Dr Richard Pugh Consultant Anaesthetics/ Intensive Care Medicine May 2010

Transcription

1 Dr Richard Pugh Consultant Anaesthetics/ Intensive Care Medicine May 2010

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3 The brainstem: Midbrain, pons, medulla Consciousness Cardiovascular and respiratory regulation Sleep- wake cycle Integration of sensory and motor function

4 1976 and 1979 Conference of Medical Royal Colleges and their Faculties statements, diagnosis of brain death : Preconditions Exclusions Clinical tests Brain death = death

5 No pupillary reflexes No corneal reflex Absent vestibulocochlear reflex No motor response to trigeminal nerve stimulation Absent cough/ gag reflex Apnoea

6 Donors Number 4000 Transplants Transplant list Year

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8 Number of donations after Brainstem Death,

9 As numbers of potential brainstem donors decrease, essential to: Maximise identification of potential BSD donors Optimise the function of organs which have potential for donation: Increase numbers of organs that may be donated Minimise recipient morbidity and mortality

10 < 25% potential BSD donors lost due to cardiovascular collapse Donor management protocol associated with: 87% decrease in number of donors lost due to cardiovascular collapse Significant increase in number of donated organs per donor Salim J Trauma 2006

11 Patho-physiological change Approx incidence Hypotension 80% Diabetes insipidus 65% Disseminated intravascular coagulation 30% Cardiac arrhythmias 30% Pulmonary oedema 20% Metabolic acidosis 10%

12 Midbrain ischaemia: Increased vagal activity Bradycardia Pontine ischaemia Medullary ischaemia Spinal cord ischaemia

13 Midbrain ischaemia Pontine ischaemia: Sympathetic stimulation Baro-receptor response to hypertension Bradycardia and hypertension Cushing reflex Medullary ischaemia Spinal cord ischaemia

14 Midbrain ischaemia Pontine ischaemia Medullary ischaemia: Unopposed sympathetic storm Tachycardia/ hypertension Spinal cord ischaemia

15 Midbrain ischaemia Pontine ischaemia Medullary ischaemia Spinal cord ischaemia: Loss of sympathetic tone Bradycardia/ hypotension

16 Profound instability... Hyperdynamic/ hypertensive episodes Cardiovascular collapse: Vasodilatation Impaired myocardial contractility Hypovolaemia (e.g. Diabetes insipidus)

17 Use short-acting agents! Depending on heart rate: GTN Esmolol or Labetalol SNP in event of refractory hypertension

18 Management of hypotension/ hypoperfusion: Impact on organs: Average systolic blood pressure < 80 mm Hg associated with kidney wastage Urine output< 100 ml in final hour associated with reduced kidney graft function at one year Lucas Transplantation 1987

19 Parameter Target Heart rate Blood pressure ScvO2 >70% Sinus rhythm pm Mean arterial pressure mm Hg Systolic blood pressure mm Hg Lactate Stroke volume or pulse pressure variation < 2 mmol/l Normal Cardiac index > 2.1 L/min/m 2

20 Management of hypotension/ hypoperfusion: Guides to fluid therapy? Which fluid? Which vasopressor? Role of thyroid hormones? Echocardiography?

21 CVP monitoring is strongly recommended for potential BSD donors* In the presence of hypotension, decreased CI (if applicable), ScvO2< 70% or lactate > 2 mmol/l: CVP 8-12 mm Hg Normal SVV (or PVV), if applicable *e.g. Canadian Council for Donation and Transplantation Shemie CMAJ 2006; 174 (6): S13

22 Pulse pressure variation (LiDCO) Murugan Crit Care Med 2009

23 HES 200/ 0.6 HES 130/ 0.4 Cittanova Lancet 1996 and Blasco BJA 2008

24 Very high levels of catecholamine are damaging to heart muscle Noradrenaline administration may be associated with reduced recipient cardiac and renal function Rona G. J Mol Cell Cardiol. 1985; 17: Schnuelle P. Transplantation 2001; 72: Dominguez. Transplant Proc. 2009; 41: Post-mortem histology: Cardiac myocytes with associated contraction band necrosis following catastrophic brain injury

25 Posterior pituitary function lost < 80% BSD Vasopressin deficiency will contribute to haemodynamic instability: Diabetes insipidus, and hypovolaemia Contribute to vasoparesis

26 Vasopressin infusion: Seems to improve cardiovascular stability Decrease catecholamine requirement Prevent and treat diabetes insipidus Dose< 2.4 U/ hour unlikely to have direct adverse effects on organ perfusion Chen Circulation 1999; 100(19 Suppl):II244-II246 Pennefather Transplantation 1995; 59(1):58-62; Kinoshita Transpl Int 1990; 3(1):15-18

27 Vasopressin vs. Noradrenaline: Trend to reduced progression of renal injury Reduced requirement for RRT

28 Myocardial injury present >40% BSD If evidence of decreased cardiac output, despite attempts to optimise pre-load: Dobutamine

29 BSD associated with decreased TRH and TSH Thyroid deficiency associated with impaired myocardial contractility and vasoparesis

30 Unclear efficacy: Some studies have reported improved rates of retrievable organs and organ survival with thyroid hormone, T3 Rosendale Transplantation 2003 Abdelnour J Heart Lung Transplant 2009 Venkateswaran European Heart Journal 2009

31 To aid haemodynamic management To aid consideration of cardiac donation: Echocardiography abnormalities are common (e.g. 20% patients with BSD due to SAH) Concern if LVEF< 40% However, may evaluate response to fluid manipulation/ dobutamine Venkateswaran Eur J Echocardiography 2005

32 Patho-physiololgy: ALI/ ARDS Atelectasis Aspiration Nosocomial pneumonia Neurogenic pulmonary oedema

33 General aims: Minimise ventilator- induced lung injury Ensure lung recruitment Enable secretion clearance Avoid fluid overload

34 Parameter Target PaO2, SaO2 PaO2> 10 kpa, SaO2> 95% With minimal FiO2 PEEP PaCO2 Minimum 5 cm H2O Increase as required to maintain PaO2> 10 kpa, SaO2> 95% with FiO kpa Peak airway pressure Tidal volume < 30 cm H2O < 8 ml/kg

35 Maintain regular turning, physiotherapy and tracheal suctioning Appropriate sensitivity of assisted spontaneous modes of ventilation Chest x-ray and gram stain/ culture of respiratory specimens Bronchoscopy may be requested

36 Competing needs of different organs Hypernatraemia can be common Use of vasopressin or DDAVP for diabetes insipidus

37 Vasopressin Thyroid hormone Insulin Avoidance of hyperglycaemia shouldbe associated with improved graft function Methylprednisolone Seems to improve outcome after kidney, liver, heart and lung transplantation Kotsch K, Ann Surg 2008 Selck Am J Transplant 2008 Rosendale Transplantation 2003

38 Red blood cell transfusion: Hb < 9 g/dl in presence of haemodynamic instability/ hypoperfusion Hb 7 g/dl is probably appropriate in other situations

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40 Intensive Care Society. Guidelines for adult organ and tissue donation 2005 Shemie et al.organ donor management in Canada: recommendations of the forum on Medical Management to Optimize Donor Organ Potential. CMAJ 2006; 174(6):S13-S32 Kutsogiannis et al. Medical management to optimize donor organ potential: review of the literature. CJA 2006; 53(8):820-30

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