1 - Care of the Surgical Patient Flashcards
What is the circulating blood volume made up of?
2 litres red cells and 3 litres plasma
What molecules contribute to the osmolality of blood?
285 - 295 mOsm/kg
Always double Na and K to make up for the Cl
What are some factors that can increase or decrease serum osmolality?
What is the composition of the following fluids:
- 0.9% saline
- 5% dextrose
- 0.18% NaCl/ 4% dextrose
ADD SLIDE FROM JAMES PPT
A 1% solution contains 1g per 100ml of solvent
- 0.9% saline is 150 mmol/L of Na and 150 mmol/L of Cl
- 5% dextrose is 50g of dextrose
- 0.18% NaCl/4% dextrose is 40g of dextrose and 30mmol/L of Na and 30mmol/L of Cl
How much energy is in 1L of 5% dextrose?
14kJ per g of glucose so 700kJ (50x14) or 166kCal
How does 1 litre of 5% dextrose, Hartmann’s and 0.9% NaCl get distributed across body compartments?
Dextrose can get to all body compartments but the other two are just in the extracellular fluid
Therefore saline better for raising blood pressure and dextrose better for maintenance fluids to prevent starvation ketosis
How does 0.18% NaCl/4% Dextrose distribute across body compartments?
Theorectically this fluid is 1 part 0.9% NaCl (200ml) and 4 parts 5% Dextrose (800ml)
IV fluids need to be isotonic so as not to damage red blood cells. However 4% Dextrose/0.18% Saline is hypertonic, why is this and why can it be used as a fluid?
Initially dilutes osmolality of extracellular fluid but once cell has used the dextrose, the remaining saline and electrolytes act isotonic
5% dextrose is isotonic as the dextrose is metabolised to water
What are the daily requirements for water, sodium, potassium and chloride?
Water 25-30ml/kg
Sodium 1mmol/kg
Potassium 1mmol/kg
Chloride 1mmol/kg
Glucose 50g
Obese adult patients do no require additional fluids/electrolytes above standard regime
What are two commonly used maintenance fluid regimes for NBM patients and what patients cannot be safely prescribed these regimes?
- Renal impairment as kidneys cannot correct any minor errors in fluid and electrolytes
- Cardiac impairment/heart failure
- Elderly, frail cachetic patients as risk of causing heart failure due to fluid overload
- Also need to consider nutrition, can be NBM safely for 4-5 days but need to consider nutrition!!!
How does post-operative (first 3 days) fluid prescribing differ from pre-operative fluid prescribing?
- Loss of water into third spaces (e.g drains) and from intraoperative/ongoing bleeding needs to be considered
- Maintenance fluids of 1-1.5ml/kg/day as post-op phase of sodium retention due to increased ADH and cortisol from surgical trauma so more free water absorbed so a hyponatremia
- Do not want to prescribe potassium in the post op phase due to rhabdomyolysis from surgery raising K+
Why is there a normal postoperative phase of oliguria?
Surgery is trauma which causes ADH and cortisol release which causes more water to be reabsorbed in the kidney so less urine produced
What are some questions you need to ask yourself when prescribing fluids for a patient?
Always check inputs and outputs on fluid chart
How do you clinically assess a patients hydration status?
Fluid depleted
- Dry mucous membranes and reduced skin turgor
- Decreasing urine output (should target >0.5 ml/kg/hr)
- Orthostatic hypotension
- Increased capillary refill
- Tachycardia
- Low blood pressure
Fluid Overloaded
- Raised JVP
- Peripheral or sacral oedema
- Pulmonary oedema
Why are many surgical patients in fluid/electrolyte deficits?
- Vomiting from intestinal obstruction: vomiting causes loss of isotonic fluid leaving space in gut for more to be sequestered so many patients in hypovolaemic shock as lost a lot of fluid from ECF
- Peritonitis: large surface area so if inflammad can give off litres of fluid as normal blood flow is 150ml/min and SA is 2m2
- Fistulae
- Bleeding
What are some useful biochemical markers for dehydration in a patient who is vomiting due to a bowel obstruction?
- Raised haematocrit (>55%)
- Raised serum urea
- Raised serum urea in comparison to creatinine as urea can be reabsorbed but creatinine cannot
Why is it important to correct fluid balance and electrolytes before anaesthesia?
How can you work out fluid replacement in patients with severe and complex fluid disturbances?
Use fluid chart, see orange section
- Are there any third-space losses?
- Third-space losses such as bowel lumen (in bowel obstruction) or retroperitoneum (as in pancreatitis).
- Is there a diuresis?
- Is the patient tachypnoeic or febrile ?
- Is the patient passing more stool than usual (or high stoma output)?
- Are they losing electrolyte-rich fluid?
What are some of the reasons colloids are not often used?
- High cost
- Risk of anaphylaxis
- Increased risk of coagulopathy
What is a fluid challenge?
- 500ml 0.9% NaCl over 15 minutes (if elderly and frail use 250ml)
- Always reassess after
- Use lactate as a guide for fluid resus
What are some of the complications of parenteral feeding?
Nutrition pumped straight into the blood stream, can irritate the veins
- Dehydration and electrolyte imbalances.
- Thrombosis
- Hyper/hypoglycemia
- Infection
- Liver Failure.
- Micronutrient deficiencies (vitamin and minerals)
What are some of the different enteral feeding options?
- TPN is used when intestinal failure (e.g perforations or short gut from resection) or cannot access jejunum
- Hierarchy of feeding
- Tube enterostomies are used long term when need feeding over 4 weeks. PEG better as can be used for night feeds with less risk of aspiration
What does surgery do to a patients nutrition status?
Puts them in a hypermetabolic and catabolic state
How is nutrition status assessed on the wards?
- All patients must be screened for malnutrition on admission as poor surgical candidates and poor post-op complications if malnourished
- MUST score
- Dietician then looks at BMI, Grip Strength, Triceps Skin Fold thickness and Mid Arm Circumference
What causes low albumin levels?
- Chronic inflammation
- Protein losing enteropathy
- Proteinuria
- Hepatic dysfunction
NOT MALNUTRITION
What are the Enhanced Recovery After Surgery (ERAS) principles?
How are the nutritional requirements of a high output stoma met?
How can you reduce the amount of output from a high output stoma?
How is pain assessed?
- Subjective: pain score 1-10
- Objective: tachycardia, tachypnoea, hypertension, sweating, or flushing, unwilling to mobilise, agitated
What are the consequences of poor pain control?
- Slower recovery time due to reluctant to mobilise
- Inadequate ventilation leading to possible subsequent atelectasis and hospital-acquired pneumonia as they are not breathing as deeply as they would if they were not in pain
- Cardiovascular: tachycardia, hypertension
- GI: ileus, N+V, urinary retention, ileus
How is pain managed using the WHO ladder?
- Consider IV route
- Consider gabapentin and amitriptylline for neuropathic pain
What are the side effects of NSAIDs?
Work by decreasing synthesis of prostaglandins so decreased inflammation
IGRAB
What is PCA and what are the advantages and disadvantages of this?
- PCA involves the use of IV pumps that provide a bolus dose of an analgesic when the patient presses a button.
- Started in theatres
What pain relief is adminstered under anaesthesia?
- Local anaesthetics used during suturing as will help pain when patient wakes up
- Central neuroaxial methods will last 2-3 hours but often wear off suddenly
What are some of the side effects of opioids for pain relief?
What pain relief regime is usually given post surgery e.g post hip replacement?
- PCA morphine
- Regular paracetamol and NSAIDs
- PRN tramadol/codeine
What is VTE and why are surgical patients at high risk of developing this?
- PE and DVTs
- PEs are the commonest cause of preventable death!
- 2/3 of Virchow’s triad with surgery
When do PE’s after surgery ‘classically’ occur?
10-12 days postoperatively when patient is straining at stool as this causes venous pressure waves so the thrombus fractures and embolises
What patient factors and what operative factors increase the risk of postoperative DVT?
- COCP (stop 4 weeks before elective surgery)
- Obesity
- Smoking
- Malignancy
- Orthopaedic surgery
- Increasing age
- Prolong immobility (>3 days)
How can post operative DVT be prevented?
- Pharmacological prophylaxis (LMWH dalteparin)
- Pre-operative mobilisation
- Post-operative mobilisation as soon as possible
- Anti-embolism stockings (GCS)
- Intraoperative intermittent cal compression
- Maintain hydration
- Stop prothrombotic drugs (e.g COCP)
What is the thromboprophylaxis guidelines for surgery in UHL?
- LMWH 5000 units s/c
- Anti-embolic stockings
- Intermittent pneumatic compression boots in theatre
There are two doses of Dalteparin (2500 and 5000) and 5000 is given to high risk patients but 85% of patients are high risk so all are given 5000
How does the dose of dalteparin vary if a patient is renally impaired? (eGFR<30)
Need to use a lower dose (2/3 of body weight if treating VTE) OR
Use UFH
How long is dalteparin prophylaxis given for?
- Normal surgery: give dose 1-2 hours before surgery then every 24 hours whilst at risk of VTE
- Major orthopaedic surgery (e.g THR/TKR): consider Dalteparin for up to 35 days after surgery if high risk
What are some contraindications of mechanical VTE prophylaxics (AES and IPC)?
- Peripheral arterial disease
- Peripheral oedema
- Local skin conditions.
How do you reverse the following anticoagulants?
- Dabigatran
- LMWH
- Rivaroxaban
- Warfarin (reversal needed for procedure in 5 days)
- Warfarin (immediate reversal)
- Warfarin (reversal needed for procedure next day)
- Witholding drug 24 hours usually sufficient as short half life but idarucizumab can be used
- Witholding usually sufficient due to short half life but protamine can be use
- Withold drug 24 hours as not reversal, can try PCC
- Withhold drug and bridge with LMWH till 24 hours before
- Prothrombin Complex Concentrate
- Vitamin K
When do you need to do bridging therapy when stopping warfarin for surgery?
If high risk of VTE (e.g VTE within last 3/12, AF with previous stroke or TIA, or mitral mechanical heart valve) then bridge
Start LMWH and stop 24 hours before surgery if surgery has high bleeding risk
Start warfarin again at night after surgery that day
How long before surgery do you need to stop aspirin and clopidogrel?
Aspirin: 7-10 days before
Clopidogrel: 7 days before
What are the clinical features of a DVT and how are they investigated?
Features
- Unilateral leg pain and swelling
- May have low grade pyrexia, pitting oedema, tenderness or prominent superficial veins or could be asymptomatic
Investigations
- Do Well’s score and if less than or equal to 1 DVT is unlikely but also do a D-dimer test to exclude
- If score greater than 1 DVT is likely so need US or contrast venography
What is the Well’s score for DVT?
- If 1 or less DVT is unlikely but do D-Dimer to rule out. D-dimer can also be raised in recent surgery/trauma, pregnancy, liver disease, infection, prolonged hospital stay
- If 2 or more DVT likely so do US
How is a DVT managed?
DOACs first line (e.g apixaban, rivaroxaban, and edoxaban, and a direct thrombin inhibitor, dabigatran)
- Dabigatran and edoxaban need 5 days LMWH first
- Continue medication for 3/12 if unprovoked or life long if high risk
What are the clinical features of a PE?
- Sudden onset dyspnoea, pleuritic chest pain, cough, or haemoptysis
- May have clinical signs of tachycardia, tachypnoea, pyrexia, raised JVP, pleural rub or pleural effusion
- Always assess for signs of DVT
How are PEs investigated and managed?
Ix
- Wells Score less than or equal to 4: PE unlikely, but D-dimer test to exclude
- Wells Score greater than 4: PE likely and confirm diagnosis with CTPA scan (or V/Q scan in those with poor renal function).
- Can do ECG to rule out MI differential and may have S1Q3T3
Mx
- Interim anticoagulation: offer apixaban or rivaroxaban first line for 5 days then dabigatran for 5 days
- If CTPA is negative stop anticoagulation
- If CTPA positive keep on anticoagulation for 3 months if unprovoked, longer if provoke
- If haemodynamically unstable give oxygen, continuous UFH infusion and consider systemic thrombolytic therapy
When diabetic patients are due to have surgery, how is their blood glucose control altered to their normal regime? (use flowchart)
- If expected to miss more than one meal put on variable rate intravenous insulin infusion of soluble human insulin in sodium chloride 0.9 % (sliding scale)
- Need to run intravenous glucose-containing ‘substrate solution’ alongisde it
- Need to check BM hourly, especially for first 12 hours of VRII, to see if in range of 6-10 mmol/L (4-12 acceptable)
- Conversion back to s/c insulin when patient can eat and drink with no N+V with overlap of 30 minutes
What antidiabetic drugs should be stopped when before surgery?
- Sulfonylurea: omit on day of surgery until eating again due to risk of hypoglycaemia from starvation
- SGLT2: omit on day of surgery until stable as risk of DKA
- DPP4i (Gliptins), GLP1 analogues and Pioglitazone: take as normal
- Metformin: (see image)
ALWAYS TRY AND GET DIABETIC PATIENTS FIRST ON THE LIST
What level is intraoperative hyperglycaemia treated at?
Blood glucose greater than 12 mmol/L with blood ketones less than 3 mmol/L or urine ketones < +++
Higher risk of DKA for diabetic patients following surgery
What level is intraoperative hypoglycaemia treated at?
Less than 4mmol/L then start the rescue treatment of 75-100 mls of 20% glucose then recheck BM after 15 minutes
Why is there a risk of aspiration of gastric contents during induction of anaesthesia?
- Relaxation of lower esophageal sphincter
- Lower level of consciousness
- Loss of protective reflexes
How do you prescribe a sliding scale insulin and what is the half life of IV insulin?
- Half life is 6 minutes
1. Draw up 50 units of prescribed Human Actrapid Insulin and add to 49.5 ml of 0.9% sodium chloride in a 50 ml luer lock syringe. This is a concentration of 1 unit/ml
2. Set up crystalloid with dextrose in (preferably 0.45% sodium chloride 5% glucose 0.15% potassium chloride) Need to give K+ as insulin drives K+ down
3. Run both through a single cannula with syringe pumps. (the rate of fluid replacement must be set to deliver the hourly fluid requirements of the individual patient)
4. Check blood glucose hourly to see if 6-10
5. Continue until eating and drinking normally and back on normal antidiabetic medication
What is the A to E assessment?
ALWAYS TREAT PROBLEM BEFORE MOVING ON TO NEXT LETTER AND ALWAYS REASSESS!!!!
What happens to patients when they are on long term steroids and why is this a problem with surgery?
- Exogenous steroids can cause HPA axis suppression. This is because it acts like cortisol and negatively feedsback on the pituitary to stop it producing ACTH.
- This HPA suppression causes adrenal atrophy as no longer producing cortsiol
- Trauma (like surgery) usually stimulates ACTH release and cortisol but long term steroid patients cannot mount this response. If not taking their oral steroids they can have an Addisonian Crisis/Adrenal insufficiency
What are Cushingoid features?
- moon face
- buffalo hump
- acne
- obese torso
- thin, easily bruised skin
What are the clinical and biochemical features of an Addisonian crisis?
Clinical:
- Severe weakness
- Confusion/Reduced Consciousness
- Pain in lower back or legs
- Severe abdominal pain, vomiting and diarrhea, leading to dehydration
Biochemical:
- Hypotension
- Hyponatraemia
- Hyperkalaemia
- Sometimes hypoglycaemia
Addison’s crisis can cause death by circulatory collapse and arrhythmias with hypoglycaemia contributing.
What is the treatment for an Addisonian crisis?
- Bloods for cortisol and ACTH
- U+Es (do ECG for K+ and give Ca gluconate if needed, fluids and steroids will resolve low Na)
- 100mg Hydrocortisone IM/IV stat
- IV fluid bolus for hypotension
- Monitor BM for hypoglycaemia
- Continue Hydrocortisone 100mg/8hr and change to oral steroids after 72 hours
- Continue fluid resus until electrolytes balanced
It is difficult to detect hypoadrenalism intra/post operatively and surgical patients who take long term steroids are NBM so cannot take their steroids. How do we prevent an adrenal insufficiency crisis?
- Give IV hydrocortisone four times a day 25mg to cover
- Also discuss with anaesthetist as they will need to provide cover at induction and during anaesthesia
What are the diffierent classifications of surgical site infections and what are the common organisms that cause these?
Occur within 30 days of surgery. See image for types
- Staph Aureus (do MRSA screen)
- Enterococcus species
- E.Coli
How is MRSA risk stratification calculated and what are the treatment options for each risk group?
Resistant to all beta lactams!!
How are MRSA surgical site infections managed?
What are the empirical antibiotics given for post-operative pyrexia coming from the following infection sources:
What are some causes of a post-op fever?
Day 1-2 – respiratory source (often atelectasis)
Day 3-5 – urinary tract source
Day 5-7 – surgical site infection or abscess/collection f
Any day post-operatively – consider infected IV lines or central lines as a source
Others: drug induced reactions (abx or anaesthesia), transfusion reaction, PE, DVT, pyrexia of unknown origin, secondary to prosthesis
Why may a post-operative patient be presenting with shortness of breath and how do you manage this?
- See image for reasons
- Open and maintain airway
- Give high flow oxygen (15L/min)
- Solve underlying problem e.g control pain
What are some clinical signs of sepsis?
- Raised temperature
- Raised resp rate
- Confusion
- Tachycardia
- Hypotension
- Mottled skin
- Hypoxic
- Low urine output
What are the different type of oxygen delivery systems?
Low flow (do not meet inspiratory demand, oxygen dilute with air)
- Nasal cannula
- Simple face mask
High flow
- Venturi mask
- Non-rebreather mask
What are indications for O2 therapy?
OXYGEN TREATS HYPOXAEMIA NOT BREATHLESSNESS
- Sats <94% (or 90%)
- Arterial Po2 < 60 mmHg
- Cardiac and respiratory arrest
- Shock of any cause
- Increased metabolic demands (e.g sepsis, burns)
- Post operative state
- Cardiac failure or MI
- Carbon monoxide poisoning
What are the toxic effects of oxygen therapy?
O2 Toxicity
- PO2 and time of exposure affect amount of toxicity
- CNS and lung effects (patchy infiltrates on x-ray and major alveolar injury)
- Can cause coughing and difficulty breathing
Why may patients become dyspnoeic or hypoxic following surgery and how do you manage them?
Causes: pneumonia, pulmonary collapse, PE, LVF due to fluid overload, pneumothorax, drugs
Mx:
- Sit up and monitor sats
- Assess airway then give oxygen or bag valve mask
- Examine and listen to chest
- Take FBC, ABG, CXR, ECG and manage accordingly
What are some causes of confusion/agitation in a patient following surgery?
Reassure patient in well lit surroundings.
- Anaesthetic may not have warn off yet
- Pain
- Electrolyte imbalances
- Low blood sugar
- Analgesia
- Post op cognitive decline
What are some causes of hypo and hypertension following surgery?
Hypotension: hypovolaemia, haemorraghe, PE, MI, sepsis, anaphylaxis, drugs
Hypertension: pain, urinary retention, inotropic drugs
When asked to give postoperative complications in an exam how should you approach it?
What are the issues with PONV?
- increased anxiety for future surgical procedures
- increased recovery time and hospital stay
- aspiration pneumonia
- incisional hernia or suture dehiscence
- bleeding
- oesophageal rupture
- metabolic alkalosis
What happens in the surgical stress response?
- Increase heart rate and cardiac output so increase bp to get more blood to brain
- Less insulin release
- Cortisol release
What is included in a NEWS chart and how do you interpret the numbers?
- Respiratory rate
- Heart rate
- Oxygen sats
- Systolic blood pressure
- Level of consciousness AVPU
- Temperature
- ?Urine output
- Subjective opinion
If low score increase frequency of observations, if medium urgent call to patient’s primary medical team, if high emergency call to outreach
What is informed consent?
- Doctor must fully advise a patient of their treatment options and the material risks and benefits of each option
- Patient must be given time to consider advice and reflect on their own individual life circumstances
- Patients have the right to not go with the options provided and do not have to give a reason for this
What is classed as a material risk of a treatment option?
How do you present a chest x-ray?
- State who, what type, when taken
- Is film quality adequate (RIP)
- ABC
- Short summary at end
How are the components of donated blood broken down?
Red cells: to increase oxygen carrying capacity and replace blood loss
Platelets: often used prophylactically for patients with thrombocytopenia
FFP: contains clotting factors used for DIC and massive haemorraghe. Not recommended for warfarin reversal
Cryoprecipitate: source of fibrinogen and factor VIII given when low levels of clotting factors
Why is it important to get the correct ABO group during a blood transfusion?
If there is a mismatch can cause intravascular haemolysis (destruction of RBC by complement activation)
Can cause shock, renal failure, DIC
Also, can make patient produce antibodies to all antigens if given the wrong ABO group so issue if need multiple transfusions
How is safety maintained in a blood transfusion?
AT ALL STAGES ON IMAGE DO POSITIVE PATIENT IDENTIFICATION BEFORE TASK
Take patient blood sample at bedside, 3 point identification (Name, DOB, NHS no), handwrite information at bedside!!!
What are some acute transfusion reactions and how do they present?
- Acute haemolytic transfusion reaction: fever, chills, hypotension, tachycardia, haemoglobinuria, due to ABO incompatibility
- Anaphylaxis: urticaria, pruitis, wheezing, hypotension, angiooedema, due to reaction to foreign plasma proteins
- Febrile Non-Haemolytic transfusion reaction: just a temperature rise
- Transfusion related fluid overload
- Bacterial contamination
What are some alternatives to blood transfusions for surgical patients?
- Consider EPO if anaemia and stopping anticoagulant/antiplatelets in pre op assessment
- Oral/IV iron before and after surgery if iron deficiency anaemia
- Tranexamic acid for any expected blood loss >500ml
- Intraoperative cell salvage (filter loss blood and put in saline and give back to patient)
What is blood tested for once it has been donated before it goes to the bank?
- ABO
- Syphilis
- Hep B, E, C
- HIV
- HTLV
- CMV
- Malaria
- T.Cruzi
- West Nile Virus
What information should you give a patient when consenting them for a blood transfusion?
What blood is given in an emergency when there is no time for cross matching?
O-
What are some early and late complications of blood transfusions?
Always a late risk of infection!!!
When do patients need irradiated and CMV negative blood?
Irradiated:
- recieving blood from first or second degree relative, Hodgkin’s lymphoma, previous stem cell transplant, any T cell deficiency
- stops donor white cells replicating and mounting an immune response against a vulnerable patient causing transfusion-associated-graft-versus-host disease (TA-GvHD)
- only PRC and platelets need radiation
CMV Negative
- Neonates up to 28 days, pregnant women, intrauterine transfusion,
- Can cause severe, sometimes fatal, infection in foetuses, neonates and immunocompromised adults
How do you restart DOACs after surgery?
What are the aims of anaesthesia (image) and the stages of it?
Induction:
- Analgesics (fast acting opioid e.g fentanyl)
- Hypnotic (IV propofol)
- Muscle relaxant (suxamethonium)
- Airway management (laryngeal mask supraglottic or ET tube for longer operations)
Maintenance:
- Monitor BP/HR/sats/Temp
- IV infusion or volatile agent (added to N2O mix) with mechanical ventilation
Recovery
- Change inspired gases to 100% oxygen
- Discontinue anaesthesia and reverse muscle relaxant
- Extubate patient
What are the side effects of the following anaesthetic agents?
- Hyoscine, atropine
- Opioids
- Thiopental
- Propofol
- Volatile agents e.g isoflurane
What are some complications of anaesthesia and why do they arise?
- Loss of pain: urinary retention, pressure necrosis, local nerve injuries e.g arm hanging off table
- Consciousness: cannot communicate
- Loss of muscle power: corneal abrasion (tape eyes), no cough reflex so risk of pneumonia and atelectasis, no respiration
What is malignant hyperthermia?
Autosomal dominant disorder where patients react to inhaled anaesthetic (e.g suxamethonium, halothine)
Reaction opens Ca channels leading to loop circuits in muscles leading to increased temperature (1 degree every 30 mins) and hyperthermia
Masseter reflex is early sign
Hypoxaemia, hypercapnia, hyperkalaemia, metabolic acidosis (increased lactate) and arrthymias
