine rhinotracheitis (IBR) have recently been observed in vaccinated feedlot calves in Alberta a few months post-arrival. To investigate the cause of these outbreaks, lung and tracheal tissues were collected from calves that died of IBR during a post-arrival outbreak of disease. Bovine herpesvirus-1 (BHV-1), the causative agent of IBR, was isolated from 6 out of 15 tissues. Of these 6 isolates, 5 failed to react with a monoclonal antibody specific for one of the epitopes on glycoprotein D, one of the most important antigens of BHV-1. The ability of one of these mutant BHV-1 isolates to cause disease in calves vaccinated with a modified-live IBR vaccine was assessed in an experimental challenge study. After one vaccination, the majority of the calves developed humoral and cellular immune responses. Secondary vaccination resulted in a substantially enhanced level of immunity in all animals. Three months after the second vaccination, calves were either challenged with one of the mutant isolates or with a conventional challenge strain of BHV-1. Regardless of the type of virus used for challenge, vaccinated calves experienced significantly (P < 0.05) less weight loss and temperature rises, had lower nasal scores, and shed less virus than non-vaccinated animals. The only statistically significant (P < 0.05) difference between the 2 challenge viruses was the amount of virus shed, which was higher in non-vaccinated calves challenged with the mutant virus than in those challenged with the conventional virus. These data show that calves vaccinated with a modified-live IBR vaccine are protected from challenge with either the mutant or the conventional virus.

Stereotaxic delivery of corticosterone to the amygdala modulates colonic sensitivity in rats

Episodes of anxiety are often associated with the onset or exacerbation of visceral pain in patients with irritable bowel syndrome (IBS). The central amygdaloid nucleus (CeA) is a key limbic structure involved in the expression of anxiety as well as a major site for regulating autonomic and visceral responses to stress. Previous experiments have shown that glucocorticoids can act directly at the CeA to increase the level of anxiety in rats. Therefore, the goal of this study was to examine the effect of stereotaxic delivery of corticosterone into the CeA on the development of visceral hypersensitivity by measuring visceromotor response to colorectal distention in rats. Stereotaxic delivery of corticosterone to the CeA increases indices of anxiety and produces a hypersensitive colon as demonstrated by an exaggerated visceromotor response to colorectal distention in the F344 rat strain. Our findings suggest that modulation of anxiety by manipulating amygdala function with corticosterone induced colonic hypersensitivity via descending neuronal pathways from the CeA.

Short-term effects of formaldehyde on peak expiratory flow and irritant symptoms

The authors studied the respiratory effects of formaldehyde exposure among students who dissected cadavers in a gross anatomy laboratory. Peak expiratory flow and respiratory symptoms were measured before and after each weekly laboratory session. Each of 38 students was exposed to formaldehyde for 2.5 hr/wk for 14 wk. Individual, daily formaldehyde measurements averaged 1.1 ppm (standard deviation = 0.56 ppm). Multivariate models demonstrated two different time scales of effect of formaldehyde on peak expiratory flow: (1) exposure during the previous 2.5 hr reduced peak expiratory flow by -1.0% per ppm, and (2) average exposure during all preceding weeks reduced peak expiratory flow by an additional -0.5% per ppm of formaldehyde. However, the short-term exposure effect was diminished during the first 4 wk, suggesting at least partial acclimatization. Symptom reporting was also associated with exposure during the previous 2.5 hr, and similar evidence of acclimatization was observed. These results suggest that there are two different time scales of response to formaldehyde, and they emphasize the need for longitudinal studies, characterized by quantitative exposure characterization, and frequent measurements of outcome.