Critical Care Flashcards
For what patients would intensive care be appropriate for?
- Patients requiring or likely to require advanced respiratory support alone
- Patients requiring support of two or more organs
- Patients with chronic impairments to their daily activities and who require support for an acute reversible failure of another system
For what patients would high dependency care be appropriate for?
- Patients requiring support for a single failing organ system (not respiratory)
- Patients that would benefit from detailed observation or monitoring
- Patients no longer needing intensive care but not yet wll enough to return to a general ward
- Post-operative patients who need dose monitoring for longer than a few hours
What are the ideal measurements that should be seen in patients who are seriously ill?
HR - 70 BP - 120/80 RR - 14 SpO2 - 98% Temp - 37°C Concious Passing urine Acid-base normal Pain free
Describe the APACHEII scoring system
Acute Physiology and Chronic Health Evalutation
A score given to ICU patients within 24 hours of admission, between 0-71. It is based on 12 physiological measurements as well as age, previous health status etc. It is used to determine the patient’s severity of illness and risk of death
Describe the SOFA scoring system
Sequential Organ Failure Assessment
This scoring system uses six different criteria, each scored between 1 and 4;
- Resp (PaO2/FiO2)
- CNS (GCS)
- CVS (MAP)
- Liver (Billirubin)
- Coagulation (platelets)
- Renal (Creatinine or urine output)
Define SIRS
Systemic Inflammatory Response Syndrome
- Temp 38°C
- HR >90bpm
- RR >20/min
- WCC >12000/mm or 10% immature neutrophils
Define septic shock
Severe sepsis with hypotension that is not responding to antihypertensive agents or fluid challenges. This leads to inadequate tissue and organ perfusion and a rising lactic acidosis
Describe the stages of signs and symptoms of sepsis
Early - Classically unwell e.g. hot, sweaty, flushed and general malaise
Established - Patient has become more ill so has warm peripheries, pyrexia and a bounding pulse. Will also have a high CO and vasodilation
Late - Cold peripheries and mottled skin will also have a low CO
Describe the pathophysiology of sepsis
1) Microorganisms enter the blood
2) Toxins are released
3) Release of endogenous mediators and activation of the inflammatory and immune responses
4) Profound physiological systemic effects and organ dysfunction/failure
Describe the vasomotor pathophysiological responses seen in sepsis
1) Bacteraemia and endotoxaemia
2) Induction of nitric oxide synthase
3) Nitric oxide mediated arterial vasodilation
4) Poor venous return to the heart
5) Baroreceptors alert the CNS
6) The CVS increases vasoconstriction
7) The RAAS is upregulated to conserve water and sodium
Describe the three effects of nitric oxide synthase
Regionally - Body distributes blood flow to the vital organs
Microvascularly - Erythrocytes become less deformable so the tissue cannot extract oxygen and capillaries shut down
Centrally - Change in systolic and diastolic ventricular funciton
Describe the effects of capillary leaks in sepsis on the following organ systems;
- GI
- CNS and PNS
- Liver
- MSK
GI - Widening of the gap junctions allows bacterial translocation from the gut lumen to the blood
CNS/PNS - Disruption of the BBB which leads to confusion. There is also peripheral axon degeneration
Liver - May perpetuate sepsis
MSK - Breakdown of muscle to produce proteins
Describe the two main types of β receptor and their effects
β1 - - Inotropy (increases myocardial contractility) - Chronotropy (increases rate) β2 - - Vasodilation
Describe the use of dopamine as a catecholamine
A precursor to noradrenaline that increases urine output but is hardly ever used as it doesnt improve outcome
Describe the use of dobutamine as a catecholamine
Predominantly acts on β1 and β2 receptors;
- Inotropy - Strong
- Chronotropy - Weak
- Vasoconstriction - None
Always increases CO but the effect on BP is variable
Describe the use of norepinephrine as a cetacholamine
Potent α-agonist with some β-activity; - Inortropy - Weak - Chronotropy - Very weak - Vasoconstriction - Very strong Reliably increases BP
Describe the use of epinephrine as a catecholamine
- Increase CO and BP reliably
- High doses - Increases pulmonary vascular pressures (problematic)
Describe the use of phosphodiesterase inhibitors as catecholamines
Work by a different method to other inotropes so can be used if other inotropes fail
Describe the use of vasopressin as a catecholamine
Works on vasopressin in the vascular smooth muscle and renal collecting system to increase vascular tone and sensitise the blood vessels to noradrenaline
How do we measure tissue oxygenation in ICU?
Measured via mixed venous oxygenation
- Target in ICU = SVO2 of 70%
- Below 70% = Medical emergency
- Too high = Organs are failing and not using oxygen
Describe Haemofiltration as a form of RRT
In haemofiltration/ultrofiltration the blood passes across a membrane which allows blood cells etc. to stay in the patient’s circulation but water and electrolytes leave, along with waste products. Fluid is then replaced with a normal level of electrolytes
Describe Haemodialysis as a form of RRT
In haemodialysis/tubular diffusion the blood leaves the patient and passes through a dialysis machine which contains liquid with a normal level of electrolytes. The electrolytes, waste products etc. move across a membrane down their concentration gradient
Describe Haemodiofiltration as a form of RRT
This method is the same as haemofiltration, however the pump that moves fluid back into the body has a small amount of dialysis fluid
What is Diffuse Alveolar Damage?
A non-specific pattern of acute lung injury caused by a variety of noxious agents
Describe the three phases of DAD
- Exudative Phase - (1-7 days) Leakage of blood and fluid into the lungs
- Regenerative Phase - (3-10 days) Type 2 pneumocytes replace type 1 pneumocytes. They may grow over the hyaline membrane instead of under. This permanently thickens the membrane and may even occlude the opening of the alveoli
- Repair Phase - (>1-2 weeks) Lung tissue repairs however myofibroblasts contract and cause shrinkage of the lung
Describe the criteria for diagnosing ARDS
Timing - Within one week of a known clinical insult or new or worsening respiratory symptoms
Chest Imaging - Bilateral opacities, not fully explained by effusions, lobar/lung collapse or nodules
Origin of Oedema - Respiratory failure not fully explained by cardiac failure or fluid overload
Oxygenation - Mild = 200mmHg
Moderate = 100mmHg
Severe = <100mmHg
What are the three main goals for the management of ARDS?
1) Maintain tissue oxygenation
2) Minimise harm
3) Support other failing organs
For what patients is ventilatory support appropriate?
- Unresponsive hypoxemic
- Exhaustion
- Severe hypercapnia
What are the four possible causes for respiratory failure?
- Shunting
- V/Q mismatch
- Reduction in gas diffusion
- Increased dead space