ITU Flashcards
Causes of post op confusion?
Pain and infection
Hypoglycaemia
Electrolyte disturbances - namely sodium
Respiratory = hypoxia and hypercapnoea
Renal / liver failure = accumulation of toxic metabolites
Investigations of post op confusion?
bedside = ABG, bloods, BM, ECG
Radiology
Purpose of sedation in critical care?
Anxiolysis
Analgesia
Amnesia
Sedation
How do we. determine level of sedation?
Ramsay scoring:
Level 1 = awake, anxious and agitated
2 = Awake, co=operational, orientated and tranquil
3 = Awake, responds to commands only
4 = asleep, risk response to glabellar tap or loud auditory stimulus
5 = Asleep, sluggish response
6 = asleep, no response
Sedative drug classes?
Benzos
Opiates
Butyrophenones e.g. Haloperidol = neurotransmitting blocker
Anaesthetic agents e.g. Propofol or ketamine
Major SE of propofol?
Can cause hypotension on induction via decreasing SVR and myocardial depression
Sodium thiopentone?
Use = RSI
Analgesic effect = none
SE’s = marked myocardial depression and toxic metabolites
Ketamine?
Good analgesic and little myocardial depression
SE’s = dissociative nightmares
Etomidate?
No analgesic effect
Favourable cardiac profile
SE’s = prolonged use causes adrenal suppression
What can be donated?
Organs = kidney, liver, heart, lung, pancreas and small bowel
Tissues = cornea, skin, bone, tendon, heart valves and cartilage
Criteria to donate pre-donation?
- Diagnosis of brainstem death and circulatory death
- Donor maintained on a ventilator in absence of sepsis
- No hx of malignancy (except primary brain tumour)
- HIV and HBV -ve
- High risk groups excluded e.g. IVDU
Often some specific restrictions e.g. heart donor no MI
Why is managing fluid balance particularly important in organ donors with brainstem death?
If brainstem death can get cranial diabetes insipidus = severe water loss and subsequent hypernatraemia
If severe can use vasopressin to manage
Occurs in 65% of brainstem death
Physiological changes in brainstem death?
- Hypotension: due to loss of sympathetic peripheral vascular tone - 81%
(initially HTN due to immediate increase in sympathetic tone
Mx = IVF and inotropes - Coagulopathy: e.g. DIC
- Hypothermia: Occurs following loss of thermo-regulation via hypothalamus. This is exacerbated by reduced metabolic activity and loss of vascular tone.
Mx = blankets and warmed IVF - Endocrine: Loss of thyroid function can result in further arrhythmias
Mx = T3
When is it appropriate to perform an examination
- Coma - patient must be in a deep coma entirely reliant on ventilator due to absence of spontaneous ventilation
- Brain damage = must be irreversible and compatible with diagnosis of brainstem death
Must exclude following reversible causes?
Hypothermia
Metabolic = Hypoglycaemia, Na
Endocrine = hypothyroid, uraemic, encephalopathic
Drugs and ETOH
Criteria for brainstem death?
- No respiratory drive:
Preoxygenated got 10 minutes
PCO2 increases, normally respiratory stimulates at >6.5kPa - Non brainstem function:
- Absent pupillary light CN2/3
- Absent corneal reflex CN5/7
- Absent CNN motor function CN5/7
- Absent gag CN9
- Absent vestibulo-occular test following cold caloric test CN8/3
Who can assess for BSD?
Must be relevant specialty
x1 consultant and x1 registered GMC for > 5 years
When can confirmation be difficult?
COPD
Ocular injury
Brainstem encephalitis
How can we. support circulation in ITU?
Need to if cardiac index <2.2 or in septic shock.
Cann give: Inotropes Chronotropes Vasoconstrictors or dilators Mechanical e.g. intra-arterial balloon pump with counter pulsation
Commonly used drugs?
adrenergic e.g. adrenaline or noradrenaline
- increase SVR, HR, SV and CO. With aim of increasing BP
Dopaminergic agents e.g. dopamine or dobutamine
- HR and SV –> increased CO, to increase BP
- dose dependent effects however
NON-CATECHOLAMINES
- Phosphodiesterase inhibitors e.g. Milrinone
- increased contractility + SV but reduced SVR via vasodilation - Calcium channel agonists e.g. Levosimendan
- produce a transient inotropic effect
- increase sensitivity of myocardial troponin to intracellular calcium - ADH agonist = natural analogue of vasopressin and increase SVR via vasoconstriction
Effect of adrenergic receptors in heart and vessels?
a1:
- Increased vasoconstriction of arterioles = increased afterload and increased peripheral vascular resistance
- Increased venoconstriction = increased venous return = increased preload
a2 = platelet aggregation
B1 = Increased HR, contractility and automacity/conduction velocity
Effects of different inotropes on adrenergic receptors?
1. Dopamine = dose dependent... Low does (1-4) = mainly DA1 = increased splanchnic / renal blood flow @ low dose Medium dose also B2 High dose also A1
- Dopexamine = B2 and DA1 (0.5-0.6)
- inodilator
- Used in management of heart failure post cardiac surgery
- Increases hepatosplanchnic blood flow, and can ameliorate gut ischaemia in SIRS - Dobutamine = B1 and B2 (2.5 - 10)
- indicator, good in low output / high SVR states e.g. cardiogenic shock
- not beneficial if low BP e.g. sepsis - Salbutamol (0.1 - 1.0)
Severe asthma - Adrenaline = alpha 1 and B1 (0.01-0.2)
- 1st line inotrope
- High B-adrenoreceptor = increased cardiac output
- Can vasodilate at low doses, constrict at higher doses - Nor-adrenaline = alpha1 (0.01 - 0.2)
- Inoconstrictor
- Very useful in high output / low SVR states e.g. Sepsis
- Inotropic effect via A1 and B1 myocardial receptors
- Can cause reflex bradycardia + peripheral / splanchnic ischaemia - Isoprenaline - B1 and B2 (0.01 - 0.2)
- Reserved for treatment of emergency bradyrhythmias
- risk of tachyrhythmias - Phenylephrine = alpha 1 = pure vasoconstriction (0.2- 1.0)
Mechanism of PDE3
act by inhibiting hydrolysis and degradation of intracellular CAMP.
This causes increase in intracellular calcium = increased cardiac contractility and stroke volume
Effect of PDE3 on cardiac function?
Reduces afterload:
- via reduction of SVR and pulmonary vascular resistance
- useful in cardiogenic shock when high SVR
Inotropic:
- Increase in HR, but decreased myocardial oxygen requirement as lower filling pressures
Dopamine effects on circulation?
Low dose = 1-4 = DA1 only:
- renal and spleen vasodilation = increased renal perfusion and diuresis
Medium dose 4-10 = B1 too = increased contractility
High dose >10 = A1 too = Vasoconstrictor = increased afterload and SVR.
Indications for noradrenaline ?
Potent vasoconstrictor
useful in septic shock, but can lead to reduced peripheral perfusion and increased afterload
Affects of noradrenaline on circulation?
low doses = B1 = increased CO and reduced SVR
Higher doses = alpha 1 = increased CO and increased SVR
Dobutamine effects?
Strong B1 = cardiac output up and SVR down
General problems with inotropes?
Tachyarrhythmias
Bradycardia if noradrenaline
HTNN with adrenaline
Hypotension if dobutamine / PDE3
What if cardiac index still <2.2 despite maximal cardiac output?
Intra-aortic balloon pump = mechanical assistance
Reduces afterload and increases coronary flow
Sits in descending aorta
Expands during diastole, increasing coronary perfusion pressure
Deflates just prior to systole = reduced afterload
Remember thrombogenic = anticoagulant needed
Indications for ET tube?
Operative:
ET = standard when using IPPV and muscle relaxants
Endobronchial = dual lumen allows single lung ventilation cardiothoracic/oesophageal surgery
Non-operative:
airway protection e.g. from gastric aspiration in severe head injury
CPR
How long for ET tube?
2 weeks, after this tracheostomy
Basic intubation steps?
- Pre-oxygenated 100% 3-5 mins
- Position = neck extended
- Anaesthesia = local or general
- muscle relaxant if GA
- Intubate = laryngoscopy, intubate, inflate cuff, connect tube
- Auscultate
- Secure
Magill vs Macintosh laryngoscope?
Which one on paediatrics
Magill = straight blade Macintosh = curved blade
Magill in pads as epiglottis is floppy and U shaped = straight blade passes behind and fixes it in position
Sizes of laryngeal tube?
8mm for male, 7mm for female
RSI?
Emergency induction e.g. AAA
Important requirements are suction, skilled assistant and cricoid pressure
Cricoid pressure is not released until cuff inflated
When is nasotracheal intubation used?
Head and neck procedures