Critical Care Flashcards
What is the function of a chronotrope?
To increase the heart rate
What is the function of an inotrope?
To increase the contractile force of the cardiac muscle, thereby increasing stroke volume
What is the function of a vasopressor?
Constrict the arterial tree, increasing systemic vascular resistance
Where are alpha1 adrenergic receptors located, and what is their function?
Located in vascular smooth muscle, hence activation causes vasoconstriction
Also located in heart, and increases duration of contraction without increasing chronotropy
Where are beta adrenergic receptors located?
Beta1 in the heart, increasing inotropy and chronotropy without vasoconstriction
Beta2 in blood vessels and cause vasodilation
Where are dopamine receptors located and what is their function?
In renal, splanchnic (mesenteric), coronary, cerebral vascular beds.
Induces vasodilation
Second subtype causes vasoconstriction by inducing norepinephrine release
What receptors does adrenalin act on, and therefore what are its effects and uses?
Beta 1- adrenaline acts strongly on this receptor to increase inotropy and chronotropy
Beta 2, alpha 1- adrenaline acts moderately on these receptors
Used in anaphylaxis and second line in septic shock
What receptors does dobutamine act on and what effect does it have?
Beta 1 and beta 2- increases inotropy and chronotropy, reduces LV filling pressure
Has no vasopressor effects as has no action on alpha 1 receptors
What receptors does noradrenaline act on and what effect does it have?
Alpha 1 and beta 1 receptors
Producing vasoconstriction and inotropic effects
At low doses, a reflex bradycardia in response to increased mean arterial pressure, which cancels out the mild chronotropic effect and therefore there is no increase in heart rate!
What receptors does phenylephrine act on and what effect does it have?
Alpha 1 only
So purely vasoconstriction!
In septic shock, which is the first line vasoactive agent?
Noradrenalin
As it causes vasoconstriction to counteract the vasodilation from sepsis
Pure vasoconstriction alone can cause reflex bradycardia and reduce cardiac output, so the inotropic effects of noradrenalin helps to counteract this.
The inotropic effects of noradrenalin also helps to counteract the decrease in cardiac function which typically occurs in septic shock
What vasoactive drug is first line in anaphylactic shock?
Adrenalin
Vasopressin is second agent
What vasoactive drug is used in neurogenic shock?
Phenylephrine as it has purely vasoconstriction effects
What is the most appropriate vasoactive drug in cardiogenic shock
Norepinephrine
After establishing adequate perfusion, dobutamine can be added, as it is a potent inotropic drug, and it’s effects on beta 2 receptors causes vasodilation, so the heart has less pressure to pump against
What is a level 0 patient?
A patient whose needs can be met through normal ward care - eg observations greater than four hourly
What is a level 1 patient?
A patient at risk of their condition deteriorating, or recently discharged from a higher level of care.
Patients requiring additional monitoring <4 hour obs, clinical interventions or advice from critical care outreach.
What is a level 2 patient?
Patients needing pre-operative optimisation or extended postoperative care.
Patients stepping down from level 3 care.
Patients requiring single organ support! Greater than 50% oxygen or NiV Vasoactive drugs/CVP monitoring Renal replacement therapy ICP monitoring Dermatological support - burns
This is achieved on HDU
What is a level 3 patient?
Patients requiring advanced respiratory support alone - invasive mechanical ventilation
Patients requiring more than one organ supported
This is achieved on ICU
What are some early complications of endotracheal intubation?
Trauma to mouth, teeth etc Aspiration of stomach contents Tube malposition Airway obstruction Hypoxia from prolonged attempts
What are some late complications of endotracheal intubation?
Infection
Mucosal damage to mouth or trachea from cuff pressure
Injury to vocal cords
Tracheal stenosis
What are early complications of tracheostomy?
Haemorrhage Pneumothorax Tube misplacement Surgical emphysema Blockage with secretions Stomal infections Mucosal ulceration or perforations Tracheoeseophageal fistula
What are late complications of tracheostomy?
Late haemorrhage Tracheal granulomata Tracheal stenosis Scarring persistent sinus Tracheal necrosis
What precautions and monitoring should be taken when using vasoactive drugs?
Administered by central venous catheter
Haemodynamic monitoring via arterial and central venous catheters
How can death be defined?
The irreversible loss of the capacity to breath combined with the irreversible loss of the capacity for consciousness
These capacities reside in the brainstem, in the medulla and reticular activating system respectively
