Tag Archives: paediatric

Severe Traumatic Brain Injury in Children

The Brain Trauma Foundation has released updated guidelines on traumatic brain injury in children.
Most of the recommendations are Grade C and therefore based on limited evidence.

Indications for ICP monitoring

Use of intracranial pressure (ICP) monitoring may be considered in infants and children with severe traumatic brain injury (TBI) (Grade C).
Four lines of evidence support the use of ICP monitoring in children with severe TBI:

  • a frequently reported high incidence of intracranial hypertension in children with severe TBI
  • a widely reported association of intracranial hypertension and poor neurologic outcome
  • the concordance of protocol-based intracranial hypertension therapy and best-reported clinical outcomes
  • and improved outcomes associated with successful ICP-lowering therapies.

Threshold for treatment of intracranial hypertension
Treatment of intracranial pressure (ICP) may be considered at a threshold of 20 mm Hg (Grade C).
Sustained elevations in ICP (>20 mm Hg) are associated with poor outcome in children after severe TBI.
Normal values of blood pressure and ICP are age-dependent (lower at younger ages), so it is anticipated that the optimal ICP treatment threshold may be age-dependent.
Cerebral perfusion pressure thresholds
A CPP threshold 40–50 mm Hg may be considered. There may be age-specific thresholds with infants at the lower end and adolescents at the upper end of this range (Grade C).
Survivors of severe pediatric TBI undergoing ICP monitoring consistently have higher CPP values vs. nonsurvivors, but no study demonstrates that active maintenance of CPP above any target threshold in pediatric TBI reduces mortality or morbidity.
CPP should be determined in a standard fashion with ICP zeroed to the tragus (as an indicator of the foramen of Monro and midventricular level) and MAP zeroed to the right atrium with the head of the bed elevated 30°.
Advanced neuromonitoring
If brain oxygenation monitoring is used, maintenance of partial pressure of brain tissue oxygen (PbtO2) >10 mm Hg may be considered.
Neuroimaging
In the absence of neurologic deterioration or increasing intracranial pressure (ICP), obtaining a routine repeat computed tomography (CT) scan >24 hrs after the admission and initial follow-up study may not be indicated for decisions about neurosurgical intervention (Grade C).
Hyperosmolar therapy
Hypertonic saline should be considered for the treatment of severe pediatric traumatic brain injury (TBI) associated with intracranial hypertension. Effective doses for acute use range between 6.5 and 10 mL/kg (of 3%) (Grade B).
Hypertonic saline should be considered for the treatment of severe pediatric TBI associated with intracranial hypertension. Effective doses as a continuous infusion of 3% saline range between 0.1 and 1.0 mL/kg of body weight per hour administered on a sliding scale. The minimum dose needed to maintain intracranial pressure (ICP)
Temperature control
Moderate hypothermia (32–33°C) beginning early after severe traumatic brain injury (TBI) for only 24 hrs’ duration should be avoided.
Moderate hypothermia (32–33°C) be- ginning within 8 hrs after severe TBI for up to 48 hrs’ duration should be considered to reduce intracranial hypertension.
If hypothermia is induced for any indication, rewarming at a rate of >0.5°C/hr should be avoided (Grade B).
Moderate hypothermia (32–33°C) be- ginning early after severe TBI for 48 hrs, duration may be considered (Grade C).
Note: after completion of these guidelines, the committee became aware that the Cool Kids trial of hypothermia in pediatric TBI was stopped because of futility. The implications of this development on the recommendations in this section may need to be considered by the treating physician when details of the study are published.
Cerebrospinal fluid drainage
Cerebrospinal fluid (CSF) drainage through an external ventricular drain may be considered in the management of increased intracranial pressure (ICP) in children with severe traumatic brain injury (TBI).
The addition of a lumbar drain may be considered in the case of refractory intracranial hypertension with a functioning external ventricular drain, open basal cis- terns, and no evidence of a mass lesion or shift on imaging studies (Grade C).
Barbiturates
High-dose barbiturate therapy may be considered in hemodynamically stable patients with refractory intracranial hypertension despite maximal medical and surgical management.
When high-dose barbiturate therapy is used to treat refractory intracranial hy- pertension, continuous arterial blood pressure monitoring and cardiovascular support to maintain adequate cerebral perfusion pressure are required (Grade C).
Decompressive craniectomy for the treatment of intracranial hypertension
Decompressive craniectomy (DC) with duraplasty, leaving the bone flap out, may be considered for pediatric patients with traumatic brain injury (TBI) who are showing early signs of neurologic deterioration or herniation or are developing intracranial hypertension refractory to medical management during the early stages of their treatment (Grade C).
Hyperventilation
Avoidance of prophylactic severe hyperventilation to a PaCO2 If hyperventilation is used in the management of refractory intracranial hypertension, advanced neuromonitoring for evaluation of cerebral ischemia may be considered (Grade C).
Corticosteroids
The use of corticosteroids is not recommended to improve outcome or reduce intracranial pressure (ICP) for children with severe traumatic brain injury (TBI) (Grade B).
Analgesics, sedatives, and neuromuscular blockade
Etomidate may be considered to control severe intracranial hypertension; however, the risks resulting from adrenal suppression must be considered.
Thiopental may be considered to control intracranial hypertension.
In the absence of outcome data, the specific indications, choice and dosing of analgesics, sedatives, and neuromuscular-blocking agents used in the management of infants and children with severe traumatic brain injury (TBI) should be left to the treating physician.
*As stated by the Food and Drug Administration, continuous infusion of propofol for either sedation or the management of refractory intracranial hypertension in infants and children with severe TBI is not recommended (Grade C).
The availability of other sedatives and analgesics that do not suppress adrenal function, small sample size and single-dose administration in the study discussed previously, and limited safety profile in pediatric TBI limit the ability to endorse the general use of etomidate as a sedative other than as an option for single-dose administration in the setting of raised ICP.
Glucose and nutrition
The evidence does not support the use of an immune-modulating diet for the treatment of severe traumatic brain injury (TBI) to improve outcome (Grade B).
In the absence of outcome data, the specific approach to glycemic control in the management of infants and children with severe TBI should be left to the treating physician (Grade C).
Antiseizure prophylaxis
Prophylactic treatment with phenytoin may be considered to reduce the incidence of early posttraumatic seizures (PTS) in pediatric patients with severe traumatic brain injury (TBI) (Grade C).
The incidence of early PTS in pediatric patients with TBI is approximately 10% given the limitations of the available data. Based on a single class III study (4), prophylactic anticonvulsant therapy with phenytoin may be considered to reduce the incidence of early posttraumatic seizures in pediatric patients with severe TBI. Concomitant monitoring of drug levels is appropriate given the potential alterations in drug metabolism described in the context of TBI. Stronger class II evidence is available supporting the use of prophylactic anticonvulsant treatment to reduce the risk of early PTS in adults. There are no compelling data in the pediatric TBI literature to show that such treatment reduces the long-term risk of PTS or improves long-term neurologic outcome.
Guidelines for the Acute Medical Management of Severe Traumatic Brain Injury in Infants, Children, and Adolescents-Second Edition
Pediatr Crit Care Med 2012 Vol. 13, No. 1 (Suppl.)
Read online
Download PDF (617k)
Other Brain Trauma Foundation Guidelines

Capillary refill time

A review of capillary refill time (CRT) reveals some interesting details about this test:

  • CRT is affected by age – the upper limit of normal for neonates is 3 seconds.
  • It increases with age – one study recommended the upper limit of normal for adult women should be increased to 2.9 seconds and for the elderly to 4.5 seconds.
  • It is affected by multiple external factors (especially ambient temperature).
  • Although it is claimed to have some predictive value in the assessment of dehydration and serious infection in children, studies vary in where and for how long pressure should be applied, and there is poor interobserver reliability.

The latest (5th Edition) of the Advanced Paediatric Life Support Manual states:
Poor capillary refill and differential pulse volumes are neither sensitive nor specific indicators of shock in infants and children, but are useful clinical signs when used in conjunction with the other signs described
In my view, it is best used as a monitor of trends (in accordance with skin temperature and other markers of perfusion), rather than by placing emphasis on the exact number of seconds of a single reading. See below for a video of my perfectly happy and healthy son demonstrating a CRT of over six seconds in a cool room during an English Summer’s day.
The authors of the review caution:
Operating rooms are cold, patients are often draped, which limits access, and because most anesthetics are potent vasodilators, the use of CRT to guide practice is not justified. The possibility of a false-positive or false-negative assessment is simply too great.


Capillary refill time (CRT) is widely used by health care workers as part of the rapid, structured cardiopulmonary assessment of critically ill patients. Measurement involves the visual inspection of blood returning to distal capillaries after they have been emptied by pressure. It is hypothesized that CRT is a simple measure of alterations in peripheral perfusion. Evidence for the use of CRT in anesthesia is lacking and further research is required, but understanding may be gained from evidence in other fields. In this report, we examine this evidence and factors affecting CRT measurement. Novel approaches to the assessment of CRT are under investigation. In the future, CRT measurement may be achieved using new technologies such as digital videography or modified oxygen saturation probes; these new methods would remove the limitations associated with clinical CRT measurement and may even be able to provide an automated CRT measurement.

Capillary Refill Time: Is It Still a Useful Clinical Sign?
Anesth Analg. 2011 Jul;113(1):120-3
The Capillary Refill Video

Normal heart and respiratory rates in children


A large review has established normal ranges of heart rate and respiratory rate in children from birth to 18 years of age. Some of the results differed markedly from some existing ranges quoted, such as in the Advanced Paediatric Life Support Course.

BACKGROUND: Although heart rate and respiratory rate in children are measured routinely in acute settings, current reference ranges are not based on evidence. We aimed to derive new centile charts for these vital signs and to compare these centiles with existing international ranges.

METHODS: We searched Medline, Embase, CINAHL, and reference lists for studies that reported heart rate or respiratory rate of healthy children between birth and 18 years of age. We used non-parametric kernel regression to create centile charts for heart rate and respiratory rate in relation to age. We compared existing reference ranges with those derived from our centile charts.

FINDINGS: We identified 69 studies with heart rate data for 143,346 children and respiratory rate data for 3881 children. Our centile charts show decline in respiratory rate from birth to early adolescence, with the steepest fall apparent in infants under 2 years of age; decreasing from a median of 44 breaths per min at birth to 26 breaths per min at 2 years. Heart rate shows a small peak at age 1 month. Median heart rate increases from 127 beats per min at birth to a maximum of 145 beats per min at about 1 month, before decreasing to 113 beats per min by 2 years of age. Comparison of our centile charts with existing published reference ranges for heart rate and respiratory rate show striking disagreement, with limits from published ranges frequently exceeding the 99th and 1st centiles, or crossing the median.

INTERPRETATION: Our evidence-based centile charts for children from birth to 18 years should help clinicians to update clinical and resuscitation guidelines.

Normal ranges of heart rate and respiratory rate in children from birth to 18 years of age: a systematic review of observational studies
Lancet. 2011 Mar 19;377(9770):1011-8

Steroids for sepsis in kids

A small retrospective study suggests adrenal insufficiency is common in kids with septic shock, and that steroid administration in these children was associated with a decrease in vasoactive drug requirements.

INTRODUCTION: Adrenal insufficiency may be common in adults and children with vasopressor-resistant shock. We developed a protocolized approach to low-dose adrenocorticotropin testing and empirical low-dose glucocorticoid/mineralocorticoid supplementation in children with systemic inflammatory response syndrome and persistent hypotension following fluid resuscitation and vasopressor infusion.
HYPOTHESIS: We hypothesized that absolute and relative adrenal insufficiency was common in children with systemic inflammatory response syndrome requiring vasopressor support and that steroid administration would be associated with decreased vasopressor need.
METHODS: Retrospective review of pediatric patients with systemic inflammatory response syndrome and vasopressor-dependent shock receiving protocol-based adrenocorticotropin testing and low-dose steroid supplementation. The incidence of absolute and relative adrenal insufficiency was determined using several definitions. Vasopressor dose requirements were evaluated before, and following, initiation of corticosteroids.
RESULTS: Seventy-eight patients met inclusion criteria for systemic inflammatory response syndrome and shock; 40 had septic shock. Median age was 84 months (range, 0.5-295). By adrenocorticotropin testing, 44 (56%) had absolute adrenal insufficiency, 39 (50%) had relative adrenal insufficiency, and 69 (88%) had either form of adrenal insufficiency. Adrenal insufficiency incidence was significantly higher in children >2 yrs (p = .0209). Therapeutic interventions included median 80-mL/kg fluid resuscitation; 65% of patients required dopamine, 58% norepinephrine, and 49% dopamine plus norepinephrine. With steroid supplementation, median dopamine dose decreased from 10 to 4 μg/kg/min at 4 hrs (p = .0001), and median dose of norepinephrine decreased from 0.175 μg/kg/min to 0.05 μg/kg/min at 4 hrs (p = .039).
CONCLUSIONS: Absolute and relative adrenal insufficiency was prevalent in this cohort of children with systemic inflammatory response syndrome and vasopressor-dependent shock and increased with age. Introduction of steroids produced a significant reduction in vasopressor duration and dosage. Use of low-dose adrenocorticotropin testing may help further delineate populations who require steroid supplementation.

Incidence of adrenal insufficiency and impact of corticosteroid supplementation in critically ill children with systemic inflammatory syndrome and vasopressor-dependent shock
Crit Care Med. 2011 May;39(5):1145-50

FAST in kids has low sensitivity

The abstract says it all – don’t use FAST to rule out significant abdominal free fluid in kids with blunt abdominal trauma. Fine as a rule-in test (for free fluid) though.

Objectives:  Focused assessment of sonography in trauma (FAST) has been shown useful to detect clinically significant hemoperitoneum in adults, but not in children. The objectives were to determine test characteristics for clinically important intraperitoneal free fluid (FF) in pediatric blunt abdominal trauma (BAT) using computed tomography (CT) or surgery as criterion reference and, second, to determine the test characteristics of FAST to detect any amount of intraperitoneal FF as detected by CT.

Methods:  This was a prospective observational study of consecutive children (0–17 years) who required trauma team activation for BAT and received either CT or laparotomy between 2004 and 2007. Experienced physicians performed and interpreted FAST. Clinically important FF was defined as moderate or greater amount of intraperitoneal FF per the radiologist CT report or surgery.

Results:  The study enrolled 431 patients, excluded 74, and analyzed data on 357. For the first objective, 23 patients had significant hemoperitoneum (22 on CT and one at surgery). Twelve of the 23 had true-positive FAST (sensitivity = 52%; 95% confidence interval [CI] = 31% to 73%). FAST was true negative in 321 of 334 (specificity = 96%; 95% CI = 93% to 98%). Twelve of 25 patients with positive FAST had significant FF on CT (positive predictive value [PPV] = 48%; 95% CI = 28% to 69%). Of 332 patients with negative FAST, 321 had no significant fluid on CT (negative predictive value [NPV] = 97%; 95% CI = 94% to 98%). Positive likelihood ratio (LR) for FF was 13.4 (95% CI = 6.9 to 26.0) while the negative LR was 0.50 (95% CI = 0.32 to 0.76). Accuracy was 93% (333 of 357, 95% CI = 90% to 96%). For the second objective, test characteristics were as follows: sensitivity = 20% (95% CI = 13% to 30%), specificity = 98% (95% CI = 95% to 99%), PPV = 76% (95% CI = 54% to 90%), NPV = 78% (95% CI = 73% to 82%), positive LR = 9.0 (95% CI = 3.7 to 21.8), negative LR = 0.81 (95% CI = 0.7 to 0.9), and accuracy = 78% (277 of 357, 95% CI = 73% to 82%).

Conclusion:  In this population of children with BAT, FAST has a low sensitivity for clinically important FF but has high specificity. A positive FAST suggests hemoperitoneum and abdominal injury, while a negative FAST aids little in decision-making

Test characteristics of focused assessment of sonography for trauma for clinically significant abdominal free fluid in pediatric blunt abdominal trauma
Acad Emerg Med. 2011 May;18(5):477-82

Fluid Bolus in African Children with Severe Infection

Much discussion has already taken place in the blogosphere about the FEAST study of fluid resuscitation in septic children. Although a well conducted study, its external validity to Western populations is dubious, particularly in view of the proportion of malaria in the cohorts studied.

In the words of my emergency physician colleague Dr Fiona Rae from Wrexham, UK:

“Interesting. As they say, a completely different population in a resource limited setting so it doesn’t translate to UK practice. Majority of these children had malaria and if I read correctly 32% had Hb < 5g/dl. Also 20-40mls/kg is quite a lot of fluid these days as an initial bolus other than in the sort of severely shocked patients that they seemed to exclude. Their overall mortality also seems to be lower than expected for this population.

If you work in an environment without ITU and a high incidence of malaria then its a useful study. They are not the sort of children I see in my resus room with shock though.”
Nicely put Fi!
You can also read an analysis of this study on Dr G’s blog – where you can find other posts on critical care and emergency medicine.

Background
The role of fluid resuscitation in the treatment of children with shock and life-threatening infections who live in resource-limited settings is not established.
Methods
We randomly assigned children with severe febrile illness and impaired perfusion to receive boluses of 20 to 40 ml of 5% albumin solution (albumin-bolus group) or 0.9% saline solution (saline-bolus group) per kilogram of body weight or no bolus (control group) at the time of admission to a hospital in Uganda, Kenya, or Tanzania (stratum A); children with severe hypotension were randomly assigned to one of the bolus groups only (stratum B). Children with malnutrition or gastroenteritis were excluded. The primary end point was 48-hour mortality; secondary end points included pulmonary edema, increased intracranial pressure, and mortality or neurologic sequelae at 4 weeks.
Results
The data and safety monitoring committee recommended halting recruitment after 3141 of the projected 3600 children in stratum A were enrolled. Malaria status (57% overall) and clinical severity were similar across groups. The 48-hour mortality was 10.6% (111 of 1050 children), 10.5% (110 of 1047 children), and 7.3% (76 of 1044 children) in the albumin-bolus, saline-bolus, and control groups, respectively (relative risk for saline bolus vs. control, 1.44; 95% confidence interval [CI], 1.09 to 1.90; P=0.01; relative risk for albumin bolus vs. saline bolus, 1.01; 95% CI, 0.78 to 1.29; P=0.96; and relative risk for any bolus vs. control, 1.45; 95% CI, 1.13 to 1.86; P=0.003). The 4-week mortality was 12.2%, 12.0%, and 8.7% in the three groups, respectively (P=0.004 for the comparison of bolus with control). Neurologic sequelae occurred in 2.2%, 1.9%, and 2.0% of the children in the respective groups (P=0.92), and pulmonary edema or increased intracranial pressure occurred in 2.6%, 2.2%, and 1.7% (P=0.17), respectively. In stratum B, 69% of the children (9 of 13) in the albumin-bolus group and 56% (9 of 16) in the saline-bolus group died (P=0.45). The results were consistent across centers and across subgroups according to the severity of shock and status with respect to malaria, coma, sepsis, acidosis, and severe anemia.
Conclusions
Fluid boluses significantly increased 48-hour mortality in critically ill children with impaired perfusion in these resource-limited settings in Africa.

Mortality after Fluid Bolus in African Children with Severe Infection
NEJM May 26, 2011 Full text available

Kids tracheal tubes – formulas galore

An ultrasound study of paediatric airways showed sonographic measurement to be a better predictor of tracheal tube size (using a formula – derived and then validated – to estimate external tube diameter) than traditional formulae for selecting the internal tube diameter based on age. Since the measurements, taken at the lower edge of the cricoid cartilage, were made after patients were paralyzed, and were performed without ventilation or positive end-expiratory pressure to minimize fluctuation in tracheal diameter, taking about 30 seconds, this is not something I anticipate applying in critical care practice. However, the paper does provide a good opportunity to revise some of the existing formulae. They used:
(1) The Cole formula for uncuffed tubes: ID (intenal diameter) in mm= (age in years)/4 + 4
(2) The Motoyama formula for cuffed ETTs in children aged 2 yr or older: ID in mm = (age in years)/4 + 3.5
(3) The Khine formula for cuffed ETTs in children younger than 2 yr: ID in mm = (age in years)/4 + 3.0
The formula established in the study was:

  • cuffed ETT outer diameter (OD) = 0.46 x (subglottic diameter) + 1.56
  • uncuffed ETT OD = 0.55 x (subglottic diameter) + 1.16

Age in months also correlated with optimal ETT size in mm, although the correlation was weaker than for subglottic diameter:

  • cuffed ETT OD = 0.027 x (age) + 5.2
  • uncuffed ETT OD = 0.030 x (age) + 5.4

BACKGROUND: Formulas based on age and height often fail to reliably predict the proper endotracheal tube (ETT) size in pediatric patients. We, thus, tested the hypothesis that subglottic diameter, as determined by ultrasonography, better predicts optimal ETT size than existing methods.
METHODS: A total of 192 patients, aged 1 month to 6 yr, who were scheduled for surgery and undergoing general anesthesia were enrolled and divided into development and validation phases. In the development group, the optimal ETT size was selected according to standard age-based formulas for cuffed and uncuffed tubes. Tubes were replaced as necessary until a good clinical fit was obtained. Via ultrasonography, the subglottic upper airway diameter was determined before tracheal intubation. We constructed a regression equation between the subglottic upper airway diameter and the outer diameter of the ETT finally selected. In the validation group, ETT size was selected after ultrasonography using this regression equation. The primary outcome was the fraction of initial cuffed and uncuffed tube sizes, as selected through the regression formula, that proved clinically optimal.
RESULTS: Subglottic upper airway diameter was highly correlated with outer ETT diameter deemed optimal on clinical grounds. The rate of agreement between the predicted ETT size based on ultrasonic measurement and the final ETT size selected clinically was 98% for cuffed ETTs and 96% for uncuffed ETTs.
CONCLUSIONS: Measuring subglottic airway diameter with ultrasonography facilitates the selection of appropriately sized ETTs in pediatric patients. This selection method better predicted optimal outer ETT diameter than standard age- and height-based formulas.

Prediction of Pediatric Endotracheal Tube Size by Ultrasonography
Anesthesiology. 2010 Oct;113(4):819-24

Intranasal ketamine analgesia

I published a case report in the EMJ highlighting the use of intranasal ketamine in a pre-hospital paediatric burns case.
The lad had nasty scalds but did not need iv fluids and had no other indications for an iv line. The vigorous first aid had rendered him cold and veinless and an intraosseous would have been overkill. Ketamine was perfect for the job and Ambulance Service New South Wales paramedics carry a mucosal atomisation device (MAD) for the administration of i.n. fentanyl. I used the MAD to adminster 0.5 mg/kg ketamine, but there is a dead space in the device (0.1 ml) that probably resulted in actual delivery of 0.25mg/kg. This gave great analgesia and compliance enabling us to painlessly apply polyethylene film to the burns.
I received the following email from TIm Wolfe, the inventor of the MAD nasal (reproduced with permission):

Cliff,
Nice contribution to the literature. There is a lot of interest in IN ketamine in these lower doses to treat pain but not cause sedation. You eluded to the military interest and the hospice interest. I think your insights for EMS are also cutting edge – hopefully this will lead others to design a larger trial.
Thanks
Tim Wolfe, MD

More information on the use of intranasal medication is available at www.intranasal.net. I have no conflicts of interest to declare.
Case report: prehospital use of intranasal ketamine for paediatric burn injury
Emerg Med J. 2011 Feb 3. [Epub ahead of print]

Weight formula validation

Further validation of the UK-derived Luscombe weight formula has been made in the Australian setting. The nice simple formula for estimating the weight of a child based on age is:

Weight (kg) = 3 x age(years) + 7

It was compared with other formulae including the Best Guess formula, which is a bit more difficult to apply as the formula varies according to age range. This is reported in a previous post.
The authors provide the following cautionary advice:
“Whereas age-based formulae are, in the main, easy to calculate, the evidence suggests that ethnicity and body habitus pose serious challenges to their accuracy. In comparative studies, age-based formulae were found to be less accurate than the Broselow tape and parental estimate, with parental estimate being the most accurate weight estimation method. In light of this evidence, age-based formulae should only be used when these more accurate methods are not available.”

OBJECTIVE: Several paediatric weight estimation methods have been described for use when direct weight measurement is not possible. A new age-based weight estimation method has recently been proposed. The Luscombe formula, applicable to children aged 1-10 years, is calculated as (3 × age in years) + 7. Our objective was to externally validate this formula using an existing database.
METHOD: Secondary analysis of a prospective observational cohort study. Data collected included height, age, ethnicity and measured weight. The outcome of interest was agreement between estimated weight using the Luscombe formula and measured weight. Secondary outcome was comparison with performance of Argall, APLS and Best Guess formulae. Accuracy of weight estimation methods was compared using mean difference (bias), 95% limits of agreement, root mean square error and proportion with agreement within 10%.
RESULTS: Four hundred and ten children were studied. Median age was 4 years; 54.4% were boys. Mean body mass index was 17 kg/m(2) and mean measured weight was 21.2 kg. The Luscombe formula had a mean difference of 0.66 kg (95% limits of agreement -9.9 to +11.3 kg; root mean square error of 5.44 kg). 45.4% of estimates were within 10% of measured weight. The Best Guess and Luscombe formulae performed better than Argall or APLS formulae.
CONCLUSION: The Luscombe formula is among the more accurate age-based weight estimation formulae. When more accurate methods (e.g. parental estimation or the Broselow tape) are not available, it is an acceptable option for estimating children’s weight.

Validation of the Luscombe weight formula for estimating children’s weight
Emerg Med Australas 2011 Feb;23(1):59-62

Laryngospasm and ketamine

What are the factors associated with laryngospasm in ketamine sedation? A large study was unable to identify specific predictors:
Objective: The objective of this study was to assess predictors of emergency department (ED) ketamine-associated laryngospasm using case-control techniques.
Methods: We performed a matched case-control analysis of a sample of 8282 ED ketamine sedations (including 22 occurrences of laryngospasm) assembled from 32 prior published series. We sequentially studied the association of each of 7 clinical variables with laryngospasm by assigning 4 controls to each case while matching for the remaining 6 variables. We then used univariate statistics and conditional logistic regression to analyze the matched sets.

Results: We found no statistical association of age, dose, oropharyngeal procedure, underlying physical illness, route, or coadministered anticholinergics with laryngospasm. Coadministered benzodiazepines showed a borderline association in the multivariate but not univariate analysis that was considered anomalous.
Conclusions: This case-control analysis of the largest available sample of ED ketamine-associated laryngospasm did not demonstrate evidence of association with age, dose, or other clinical factors. Such laryngospasm seems to be idiosyncratic, and accordingly, clinicians administering ketamine must be prepared for its rapid identification and management. Given no evidence that they decrease the risk of laryngospasm, coadministered anticholinergics seem unnecessary.
Laryngospasm During Emergency Department Ketamine Sedation: A Case-Control Study
Pediatr Emerg Care. 2010 Nov;26(11):798-802