Vascular Problems (Clinical Problems) (Ramchandra & M Dawes)

Question 1

A 65 year-old woman experiences pain in her left leg during an economy-class _flight from London t_o Auckland. The pain continues and she sees her general practitioner immediately on arrival.

Her l_eg is swollen,_ red and feels hot, and her GP suspects deep vein thrombosis (DVT).

Ultrasound imaging identifies a blood clot in the junction of her left iliac and femoral veins (DVT) (D-dimer blood test can be done but US is definitive diagnosis)

She indicates that there is a family history on her father’s side of venous thrombosis

What are the likely causes of DVT?

Answer 1

1) Virchow’s triad?

• S_tasis,_ endothelium, blood constituents
• Stasis due to long haul flight and ?obese

2) Personal/family history (first degree relatives) of VTE?

• Lupus anticoagulant, antiphospholipid antibodies, protein C & S, antithrombim III, factor V Leiden
• Previous DVT (if you had it once, you’re more likely to have it again)

3) Tumour history?
* Tumour induced DVT need Heparin instead of Wafarin.
4) Drugs?

• In young women, COCP increases risk
• In older women, hormone replacement therapy increases risk

5) Pregnancy? (often a sign of clotting disorders if there’s intrauterine growth retardation or spontaneous miscarriages)

Question 2

Why is the Leg Swollen in the case of DVT?

Answer 2

Occluded deep limb veins -> impaired venous return -> increased venous hydrostatic pressure -> drives fluid out of capillaries into subcutaneous tissue -> swollen legs

Question 3

Why is the Leg Red and Hot in the case of DVT?

Answer 3

Venous clot is a dynamic process:

• Increased temperature (especially large clots put metabolic stress)
• Inflammation process
• WBC activation
• Cytokine release

Question 4

What are the Treatment Options for DVT?

Answer 4

Pain Relief (Analgesia)

• Paracetamol
• Elevate leg

Anticoagulation

This is different to thrombolysis (thrombolysis is contraindicated)!

• Enoxaparin (1mg/kg bd, subcutaneous) (home/inpatient) (LMWH)
  
  • Immediate anticoagulant affect (stabilises thrombus, prevents its propagation).
  • Do not thrombolyse clot (body’s own proteases do that)
• Warfarin
  
  • Maintain INR 2-3 (must do INR checks regularly)
  • Duration 3-6 months (if first event) (takes a few days for vitamin K dependent factor II, VII, IX, X to break down)
  • Reverse by vitamin K or prothrombinex
  • Careful of Drug interactions (CP450 metabolism)
• Dabigatran (an alternative to warfarin?) (bd)
  
  • Do not need monitoring
  • Reverse with idarucizumab
  • Renal excretion, therefore do not use with eGFR <30
  • Side effect of indigestion due to tartaric acid in capsule (enhance absorption)
  • Thrombin inhibitor
  • Renally excreted- so need to be careful in people with renal impairment.

Course normally s_tarts with enoxaparin_ for its instantaneous effect, then _add warfarin/dabigatran as it takes a few days to kick i_n, then stop enoxaparin when warfarin kicks in.

This is l_ifelong treatment if second VTE event occurs._

Question 5

Describe PE Treatment

Answer 5

PE Treatment (Similar To DVT)

• Drug treatment of LMWH and warfarin (longer duration for 6 months if first event).
  
  • Be aware of interactions (monitor INR)!
• If severe PE, use thrombolysis but have significant side effects, or use surgery to remove thrombus.

Question 6

76 year old man with atrial fibrillation. Had stroke 5 years ago, which made good recovery. Rate 110bpm. BP 190/100mmHg.

WHat are the treatment issues we need to address?

Answer 6

• Hypertension (BP control)
• Lipid control
• Atrial fibrillation (very strong risk factor for systemic embolization)
  
  • Rate control (target ~80bpm) with beta blocker +/- diltiazem
    
    • Atrial fibrillation predisposes people to tachycardia
    • Also at risk of embolism
• Anticoagulation (aspirin vs warfarin vs other anticoagulants)

Question 7

What are the symtpos of PE?

Answer 7

• Common signs and symptoms include:
  
  • Shortness of breath. This symptom typically appears suddenly and always gets worse with exertion.
  • Chest pain. You may feel like you’re having a heart attack. The pain may become worse when you breathe deeply (pleurisy), cough, eat, bend or stoop. The pain will get worse with exertion but won’t go away when you rest.
  • Cough. The cough may produce bloody or blood-streaked sputum.
• Other signs and symptoms that can occur with pulmonary embolism include:
  
  • Leg pain or swelling, or both, usually in the calf
  • Clammy or discolored skin (cyanosis)
  • Fever
  • Excessive sweating
  • Rapid or irregular heartbeat
  • Lightheadedness or dizziness

Question 8

How would you treat this patient?

76 year old man with atrial fibrillation. Had stroke 5 years ago, which made good recovery. Rate 110bpm. BP 190/100mmHg.

Answer 8

1) Rate control

• Betal Blocker
• +/- diltizaen

2) BP control
3) Lipid control
4) Anticoagulation

• Aspirin vs wafarain
• (Depending on AF + Chads-Vas score)

Question 9

How do you determine if someone with Atrial Fibrillation should be prescribed Wafarin?

Answer 9

CHADS-VAS score = Important scoring system for AF

• Congestive cardiac failure 1
• Hypertension 1
• Age (>75) 2
• Diabetes 1
• Stroke 2
• Vascular disease 1
• Age (>65) 1
• Sex (female) 1

If score is 2 or above, prescribe Wafarin

CHADS-VAS Score and Stroke Risk (%/Year)

Learn these scores!!! These are useful when making decisions about putting AF patients on long-term anti-coagulation.

As CHADS-VAS score increased, stroke risk increased.

If score is ≥2, high risk of thromboembolism, give warfarin!

Question 10

How do you determine someone’s Bleeding Risk for AF patients- (when considering prescribing anticoagulants)?

Answer 10

HASBLED Score

Bleeding risk for AF patients on anticoagulation is calculated by HASBLED score (each risk factors worth 1 point).

• Hypertension
• Abnormal blood results (creatinine/LFTs)
• Stroke
• Bleeding
• Labile INR (unstable/high)
• Elderly (>65)
• Drug use (alcohol/recreational drugs)

As _HASBLED score is hig_h, bleeding risk increases.

If score is ≥3, don’t give anticoagulant!

Question 11

What is the timeframe for administrating Anticoagulants?

Answer 11

Anticoagulation Time Frame

In DVT/PE, initiating anticoagulation is urgent

• Usually initially as inpatient commencing with LMWH (enoxaparin)

In AF, Initiating anticoagulation is not so time sensitive

• Usually as outpatient
• No LMWH needed
• Warfarin vs. dabigatran

Question 12

What is Criteria for Diabetes?

Answer 12

Diabetes diagnosis include:

• Symptomatic
  
  • Random plasma glucose >11.1
  • Fasting plasma glucose >7.0 (N<5.6)
  • HbA1c ³ 48mmol/mol
• Asymptomatic
  
  • 2 abnormal blood tests

Question 13

What Is The Cause Of The Intermittent Calf Pain Experienced When Walking? Why Is It Relieved With Rest?

Answer 13

This is intermittent claudication (condition in which cramping pain in the leg is induced by exercise, typically caused by obstruction of the arteries), which is caused by:

• Obstruction ® decreased blood flow ® ischemic muscles ® build-up of lactate/acylcarnitines/inflammation (anaerobic mechanism)
• Collateral development (long term)
• Pre-conditioning (if you give tissue an ischemic insult, this allows muscle to work for longer next time before the next ischaemic insult, e.g. walk ® rest ® walk again, second time you can walk further)

Question 14

Explain Loss Of Feeling In Patient’s Feet And Tingling And Burning Sensations In Hands And Feet At Night.

Answer 14

Loss of feeling and tingling/burning is due to diabetic neuropathy (of sensory nerves)

• Chronic neuropathy
• Acute peripheral neuritis
• Ischemia of nerves

These causes glove and stocking numbness.

Question 15

Explain Why Patient Feels Faint When He Stands Up Suddenly And Why He Is Sweaty After Eating A Meal.

Answer 15

Autonomic neuropathy (neuropathy of the autonomic nerves) results in:

• Impact on SNS response ® BP not maintained when standing up ® postural hypotension ® feeling of faintness
• Damaged ANS nerve ® miscommunication of autonomic nerves with GI system and brain ® bizarre sweating

Question 16

Explain The Dry And Cracked Appearance Of The Patient’s Hands And Feet. How Does This Add To Risks Associated With LEAD?

Answer 16

Poor blood flow (ischemia) ® reduced skin metabolism ® reduced skin growth

• ® hairless skin (not enough circulation to provide hair metabolism ® dry skin)
• ® reduced skin growth ® increased risk of infection
• ® reduced peripheral sensation ® increased risk of infection

Question 17

What Advise Would You Give To The Patient? Speculate On Possible Treatment Options.

Answer 17

• Good glycaemic control
• Vascular risk factor control
  
  • Stop smoking
  • Other vascular sites
  • Aspirin
  • BP and cholesterol management
  • Exercise/diet/weight
• Angioplasty/surgery

Question 18

84 year old woman living in a rest home progressively becomes more pale and listless (lack energy). She complains of feeling faint and of a roaring sound in her ears. There is evidence of _blood in her stoo_l and her pulse is rapid, but full.

She is seen by GP. B_P 130/50mmHg_. HR 130bpm. Systolic murmur.

Low haemoglobin (45g/L (115-165)) upon blood test. Haematocrit is also reduced. She is admitted to hospital with suspected intestinal bleeding

Why Is Patient’s Hb Reduced And What Does This Suggest About The Extent And Time-Course Of Her Blood Loss?

Is it Chronic or Acute? How can you confirm this?

Answer 18

Patient’s haemoglobin is reduced due to chronic GI bleeding

• This indicates chronic bleeding, since fluid translocation with compensated increased volume would result in decreased Hb. (note that acute bleeding decreases blood volume, but not reducing haematocrit)
• History also suggests chronic history (progressively become more pale and listless)

This can be investigated through iron studies:

• In acute blood loss, iron would be normal
• In chronic blood loss, iron would be low

In addition, blood film can be used to investigate MCV:

• If chronic anaemia (weeks/months), there is reduced MCV (microcytic)
• If acute anaemia, there is normal MCV

Question 19

84 year old woman living in a rest home progressively becomes more pale and listless (lack energy). She complains of feeling faint and of a roaring sound in her ears. There is evidence of blood in her stool and her pulse is rapid, but full.

She is seen by GP. BP 130/50mmHg. HR 130bpm. Systolic murmur.

Low haemoglobin (45g/L (115-165)) upon blood test. She is admitted to hospital with suspected intestinal bleeding

Do You Think That The Patient’s (1) Cardiac Output And (2) Total Peripheral Resistance Are Higher Or Lower Than Normal? What Evidence Supports This View?

Answer 19

Our system would try and maintain the same amount of oxygen delivery to tissues (maintain V_O2)

1. Hb reduced - COincreased - Q increased (maintain perfusion -> maintain V_O2), also SNS increased - HRincreased- CO increased
2. Hb reduced and hypoxia - metabolic vasodilation - TPRreduced -Qincreased (increase perfusion to vital organs)

Even though SNS increased to heart (increase CO), SNS increased to peripheral vascular beds, metabolic vasodilation override SNS effect

Question 20

Describe the equation of Change in volume (O2) and Cardiact output

Answer 20

V(dot) O2 = Cardiac output x 1/33 x Hb x (SaO2-SVO2)

Question 21

84 year old woman living in a rest home progressively becomes more pale and listless (lack energy). She complains of feeling faint and of a roaring sound in her ears. There is evidence of blood in her stool and her pulse is rapid, but full.

She is seen by GP. BP 130/50mmHg. HR 130bpm. Systolic murmur.

Low haemoglobin (45g/L (115-165)) upon blood test. She is admitted to hospital with suspected intestinal bleeding

Explain the Murmer

Answer 21

Explain The Murmurs (Reynolds Number)

_Normal laminar flow i_s more likely to become turbulent (Re >2400), resulting in systolic murmurs. This is due to:

• Increased fluid velocity (V)
• Possibly increased vessel diameter (D) due to heart chamber dilatation
• Decrease in viscosity (u) due to Hb decrease

Question 22

84 year old woman living in a rest home progressively becomes more pale and listless (lack energy). She complains of feeling faint and of a roaring sound in her ears. There is evidence of blood in her stool and her pulse is rapid, but full.

She is seen by GP. BP 130/50mmHg. HR 130bpm. Systolic murmur.

Low haemoglobin (45g/L (115-165)) upon blood test. She is admitted to hospital with suspected intestinal bleeding

Why Is She Pale, Listless (Lacking Energy) And Cold?

Answer 22

This is due to reduced flow to peripheral arteries (maintain perfusion to vital organs!)

Question 23

84 year old woman living in a rest home progressively becomes more pale and listless (lack energy). She complains of feeling faint and of a roaring sound in her ears. There is evidence of blood in her stool and her pulse is rapid, but full.

She is seen by GP. BP 130/50mmHg. HR 130bpm. Systolic murmur.

Low haemoglobin (45g/L (115-165)) upon blood test. She is admitted to hospital with suspected intestinal bleeding

Speculate On The Appropriate Treatment For This Patient.

Answer 23

1. Blood transfusion until Hb increases to 90-100
2. Intravenous iron transfusion (due to iron deficiency anaemia), tolerant better than oral iron tablets (very unpleasant)

Question 24

A young man experiences a compound fracture of the forearm

His bones are set, a rigid cast is placed on his arm and he is held in Accident and Emergency for further observation

More than an hour after treatment, the patient complains of discomfort and loss of feeling in his fingers

There is a palpable radial pulse, but his fingers are pale and cold

Explain Why The Patient’s Fingers Are Pale And Cold

Answer 24

There is reduced blood flow due to build-up of internal tissue pressure (possibly caused by internal bleeding).

rigid fascia + blood leakage -> increase in interstitial tissue pressure -> compress precapillary vessels -> r_educed blood flow_

Compartment syndrome is muscle groups and their blood vessels are compressed due to their surrounding of stiff deep fascia (cannot expand). Examination for compartment syndrome involves 5 P’s:

• Pallor (skin colour)
• Paraesthesia (sensation)
• Pulse deficit
• Paralysis
• Pain (on passive extension of the compartment) and perishing cold (poikilothermia)

Question 25

What are the symptoms of compartment Syndrome?

Answer 25

. Examination for compartment syndrome involves 5 P's: * Pallor (skin colour) * Paraesthesia (sensation) * Pulse deficit * Paralysis * Pain (on passive extension of the compartment) and perishing cold (poikilothermia)

Question 26

A young man experiences a compound fracture of the forearm His bones are set, a rigid cast is placed on his arm and he is held in Accident and Emergency for further observation More than an hour after treatment, the patient complains of discomfort and loss of feeling in his fingers There is a palpable radial pulse, but his fingers are pale and cold ***Why Does The Patient Have A Radial Pulse?***

Answer 26

Because _systolic pressure_ is still e_nough to overcome the tissue pressure._ * This is likely to suggest that the _damage is venou_s rather than arterial * If it is arterial damage, pressure within would be much weaker, thus less likely to overcome tissue pressure so no pulse

Question 27

A young man experiences a compound fracture of the forearm His bones are set, a rigid cast is placed on his arm and he is held in Accident and Emergency for further observation More than an hour after treatment, the patient complains of discomfort and loss of feeling in his fingers There is a palpable radial pulse, but his fingers are pale and cold ***Explain The Loss Of Feeling In The Patient's Fingers***

Answer 27

There is _compression_ and _ischemia_ of _nerves_, therefore afferent sensation cannot communicate and travel along nerves.

Question 28

A young man experiences a compound fracture of the forearm His bones are set, a rigid cast is placed on his arm and he is held in Accident and Emergency for further observation More than an hour after treatment, the patient complains of discomfort and loss of feeling in his fingers There is a palpable radial pulse, but his fingers are pale and cold What would you do in this case?

Answer 28

Take the cast off and get rid of clot via surgery.

Question 29

A 62 year old man presents with a three day history of progressive dyspnoea, a non-productive cough and low grade fever. His BP is 95/55mmHg, HR 110bpm, temperature 37.9C, O2 saturation breathing on ambient air is 86% Chest auscultation reveals rales and rhonchi bilaterally CXR shows bilateral pulmonary infiltrates consistent with pulmonary oedema, but little enlargement of the cardiac silhouette What are the possible causes of Acute Pulmonary Oedema?

Answer 29

1. Cardiogenic pulmonary oedema (e.g. **acute left heart failure**) * Impaired pump function * build-up of LV pressure * back flow into LA * flow into pulmonary circulation * _increased capillary hydrostatic pressure (Pc)_ * increased fluid filtration * fluid into alveoli * oedema 1. Non-cardiogenic pulmonary oedema (e.g. **pneumonia**) * Normal hydrostatic pressure * Alveolar infiltrate of inflammatory mediators * build-up of protein-rich interstitial fluid * _Increased colloid osmotic pressure of interstitial fluid (__Õ___if__)_ * increased fluid filtration * fluid into alveoli * oedema

Question 30

Compare the cardiogenic vs noncardiogenic pulmonary oedema

Answer 30

**_Cardiogenic pulmonary oedema (e.g. acute left heart failure)_** * Impaired pump function * build-up of LV pressure * back flow into LA * flow into pulmonary circulation * increased capillary hydrostatic pressure (Pc) * increased fluid filtration * fluid into alveoli * oedema **_Non-cardiogenic pulmonary oedema (e.g. pneumonia)_** * Normal hydrostatic pressure * Alveolar infiltrate of inflammatory mediators * build-up of protein-rich interstitial fluid * Increased colloid osmotic pressure of interstitial fluid (Õif) * increased fluid filtration * fluid into alveoli * oedema

Question 31

How can you establish the cause (cardiogenic vs pulmonary odema)?

Answer 31

***Symptoms*** * Shortness of breath is present in a cardiac and pulmonary cause (hard to know if cardiogenic or non-cardiogenic). * _Cough with sputum is present in pneumonia_ (non-cardiogenic). * If _no sputum,_ it could be either causes. ***History*** * _Previous history of heart failure_ indicate cardiogenic cause. ***Investigations*** * Aspirate of _oedema fluid to get protein coun_t (increased in non-cardiogenic). * Chest X-ray to see enlarged LV (cardiogenic) or lung consolidation (non-cardiogenic) * _Blood test of increased BNP_ shows impaired cardiac function * _BNP_ \>500pg/ml shows damaged heart. * BNP 100-500pg/ml is hard to differentiate (severe case of pneumonia impair cardiac function)

Question 32

What is BNP?

Answer 32

Brain natriuretic peptide (BNP) test is a blood test that measures _levels of a protein called BPN that is made by your heart_ and _blood vessels._ _BNP levels are higher_ than normal when you have _heart failure._

Question 33

A 62 year old man presents with a three day history of progressive dyspnoea, a non-productive cough and low grade fever. His BP is 95/55mmHg, HR 110bpm, temperature 37.9C, O2 saturation breathing on ambient air is 86% Chest auscultation reveals rales and rhonchi bilaterally CXR shows bilateral pulmonary infiltrates consistent with pulmonary oedema, but little enlargement of the cardiac silhouette **_Speculate on the appropriate treatment for this patient_**

Answer 33

First management is _oxygen supplementation_ (but evidence shows that at some point elevated _O2 levels might cause coronary constriction,_ so guidelines might change in the future) If **cardiogenic**, then treat the _cause._ If **non-cardiogenic**, then _treat the infection._

Question 34

* An ambulance is called to a 24 year old psychiatric outpatient found in his flat sometime after attempting suicide by slashing his wrists. The ambulance team immediately stops the bleeding. However, the patient appears to have lost a great deal of blood and is pale, restless and sweaty. * His BP is 90/70mmHg and HR 120bpm, haematocrit 34% * A venous catheter is introduced and advanced into superior vena cava. A saline drip is initially administered and, on completion of blood matching, the patient is given a transfusion of 2000mL of whole blood. * His colour returns, his HR slows to 85bpm and BP increases to 120/75mmHg, while his central venous pressure rises to 6cmH2O * However, his BP falls to 100/70 within half an hour. His central venous pressure is now 2cmH2O and his HR 105bpm ***Explain Initial Reduction In Patient's Pulse Pressure And MAP, And His Elevated Heart Rate. Why Is He Pale And Sweaty?***

Answer 34

* _Decreased PP_ and MAP is due to _decreased blood volume_ * _Increased HR_ is to _maintain cardiac output_ (in response to decreased baroreceptor and cardiopulmonary receptor activation) * _Pale_ is due to _increased SNS_ -\> redistribution of blood flow -\> lack of perfusion * _Sweating_ is due to _increased SNS_ -\> sweat glands and receptors ## Footnote *Note that as blood is lost, SNS initially increases, but _SNS later begins to drop._*

Question 35

* An ambulance is called to a 24 year old psychiatric outpatient found in his flat sometime after attempting suicide by slashing his wrists. The ambulance team immediately stops the bleeding. However, the patient appears to have lost a great deal of blood and is pale, restless and sweaty. * His BP is 90/70mmHg and HR 120bpm, haematocrit 34% * A venous catheter is introduced and advanced into superior vena cava. A saline drip is initially administered and, on completion of blood matching, the patient is given a transfusion of 2000mL of whole blood. * His colour returns, his HR slows to 85bpm and BP increases to 120/75mmHg, while his central venous pressure rises to 6cmH2O * However, his BP falls to 100/70 within half an hour. His central venous pressure is now 2cmH2O and his HR 105bpm ***Why Is The Patient's Haematocrit Reduced And How Could This Information Be Used To Provide Information On The Extent Of His Blood Loss?***

Answer 35

* Dilution of blood via _IV saline_ drip prior to blood transfusion * Physiological response to decreased BP by r_etaining fluid to maintain blood volume_ * Blood loss (both RBCs and fluid loss) -\> decreased blood volume -\> decreased BP -\> respond by increase precapillary resistance -\>increasing fluid filtration from interstitial fluid to plasma -\> increased fluid with decreased RBCs -\>decreased HCT * _Low haematocrit suggests that blood loss had been ongoing for at least a couple of hours_

Question 36

* An ambulance is called to a 24 year old psychiatric outpatient found in his flat sometime after attempting suicide by slashing his wrists. The ambulance team immediately stops the bleeding. However, the patient appears to have lost a great deal of blood and is pale, restless and sweaty. * His BP is 90/70mmHg and HR 120bpm, haematocrit 34% * A venous catheter is introduced and advanced into superior vena cava. A saline drip is initially administered and, on completion of blood matching, the patient is given a transfusion of 2000mL of whole blood. * His colour returns, his HR slows to 85bpm and BP increases to 120/75mmHg, while his central venous pressure rises to 6cmH2O * However, his BP falls to 100/70 within half an hour. His central venous pressure is now 2cmH2O and his HR 105bpm * ## Footnote **Explain The Patient's Status Immediately After Transfusion**

Answer 36

Transfusion restores blood volume and HCT (O2 carrying capacity), so everything went back to normal

Question 37

* An ambulance is called to a 24 year old psychiatric outpatient found in his flat sometime after attempting suicide by slashing his wrists. The ambulance team immediately stops the bleeding. However, the patient appears to have lost a great deal of blood and is pale, restless and sweaty. * His BP is 90/70mmHg and HR 120bpm, haematocrit 34% * A venous catheter is introduced and advanced into superior vena cava. A saline drip is initially administered and, on completion of blood matching, the patient is given a transfusion of 2000mL of whole blood. * His colour returns, his HR slows to 85bpm and BP increases to 120/75mmHg, while his central venous pressure rises to 6cmH2O * However, his BP falls to 1_00/70 within half an hour_. His central venous pressure is now 2cmH2O and his HR 105bpm ***Explain Why Patient Is Unable To Maintain Blood Pressure In Medium Term, Despite Replacement Of Blood He Had Lost***

Answer 37

The patient is going into **_Circulatory Shock_** The patient went into circulatory shock due to _sustained ischemia._ While many organs have capacity to accommodate perfusion debt, _sustained ischaemia_ can cause _changes in__microcirculation that are not easily reversed_ and are categorized as circulatory shock * Features of process are _loss of vascular tone_ due to: * _Inadequate perfusion of blood vessel_ walls via vasa vasorum (spasm so would not open) * _Impaired adrenergic neurotransmission_ due to depletion of noradrenaline in nerve terminals (prolonged SNS activation) * _Perivascular accumulation of vasodilator metabolites_ and local release of histamine, serotonin, kinins and prostaglandin * Local accumulation of autocoids, cytokines and toxins -\> compromise capillary integrity -\> _increased capillary permeability_ -\> leakage of plasma proteins into interstitial space, and transfer of fluid from vascular space to interstitial compartment * Capacity to maintain smooth muscle activity in precapillary vessels diminished, but _post-capillary vessel tone maintained_. As a result, _capillary hydrostatic pressures rise_ (relative to very low levels seen initially as a result of blood loss) -\> transfer of fluid from vascular space to interstitial compartment * With reduced blood flow, shear rates in venous circuit are reduced. This may result in _stasis and clogging of microcirculation_. These effects lead to net transfer of fluid from the vascular space to the interstitial compartment, hence failure to maintain blood volume despite replacement of initial blood volume deficit, _resulting in failure to maintain BP._

Question 38

* An ambulance is called to a 24 year old psychiatric outpatient found in his flat sometime after attempting suicide by slashing his wrists. The ambulance team immediately stops the bleeding. However, the patient appears to have lost a great deal of blood and is pale, restless and sweaty. * His BP is 90/70mmHg and HR 120bpm, haematocrit 34% * A venous catheter is introduced and advanced into superior vena cava. A saline drip is initially administered and, on completion of blood matching, the patient is given a transfusion of 2000mL of whole blood. * His colour returns, his HR slows to 85bpm and BP increases to 120/75mmHg, while his central venous pressure rises to 6cmH2O * However, his BP falls to 100/70 within half an hour. His central venous pressure is now 2cmH2O and his HR 105bpm What Would You Do In This Case?

Answer 38

What Would You Do In This Case? (\*Probably Won’t Ask About Chronic Anaemia In Exam) * Salvage * Obtain a minimal acceptable BP * Optimization * Provide adequate oxygen availability * Stabilization * Provide organ support * De-escalation * Wean from vasoactive agents **_In an ambulance:_** * _Maintain perfusion pressure_ by lying down and elevating legs (hopefully ischaemia effects will reverse) * Infusion of _small amount of hypertonic NaCl salin_e, therefore drag more fluid from tissues to blood. This leads to better recovery of SNS.