Archive for October, 2009


DLCO: The diffusing capacity of the lung for carbon monoxide, also known as

TLCO : Transfer factor of the lung for carbon monoxide.

Used to determine transfer of gas from the distal airspaces-alveoli into the pulmonary capillaries.



  • V(.) = uptake of CO in ml of CO at STPD conditions/min
  • PACO2 is the average partial pressure of CO in alveoli
  • PC(-)CO is the average partial pressure of CO in the pulmonary capillary plasma.

(Hb) has a very high affinity for CO (200 times > then 02).

Partial Pressure of CO in plasma (PC(-)) =0 when COHb is low

As a result, DLCO=V(.)CO/PACO

Increases in DLCO occur in:

  • Pulmonary hemorrhage
  • Polycythemia
  • Exercise
  • Diseases with increased blood flow
  • Asthma

Decreases in DLCO occur in:

  • Cardiovascular diseases
  • Emphysema
  • Parenchymal lung disease (Fibrosis)
  • Anemia
  • CRF



Good resource base containing:

RECENT Literature

Critically ill patients with H1N1 (Critical Care Rounds, Oct 2009)

Critical care and H1N1 in Canada (JAMA, Oct 12th, 2009)

Critical care and H1N1 in Mexico (JAMA, Oct 12th 2009)

ECMO for H1N1 (JAMA, Oct 12th 2009)

Preparing for H1N1 (JAMA editorial, Oct 12th 2009)

Critical care and H1N1 in Australia (N Engl J Med, Oct 8th 2009)

Surgical mask versus N95 for HCW protection (Loeb et al, JAMA, Oct 1st)

Development of a Critical Care Triage Protocol (Healthcare Quarterly)

Guidance for establishing standards of care for use in disaster situations (With full Institute of Medicine report)

H1N1 during pregnancy (Jamieson et al, Lancet)

Anion Gap explained…..



Non-anion gap Metabolic Acidosis (NAGMA)


The routine management of mechanical ventilation in the ICU includes monitoring of peak airway pressures, plateau pressures and determining airway resistance.
When volume or pressure is pushed through an airway, a peak pressure is generated. This peak pressure is the sum of the amount of pressure necessary to get through the airways, inflate the alveoli and displace the chest wall and diaphragm. An inspiratory hold is performed on the ventilator to measure how much this pressure (plateau pressure) is actually being sensed in the alveoli once the lungs are inflated. By subtracting the plateau pressure from the peak pressure, we can calculate the resistance from the airways.
In managing mechanical ventilation, we routinely look at the plateau pressure to determine the limits to which we can increase our ventilating volumes. For the majority of patients, the chest wall and diaphragm are relatively compliant so are not a major factor in ability to ventilate patients. In cases of stiff chest wall or distended abdomens, the plateau pressure may be misleading as the pressure sensed within the alveoli is in part due to the pressures from the stiff chest wall or diaphragm.
Recently, esophageal catheters have been used to help optimize ventilation of patients with concerns re. stiff chest walls or diaphragms (distended abdomens). A catheter inserted in the esophagus is in close proximity to the pleural space. Esophageal pressures can be used as a surrogate to pleural pressures. Use of esophageal pressure monitoring can then help to differentiate between:

o pressure in the pleural space, attributable to chest wall and diaphragm and
o pressure distending the lungs (transpulmonary pressure) which might result in barotrauma

Ptpt (transpulmonary) = Paw (plateau) – Pes (esophageal)

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October 12, 2009 — H1N1 critical illness mostly affects young patients and is often fatal, according to the results of a Canadian and Mexican study and an editorial published online October 12 in the Journal of the American Medical Association(JAMA).


“Of 215 patients with critical illness, 162 had confirmed, 6 had probable, and 47 had suspected community-acquired 2009 influenza A (H1N1) infection. Mean age was 32.3 ± 21.4 years in the 168 patients with confirmed or probable 2009 influenza A (H1N1); 113 patients (67.3%) were women and girls, 50 patients (29.8%) were children, and 43 patients (25.6%) were aboriginal Canadians…”

H1N1 Critical Illness Mostly Affects Young Patients and Is Often Fatal has an interesting site devoted to following flu trends. You can chart by “National” or by “Province.

Google Flu Trends uses aggregated Google search data to estimate current flu activity around the world in near real-time.


Check out the site below:logo_tiny

Learn more about the research behind Google Flu Trends:
Read the article published by Nature, Detecting influenza epidemics using search engine query data.

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