Critical Care Mo's Notes Flashcards
What is the pathophysiology of ARDS?
- Acute phase
* exudate with neutrophils and cytokines causing destruction of the alveolar basementmembrane and capillary endothelim - Chronic phase
* fibroproliferation and organisation of the lung parenchyma, leads to scarring
What are the causes of ARDS?
VITAMIN
Vascular - TRALI, DIC
Infection - sepsis, diffuse pulmonary infections
Trauma - burns, pulonary contusions, fat embolism, drowning, smoke injury
Autoimmune - drugs,
Metabolic -
Idiopathic/iatrogenic - cardiopulmonary bypass
Neoplasia -
What is the Berlin criteria?
Classification of ARDS as mild moderate or severe accoding to PaO2/FiO2 (arterial oxygen to inspired oxygen)
What is the management of ARDS
Ventilation, Steroids, Fluids, Nutrition
What are two systems to calculate the % surface area of burns?
Wallace Rule of 9s
Lund and Browder
What is the normal value of ICP?
7 to 15mmHg
What is cushing’s triad?
hypertension
bradycardia
bradypnoea
MAP = ?
diastolic + 1/3 (systolic -diastolic)
What is a normal MAP?
50 - 150 mmHg
CPP = ?
MAP - ICP
How to manage raised ICP?
Sit up
Mannitol, furosemide
Avoid hyperthermia
Sedation
Hyperventilation
Burr hole/craniectomy
Describe the stages of shock
What is a normal intramuscular compartment pressure?
0 - 15mmHg
What is a pathological compartment pressure?
30 mmHg
Where to incise for faschiotomy of the leg?
2cm anterior and posterior to the tibial border
What is the pathogenesis of rhabdomyolysis?
myoglobin and other tissue breakdown products cause ATN and renal failure
What are some causes of rhabdomyloysis?
- Blunt trauma to skeletal muscle, e.g. crush injury
- Massive burns
- Hypothermia or hyperthermia
- Ischemic reperfusion injury, e.g. clamp on an artery during surgery
- Prolonged immobilization on a hard surface
- Strenuous and prolonged spontaneous exercise, e.g. marathon running
- Drugs, e.g. statins, fibrates, alcohol
What bloods could be derranged in rhabodmyolosis?
- Increased creatine kinase (CK) > 5 times the normal
- Increased lactate, LDH, creatinine
- Electrolyte disturbances:
o Hyperkaliemia (and metabolic acidosis with an ↑ anion gap)
o Hypocalcemia
o Hyperphosphatasemia
o Hyperuricemia - Myoglobinuria suggested by positive dipstick to blood in the absence of hemoglobinuria (red cells on microscopy)
How to manage rhabdomyolysis?
- ABC
- Fluid resuscitation: ensure good hydration to support urine output >300 ml/h using IV crystalloid until myoglobinuria has ceased.
- Diuretics, e.g. mannitol, may also be used
- Alkalinization of urine: NaHCO3 to prevent renal damage
- Treat electrolyte disturbances (hyperkalemia)
- Monitor ECG, electrolytes, UOP, CK (6-12h), LDH, urine myoglobulin, compartment pressure.
What is the mechanism of action of PPIs?
The PPI binds irreversibly to a hydrogen/potassium ATPase enzyme (proton pump) on gastric parietal cells and blocks the secretion of hydrogen ions, which combine with chloride ions in the stomach lumen to form HCL
What are the functions of hydrogen chloride in the stomach/small intestine?
- Activates pepsinogen to pepsin which help in proteolysis
- Antimicrobial
- Stimulates small intestinal mucosa to release CCK and secretin
- Promotes absorption of calcium and iron in the small intestine
What are the phases of gastric secretions?
- Cephalic phase (smell / taste of food)
* 30% acid produced
* Vagal cholinergic stimulation causing secretion of HCL and gastrin release from G cells - Gastric phase (distension of stomach)
* 60% acid produced
* Stomach distension / low H+ / peptides causes Gastrin release - Intestinal phase (food in duodenum)
* 10% acid produced
* High acidity / distension / hypertonic solutions in the duodenum inhibits gastric acid secretion via enterogastrones (CCK, secretin) and neural reflexes.
What are the NCEPOD classifications of surgery?
- immediate - life of limbsaving - minutes - e.g. ruptured AAA, compartment syndrome
- urgent - deterioration of condition that could affect life - within hours e.g. bowel perf with peritonitis, critical limb ischaemia
- expediated - early intervention not a threat to life - within days e.g. tendon rupture
- elective - planned - as planned e.g. all others
What are the constituents of bile?
- Water.
- Cholesterol.
- Lecithin (a phospholipid)
- Bile pigments (bilirubin & biliverdin)
- Bile salts and bile acids (sodium glycocholate & sodium taurocholate)
- Small amounts of copper and other excreted metals.
What is a pancreatic pseudocyst?
when? where?
Collection of amylase-rich fluid enclosed in a wall of fibrous or granulation tissue
It requires 4 weeks or more from the onset of the attack
What are the symptoms of a pancreatic pseudocyst?
- Epigastric swelling
- Dyspepsia
- Vomiting
- Mild fever
What is the management of a fistula?
SNAP
- Sepsis control
- Nutritional support – a period of parenteral nutrition may be required
- Anatomical assessment
- Adequate fluid and electrolyte replacement
- Protect skin to prevent excoriation
- Planned surgery
What is refeeding syndrome?
It is a metabolic disturbance which occur on feeding a person following a period of starvation. The metabolic consequences include:
* Hypophosphataemia
* Hypokalaemia
* Hypomagnesaemia
* Abnormal fluid balance
Who is at risk of refeeding syndrome?
If one or more of the following:
* BMI < 16 kg/m2
* Unintentional weight loss >15% over 3-6 months * Little nutritional intake > 10 days
* Hypokalaemia, Hypophosphataemia or hypomagnesaemia prior to feeding (unless high)
If two or more of the following:
* BMI < 18.5 kg/m2 * Unintentional weight loss > 10% over 3-6 months
* Little nutritional intake > 5 days
* History of: alcohol abuse, drug therapy including insulin, chemotherapy, diuretics and antacids
How to prevent re-feeding syndrome?
- Start at up to 10 kcal/kg/day increasing to full needs over 4-7 days
- Start immediately before and during feeding: oral thiamine 200-300mg/day, vitamin B co strong 1 tds and supplements
- Give K+ (2-4 mmol/kg/day), phosphate (0.3-0.6 mmol/kg/day), magnesium (0.2-0.4 mmol/kg/day)
When is TPN indicated?
General critical illness:
* Severe malnutrition (> 10 % weight loss)
* Multiple trauma
* Sepsis with MOF
* Severe burns
Gut problems:
* Short bowel syndrome (short gut)
* Enterocutaneous fistula
* Bowel obstruction
* IBD
* Radiation enteritis
coronary artery perfusion pressure =
systemic diastolic arterial pressure - LVED pressure
What are some complications of hypothermia?
Systems
- Cardiovascular: decreased cardiac output (anaesthetized), arrhythmias, vasoconstriction, ECG abnormalities (increased PR interval, wide QRS complex)
- Respiratory: increased pulmonary vascular resistance and V/Q mismatch, decreased ventilator drive. Increased gas solubility
- Renal: decreased renal blood flow and glomerular filtration rate, cold diuresis.
- Hematological: reduced platelet function and coagulation, increased fibrinolysis, increased hematocrit, left shift of oxygen dissociation curve.
- Metabolic: reduced basal metabolic rate, metabolic acidosis, insulin resistance, hyperglycemia.
- Gastrointestinal / hepatic: reduced gut motility.
- Neurological: reduced cerebral blood flow, impaired conscious state leading to coma.
What are the three stages of haemostatsis?
- Vasoconstriction: smooth muscle contraction by local reflexes, thromboxane A2, serotonin released from activated platelets
- Platelet activation: adherence, aggregation, plug
- Coagulation: intrinsic and extrinsic pathway → fibrinogen → fibrin
How to insert a central line?
- Anatomical landmarks: mastoid process, carotid pulse and the depression between the two heads of sternocleidomastoid immediately above the clavicle.
- Locate:
o Clavicle
o 2 heads of sternomastoid - In the center of the triangle formed by the previous land marks, palpate the carotid artery and insert the needle lateral to it.
- The needle is directed at 30ᵒ angle towards the patient in the coronal plane aiming towards the ipsilateral nipple
- Aspirate as the needle advances, once the blood is aspirated, cannulate the vein with Seldinger technique
- Suture the line in place
What is the naloxone dose?
0.4 -2 mg IV initially and repeat every 2-3 min if no response, to a maximum of 10 mg