General surgery

Anatole V Wiik

Outline

Station 8.1: Venous thromboembolism (VTE) prophylaxis

Station 8.4: Diabetes in the surgical patient

Station 8.1: Venous thromboembolism (VTE) prophylaxis

You are the surgical junior doctor. A 23-year-old woman (Nicole Smith 05/03/91) is brought to the emergency department with periumbilical pain that has radiated to the right iliac fossa. She also has fever. She is on the oral contraceptive pill and previously her mother had a DVT. Your registrar has reviewed the patient and has decided that this patient requires an appendicectomy tomorrow. She has normal renal function, raised CRP and raised white cell count. The registrar wants you to start regular pain killers (paracetamol and codeine), IV fluids, and IV antibiotics (cefuroxime and metronidazole). Please also perform a VTE prophylaxis assessment and prescribe the appropriate treatment.

Patient Details

Name:	Nicole Smith
DOB:	05/03/91
Hospital Number:	1208973948
Weight:	60 kg
Height:	1.6 m
Consultant:	Mr King
Hospital/Ward:	WGH Ward 3
Current Medications:	Oral contraceptive pill only
Allergies:	No known drug allergies
Admission date:	22/09/14

Stop all antiplatelets prior to procedures/operations to prevent bleeding, ideally 10 days (t_½ of platelets).

Warfarin should be stopped and covered with LMWH. If INR is significantly raised, consider reversal with Vitamin K, and take advice from haematology. Recommence all as soon as bleeding risk is minimal (which will vary depending on the procedure).

Thromboprophylaxis

All patients admitted to hospital require a VTE prophylaxis assessment.

General measures to reduce VTE risk

1. Keep patient well hydrated

2. Encourage early mobilization

3. Aspirin or clopidogrel is not adequate VTE prophylaxis

4. Consider caval filter if prophylaxis is contraindicated (CI)

5. Utilize regional rather than general anaesthesia

VTE prophalaxis (pharmacological or mechanical) does not need to be routinely offered to all surgical patients. For example, it is not indicated in a patient undergoing a surgical procedure with local anaesthesia by local infiltration with no limitation of mobility.

However, most surgical patients at increased risk of VTE (by the above criteria) should receive mechanical VTE prophylaxis as well as pharmacological (unless contraindicated).

Pharmacological thromboprophalaxis

Risk of bleeding on VTE prophylaxis

Potential contraindications to pharmacological VTE prophylaxis:

1. Active bleeding

2. On anticoagulants INR>2

3. Significant procedure-related bleeding risk

4. Acute stroke: haemorrhagic or large infarct

5. Untreated inherited or acquired bleeding disorders (e.g. haemophilia, Von Willebrand disease)

6. Severe/acute liver disease

7. Platelets<75×10⁹/L or abnormal clotting screen

8. BP>230 mmHg systolic or>120 mmHg diastolic

9. Lumbar puncture/epidural/spinal anaesthesia in previous 4 hours or within next 12 hours

10. Heparin-induced thrombocytopenia.

Offer to patient and/or families information on:

1. Risks and possible consequence of VTE

2. Importance of VTE prophylaxis and its possible side effects

3. The correct use of VTE prophylaxis

4. How patients themselves can reduce their risk of VTE.

In those whom thromboprophylaxis is felt not indicated, this should be reassessed on a daily basis while in hospital.

Prescribing pharmacological thromboprophylaxis

The option depends on renal function.

If normal renal function, prescribe subcutaneous LMWH/factor Xa inhibitor (e.g. enoxaparin, or dalteparin, or fondaparinux).

Several possible variants occur in reduced renal function, so consult your local hospital formulary. Both the definition of reduced renal function, and the management will vary from trust to trust.

Two example protocols:

Definition of reduced renal function: eGFR<30 mL/min

Action in reduced renal function: prescribe subcutaneous unfractionated heparin instead of LMWH

Definition of reduced renal function: eGFR<20 mL/min

Action in reduced renal function: a standard dose of dalteparin can be prescribed, but antifactor Xa levels need to be monitored. The peak level is measured 4 hours post-dose, and trough level immediately pre-dose. This should be done every 4–5 days while on LMWH. Peaks>0.6 and troughs>0.3 anti-Xa units/mL indicate a need for dose reduction.

Nicole’s Risk Factors and Bleeding Risk

1. Nicole is a surgical patient

2. She is an acute admission with an inflammatory/infective/intra-abdominal condition

3. She currently is using the OCP, which promotes a prothrombotic state

4. She has a family history of DVTs, which gives her a theoretical risk of thrombosis

5. She potentially could be a critical care admission if she becomes septic

6. If she has a complicated appendicectomy and her procedure could potentially take longer than 90 minutes.

Nicole has no bleeding risk factors. Therefore, in addition to mechanical VTE prophylaxis, heparin prophylaxis is required as her VTE risk is high.

Figure 8.1

Figure 8.2

Note that the patient will need to be fasted preoperatively. Policy for this will vary between units. Once a time for surgery is settled, the patient, for instance, would not be allowed water or oral medications for 4 hours preoperatively. Therefore, oral medications would not be allowed in this time window.

Station 8.2: Acute pancreatitis

You are the surgical junior doctor in the emergency department. A 42-year-old obese female with a background of gallstones presents with severe epigastric pain radiating to the back. She has vomited on multiple occasions and feels that she is becoming more breathless. Please assess her and commence appropriate management.

Patient Details

Name:	Jane Smith
DOB:	05/03/72
Hospital Number:	J345789
Weight:	85 kg
Height:	1.6 m
Consultant:	Mr King
Hospital/Ward:	BFH Surgical
Current Medications:	None
Allergies:	No known drug allergies
Admission date:	22/09/14

Complications of pancreatitis

Early: shock, acute respiratory distress syndrome (ARDS), SIRS, hypocalcaemia, renal failure, hyperglycaemia, retroperitoneal haemorrhage

Late: pseudocyst formation, pancreatic abscess formation, necrotizing pancreatitis, recurrent pancreatitis, pancreatic cancer

Initial Assessment

Airway

Assess the patency of her airway. Does she have any vomitus obstructing her airway?

‘The airway is secure and patent, as she is responding to questions.’

Continue to monitor the airway, but no intervention currently required.

Breathing

Assess the rate and depth of respiration. Is she using her accessory muscles for respiration? Check oxygen saturations. Auscultate her chest: does she have any degree of lung impairment, crackles or wheeze?

‘RR 28/min, oxygen saturations are 92% pre-oxygen therapy. She is using her accessory muscles of respiration. She has reduced air entry and crackles are heard throughout both lung fields bilaterally with some wheeze. She is complaining that she cannot catch her breath.’

This lady is tachypnoeic and unable to maintain normal saturations. She requires high- flow oxygen on a non-rebreather mask, and optimization of pain control. Could consider NSAIDs or other opiates such as pethidine or tramadol, but trial morphine if pain is severe: a PCA may be required to control the pain.

Circulation

Assess her CRT, pulse and blood pressure. Check her mucous membranes and assess her hydration status by looking at her tongue and skin turgor

‘HR 115 bpm, BP 90/60 mmHg, and CRT 3 seconds peripherally. Her hands are moist and cool with a thready pulse. Her mucous membranes are dry. Her eyes appear sunken. Her heart sounds are normal with no murmurs.’

This lady is intravascularly depleted. She needs aggressive fluid resuscitation. Two large bore IV cannulae (14 or 16 G) should be inserted (while simultaneously taking bloods) and a fluid challenge should be given (e.g. over 15 minutes). A urinary catheter should be inserted to assess end-organ perfusion.

Exposure

Examine the abdomen as this is the source of the pain. Does she have any bruising around the flanks or periumbilical region? Does she have any tenderness on palpation? Are there any signs of peritonism, such as rebound, guarding or percussion-induced pain? Assess for flank tenderness. Measure temperature

‘This lady does not have any ecchymosis in the flank (Grey–Turner’s sign) or periumbilical (Cullen’s sign) area. Her abdomen is soft, but extremely tender throughout, mainly around the epigastric region. There is voluntary guarding, but no abdominal distension, or percussion tenderness. Her bowel sounds are present and her temperature is 37.5°C.’

Initial Investigations

Arterial blood gas: A metabolic acidosis is characterized by a low pH and bicarbonate with an increasingly negative base excess and elevated lactate. She may be compensating her pH by hyperventilating; a low CO₂ would confirm this

Baseline bloods: FBC, U&E, CRP, LFT, amylase, LDH, calcium, coagulation profile and blood sugar. A raised amylase, 3 times its upper limit, is highly sensitive for acute pancreatitis. Assess her LFTs, raised ALP and bilirubin may be due to a stone in her common bile duct, and this could be causing pancreatitis. A CRP is a good surrogate to assess inflammation, the greater the more aggressive the inflammatory process. A raised WCC count may indicate infection (sometimes upper abdominal pain can be caused by a lower lobe pneumonia, or abdominal sepsis) but may be raised purely due to pancreatitis. A dropping Hb may be a sign of retroperitoneal haemorrhage. Additional bloods listed are used for severity scoring

Imaging: A CXR is extremely important to assess any element of ARDS. Diffuse bilateral pulmonary infiltrates are indicative of severe pancreatitis and that respiratory support may be pending. No free air under the diaphragm reduces the likelihood of perforation. An ultrasound is important; this will determine the aetiology and severity of the pancreatitis, 40% of pancreatitis is due to gallstones. The presence of stones and a dilated CBD is a good indicator of its origin. A non-dilated CBD does not exclude gallstones as the cause of pancreatitis

Table 8.1

Miss Smith’s blood results, and ABG result

Parameter	Value	Normal range (Units)
WCC	18×10⁹/L	4–11 (×10⁹/L)
Neutrophil	12×10⁹/L	2–7.5 (×10⁹/L)
Lymphocyte	4×10⁹/L	1.4–4 (×10⁹/L)
Platelet	300×10⁹/L	150–400 (×10⁹/L)
Haemoglobin	135 g/L	Men: 135–177 (g/L)Women: 115–155 (g/L)
PT	12 seconds	11.5–13.5 seconds
APTT	30 seconds	26–37 seconds
CRP	250 mg/L	0–5 (mg/L)
Urea	16.5 mmol/L	2.5–6.7 (mmol/L)
Creatinine	175 μmol/L	79–118 (μmol/L)
Sodium	138 mmol/L	135–146 (mmol/L)
Potassium	4 mmol/L	3.5–5.0 (mmol/L)
eGFR	36 mL/min	>60 (mL/min)
Bilirubin	50 μmol/L	<17 (μmol/L)
ALT	45 IU/L	<40 (IU/L)
ALP	200 IU/L	39–117 (IU/L)
Amylase	477 IU/L	25–125 (IU/L)
LDH	460 IU/L	240–480 (IU/L)
Glucose	5.6 mmol/L	4.5–5.6 (mmol/L) (fasting)
Calcium (corrected)	2.20 mmol/L	2.20–2.67 (mmol/L)
Albumin	40 g/L	35–50 (g/L)
Lactate	3 mmol/L	0.6–2.4 (mmol/L)
pH	7.32	7.35–7.45
PaCO₂	4 kPa	4.8–6.1 (kPa)
HCO₃	18 mmol/L	22–26 (mmol/L)
PaO₂	10 kPa	10.6–13.3 (kPa) on air
BE	−4 mmol/L	±2 (mmol/L)

‘ABG shows a pH of 7.32, PaCO₂4 kPa, PaO₂10 kPa, HCO₃18 mmol/L, lactate 3 mmol/L and BE is−4 mmol/L. Hb 135 g/L, CRP 250 mg/L, WCC 18×10⁹/L, amylase 477 IU/L, bilirubin 50 µmol/L, ALT 45 IU/L, ALP 200 IU/L, potassium 4 mmol/L, sodium 138 mmol/L, creatinine 175 µmol/L and urea 16.5 mmol/L (eGFR 36 mL/min). Initial Imrie score is 2 (WCC and urea). CXR shows mild bilateral pulmonary infiltrates, no free air under the diaphragm. USS shows multiple gallstones with a CBD diameter of 12 mm. The pancreas is markedly inflamed, but no obvious collections.’