Critical care

Critical care medicine is the "health care provided to a critically ill patient during a medical emergency or crisis".

Respiration and oxygenation
This measure is easier to calculate. Comparative studies suggest it correlates better with pulmonary shunts than does the A-a gradient.
 * PaO2/FiO2 ratio (PF ratio)

The A-a gradient is harder to calculate, but accounts for changes in respiration as measured by the partial pressure of carbon dioxide. However, this calculation relies on the respiratory quotient being constant in the prediction of alveolar CO2 When compared to the PF ratio, the A-a gradient is found to correlate less well with pulmonary shunting.
 * Alveolar-arterial oxygen (A-a) gradient (alveolar-arterial oxygen difference - AVO2D)

Among outpatients with possible pulmonary embolism, the A-a gradient may be a better test.

An online calculator for the A-a gradient is at http://www.mdcalc.com/aagrad.

Abdominal compartment syndrome
Abdominal compartment syndrome is associated with increased mortalty.

Medical error
Examining errors in administration of parenteral medications, a study found:
 * 74 errors per 100 patient-days
 * Independent risk factors were:
 * Patient complexity as measured by
 * number of organ failures
 * number of parenteral administrations
 * Work load as measured by
 * Larger intensive care unit
 * Increased ratio of patient turnover to the size of the unit
 * Number of patients per nurse
 * Occupancy rate of the unit

Glucose control
Two clinical practice guidelines are available for patients with ; however, both of these guidelines were developed without broad representation of stakeholders. This may lead to overly aggressive clinical recommendations.

A clinical practice guideline from the American Association of Clinical Endocrinologists (AACE) recommends the following target blood glucose levels:
 * "Critically ill patients, between 80 to 110 mg/dL (grade A recommendation)"

A clinical practice guideline from the American Diabetes Association (ADA) states
 * "Critically ill patients: blood glucose levels should be kept as close to 110 mg/dl (6.1 mmol/l) as possible and generally <140 mg/dl (7.8 mmol/l). (A) These patients require an intravenous insulin protocol that has demonstrated efficacy and safety in achieving the desired glucose range without increasing risk for severe hypoglycemia. (E)"

Randomized controlled trials of tight glucose control in the critical care and perioperative care settings have produced mixed results. A meta-analysis of trials in the critical care setting concludes there is no benefit to tight control.

Since the meta-analysis, two negative randomized controlled trials have been published.

Regarding surgical patients in a critical care setting, a large randomized controlled trial (1548 patients) concluded "intensive insulin therapy to maintain blood glucose at or below 110 mg per deciliter reduces morbidity and mortality among critically ill patients in the surgical intensive care unit." However, other trials have not found this benefit according to a meta-analysis. This trial has been criticized for the following reasons:
 * 1) "The trial was stopped early for an unexpectedly large treatment effect, which can overestimate the efficacy of treatment or result in a false-positive finding;"
 * 2) "The relative reduction in mortality for a decrease of 50 mg/dL in morning glucose levels seems biologically implausible and exceeds that for any other intervention in critically ill patients;"
 * 3) "The mortality rate in the control group was much higher than that noted in tertiary care medical centers in the United States. On admission to the ICU, all patients received 200 to 300 g/d of intravenous dextrose followed by enteral or parenteral nutrition, an unusual practice considering the deleterious effects of parenteral nutrition; at least in part, the difference in outcomes between the 2 arms in this study might have reflected the harm of maintaining the control group as hyperglycemic rather than the benefit of strict glucose control in the intervention group."

Regarding medical patients in a critical care setting, a large randomized controlled trial that compared a goal blood glucose level of 80 to 110 mg per deciliter (4.4 to 6.1 mmol per liter) to a goal blood glucose level of between 180 and 200 mg per deciliter (10 and 11 mmol per liter) concluded "intensive insulin therapy significantly reduced morbidity but not mortality among all patients in the medical ICU. Although the risk of subsequent death and disease was reduced in patients treated for three or more days, these patients could not be identified before therapy." Tight control may protect renal function.

Among medical patients with septic shock, intensive insulin therapy and pentastarch increased adverse events in a randomized controlled trial.

A meta-analysis was published in 2006 that did not include the two trials above that were published later that did not reduce mortality. This meta-analysis concluded that tight control was beneficial in surgical critical care. However, in addition to not including the two more recent negative trials, this meta-analysis overlooked the problems with the largest trial

Blood transfusion
There may not be a meaningful difference in outcomes between transfusing blood to maintain a hemoglobin > 7.0 g/dl versus a hemoglobin > 10.0 g/dl.

Erythropoietin
A randomized controlled trial reported "epoetin alfa does not reduce the incidence of red-cell transfusion among critically ill patients, but it may reduce mortality in patients with trauma. Treatment with epoetin alfa is associated with an increase in the incidence of thrombotic events."

Selective gastrointestinal decontamination
Systematic reviews conclude that selective decontamination of the digestive tract may reduce morbidity in critically ill patients  although some randomized controlled trials have   and others have not found benefit.

Medical error in the intensive care
Regarding overlooked diagnosis among patients receiving artificial respiration in the intensive care, an autopsy study concluded "abdominal pathologic conditions--abscesses, bowel perforations, or infarction--were as frequent as pulmonary emboli as a cause of class I errors. While patients with abdominal pathologic conditions generally complained of abdominal pain, results of examination of the abdomen were considered unremarkable in most patients, and the symptom was not pursued."

Predicting outcomes of adult patients
Although there is much research into prognosing patients in intensive care, patients are not very confident in thei accuracy of prognoses.

Apache II score
The APACHE II is available at http://www.sfar.org/scores2/apache22.html.

SAPS II

 * SAPS II
 * SAPS II (expanded)