Multiple Organ Dysfunction Syndrome
Multiple organ failure
DEFINITIONS - TERMINOLOGY - CLASSIFICATION - SCORES
The multiple organ failure is a clinical, biological dating from 1970, but this concept already was raised by teams of gynecology and obstetrics in the 1940s. This "syndrome" is actually the result of the interaction of a disease or a primitive aggression of the body (trauma, infection, bruising, pancreatitis) and clinical transformation qu'imperilment evolving new therapeutic materials vital now available. A few years ago, during a state of severe shock, burns or trauma, the patient died in a very short time today the assistance ventilatory, circulatory, hemodialysis, hemodiafiltration, allowing prolonged survival in patients. It was during this period that is developing a biological and clinical entity that we are used to group together under the term multiorgan failure syndrome (MODS) (multiple organ failure syndrome in the Anglo-Saxon).
If literature was particularly abundant during the last 15 years of that entity, the definition of MODS and terminology of this syndrome are not very accurate. The term "failure" is an abnormal function of an organ, or more precisely to the abnormal expression of a clinical or biological parameter reflecting the functions of the body: ex. the serum creatinine is often referred to as "renal failure," the elevation of serum bilirubin, a "liver failure."
Recently, Marshall attempted to characterize the "dysfunction" or "failure" of a body in three ways:
1) by analyzing the degree of "abnormality" of a single functional parameter;
2) the existence of a combination of variables that "describe" a situation physiologically abnormal;
3) the need for therapeutic interventions to maintain function, e.g. dialysis.
In fact, the "ideal variable," allowing it to be the witness of organ dysfunction should be:
1) simple;
2) easily measured routinely, without error;
3) objective, independent of the clinical course;
4) a reflection of a real function of an organ;
5) little affected by transient disturbances related to resuscitation or therapeutic interventions General;
6) vary widely, even before an agonal or terminal stage;
7) a reflection of acute disturbance and not a chronic condition affecting the body;
8) be a continuous variable rather than discontinuous.
Consensus Conference conducted in the United States in 1991 attempts to distinguish the multiple organ dysfunction syndrome, sepsis, SIRS, the hypermetabolisms and introduced the term multiple organ dysfunction (MODS multiple organ dysfunction). Each term consists of fixed entities, but a clinical and biological state may evolve to produce a moving entity leading to multiple organ failure. Thus, it now seems preferable to speak of multiple organ dysfunction, a term more suited to the description of clinical and laboratory abnormalities observed after a significant stress to the body such as trauma, burns, infections, massive blood transfusions, pulmonary contusion or pancreatitis. Organ dysfunction actually covers broad physiological realities, ranging from complete failure of an organ, e.g. anuria in renal failure to a simple purely biological subclinical abnormality such as a relevant elevation of serum creatinine.
In fact, the notion of multiple organ failure has been established notably by Knauss in order to build a system aimed at better characterizing ICU patients, to assess the severity of their condition and the prognosis. Since these initial descriptions, several other definitions of organ failure have been proposed (see Table, I in Table IV ). None of the systems and none of the entities has proven to date of its superiority and its ability to describe for a specific patient's prognosis it according to the primary disease.
Table I. Definitions of organ failure (OSF)
1. Cardiovascular failure (presence of at least one of the following)
- Heart 54 b · min -1
- Mean Arterial Pressure 49 mmHg
- Ventricular tachycardia and / or ventricular fibrillation
- PH 7.24 with PaCO2 mmHg
2. Respiratory failure (presence of at least one of the following)
- Respiratory rate 5 or 49 c · min -1
- PaCO 2 50 mmHg
- 2 AaDO 350 mmHg (713 AaDO 2 = FIO 2 - PaCO 2 - PaCO 2)
- Ventilation at day 4 of organ failure
3. Renal failure (presence of at least one of the following criteria in patients without chronic renal failure)
- Diuresis 479 ml/24 h or 159 mL / 8 h
- Creatinine 3.5 mg/100 ml
4. Hematologic failure (presence of at least one of the following)
- Leukocytosis 1000 / m 3
- Plaquetttes 20 000 mm 3
- Hematocrit 20%
5. Neurological failure
- Score of Glasgow 6, in the absence of sedation
Table II. Definitions of organ failure
1. Cardiovascular failure
- Heart 54 b · min -1
- Mean Arterial Pressure 49 mmHg
- Ventricular tachycardia and / or ventricular fibrillation
- PH 7.24 with PaCO2 49 mmHg
2. Respiratory failure
- Respiratory rate 5 or 49 c · min -1
- PaCO 2 50 mmHg
- 2 AaDO 350 mmHg
- Ventilation at day 4 of organ failure
3. Renal failure (in patients without chronic renal failure)
- Diuresis 479 ml/24 h or 159 mL / 8 h
- Urea and 214 mg/100 mL
- Creatinine 3.5 mg/100 ml
4. Hematologic failure
- Leukocytosis 1000 / m 3
- Chips 20 000 mm 3
- Hematocrit 20% (in the absence of chronic renal failure)
5. Neurological failure
- Score of Glasgow 6 (in the absence of sedation)
6. Liver failure
- Acute clinical failure associated with P 0.66
- Heart 50 b · min -1
- Ventricular tachycardia or ventricular fibrillation or cardiac arrest or myocardial infarction
2. Respiratory failure
- Respiratory rate 5 or 49 c · min -1
- Mechanical ventilation for at least 3 days or with FIO 2> 0.4 and PEEP> 5 cmH 2 O
3. Renal failure (in patients without chronic renal failure)
- Creatinine 280 m mol · L -1 (3.5 mg · dL)
- Purification extrarenal
4. Neurological failure
- GCS 6 (in the absence of sedation)
5. Hematologic failure
- Hematocrit 20%
- Leukocytosis 300/mm 3
- Chips 50 000/mm 3
- DIC
6. Liver failure
- Clinical jaundice or total bilirubin 51 m mol · L -1 (3 mg · dL -1)
- ALT> 2 ×
- Hepatic encephalopathy
7. Gastrointestinal failure
- Acute ulcer bleeding (requiring more than 2 units sanguines/24 pm)
- Acute pancreatitis haemorrhagic, acute acalculous cholecystitis, necrotizing enterocolitis,
gastrointestinal perforation
Table IV. Definitions of organ failure
1. Respiratory failure (at least one of the following)
- PaCO 2 <60 mmHg with FIO 2 = 0.21 - Artificial ventilation 2. Cardiovascular failure (at least one of the following criteria in the absence of hypovolemia) - Systolic blood pressure <90 mmHg with signs of peripheral hypoperfusion - Use of inotropic or vasopressor drugs to maintain systolic blood pressure> 90 mmHg
3. Renal failure (at least one of the following criteria in the absence of chronic renal failure)
- Serum creatinine> 300 m mol / L
- Urine output <500 ml/24 h or <180 mL / 8 h - Need for renal replacement therapy 4. Neurological failure (at least one of the following) - Score of Glasgow 6 (in the absence of sedation) - Acute onset of a delirium 5. Liver failure (at least one of the following) - Bilirubin> 100 m mol / L
- Alkaline phosphate> 3 ×
6. Hematologic failure (at least one of the following)
- Hematocrit 20%
- Leukocytosis <000/mm 3 2
- Platelets <40 000/mm 3
As shown in Tables I to IV, the definitions vary greatly from one author to another. And Knauss (Table I) does not include liver failure; Chang (Table II) uses the OSF Knauss taking into account liver failure. Tran (Table III) a special place in heart rhythm disturbances and gastrointestinal failure, whereas Fagon (Table IV) defines a different way from other authors, liver failure in a system failure; score body (ODIN). These four systems based on the presence of clinical and laboratory abnormalities affecting various vital systems (cardiovascular, respiratory, renal, hepatological hematological, neurological) through their differences, reveal much uncertainty that currently exists on the actual definition of 'organ failure and its prognostic significance. This results from the concept "syndromic" to this question: dysfunction syndrome or multiple organ failure or uni is a combination of parameters "deviant" clinical and laboratory findings occurring after very different pathophysiological processes. Therefore, the consequences of organ dysfunction on the prognosis of a patient are variable and are more useful in the analysis of targeted populations. Thus, the use of the concept of multiple organ failure or organ failure classification is put forward in a more "humanitarian and economic" as pathophysiologic: avoid excessive prolongation of the agony of patients accompanied with loss of dignity for them, suffering for the entourage and by dehumanization of "medicine" can be a purpose served by the established prognosis by the extent of organ failure.
In addition, an unnecessary prolongation of life, represents a considerable cost to zero profits, "expense" that could be used in a better way for other patients. To this end economic and humanitarian, some computer algorithms were developed to assess the "predictions" from the extent of organ failure coupled with severity ratings.
To refine this methodology, some recent publications have attempted to describe the syndrome of organ failure in targeted populations, e.g. in elderly trauma victims. In this population, validation of organ failure scores is significantly different and allows better management of these patients by defining multiple stages of organ failure: a pre-failure stage, a stage of failure compensated by assistance and a stage of decompensation beyond any therapeutic resource. In the same vein, recent studies have attempted to validate systems failure including "six bodies" in children.
In general, after all validations, seven organ failures are the organ dysfunction syndrome (respiratory failure, renal, hepatic, cardiovascular, hematologic, gastrointestinal, neurological). Each of these organ dysfunctions found in more than half of the published descriptions constitute the organ dysfunction syndrome.
The description of each of this organ failure is at best described by the variations attributed to a single variable reflecting a physiological abnormality, such as the PaO 2 / FIO 2 to the lung. This way of describing organ dysfunction seems better to variables using the nature of the therapeutic interventions necessary to maintain the function: e.g the use of mechanical ventilation or the use of a certain level of PEEP. The description by a single variable, also appears preferable to the combination of composite variables: e.g for ARDS, the association of hypoxemia with bilateral infiltrates on the chest radiographs in the absence of a rise in pulmonary capillary wedge pressure. Satisfactory and physiological markers corresponding to the criteria identified as necessary and sufficient for the description of organ dysfunction, are five in number, PaO 2 / FIO 2 to the respiratory system, elevation of serum creatinine for renal dysfunction, elevated serum bilirubin for hepatic dysfunction, platelet counts for hematologic dysfunction Glasgow Coma Score and for central nervous system dysfunction.
Markers to describe dysfunction of the cardiovascular system or the gastrointestinal system are not optimal. The five markers described above are validated and correlated with mortality in intensive care independently. Hypotension is relatively validated in terms of predicting mortality. Assessment of gastrointestinal dysfunction using a continuous marker has not been achieved to date. The combination of each of these variables increases the predictive power of mortality in a population of resuscitation. These descriptions, statistically validated, allow the use of organ dysfunction scores, based on these physiological parameters to assess for phases II and phase III, the efficacy of new treatments.
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