martes, 12 de mayo de 2015

MULTISYSTEM FAILURE - SHOCK

SHOCK

Classical features of shock:
-A systolic blood pressure of less than 90 mmHg
-Tachycardia
-An increased respiratory rate (>20 breaths/min) and reduced oxygen saturations
-Mottled, cool and clammy skin
-Evidence of hypovolaemia: dry mouth, dry axillary skin, postural hypotension, thirst.
-Low urine output (less than 0.5 ml/kg per h)
-Confusion or agitation progressing to coma.

Cardiogenic shock
In cardiogenic shock, the heart as a pump fails to propel blood around the circulation. The common causes are:
-heart muscle damage
-severe arrhythmia
-valve disease
-output obstruction


Hypovolaemic shock
In hypovolaemic shock, there is a reduction in the circulating blood volume due to either external fluid loss (upper gastrointestinal bleeding, severe diarrhoea and vomiting, DKA) or "internal loss" (acute pancreatitis, severe paralytic ileus).


Redistributive (low-resistance) shock
Redistributive shock is due to the effect of circulating toxins disturbing the normal distribution of blood flow within the body. Some vessels, notably those in the skin, open up and provide little or no resistance to blood flow.
Other vessels shut down in a pattern in which organs such as the kidney are starved of blood. In contrast to the other forms of shock, in redistributive shock the overall resistance to blood flow is reduced: the cardiac output is therefore high, the pulse is bounding and the peripheries are warm. The patient appears flushed and warm rather than grey and clammy. Without treatment, however, the progression is the same as that in other forms of shock - to kidney failure and to increasingly severe acidosis.
The main causes are sepsis (especially from gut and renal tract infections) and anaphylaxis.

ACUTE SEVERE HYPOTENSIVE COLLAPSE
Clinically, patients with shock present to the Acute Medical Unit as a problem of acute severe hypotensive collapse. Given this clinical situation, there are five groups of conditions to consider: cardiorespiratory collapse, massive pulmonary embolus, septicaemia, hypovolaemia and anaphylaxis.

Critical nursing tasks:
-Rapid assessment of the criticaly ill: ABCDE, maintain the safety of the patient.
-Recognition of a deteriorating patient:


-Measure the respiratory rate and the oxygen saturations.
-Measure the radial and apical pulse rates - monitor the heart.
-Measure the lying blood pressure and look for any postural decrease.
-Ensure large-bore venous access.
-Obtain an immediate 12-lead ECG.
-Assess the site and severity of any pain.
-Reassure the patient about the management plan and initiate symptom relief.
-Keep the relatives on the ward.


ANAPHYLACTIC SHOCK
Anaphylaxis is the term used for a severe generalised allergic reaction. The most common causes are foods (especially nuts), insect stings, drugs (especially antibiotics, aspirin and ACE inhibitors) and latex allergy.
From 5 min to an hour after exposure, the patient develops a generalised reaction with swellling, redness and itch. In cases of oral ingestion in food allergy, the swelling usually starts in the mouth and tongue progresses to upper airway obstruction. Occasionally, the delay from exposure to reaction is as long as 6h. 
The two potentially fatal complications are: airway obstruction and ciculatory collapse.


Emergency treatment:
-Intramuscular adrenaline (epinephrine).
-Oxygen.
-Fluids.
-Bronchodilators.
-Antihistamines.
-Steroids.
-Prevention: there must be effective education in allergen avoidance and good control of any underlying asthma by optimising the use of prophylactic anti-inflammatory treatment with inhaled steroids.

ACUTE KIDNEY INJURY (AKI)
The term Acute Kidney Injury applies to situations where there is a risk of acute renal failure and also to situations where renal failure is fully established. There are three stages in the deterioration from "at risk of" to "established" renal failure. They are defined by the urinary output:
1. Risk: urine output < 0.5ml/kg/hr for > 6 hours
2. Injury: urine output < 0.5ml/kg/hr for > 12 hours
3. Failure: urine output < 0.5ml/kg/hr for > 24 hours or anuric for 12 hours.


Nursing tasks in acute kidney injury:
-Prepare to start treatment for hyperkalaemia
-Carry out basic management of pulmonary oedema
-Identify sepsis: strong clues are fever, malaise, rigors and perhaps dysuria
-Identify hypovolaemia: symptoms of thirst and dizziness, signs of postural fall in blood pressure and low CVP (Central Venous Pressure)
-Confirm that the problem is not a simple outflow obstruction
-Take a full history
-Exclude rhabdomyolysis in prolonged immobility/coma
-Check the urine
-Ensure there is a system for reviewing the abnormal urea and electrolyte results on the ward.

Source:
-A nurse´s survival guide to acute medical emergencies, R. Harrison and L. Daly, Elsevier 2011

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