Anaesthesia in the Beach Chair Posi0on. NEURO SIG Mee0ng Queenstown Mark Hayman MBBS, MPH, FANZCA

Transcription

1 Anaesthesia in the Beach Chair Posi0on NEURO SIG Mee0ng Queenstown Mark Hayman MBBS, MPH, FANZCA

2 Outline 1. Incidence of strokes during beach chair posi0oning (BCP) 2. Physiology of CBF in upright posi0on 3. Monitoring for inadequate CBF 4. Management sugges0ons 5. Conclusions

3 None! Disclosures

4 Case Report: NSW yo former rugby player died of a massive stroke during arthroscopic shoulder surgery in beach- chair posi0on...caused by a failure to es0mate and maintain an appropriate level of mean arterial pressure in the blood supply of the brain (NSW coroner) recommenda/on that all anaesthe0c departments develop guidelines for the appropriate adjustment for the hydrosta0c gradient by anaesthe0sts when calcula0ng MAP for beach- chair surgery.

5 Other case reports 4 cases reported by Pohl & Cullen in 2005, ages recent cases from France with GA & interscalene block, ages Common features: young pa0ents, minor comorbi0es & periods of intra- op hypotension. Morbidity presumed to be result of ischaemic stroke due to cerebral hypoperfusion. Pohl & Cullen, J Clin Anesth, 2005 Villevieille, Ann Fr Anesth, 2012

6 Case: Incomplete Circle of Willis 50yo male, 180cm tall, smoker, Pre- op BP 110/75 arm = mmHg, lowest MAP=61mmHg ( Head)? ACom? PCom CTA: incomplete circle of willis. 2 months: Lei Anterior & Middle Cerebral Artery territory infarct Drummond, A&A, 2012

7 Incidence of Brain Injury following surgery in N=5177 Retrospec1ve Series Shoulder Surgery Neuro Cases Beach Chair Posi0on? BP Measureme nt A Line (heart) n=682 NIBP n=3545 A line (heart) n=422 A Line (head) n=528 Av. Mean BP Average BP Drop % % Pa1ents >1 episode BP Drop >40% from baseline % % No immediate postopera0ve catastrophic outcomes occurred, upper 95% CI = 7 per Average Hypotensio n Time per episode 16.6min 52% 16.7min Pin- On & Munis, A&A 2013

8 Incidence of Intraopera0ve Stroke Survey of orthopaedic surgeons, cases > 200K Es0mated stroke rate: 0.004% All events occurred in pa0ents in the BCP Friedman, Orthopaedics, 2009 And yet hypotension is common in the BCP posi0on. Pin- On, 2013, Friedman 2009, Yadeau 2011, Rohrbaugh 2013 So is hypotension the cause? Perhaps Lam & Baldwin, Blood Pressure & Adverse Periopera/ve Neurologic Outcomes: An Uncomfortable Posi/on, A&A 2012

9 What is Hypotension? BP while asleep: drop 30% from baseline SBP MAP Soo et al, Anaesthesia, 2011

10 Blood Pressure what is baseline? Pre- op baseline MAP mmhg Day0me median - 9.5% Sleep median % Sleep nadir Intra- op nadir % % Soo et al, Anaesthesia, 2011

11 Siphon Model of CBF Head? A V Flow α A - V

12 Does a Siphon exist in upright humans? CVP IJV CVP EJV IJVP=Internal Jugular Venous Base of skull Dawson et al, Standing up to the challenge of standing: a siphon does not support CBF in humans, ajpregu, 2004.

13 & in Giraffa camelopardalis MAP = 118 Cranial VP = - 4 5m MAP = 200 CVP = 4 Brondum, Jugular venous pooling during lowering of the head affects blood pressure of the anesthe/zed giraffe, AmJPhysiolRegulIntegrCompPhsiol, 2009.

14 Monitoring NIRS BP TCD?EEG

15 Cerebral Oximetry (SctO2) OXIPLEX Con0nuous wave technology: interpret photon scaver & absorp0on Frequency domain systems differen0ate scaver & absorp0on. Davie et al, Anesthesiology, 2012

16 NIRS in Sixng versus Lateral Posi0on Cerebral Desatura0on Events (CDEs) LDP = 0% BCP = 80% Murphy, A&A, 111(2), 2010

17 SctO 2 & Upright posi0on N=20 SctO2 LeN SctO2 Right Head Awake Supine Upright Min Value 57* 59* ~30 * p < 0.05 comapred to awake & compared to supine asleep Decrease of >20% in SctO 2 in >80% pa0ents. Decreases in SctO 2 correlated with BP drops (R= 0.6) & EtCO 2 (R = 0.47) Moerman et al, Eur J Anaesthesiology, 2012

18 Influence of BP on Cerebral Perfusion & Oxygena0on SctO2 vs MAP MCAv mean vs MAP Change in MAP (mmhg) Change in MAP (mmhg) Lucas, Blood Pressure & Cerebral Autoregula/on, Hypertension, 2010

19 SctO2 with phenylephrine & head up posi0on? N=34 RCT Saline Phenylephrine SCO2% MAP MCAv SCO2% MAP MCAv Rm Air Pre- O Post Induc0on Post Infusion Upright Posi0on MAP: level of head Soeding et al, BJA 2013

20 Sct0 2 & SjVO 2 SctO 2 SjVO 2 Brassard, BJA, 2009

21 Cerebral Oximetry & SjvO2% SctO2% SjvO2% Jeong et al, Anesthesiology, 2012

22 NIRS & Extracranial Contamina0on % change from baseline of SctO2 Davie & Grocoa, Anesthesiology, 2012

23 Theore0cal explana0on for SctO2 changes seen with phenylephrine. Modified from Meng & Gelb, BJA, 2012

24 Transcranial Doppler (TCD) Hypercapnia used to validate TCD against Xenon. Correla0on: R = MCAv Reac0vity (Doppler) CBF Reac0vity (Xenon) Bishop et al, Stroke, 1986.

25 TCD & Hypotension with Beach Chair Posi0oning Possible mechanisms for reduced MCAv: 1. Impaired autoregulatory response 2. Cerebral arterial pressure may have been below lower limit of autoregula0on head <50mmHg in 11 of 19 pa0ents. McCulloch et al, AAIC, 2010

26 Components of Autoregulatory response azfp McCulloch et al, AAIC, 2010

27 Influence of BP on MCAv Lucas, Blood Pressure & Cerebral Autoregula/on, Hypertension, 2010

28 The impact of Cardiac Output on MCAv? MCAv Cardiac Output l/min Ogoh, et al, J Physiol, 2005

29 Management Sugges0ons

30 Avoid Sixng Posi0on US Survey of Shoulder Surgeons Low rate of stroke reported rate in the beach chair posi0on % % But.. All cerebrovascular events were associated with surgeries in the beach chair posi0on. Friedman, Orthopedics, 2009, 32(4)

31 Avoid GA? Koh & Murphy et al, J Shoulder Elbow Surg, 2013

32 Maintain a Normal BP Supine with 20% BP level of heart Beach Chair with 20% BP drop Awake

33 Maintain or augment Cardiac Output MAP CO SctO2 Supine pa0ents, controlled ven0la0on, propofol/remi. Meng, BJA, 2011

34 Head Posi0on Toole J, Arch Neurol, 1960

35 Vola0le vs Propofol? Jeong et al, 2012

36 Other Monitors: Cerebral Oximtery or TCD? Interpret Cerebral Oximetry with cau0on. Future studies may provide clinical outcome data. TCD probably more robust but less convenient and unlikely to become a standard monitor.

37 Summary Incidence of stroke in BCP: seems to be low. Mechanism is likely to be hypoperfusion in these cases. Cerebral Oximetry as monitor of cerebral oxygena0on in BCP is problema0cal, par0cularly following vasopressor use. TCD is a more robust but less convenient monitor of CBF BP measurement or calcula0on at level of head should be standard of care (there is no siphon) Maintenance of pre- op BP is probably reasonable approach. Consider augmen0ng CO rather than simply BP support. Consider use of regional & seda0on rather than GA. Maintain neutral head posi0on. If GA used aim for mild hypercapnia & perhaps use vola0le rather than propofol based GA.

38 Discouraging data on the anti-depressant