Optic nerve sheath diameter: window to the soul?

Almost exactly 3 years ago I posted an article looking at the utility of ultrasonographic Optic Nerve Sheath Diameter measurement to assess patients for raised intracranial pressure.  That post is here

The idea is sound, the optic nerve sheath is an extension of the subarachnoid space – so if ICP goes up it should expand and this ought to be measurable.  So – does it actually work?

Well – yes and no….  there is a pile of studies of various size, measuring various things.  So the better question is – who knows all this stuff?

To that – the answer is: Dr Leanne Hartnett, Emergency Physician and Ultrasound Doc from my old alumni – Fremantle Hospital in W. Australia.

Leanne presented a review of the evidence and techniques involved in ONSD assessment last year at the ACEM meeting here in Broome.  It was one of those talks that left me scratching my head – the data was there, but when you look at studies beside one another – they just don’t make sense.

For example – here is a summary of the measurements from the largest trials.  As you can see the mean in one trial might be completely “abnormal” in another.

Normal range of ONSD with US


However – when you compare ONSD to invasive measures of ICP there seems to be great correlation – as below:


So I managed to catch up with Leanne at the SMACC GOLD conference in March – [ we were both dateless for the gala dinner ]

We got chatting and this podcast is what we decided to do. DOWNLOAD HERE

Here are a few more images to refer to as we go through the numbers and the papers – and try to make sense of it all!

If you are busy and want the punch line:

- more data required… not yet for prime time

- under 5mm = probably OK

- over 6 mm = probably not OK

- And in between 5 and 6 mm = who knows, not us for sure!

Typical image and caliper placement used in many centres

Typical image and caliper placement used in many centres

The caliper placement described by Bauerle in his papers

The caliper placement described by Bauerle in his papers

Counties in California sue manufacturers of opioid analgesics

This week, two counties in California sues five manufacturers of opioid analgesics, accusing them of carrying out a “campaign of deception” to boost sales of their products. According to a report in the Los Angeles Times:

In sweeping language reminiscent of the legal attack against the tobacco industry, the lawsuit alleges the drug companies have reaped blockbuster profits by manipulating doctors into believing the benefits of narcotic painkillers outweighed the risks, despite “a wealth of scientific evidence to the contrary.” The effort “opened the floodgates” for such drugs and “the result has been catastrophic,” the lawsuit contends.

The five defendants named in the suit are: Purdue Pharmaceuticals (OxyContin), Teva/Cephalon (Actiq and Fentora), Janssen (Duragesic and Ultram), Endo (Opana, Percoset, and Percodan), and Actavis (Kadian and various generics.)

The 100-page filing is extremely detailed and the best document I know outlining the history of how use of opiate analgesics for chronic non-cancer pain — viewed as carrying a high risk of addiction and overdose not even 2 decades ago — became so common that in 2010 over 16,000 overdose deaths were linked to prescription opioids. According to the allegations, the defendant pharmaceutical companies engaged in a deceptive and fraudulent campaign to destigmatize opioids and minimize the associated risk of addiction. Tactics they used included: co-opting professional societies and so-called patient advocacy groups; exercising improper influence on panels that created guidelines for use of opioid analgesia; creating deceptive advertising to both health professionals and the lay public; and collaborating in the production of biased CME programs and scientific papers.

The legal filing  is extremely powerful and essential reading for anyone who treats pain and/or prescribes opioid analgesics. Some excerpts:

“To shift medical convention and unleash this epidemic, Defendants engaged in a campaign of deception that: (1) misrepresented the efficacy of opioids, (2) trivialized or obscured their serious risks and adverse outcomes, and (3) overstated their superiority, compared with other treatments. Defendants supported, encouraged, and directed employees, front groups, and doctors they identified as “Key Opinion Leaders (“KOLs”) to publicize biased and misleading studies and promotional materials and conduct thousands of medical education programs that were deceptive and lacked balance.”

“Although opioids may initially improve patients’ function by providing pain relief in the short term, there were — and are — no controlled studies of the use of opioids beyond 16 weeks and no evidence that opioids improve patients’ function in the long-term. Indeed, research such as a 2008 study in Spine has shown that pain sufferers prescribed opioids long-term suffered addiction that made them more likely to be disabled and unable to work. Despite this lack of evidence, and evidence to the contrary, Defendants consistently promoted opioids as capable of improving patients’ function and qua lit of life.”

“Defendants needed a way to explain why so many chronic pain patients on opioids seemed to be addicted: they ask for drugs by name, seek refills earlier than their supplies should have run out, hoard drugs, or self-escalate their doses. Defendants, led by Purdue, managed masterfully to turn these recognized signs of addiction into a way to sell more opioids through the concept of ‘psuedoaddiction’”


Related post:

The money and influence behind “Pain as the Fifth Vital Sign”

CCC Update 005

It’s that time again, time to recap what is new in the LITFL Critical Care Compendium (remember, the quick way to get there is to click on the CCC at the very top of every LITFL page).

However, first I must congratulate all those who succeeded at the recent FACEM and FCICM clinical examinations. It is particularly heartening to hear from people who have used LITFL and the CCC as their primary study resources for these daunting Fellowship examinations, and doing well.

As always, I’m very grateful to everyone who continues to send me comments and suggestions about what to correct, improve or add to the CCC. Again, there have been many great contributions from Sarah Yong. With everyone’s help this resource just keeps on getting better.

So, in addition to a hundreds of minor edits not worth mentioning, let’s recap what’s new in the CCC:


We usually see this in the context of external ventricular drains (EVDs) in ICU. It’s a tricky disorder to diagnose. Should the EVD come straight out?

Starvation response

Updated with a table comparing the starvation and stress responses as well as the consequences of underfeeding. This topic has popped up in the FCICM exam a couple of times and it looks like people find it tough…

Iron overdose

Another topic done poorly on the whole in a recent FCICM exam — this CCC entry will enable you to ‘own’ the next iron OD you see! (whether in the exam, FACEM or FCICM, or in real ife)


The section on adverse effects and oxygen toxicity has been reworked.

Validity of Clinical Research

Can’t tell your internal from your external? Look here, with extended list of factors affecting external validity.

Surrogate outcomes

The cynic would say that surrogate outcomes are a blessing for researchers who want to get their trials done, but a curse for clinicians who want to really help patients. Know the pros and cons.


This page has been completely reworked, and the originally separate viral encephalitis page has been discarded. Includes an approach to viral and other infective causes, as well as auto-immune causes. Has links to separate pages on HSV encephalitis and Anti-NMDA receptor encephalitis.

Hyperthermia-associated toxidromes

Don’t get caught out by toxidromes that cause hyperthemia. Not all fever is infection. This page compares and contrasts the key aspects of the most important pyrexial toxidromes that do this such as anticholinergic, serotonergic, and sympathomimetic toxidromes, as well as neuroleptic malignant syndrome and malignant hyperthermia.

That’s all for now.

Vive la FOAM.

The post CCC Update 005 appeared first on LITFL.

“Sleeping with the Fishes” smaccUS June 2015

Sleepin' with da fishes
Sleepin’ with da fishes


Sydney’s smacc2013 was hailed by Mike Cadogan as “the birth of FOAMed” (the conception being ICEM2012); rather than just ‘five guys in a bar talking about Twitter’, this conference raised the bar for inspiring those who care for the critically unwell patient.

smaccGOLD built upon this – breaking down the traditional tribal barriers that are inherent in medicine and drawing on experiences of not just doctors, but nurses and paramedics. The interlinking of likeminded persons via social media in the lead up ensured that the conference was abuzz with interactivity and minimal displays of traditional hierarchy.

Ugly Mug
Where else could a rural doctor mix it up with intensivists?

2015 sees the conference head overseas – smaccUS in Chicago.


SMACC 2015 Move to June (1)

[Please note that KIDocs.com on the flyer is incorrect - use KIDocs.org &/or RuralDoctors.Net instead!]

FOAMed is now embedded in the critical care and emergency medicine fields; yet it has so much more to offer outside of this. It was god to see a smattering of rural doctors at smaccGOLD – I hope that there will be a larger contingent at smaccUS, especially from our Canadian rural doctor cousins … the workload and skillset of rural Aus and Canadian docs appears very similar.

Regardless, other specialities could learn a LOT from how smacc is run – inclusive, clinically relevant, interactive and fun!

Hope to see some of you there! With old mates like Mark Wilson there, it’s going to be a KNOCKOUT event…

…if you can’t make it – might as well be “sleeping with da’ fishes” as Al Capone would say.

Last word to Damian Roland commenting from smacc2013 via Rob Rogers…


REMI 1963. Interrupción diaria y sedación intermitente: dos técnicas con el mismo objetivo

Artículo originalDaily sedative interruption versus intermittent sedation in mechanically ventilated critically ill patients: a randomized trial. Ann Intensive Care 2014, 4: 14. Nassar Jr AP, Park M. [Resumen] [Artículos relacionados] [Texto completo] [PDF]
Introducción: La sedoanalgesia es un componente esencial del manejo de los enfermos críticos, pero también es causa de yatrogenia significativa, por lo que en los últimos años se han propuesto distintas estrategias para evitar la sobresedación, entre ellas la sedación intermitente (SI, en vez de en infusión continua) [1] y la interrupción diaria de la sedación (IDS) [2]. Las ventajas y desventajas relativas de una y otra no está claras. Por otra parte, se considera que las estrategias dirigidas a mantener al paciente despierto requieren un nivel de atención de enfermería superior al habitual para evitar los riesgos asociados, como la autoextubación.
Resumen: Se llevó a cabo un ensayo clínico no ciego en una UCI polivalente cerrada de seis camas de un hospital brasileño, en el que se incluyeron 60 pacientes con una duración esperada de la ventilación mecánica superior a 24 horas. La relación enfermera:paciente era de 1:6 y la de auxiliar:paciente de 1:2, y se disponía además de dos fisioterapeutas en los turnos de día. Los pacientes se aleatorizaron a recibir IDS o SI, con el objetivo de mantener al paciente despierto o despertable con estímulos ligeros (puntuación SAS: 4 o 3), incluso cuando recibían infusión continua de sedantes. El desenlace principal, los días libres de ventilación mecánica hasta el día 28, no difirió entre ambos grupos (mediana 24 frente a 25 días). Tampoco hubo diferencias en la mortalidad en UCI ni en el hospital, en la incidencia de delirio, de autoextubaciones o de estrés psicológico a los seis meses del alta. Los pacientes del grupo IDS tuvieron un SAS más bajo que los del SI (mediana 3,2 frente a 3,6), pero no hubo diferencias en el porcentaje de las mediciones con el SAS dentro del rango deseado de 3-4 (63% frente a 75%). Las dosis totales de fentanilo y midazolam fueron más altas en el grupo IDS, y el volumen corriente fue más alto en el grupo SI.
Comentario: El estudio no encuentra diferencias entre las dos estrategias, aunque con la importante limitación de su pequeño tamaño y su interrupción prematura, debido al lento reclutamiento, lo que impide extraer conclusiones definitivas del mismo; más importante que ello sin embargo es que muestra que es posible y seguro implantar una estrategia de mínima sedación en una UCI con una plantilla de enfermería limitada, frente a los estudios previos, que disponían de más personal. Es necesario seguir investigando en las distintas opciones existentes para evitar la sobresedación, que no son mutuamente excluyentes; el objetivo común a todas ellas es mantener al paciente lo más despierto y colaborador posible y libre de síntomas durante la mayor parte del tiempo y de forma segura [3].
Eduardo Palencia Herrejón
Hospital Universitario Infanta Leonor, Madrid.
© REMI, http://medicina-intensiva.com. Mayo 2014.
  1. Kollef MH, Levy NT, Ahrens TS, Schaiff R, Prentice D, Sherman G. The use of continuous i.v. sedation is associated with prolongation of mechanical ventilation. Chest 1998; 114: 541-548. [PubMed] [PDF]
  2. Kress JP, Pohlman AS, O'Connor MF, Hall JB. Daily interruption of sedative infusions in critically ill patients undergoing mechanical ventilation. N Engl J Med 2000; 342: 1471-1477. [PubMed] [Texto completo]
  3. Effects of increasing compliance with minimal sedation on duration of mechanical ventilation: a quality improvement intervention. Amaral AC, Kure L, Jeffs A. Crit Care 2012; 16: R78. [PubMed] [Texto completo]
    Búsqueda en PubMed:
  • Enunciado: Sedación mínima en ventilación mecánica
  • Sintaxis: "minimal sedation" AND mechanical ventilation
  • [Resultados]