Ultrasound-guided subclavian vein cannulation has reduced complications, but there is still a high incidence of failure to cannulate the vein and of accidental arterial cannulation. Vassallo & Bennett noticed that a fast running intravenous infusion in the ipsilateral arm of a patient produced variable echogenicity (lighter echos) in the subclavian vein. They describe deliberately using this appearance to both identify the subclavian vein and differentiate it from the subclavian artery.
With the intravenous infusion running with frequent drips in the drip chamber, the ultrasound beam is placed in long axis to the subclavian vessels in the subclavicular position. The angle of the ultrasound beam is adjusted to reveal both the subclavian vein and artery. The variable echogenicity, together with compression, can then be used to identify the vein. The presence of variable echogenicity in the vessel gives continuous feedback that the ultrasound beam has not drifted onto the artery. In cases where the ultrasound beam has included both artery and vein in the same image, this method has clearly identified the intended target vessel.
Subclavian cannulation with ultrasound: a novel method
Anaesthesia, 2010;65:1041
Tag Archives: Tips
Two smaller lines may be quicker
Using Poiseuille’s law and standardized gauge sizes, an 18-gauge (g) intravenous catheter (IV) should be 2.5 times faster than a 20-g IV, but this is not borne out by observation, in vitro testing, and manufacturer’s data. A nice simple study on normal volunteers compared simultaneous flow rates between a single 18G iv in one arm with two 20G ivs in the other arm. The two smaller ones provided significantly faster flow than the single larger one, although flow rates were slower than manufacturer’s estimates. This is in keeping with this other study on cannula flow rates.
Are 2 smaller intravenous catheters as good as 1 larger intravenous catheter?
Am J Emerg Med. 2010 Jul;28(6):724-7
ABCDE of ICU cognitive outcomes
Applying best evidence using simple easily remembered tools appeals to my small and busy brain. A system of minimising the impact of intensive care on long term brain function is proposed using an ABCDE mnemonic: awakening, spontaneous breathing trials, coordinating these two with target-based sedation, delirium monitoring and scoring, and early mobility therapy / exercise.
A screening, prevention, and restoration model for saving the injured brain in intensive care unit survivors
Critical Care Medicine Oct 2010;38(10):S683-S691
Alternative toothless mask position
An alternative position for holding the facemask when bag-mask ventilating edentulous patients is described and evaluated. 49 patients with inadequate seal and air leak during two-hand positive-pressure ventilation had significantly improved ventilation as measured by reduced air leak and increased expiratory volume when the caudal end of the mask was repositioned above the lower lip while maintaining neck extension.
Face mask ventilation in edentulous patients: a comparison of mandibular groove and lower lip placement
Anesthesiology. 2010 May;112(5):1190-3
UK Capacity Assessment Mnemonic
GPs Drs Hoghton & Chadwick have produced a bioethical mnemonic ‘CURB BADLIP’, for all healthcare professionals in England, Scotland, and Wales for use in patients aged 18 or over in an emergency:
C—communicate. Can the person communicate his or her decision?
U—understand. Can the person understand the information being given?
R—retain. Can the person retain the information given?
B—balance. Can the person balance, or use, the information?
B—best interest. If there is no capacity can you make a best interest decision?
AD—advanced decision. Is there an advanced decision to refuse treatment?
L—lasting power of attorney. Has lasting power of attorney been appointed?
I—independent mental capacity advocate. Is the person without anyone who can be consulted about best interest? In an emergency involve an independent mental capacity advocate
P—proxy. Are there any unresolved conflicts? Consider involving the local ethics committee or the court of protection appointed deputy.
Assessing patient capacity: Remember CURB BADLIP in the UK
BMJ 2010 340: c1285
Saline can be used in place of US gel
A study comparing sterile saline as a conduction agent with ultrasound gel showed adequate visualization of anatomic structures for ultrasound-guided vascular access. The authors state that given sterile saline’s theoretical advantages over gel in terms of availability, cost, safety and ease of use in the procedural field, it should be considered as a viable alternative to gel as a conduction agent.
Use of sterile saline as a conduction agent for ultrasound visualization of central venous structures
Emerg Med Australas. 2010 Jun;22(3):232-5
Complex acid-base problems
Working out the expected compensatory response to an acid base disturbance often reveals a second acid-base problem that was otherwise hidden. I regularly use Winter’s formula when I see a metabolic acidosis, but I have trouble remembering the others, so here they are, from Harwood-Nuss’ Clinical Practice of Emergency Medicine (apologies if you ‘think’ in kilopascals):
Formulas Describing Expected Compensatory Response to Primary Acid–Base Disturbances
Simple Metabolic Acidosis
- Predicted decreased PCO2 mm Hg = 1.2 × Δ(HCO3-) mEq/L
- Predicted PCO2 mm Hg = 1.5(HCO3-) mEq/L + 8 ± 2
- Anticipated PCO2 approximates last two digits of arterial pH
Simple Metabolic Alkalosis
- Predicated increased Δ PCO2 mm Hg = 0.67 × Δ(HCO3-) mEq/L
Simple Acute Respiratory Acidosis
- Predicted decreased ΔpH units = 0.8 × Δ PCO2 mm Hg
- Predicted increased Δ(HCO3-) mEq/L = 0.1 × Δ PCO2 mm Hg
Simple Chronic Respiratory Acidosis
- Predicted decreased ΔpH units = 0.3 × Δ PCO2 mm Hg
- Predicted increased Δ(HCO3-) mEq/L = 0.35 × Δ PCO2 mm Hg
Simple Acute Respiratory Alkalosis
- Predicted increased ΔpH units = 0.8 × Δ PCO2 mm Hg
- Predicted decreased Δ(HCO3-) mEq/L = 0.2 × Δ PCO2 mm Hg
Simple Chronic Respiratory Alkalosis
- Predicted increased ΔpH units = 0.17 × Δ PCO2 mm Hg
- Predicted decreased Δ(HCO3-) mEq/L = 0.5 × Δ PCO2 mm Hg
Sucking chest wound
The old idea of three-sided taping of an occlusive dressing to treat open / sucking chest wounds has been replaced with just closing the hole with an occlusive dressing and treating any tension pneumothorax. If you don’t have an alternative then you can use an adhesive defibrillator pad to achieve this.
Tactical Combat Casualty Care
Inhaled NPA
A case is reported of a stroke patient who aspirated his nasopharyngeal airway, resulting in coughing and desaturation. After iv propofol and topical anaesthesia to the oropharynx and hypopharynx, it was seen on laryngoscopy to be within the trachea but could not be retrieved with Magill forceps. Instead, his doctors inserted a well lubricated 14 Fr foley catheter through the lumen of the tube, inflated the balloon, and pulled it out.
Retrieval of Aspirated Nasopharyngeal Airway Using Foley Catheter
Anesth Analg. 2010 Apr;110(4):1245-6
Child development milestones
Does anyone else find these hard to remember as a non-paediatrician?
I’ve written a crappy little poem to act as a mnemonic for some important milestones and age-related features pertinent to ED assessment and communication. If someone wants to turn it into something sounding more like Gangsta Rap it might catch on.
At zero months some tone is neat
And keep them pink and warm and sweet
At two months head control is more
and smiles are something to adore
At four months when they find things funny
They laugh and roll back from their tummy
Roll both ways when half a year
Hand to hand and turn to hear
Should be sitting up by nine
Put things in mouth and waving fine
Speaking when a year has passed
They’re crawling with a pincer grasp
They’ll walk alone at 15 months
And use a spoon to eat their lunch
By month eighteen they’ll point to faces
Scribble pics and climb staircases
At two they run and have some dress sense
Rides trike at three and speaks full sentence
At four they have imagination
From five you try negotiation
At months nine up to fifteen
Stranger anxiety’s often seen
Distraction helps things seem less mean
But you may need some ketamine
**2104 Update** The amazing Grace Leo has recorded this as a song. I have no idea why but I’m impressed as always by her creativity and drive.
Here it is: