Neuro Resus

Professor Cornely is Professor of Internal Medicine and Director for Clinical Trials at University Hospital, Cologne, Germany. His research interests include invasive fungal diseases in haematology/oncology and in the ICU setting. Here he discusses the epidemiology, diagnostic challenges, appropriate prophylaxis and treatment of fungal infections in the ICU with a focus on haematology patients.

Irma Bilgrami gives an insightful and engaging talk on mentorship, the mentor and mentee roles and how to ensure everyone has equal access to these important relationships. This was recorded at the May 2016 Women in Intensive Care Network (WIN) meeting in Victoria.

Professor Theodore "Jack" Iwashyna presents an entertaining and informative talk on randomised controlled trials, how we could be getting more useful and better data, and strategies for getting the most out of RCT data in the future. This was recorded at the December 2015 ICN Victoria educational meeting.

Basic Science Clinic by Steve Morgan & Sophie Connolly

An expert is a person who has made all the mistakes that can be made in a very narrow field.

Niels Bohr

Welcome to Basic Science Clinic Raw Science 8. Convective gas flow through the tracheobronchial tree is the end-point of pulmonary mechanics but the fundamental purpose of the lung is gas exchange, comprised of three interlinked physiological processes: ventilation, diffusion and perfusion. Today we examine the incredible structural adaptation of the human lung down to the alveolus as the centrepoint of gas exchange, a process itself best conceptualized via the elegant physiological model of the alveolar gas equation.

The unraveling of the procession of pulmonary blood flow from right ventricle to lung to facilitate the mingling of blood and air involved protagonists that spanned epochs from Hippocrates to Galen and eventually in 1661 to Marcello Malpighi. He was the first person to view the pulmonary capillaries and alveoli through the augmented reality offered by the light microscope that had been invented in 1590.

The composition of gas in the alveoli determines and represents the process of pulmonary gas exchange and provides a framework for understanding the mechanisms and practical physiological limitations. Alveolar gas is practically inaccessible in vivo and hence requires an accurate and precise model to ascertain its configuration under specific conditions.

The alveolar gas equation relates the alveolar partial pressure of oxygen to inspired partial pressure of oxygen, alveolar and hence arterial partial pressure of carbon dioxide and the respiratory quotient.

How is the lung adapted to optimise gas exchange?

So how does the alveolus fit in?

What are the cell populations in the alveolar region?

How can we model pulmonary gas exchange?

Raw Science factoids:

The oxygen content of arterial blood is ~21 mls/dl, ie 21% by volume. The oxygen content of mixed venous blood is 15-16 mls/dl indicating a total body oxygen extraction of 25%.

The total alveolar surface area is approximately 80x greater than the total surface area of the skin.

Each erythrocyte contains approximately 250 million haemoglobin molecules and 400 billion erythrocytes occupy the total pulmonary capillary blood volume.

For feedback, corrections and suggestions find us on twitter @falconzao and @sophmconnolly or post on ICN.

Thanks for listening. Next up we'll continue our examination of pulmonary gas exchange by looking in more detail at ventilation, perfusion and diffusion. Coming soon is our video series Raw Focus to delve deeper into the key concepts from each of the podcasts.

Basic Science Clinic by Steve Morgan & Sophie Connolly

What we know is not much. What we do not know is immense.

Pierre-Simon Laplace

Welcome to Basic Science Clinic Raw Science 7. As a prelude to deconstructing gas exchange we have been examining how humans, as tidal ventilators, replenish the composition of the gas in the functional residual capacity to provide a plentiful oxygen repository to buffer fluctuations in the oxygen content of blood leaving the lung with every beat of the heart.

Convective, pressure gradient driven, bulk gas volume displacement can only occur if the displacing force is greater than the forces that oppose gas flow. These oppositional forces are the physiological targets of pathological processes that affect the lung, that alter pulmonary mechanics, increase work of breathing eventually critically compromising respiratory function and indicating the need for respiratory support measures. To effectively manage organ system dysfunction it is vital to develop an intimate understanding of your enemy so today we will examine the oppositional forces to gas flow that are among the key perpetrators of respiratory failure.

In this pod we'll cover:

What are the oppositional forces to gas flow?

What is elastance?

What is elastic recoil and what are its determinants?

How does the lung prevent surface tension induced alveolar instability?

What is the 2nd major oppositional force to gas flow?

How do these driving and oppositional forces relate to work of breathing?

Raw Science Factoids

During inspiration the alveolar radius increases from 0.05mm to 1mm which should require a distending pressure of 10 cmH2O but surfactant's detergent action means that 1 cmH2O will suffice.

Normal resting VO2 is approximately 2-4 mls/kg/min. In terms of VO2max an average untrained healthy male would approximate 35-40 ml/kg/min and former multiple Tour de France champion and King of the Mountains Miguel Indurain hit 88ml/kg/min at his peak. Racing Siberian sled dogs can reach 240 ml/kg/min.

Elite rowers can escalate their total minute ventilation to 240 L/min by hitting respiratory rates of 60/min and tidal volumes of 4000 mls and inspite of this heroic effort still generate lactates of 15-18 mmol/L.

For feedback, corrections and suggestions find us on twitter @falconzao and @sophmconnolly or post on ICN.

Thanks for listening. Next up we'll begin our examination of pulmonary gas exchange, also coming soon is the second Crit Think series, Doors of Deception, in which we will look at the labyrinthine and mendacious ways our decision making faculties can deceive us.

Burns Microbiology by Janin

Infection is a major cause of morbidity & mortality in burns. Pierre goes through the common bugs responsible and how to manage them.

Jon Gatward goes through everything you need to know about approaching the airway of a patient with burns.

Basic Science Clinic by Steve Morgan & Sophie Connolly

Although this may seem a paradox, all exact science is dominated by the idea of approximation.

Bertrand Russell

Welcome to Basic Science Clinic. This is Crit Think episode 6, the final podcast in our mathematics series in which we will discuss the mathematics behind clinical measurement.

The use of ever advancing technologies is an inherent and necessary component of critical care, encompassing the most basic of measurement devices (the sphygmomanometer, the stethoscope) to the most complex methods of organ support. Such devices enable continuous monitoring and measurement of physiological variables, informing decision-making processes and underpinning management choices.

Unfortunately, the fallibilities of the clinical process extend far beyond that of human error, and increasingly so, as technological developments entail greater reliance on medical devices. Along with this, comes the tendency to overplay the perceived accuracy and precision of such devices, permitting clinical judgment to be overshadowed or misled by numerical outputs.

Accuracy and precision are terms that are colloquially interchanged, but in truth carry different meanings and different implications for specific features of the variables they are describing. While we strive for accuracy, precision represents our chance of reliably achieving it.

In this pod we'll cover:

• Accuracy and precision
• Signal to noise ratio
• Zeroing and calibration
• Fourier analysis

Without language, thought is a vague, uncharted nebula

Ferdinand De Saussure

Word of the day: sententious (adjective). Given to moralizing in a pompous or affected manner.

For feedback, corrections and suggestions you can contact us on our twitter handles @falconzao and @sophmconnolly or post on the Intensive Care Network.

This talk covers burns assessment and initial wound management, including the types of dressings available. Very easy to get wrong, with serious ramifications if you do!

Burns Resuscitation.

Lewis Macken takes us through the initial 24 hours of managing a patient with significant burns. Lewis tackles the tricky questions of how much and what kind of fluid to give, and explains the history behind burns resuscitation.