Tag Archives: diagnosis

Acute Med, All Updates, PHARM, Resus, Ultrasound

Pre-hospital Echo

Leave a comment

Pre-hospital physicians in Germany performed basic echo on patients with symptoms either of profound hypotension and/or severe dyspnoea/tachypnoea where judged by the physician to be in a ‘peri-resuscitation’ state, and on patients undergoing CPR. Features noted were; cardiac motion (present or absent), ventricular function (normal, moderately impaired, severely impaired, absent), right ventricular dilatation or pericardial collection.
A few interesting findings to note:

  • In almost all patients an interpretable view was achieved; in the CPR patients, the subcostal view was best
  • In PEA patients, there was a difference in survival to admission (to discharge isn’t documented) between those with and without sonographically evident cardiac wall motion (21/38 = 55% vs 1/13 = 8%)
  • In ‘suspected asystole’, some patients had sonographically evident cardiac wall motion, and 9/37 (24%) of these survived to hospital admission vs 4/37 (11%) with no wall motion. On this point, the authors note: ‘The ECG performance and interpretation were by experienced practitioners, and this therefore raises questions regarding the accuracy of an ECG diagnosis of asystole in the pre-hospital setting‘.

Purpose of the study: Focused ultrasound is increasingly used in the emergency setting, with an ALS- compliant focused echocardiography algorithm proposed as an adjunct in peri-resuscitation care (FEEL). The purpose of this study was to evaluate the feasibility of FEEL in pre-hospital resuscitation, the incidence of potentially treatable conditions detected, and the influence on patient management.
Patients, materials and methods: A prospective observational study in a pre-hospital emergency setting in patients actively undergoing cardio-pulmonary resuscitation or in a shock state. The FEEL protocol was applied by trained emergency doctors, following which a standardised report sheet was completed, including echo findings and any echo-directed change in management. These reports were then analysed independently.
Results: A total of 230 patients were included, with 204 undergoing a FEEL examination during ongoing cardiac arrest (100) and in a shock state (104). Images of diagnostic quality were obtained in 96%. In 35% of those with an ECG diagnosis of asystole, and 58% of those with PEA, coordinated cardiac motion was detected, and associated with increased survival. Echocardiographic findings altered management in 78% of cases.
Conclusions: Application of ALS-compliant echocardiography in pre-hospital care is feasible, and alters diagnosis and management in a significant number of patients. Further research into its effect on patient outcomes is warranted.
Focused echocardiographic evaluation in life support and peri-resuscitation of
emergency patients: A prospective trial
Resuscitation. 2010 Nov;81(11):1527-33

All Updates, Kids, Ultrasound

US determined best LP position

Leave a comment

Here ultrasound was used to ascertain the best position for doing a lumbar puncture in kids, where the interspinous space was maximised:
BACKGROUND Lumbar punctures are commonly performed in the pediatric emergency department. There is no standard, recommended, optimal position for children who are undergoing the procedure.
OBJECTIVE To determine a position for lumbar punctures where the interspinous space is maximized, as measured by bedside ultrasound.
METHODS A prospective convenience sample of children under age 12 was performed. Using a portable ultrasound device, the L3-L4 or L4-L5 interspinous space was measured with the subject in 5 different positions. The primary outcome was the interspinous distance between 2 adjacent vertebrae. The interspinous space was measured with the subject sitting with and without hip flexion. In the lateral recumbent position, the interspinous space wasmeasured with the hips in a neutral position as well as in flexion, both with and without neck flexion. Data were analyzed by comparing pairwise differences.

RESULTS There were 28 subjects enrolled (13 girls and 15 boys) at a median age of 5 years. The sitting-flexed position provided a significantly increased interspinous space (P < .05). Flexion of the hips increased the interspinous space in both the sitting and lateral recumbent positions (P < .05). Flexion of the neck, did not significantly change the interspinous space (P = .998).
CONCLUSIONS The interspinous space of the lumbar spine was maximally increased with children in the sitting position with flexed hips; therefore we recommend this position for lumbar punctures. In the lateral recumbent position, neck flexion does not increase the interspinous space and may increase morbidity; therefore, it is recommended to hold patients at the level of the shoulders as to avoid neckflexion.
Positioning for lumbar puncture in children evaluated by bedside ultrasound
Pediatrics. 2010 May;125(5):e1149-53
A more recent study also used ultrasound in infants to investigate the anatomic necessity and advantage derived from a tight flexed lateral recumbent position, since hypoxia has been observed in that position:
Objectives:  Hypoxia has been observed when infants undergo lumbar puncture in a tight flexed lateral recumbent position. This study used sonographic measurements of lumbar interspinous spaces to investigate the anatomic necessity and advantage derived from this tight flexed positioning in infants.
Methods:  This was a brief, prospective, observational study of a convenience sample of patients. Twenty-one healthy infants under 1 month of age were scanned in two positions: prone in a spine-neutral position and lateral recumbent with their knees bent into their chest and their neck flexed. In each position, a 5- to 10-MHz linear array transducer was used to scan midline along the lumbar spinous processes in the sagittal plane. The distances between the spinous processes were measured near the ligamentum flavum using the ultrasound machine’s calipers. Pulse oximetry was monitored on all infants during flexed positioning.
Results:  In the spine-neutral position, all studied interspinous spaces were much wider than a 22-gauge spinal needle (diameter 0.072 cm). The mean (±SD) interspinous spaces for L3-4, L4-5, and L5-S1 in a spine-neutral position were 0.42 (±0.07), 0.37 (±0.06), and 0.36 (±0.11) cm, respectively. Flexing the infants increased the mean lumbar interspinous spaces at L3-4, L4-5, and L5-S1 by 31, 51, and 44%, respectively.
Conclusions:  This study verified that tight, lateral flexed positioning substantially enhances the space between the lumbar spinous processes and that a spine-neutral position also allows for a large enough anatomic interspinous space to perform lumbar puncture. However, further clinical research is required to establish the feasibility of lumbar puncture in a spine-neutral position.
Evaluating infant positioning for lumbar puncture using sonographic measurements
Acad Emerg Med. 2011 Feb;18(2):215-8

All Updates, PHARM, Resus, Trauma, Ultrasound

Inadequate pre-hospital needle thoracostomy

Leave a comment

The purpose of this study was to evaluate the frequency of inadequate needle chest thoracostomy in the prehospital setting in trauma patients suspected of having a pneumothorax (PTX) on the basis of physical examination.
This study took place at a level I trauma center. All trauma patients arriving via emergency medical services with a suspected PTX and a needle thoracostomy were evaluated for a PTX with bedside ultrasound. Patients too unstable for ultrasound evaluation before tube thoracostomy were excluded, and convenience sampling was used. All patients were scanned while supine. Examinations began at the midclavicular line and included the second through fifth ribs. If no sliding lung sign (SLS) was noted, a PTX was suspected, and the lung point was sought for definitive confirmation. When an SLS was noted throughout and a PTX was ruled out on ultrasound imaging, the thoracostomy catheter was removed. Descriptive statistics were calculated.

Image used with kind permission of Bret Nelson, MD, RDMS (click image for more great ultrasound images)

A total of 57 patients were evaluated over a 3-year period. All had at least 1 needle thoracostomy attempted; 1 patient underwent 3 attempts. Fifteen patients (26%) had a normal SLS on ultrasound examination and no PTX after the thoracostomy catheter was removed. None of the 15 patients were later discovered to have a PTX on subsequent computed tomography.
In this study, 26% of patients who received needle thoracostomy in the prehospital setting for a suspected PTX appeared not to have had a PTX originally, nor had 1 induced by the needle thoracostomy. It may be prudent to evaluate such patients with bedside ultrasound instead of automatically converting all needle thoracostomies to tube thoracostomies.
Inadequate needle thoracostomy rate in the prehospital setting for presumed pneumothorax: an ultrasound study
J Ultrasound Med. 2010 Sep;29(9):1285-9

Acute Med, All Updates, Resus

RV involved in AMI more often than you think

Leave a comment

We know that inferior STEMI may be complicated by right ventricular involvement, which is why I whack a V4R lead on all my inferior AMI patients. A recent study using cardiac magnetic resonance imaging showed that RV oedema and regional or global RV dysfunction were common in anterior infarcts too, although the proportion significantly decreased at four month follow up.

T2w image of patient with LAD occlusion. Hyperintense appearance of jeopardised anteroseptal and anterior LV myocardium (arrowheads), extending to adjacent RV lateral free wall (arrows)

RV abnormalities are contiguous to the jeopardized LV myocardium and do not occur exclusively in inferior LV infarcts, but are found in up to 33% of anterior LV infarcts as well. The presence of RV ischemic injury is associated with early RV dysfunction as well as with RV functional recovery at follow-up.
Right Ventricular Ischemic Injury in Patients With Acute ST-Segment Elevation Myocardial Infarction: Characterization With Cardiovascular Magnetic Resonance.
Circulation. 2010 Oct 5;122(14):1405-12

All Updates, Kids, PHARM, Resus

Swimming the Channelopathy

Leave a comment

Drowning is one of the leading causes of accidental death in children. Some apparent drownings may be related to sudden cardiac death, in particular to unidentified channelopathies, which are known to precipitate fatal arrhythmias during swimming-related events.
The majority of cases of sudden cardiac death in children and adolescents are secondary to either hypertrophic or right ventricular cardiomyopathy with coronary artery abnormalities also prevalent, and reports have demonstrated these cardiac abnormalities on autopsy following sudden swimming-related deaths.
However, the majority of autopsies in swimming-related sudden deaths are normal suggesting causation at molecular level, in particular ion channel defects such as type 1 long-QT syndrome (LQT1) and catecholaminergic polymorphic ventricular tachycardia (CPVT).

The gene deletion in LQT1 (KCNQ1) leads to a reduction in the repolarising potassium current (IKs) and prolongation of repolarisation. This lengthens the QT interval (which may be lengthened further by facial immersion in cold water). A premature ventricular contraction (PVC) again which may be initiated by swimming occurring during the vulnerable part of repolarisation leads to establishment of polymorphic ventricular tachycardia (torsades de pointes).

The ryanodine receptor gene mutation (RyR2) in catecholaminergic polymorphic ventricular tachycardia leads to defective closure of the receptor on the surface of the sarcoplasmic reticulum during diastole. This leads to increased calcium (Ca2+) leakage from the sarcoplasmic reticulum and increased potential for delayed afterdepolarisations and subsequent ventricular tachycardia.

Some recommendations are made in an article in Archives of Disease in Childhood:
Proposed implementations to improve detection and appropriate management of apparent drownings secondary to cardiac channelopathies

  1. Improving awareness in the coronial service of the possibility of a cardiac cause for poorly explained drownings.
  2. Education of lifeguards and provision of automated defibrillators in swimming pools.
  3. Molecular autopsy for non-survivors to look for potential channelopathies.
  4. Screening for survivors and family members of non-survivors to identify those with a channelopathy.
  5. Proper counselling for those identified to have a channelopathy on family screening.

Drowning and sudden cardiac death
Arch Dis Child 2011;96:5-8

All Updates, Kids, Resus

Tracheobronchial Foreign Bodies in Children

Leave a comment

Asphyxiation by an inhaled foreign body is a leading cause of accidental death among children younger than 4 years. A review article examining 12,979 paediatric bronchoscopies made the following observations:
Epidemiology

  • Most aspirated foreign bodies are organic materials (81%, confidence interval [CI] = 77%-86%), nuts and seeds being the most common.
  • The majority of foreign bodies (88%, CI = 85%-91%) lodge in the bronchial tree, with the remainder catching in the larynx or trachea.
  • The incidence of right-sided foreign bodies (52%, CI = 48%-55%) is higher than that of left-sided foreign bodies (33%, CI = 30%-37%). A small number of objects fragment and lodge in different parts of the airways.
  • A history of a witnessed choking event is highly suggestive of an acute aspiration.
  • A history of cough is highly sensitive for foreign body aspiration but is not very specific. On the other hand, a history of cyanosis or stridor is very specific for foreign body aspiration but is not very sensitive.
  • Signs and symptoms typical in delayed presentations include unilateral decreased breath sounds and rhonchi, persistent cough or wheezing, recurrent or nonresolving pneumonia, or rarely, pneumothorax.
  • Only 11% (CI = 8%-16%) of the foreign bodies were radio-opaque on radiograph, with chest radiographs being normal in 17% of children (CI = 13%-22%).
  • The common radiographic abnormalities included localized emphysema and air trapping, atelectasis, infiltrate, and mediastinal shift.
  • Although rigid bronchoscopy is the traditional diagnostic “gold standard,” the use of computerized tomography, virtual bronchoscopy, and flexible bronchoscopy is increasing.
  • Reported mortality during bronchoscopy is 0.42%.
  • Although asphyxia at presentation or initial emergency bronchoscopy causes some deaths, hypoxic cardiac arrest during retrieval of the object, bronchial rupture, and unspecified intraoperative complications in previously stable patients constitute the majority of in-hospital fatalities.
  • Major complications include severe laryngeal edema or bronchospasm requiring tracheotomy or reintubation, pneumothorax, pneumomediastinum, cardiac arrest, tracheal or bronchial laceration, and hypoxic brain damage (0.96%).
  • Aspiration of gastric contents is not reported.

End expiratory film: delayed emptying of the left lung suggests local air trapping

Anaesthetic considerations

  • Preoperative assessment should determine where the aspirated foreign body has lodged, what was aspirated, and when the aspiration occurred (“what, where, when”).
  • The choices of inhaled or IV induction, spontaneous or controlled ventilation, and inhaled or IV maintenance may be individualized to the circumstances. Although several anesthetic techniques are effective for managing children with foreign body aspiration, there is no consensus from the literature as to which technique is optimal.
  • An induction that maintains spontaneous ventilation is commonly practiced to minimize the risk of converting a partial proximal obstruction to a complete obstruction.
  • Controlled ventilation combined with IV drugs and paralysis allows for suitable rigid bronchoscopy conditions and a consistent level of anesthesia.
  • Close communication between the anesthesiologist, bronchoscopist, and assistants is essential.

The Anesthetic Considerations of Tracheobronchial Foreign Bodies in Children: A Literature Review of 12,979 Cases
Anesth Analg. 2010 Oct;111(4):1016-25

All Updates, Resus, Trauma

Missed PTX signs on CXR

Leave a comment

Chest x-rays often miss pneumothoraces in the trauma room. These are occult pneumothoraces. A study using agreement by two fellowship trained radiologists as the gold standard for CXR interpretation showed that 80% of these were truly occult, ie. not detectable by the radiologists from CXR and only demonstrable on CT. Of those seven cases that could or should have been identified by emergency physicians (ie. ‘missed’ pneumothoraces) subcutaneous emphysema (5), pleural line (3), and deep sulcus sign (2) were detected by the radiologist reviewers.

This serves both as a reminder of the signs to look for on CXR for pneumothorax, and of the inadequacy of plain radiography in trauma patients. The authors advise in their discussion that  ‘Thoracic ultrasonography may be the ideal diagnostic modality as it has a high sensitivity for the detection of PTX and it may be performed quickly at the bedside while maintaining spinal precautions’.
If you don’t know how to detect a pneumothorax with ultrasound yet, have a look here.
Occult Pneumothoraces Truly Occult or Simply Missed: Redux
J Trauma. 2010 Dec;69(6):1335-7

Acute Med, All Updates, ICU

'AMI' on ICU

Leave a comment

ECG machines may give a printed report saying ***ACUTE MI***. In a retrospective study, patients on the ICU whose 12 lead ECGs contained this electronic interpretation did not have an elevated troponin 85% of the time. Even in the minority of patients whose electronic ECG diagnosis of MI was agreed with by a cardiologist, only one third developed an elevated troponin.
The authors state ‘In contrast to nonintensive care unit patients who present with chest pain, the electrocardiographic ST-segment elevation myocardial infarction diagnosis seems to be a nonspecific finding in the intensive care unit that is frequently the result of a variety of nonischaemic processes. The vast majority of such patients do not have frank ST-segment elevation myocardial infarction.’
Electrocardiographic ST-segment elevation myocardial infarction in critically ill patients: An observational cohort analysis
Crit Care Med. 2010 Dec;38(12):2304-230

All Updates, Kids, Resus, Ultrasound

Aorta/IVC ratio and dehydration

Leave a comment

Two studies this month report a correlation between ultrasound detected aorta/IVC ratio and dehydration in children presenting with diarrhoea and/or vomiting. In both studies the IVC diameter was measured in expiration and the aortic diameter in systole, using a transverse view in the subxiphoid area. Both used acute and post-discharge weight comparison to ascertain degree of dehydration.
The first study took place in Rwanda and a percent weight change between admission and discharge of greater than 10% was considered the criterion standard for severe dehydration. 52 children were included ranging in age from 1 month to 10 year. Vessel diameter measurements were inner wall to inner wall. The IVC-to-aorta ratio correlated significantly with percent weight change (r = 0.435, p < 0.001). Using the best ROC curve cutoff of 1.22, aorta/IVC ratio had a sensitivity of 93% (95% CI = 81% to 100%), specificity of 59% (95% CI = 44% to 75%), LR+ of 2.3 (95%CI=1.5to3.5), and LR– of 0.11 (95%CI=0.02to 0.76) for detecting severe dehydration. The same study did not find ultrasound assessment of inferior vena cava inspiratory collapse or the World Health Organization scale to be accurate predictors of severe dehydration in this same population of children.
Ultrasound Assessment of Severe Dehydration in Children With Diarrhea and Vomiting
Acad Emerg Med. 2010 Oct;17(10):1035-41
The second study took place in the USA. The subjects were considered to have significant dehydration if the weight loss was at least 5%. 71 were children were included. The area under the curve (AUC) was 0.73 (95% CI = 0.61 to 0.84). An IVC ⁄ aorta cutoff of 0.8 produced a sensitivity of 86% and a specificity of 56% for the diagnosis of significant dehydration. The positive predictive value was 56%, and the negative predictive value was 86%. Note this equates to an aorta/IVC ratio of 1.25, similar to that in the first study.
My rough-and-ready take home message from these two studies appears to be that an aorta/IVC ratio less than about 1.2 makes severe dehydration less likely in children with symptoms of gastroenteritis.
Use of Bedside Ultrasound to Assess Degree of Dehydration in Children With Gastroenteritis
Acad Emerg Med. 2010 Oct;17(10):1042-7