SHOCK.doc - adult emergency department by dagedaer

VIEWS: 0 PAGES: 8

									            Shock                         Septic shock                   Resuscitation fluids


                                           SHOCK
DEFINITION OF SHOCK

   Circulatory insufficiency
   Global hypoperfusion
   Inadequate tissue oxygenation
   Inadequate removal of toxic metabolites


CLASSIFICATION OF SHOCK

Hypovolaemic

Inadequate circulating volume

        Haemorrhagic
        Trauma, Gastrointestinal (peptic ulcer, oesophageal varices , ca lower bowel, angiodysplasia)
        Vascular (ruptured AAA) Gynaecological emergencies (ruptured ectopic pregnancy)

        Loss of extravascular fluid
        Gastroenteritis, burns

Cardiogenic

Inadequate cardiac pump action

        Myocardial infarction
        Arrhythmias
        Severe valvular disease, valve rupture
        Myocarditis/cardiomyopathy
        Cardiac drugs – antiarrhythmics, beta blockers, Ca channel blockers
        Cardiac obstruction or compression
                 Pericardial tamponade
                 Pulmonary embolus
        Atrial myxoma
        Hypertrophic cardiomyopathy
        Aortic dissection

Distributive

Maldistribution of blood flow
         Anaphylactic
         Neurogenic
         Septic shock
                                      SEPTIC SHOCK
                                  (especially in the elderly)

DEFINITION OF SEPTIC SHOCK
Criteria proposed by the American College of Chest Physicians and the Society
of Critical Care 1991

Sepsis

         2 or more of the following ( SIRS ), as a result of infection
         Temperature >38deg C or < 36 deg C
                 HR > 90 bpm
                 RR> 20, or PaCO2< 32mmHg
                 WCC > 12,000, < 4,000 or > 10 % immature forms

Septic shock is present when there is sepsis as defined by the criteria above, as well as

         Hypotension, usually defined as SBP< 90mmHg, and
         Evidence of inadequate organ perfusion, such as
                           Altered mental status
                           Decreased urine output
                           Lactic acidosis
         And failure of the hypotension to respond to at least 1 L of isotonic saline

Aetiology
        Any infection - bacterial, fungal, viral , parasitic- can cause fever and SIRS.

         G+ve bacteria are the causative organisms in 35 to 40 % of cases, G-ve in 55 to 60 %.

         The most frequent sites of infection are the lungs, the abdomen and the urinary tract.

Factors predisposing to G-ve bacteremia are:

         Diabetes mellitus
         Lymphoproliferative disease
         Cirrhosis of the liver
         Burns
         Invasive procedures
         Indwelling catheters
         Chemotherapy




Factors predisposing to G + bacteremia are:

         Vascular catheters
         Indwelling mechanical devices
         Burns
         IV drug injection

Incidence

         Not uncommon - exact statistics?
         USA 2 cases of sepsis per 100 admissions to hospital
         55% ICU, 12 % ED, 33 % other inpatient specialty.
        5O % of patients with sepsis develop septic shock.

Age - mean age is 55 to 60 years


Mortality

Mortality of septic shock ranges from 20 to 80 %, average about 45 %. The
higher statistics apply to the elderly and the immune compromised.

Complications of septic shock

                 CNS dysfunction
                 ARDS 18 %
                 Liver failure
                 ARF 50 %
                 DIC 38 %


CLINICAL FEATURES

Elderly patients are more susceptible to sepsis. They have less physiological
reserve to tolerate sepsis and are more likely to have underlying disease.
They are also more likely to be on medications such as betablockers and
steroids, which will modify their response to the disease and the therapy.




HISTORY

Nonspecific symptoms - fever, chills, malaise, fatigue, anxiety or confusion. Dizziness or syncope.
Sometimes, there may have been a fall or an RTC or other accident.

        In the elderly there may be no fever.

        The most consistent feature is altered mental status. This can be subtle.
        Mild disorientation or confusion is especially common.
        Unexplained apprehension, anxiety and agitation may be present.

        The very ill patients may be obtunded or comatose.

Hyperventilation with a respiratory alkalosis is a common feature.
Some may complain of shortness of breath, or family or friends may observe SOB.

Localizing symptoms may be present -chest, abdomen, head and neck, pelvic or genitourinary, or to
the musculoskeletal system and soft tissues.


EXAMINATION FINDINGS
General condition
The patient may look unwell. Or may look acutely ill with a toxic appearance. This is not specific but
will alert the examiner (or triage nurse). Or the patient may look deceptively "well".

Simple observation will tell you if the patient is hyperventilating. Raised respiratory rate ( > 20
Breaths ) and respiratory alkalosis are common.

Vital Signs
An accurate temperature is essential, using a rectal thermometer if necessary. Temperature may be
raised or lower than normal.

Look at and feel the skin, the hands and the feet. In the early stages they feel warm. Capillary refill
is normal. The heart rate is commonly increased. The blood pressure is low and the pulse pressure
will often be increased. However, again if the patient is on BBlockers, then the heart rate may not go
up significantly.



Later stages, as sepsis progresses, the stroke volume and the cardiac output fall. Signs of poor
peripheral perfusion develop - cool skin, cool extremities and delayed capillary refill.

Findings depending on focus of infection

CNS : altered mental status, neck stiffness
Head and neck: sinus swelling or tenderness, lymph glands, tonsillar or peritonsillar abscess.
Chest : tachypnoea, cough, phlegm, crackles, dullness to percussion.
Heart: murmurs
Abdomen and GIT : tenderness, guarding, jaundice, perianal abscess
Pelvic and genitourinary tenderness: mass or discharge
Skin and Soft tissue - swelling, redness, tenderness, blistering, discharge
Musculoskeletal - muscle swelling, fluctuance, tenderness, joint pain and
limitation of movement.


MANAGEMENT
Similar to the trauma “Golden Hour”, management in septic shock must be
prompt.


Triage :

   If obtunded and requiring immediate resuscitation and intubation, triaged
    category 1 and a medical emergency call put out.
   If presenting with altered mental status, looking unwell, extremities warm,
    or skin colour not looking good, moderately hypotensive as informed by
    ambulance, with any other history suggestive of sepsis, Triaged 2 and
    admitted to resuscitation room.


Airway and breathing are assessed immediately.
  Oxygen.
  Intubation and ventilation are required.
   Monitor O2 saturation, respiratory rate, BP, ECG and temperature
   12 lead ECG.
   Two16 gauge intravenous canulae. If immediate peripheral access is unobtainable, an EJ, a
    subclavian or an IJ line is inserted. Bloods for investigations as below
Volume resuscitation is commenced.

   500ml boluses of 0.9 % saline, every 5 to 10 minutes, with repeat clinical assessment after each
    bolus. After 1 to 2 Litres of saline colloid is infused
   Urinary catheter.
   A diligent fluid balance chart is commenced.

   The patient must be monitored for signs of volume overload, such as
    dyspnoea, pulmonary crackles, and pulmonary oedema on xray.
   There is relative and absolute intravascular fluid depletion. Causes of fluid depletion include
    increased microvascular permeability, decreased fluid intake, increased insensible fluid loss,
    vomiting and diarrhoea, and third spacing of fluids.
   The choice of fluid remains controversial.
Clinical indicators for improved perfusion are improvement in heart rate, blood pressure, mental
status, capillary refill, and urine output.

Inotropic support

   The need for inotropes is assessed after 2 to 4 litres of fluid as the majority
    will require inotropes for hypotension, or if there are signs of fluid overload.
   Dopamine infusion 5ug/kg/min and increasing to 20 ug/kg/min.
   Insert an arterial line and commence invasive blood pressure monitoring.
   If with maximum dopamine therapy the patient remains hypotensive,
    further inotropes are warranted. Noradrenaline has been shown to be
    effective for patients failing to respond to fluid and dopamine. The patient
    requires intensive care support. The patient will need a central line if one
    has not been placed and will require invasive haemodynamic monitoring.
    Therefore if it appears that dopamine is not making any significant
    improvement DCCM assessment is called for early.

   All of the above measures should have taken less than 1 hour.


INVESTIGATIONS
Laboratory
  FBC: WCC may be raised or low, or indicate severe neutropenia.
   U&E/Cr, Ca, PO4, Mg
   Glucose
   ABG
   Lactate: elevation reflects degree of tissue hypoperfusion and shock. Predictor of mortality.
   Clotting profile : platelet count falls with DIC.
   Blood cultures x 2 : Positive 30 % of the time in the febrile elderly, febrile adult patients with
    elevated WCC or band forms , and the febrile neutropenic patients. Positive 50 % of the time
    inpatients who have sepsis and end organ dysfunction. Also useful in patients with prosthetic heart
    valves.
   Urine MC&S
   LP if meningitis suspected. See LP guide lines.
   Appropriate cultures, such as of pus, sputum, joint aspirate.

Imaging
  Chest xray - routine chest Xray has shown clinically occult infiltrates in 3 to 4 % of febrile
   patients.
  Ultrasound for biliary tract sepsis.
   CT scan for intra-abdominal and retroperitoneal abscess.
   Head CT if increased ICP is suspected.


TREATMENT OF INFECTION

   Empirical antibiotics are given as soon as possible or at the latest within
    30 minutes of patient's arrival. They are to be given in the resuscitation
    room. There is no excuse for delaying antibiotic therapy.
   The initial therapy depends on the suspected cause – see Antimicrobial
    Guidelines, Neutorpaenic Sepsis Guidelines.
   A suitable empirical therapy in a normal adult is gentamicin 5 – 7mg/kg
    daily and flucloxacillin 2g IV 6 hourly,
   If unsure about antibiotic regime or need clearance for use of a controlled antibiotic ring the ID
    registrar or consultant or the ED consultant.
   Surgical sepsis. Call the surgical registrar on call early if abscess or other surgical sepsis is
    suspected. If septic arthritis or other orthopaedic sepsis is suspected, call the orthopaedic registrar.


FURTHER CARE
   Those responding to initial fluids or low dose dopamine may be admitted to a medical ward.
    Failure to significantly improve within the first hour of treatment indicates a need for DCCM
    review. Those with severe sepsis and septic shock need referral to DCCM on arrival.


PITFALLS
   Under triaging
   Failure to initiate adequate fluid therapy
   Failure to initiate antibiotic therapy
   Failure to commence inotropes at the appropriate time
   Failure to admit to DCCM early.
   Failure to address surgical sepsis


REFERENCE:

   Tintinalli
   Antimicrobial Guidelines, Auckland Hospital ,1999.
   Medline
                           RESUSCITATION FLUIDS
Controversy in the choice of fluid, the rate and the volume of resuscitation. Recently, the controversy
in haemorrhagic shock has been when to give fluid resuscitation.
.
Comparison between types of fluids available

Isotonic Crystalloids

Safe, nontoxic, no allergic reaction. No risk of infection. Inexpensive. In large
volumes will sufficiently expand the plasma volume.


Disadvantages
   Does not carry oxygen.
   Large volumes required - 3 x the amount of blood lost, 2 to 4 x the amount of colloid required.
   Short 1/2 life, only 20 % of infused volume remain in the intravascular space after 2 hours. That
    implies if 1000 mls are infused only about 200 mls remain in the circulation.
   Large volumes theoretically associated with more tissue oedema.
   However, no real documentation that adverse SEs such as pulmonary oedema are any more
    common with crystalloids than with colloids.
   Electrolyte abnormalities - hyperchloraemia - may contribute to acidosis.

Colloids
Haemaccel or Gelofusine.
Hetastarch.
Dextran 40 and 70 , 5 % and 25 % albumin

   Result in more rapid resuscitation, as they expand the plasma volume faster and for a longer
    duration.
   Associated with anaphylactic reaction. Dextran solutions additionally can cause bleeding and renal
    failure.

More expensive.
  In a recent meta-analysis (BMJ ) colloid use associated with slightly higher mortality in critically
   ill patients. Metaanlysis not without flaws.
  The right choice of fluid till there is any evidence to the contrary is colloids and crystalloids

Hypertonic saline

   Effective volume expander. Smaller infusion volumes, shorter infusion times, less third spacing.
   Improved haemodynamic, improving cardiac output and contractility Less oedema. Cheap. No
    infection risk.. Reduces cerebral oedema while raising blood pressure. Improves cerebral
    oxygenation. Increases tissue perfusion.
   Particularly good for head injury and burns shock.
   Results of trial for prehospital use in trauma and haemorrhagic shock ongoing. Some conflicting
    results.

Neg : Increases serum sodium and chloride, osmolarity, can cause metabolic acidosis and hypokalemia.
         Adverse CNS effects from high sodium load - central pontine demyelination, altered mental
         status, seizures. Too rapid dehydration of the brain could increase intracerebral bleeding.


Blood substitutes
Perfluorochemical solutions which can carry a larger amount of dissolved
oxygen.
Haemoglobin solutions.
All experimental.

Blood
   The only fluid that is available to us that will carry oxygen!
   Indication : If the patient is haemodynamically unstable, or has persistent hypoxia, or has lost
    significant amount of blood ( 30 % of blood volume ).
   Best - fully typed and crossmatched, but this takes 45 minutes.
   Type specific blood can be available in 10 minutes, avoids the majority of incompatibility
    reactions.
   In desperate situation, uncrossed O + for men and O - for women.

Timing of fluid resuscitation

Traditional management of all haemorrhagic shock
   Two or more large bore IV lines, rapid infusion of large volumes of crystalloid and colloids.
   Massive units of blood rapidly infused.
   Resuscitate the patient, then take to theatre

Recent studies have shown adverse outcomes with aggressive fluid
resuscitation and restoration of blood pressure prior to control of bleeding
source, esp. in penetrating torso trauma.
            Concept : two models : Uncontrolled Haemorrhagic Shock and Controlled haemorrhagic
             shock

Theory of Hypotensive Resuscitation : In UCHS aim for a map of 40 mm Hg or a SBP of 60 to 80 mm
Hg - minimal volume resuscitation,


Remember : Prevent hypothermia - warm the fluids.

								
To top