062_Cerebral-challenge_5_Update_2011.pdf

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Case 1

Anotherwisetandwell60-year-oldmanpresentsforelective varicose vein surgery. Te junior doctor on the

ward orders a chest Xray as the patient has recently hada chest inection he is now asymptomatic.

Cerebral Challenge

AnaesthesiaUpdate in

Figure 1. Chest Xray o patient 1

1. What coincidental abnormality does this chest Xrayshow?

2. Would this change your preoperativemanagement?

3. How would you alter the anaesthetic you givehim?

Education

SuzanneCoulter*andLouiseFinch*Correspondence email: [email protected]

Case 2

You are on a ward assessing patients or surgery when

a patient in a nearby cubicle collapses. Te emergencyteamiscalledbutyouarerstonthescene.epatientis 65-years-old and is awaiting elective surgery. Heresponds to a painul stimulus, a weak radial pulse ispalpable and the nurse has recorded a blood pressureo 70/45mmHg. His ECG is shown below.

Figure 2. ECG o patient 2

1. What abnormality is shown on the ECG?

2. How would you initially manage this patient?

3. How would you manage this patient i theywere not compromised by the arrhythmia?

4. How would you decide i this was a ventricularor supraventricular rhythm?

5. Would it change your initial management?

Suzanne Coulter

Core Trainee in Anaesthesia

Louise Finch

Core Trainee in AnaesthesiaDepartment o AnaesthesiaRoyalDevonandExeter

NHS Foundation TrustBarrack RoadExeter

DevonEX25DW

UK

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DISCUSSION

Tis chest Xray shows a large hiatus hernia. Tis can be seen behindthe heart as a globular structure with a uid level within it. Te Xraylmmustbeadequatelypenetratedtoshowstructuresbehindtheheart - i.e. you should just be able to see the thoracic vertebral bodiesbehind the heart. A hiatus hernia arise due to a deect in the diaphragmallowing part or all o the stomach to pass into the thorax. Te patientmay have symptoms o dyspepsia, belching, chest pain (which canmimic cardiac ischaemia) or rank reux.

Hiatus herniae are relevant in anaesthesia because o the increased risko reux and subsequent aspiration. Pulmonary aspiration o gastriccontentscarriesa signicantmorbidityandmortality.Injuryfromaspiration o gastric contents results rom chemical pneumonitis,mechanical obstruction rom particulate material and bacterialcontamination. Te morbidity is related to the pH and the particlesize o the aspirate. Patients can be at greater risk o reux due to avariety o actors (able 1).

In order to minimise the risk o reux, aspiration and resultantmorbidity, anaesthetic practitioners should consider the ollowing:

Case 1

Preoperative care

Patientsshouldbeappropriatelyfasted(2hoursforclearuids,6 hours or ood/milk).

Patientsshouldbequestionedaboutthepresenceofsymptomssuch as heartburn, relux or previous diagnosis o hiatushernia.

Considerationshouldbegiventotheuseofpremedicatingagents

to reduce the volume and increase the pH o gastric contents (seeable 2).

In the presence o signiicant symptoms o relux, the generalanaesthesia technique should include intubation, with the tubeinserted as part o a rapid sequence induction.

Signicantreuxsymptomsshouldbeconsideredas:

frequent(dailytoweekly)reuxfeltasacidinthemouthorburning in the oesophageal area.

reuxrelatedtoposition(lyingatorbendingover).

Increased gastric Delayed gastric Gastro-oesphageal Raised Miscellaneous

volume emptying junction intra-abdominal

incompetence pressure

recent solid or pregnancy hiatus hernia obesity peritonitis

headinjury nasogastrictube latepregnancy pancreatitis

opioids scleroderma steep head-down vagal stimulation

pain,fearandanxiety magnesium

volatile agents

oesophageal strictures

pharyngeal pouch

Case 3

Apreviouslyt30-year-oldmanisbroughttotheEmergencyDepartmentwithaGlasgowComa Score o 3/15 having been knocked of his motorcycle. He is being ventilated using

a bag-valve-mask, has a heart rate o 80bpm and a blood pressure o 150/80mmHg. Youimmobilise his cervical spine, intubate him and take him or an urgent C head scan (Figure3).Noothersignicantinjurieshavebeenfoundclinicallyorradiologically.

Figure 3. CT head o patient 3

1. What does his CT head show?

2. How would you manage this patient?

Table 1. Risk actors or gastro-oesophageal reux

small or largebowel obstruction

gastricinsuationduring mask ventilation

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position

diabetic autonomicneuropathy

renal ailure

shock o any cause


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Prokinetic H2

receptor antagonist Proton pump inhibitor Antacid

Drug metoclopramide10mgPO/IV ranitidine150-300mgPO omeprazole20-40mgor 30%sodiumcitrate

lanzoprazole30mg 30ml

Timing 30-60min prior to anaesthesia 2hr prior to anaesthesia 2-6hr prior to surgery and immediately prior to

(efects last or 2 hours) and preceding evening i preceding evening i possible. induction (short duration)possible.

Mechanism reduction o volume o alkalinisation o gastric reduction o gastric alkalinisation o gastricgastric contents contents acid secretions contents

Tis ECG shows a broad complex tachycardia (the QRS durationis greater than 0.12s or more than 3 small squares) which should be

Case 2

managed according to the European Resuscitation Councils guidance(Figure 4).

Figure 4. Broad complex tachycardia algorithm (By kind permission o the European Resuscitation Council) Available at www.cprguidelines.eu/2010/

Table 2. Summary o premedicant drugs available or patients with reux oesophageal disease

For some patients, who give a history o inrequent reux, you mayeel that intubation is not necessary. For these patients one or moreo the premedicant drugs shown in able 2 may be used to enhancegastric emptying or reduce the acidity o the stomach contents. Tis

decision will also be inuenced by the planned procedure and otheractors that may make reux more likely.

Ifyouareuncertainwhetherthereuxhistoryissignicant,thesafestcourse o action is to intubate using a rapid sequence induction.

Postoperative care

Musclerelaxant shouldbeadequately reversedandthepatientully awake (able to sustain a head lit or 5 seconds and maintain

armgrip)priortoextubation.

Extubationshouldbeperformedwiththepatientontheirsideorsitting up to minimise risk o aspiration at this critical point.

Makethepatientawareoftheneedtoinformfutureanaesthetic practitionersoftheirsignicantaspirationrisk.



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As or any acutely unwell patient, management should ollow anABC approach:

A: Airway support i necessary and administer oxygen (15L.min-1

as available). B: Pulse oximetry should be recorded and assessment should be

made o his breathing which might be compromised, in thissituation by pulmonary oedema.

C: Circulation is compromised here - his blood pressure is 70/45.IV access should be obtained.

Te cause o this patients collapse is his arrhythmia. Te managemento arrhythmias is determined by two major actors:

1. Whether the patient is stable or unstable (as here).

2. Te nature o the arrhythmia.

Presence o any o the adverse signs in the table below indicates thata patient is unstable.

erststepinmanagementistotreatanyreversibleprecipitantssuch as electrolyte abnormalities (particularly low plasma potassiumand low plasma magnesium) or pro-arrhythmic drugs.

Electrical cardioversion is indicated or unstable patients andantiarrhythmic drugs (which are less reliable and have a slower onset)are used or patients with no adverse signs.

Electrical cardioversion would be appropriate in this patient as hehas some signs o instability. He is conscious and so some orm osedationshouldbeused.reecardioversionsmaybeattempted;if

these ail to restore sinus rhythm, amiodarone 300mg should be givenintravenously over 10-20 minutes, ollowed by a urther attempt atelectrical cardioversion.

Te shocks must be synchronised and this can be achieved by pressingthe syncbuttononthedebrillator.isavoidsthetheoreticalriskofdelivering the electrical shock on the -wave which may precipitateventricularbrillation.Anenergylevelof150Jbiphasic(or200Jonoldermonophasicdebrillators)shouldbeusedforbroadcomplextachycardias (BC).

I the patient is stable, pharmacological treatment may be appropriateand an eort should be made to determine the nature o the

arrhythmia. BCs are usually ventricular in origin (80%) and shouldbe assumed to be so i the patient is unstable. However, less commonly,

they may also represent an SV with aberrant conduction (usuallya bundle branch block, which makes the QRS complex prolonged).Tis may be the case i the rhythm is irregular (underlying AF), or ithe patient is previously known to have a bundle branch block (BBB).

In practice it can be very diicult to dierentiate Ventricularachycardia (V), rom SV with a BBB. Features that suggest thediagnosis is V are described in able 4.

Adverse sign Shock Syncope Heart failure Myocardial ischaemia

Indicated by pallor loss o consciousness pulmonary oedema chest pain or ECG changes(reduced cerebral (i the let ventricle ails)

sweating bloodow)

coldandclammy and/or

hypotension raisedjugularvenous

(SBP140msinarightBBBpattern,

or>160msinleftBBBpattern.

Concordance Allthechestleads(V1-V6)areofonepolarity

(either all positive or all negative.

Table 4. ECG criteria suggestive o VT

Table 3. Signs indicating that the patient is cardiovascularly unstable

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TraumaticbraininjuriescanbeclinicallyclassiedonthebasisoftheGlasgow Coma Score (GCS):

Glasgow Coma Score Grading of head injury

3-8 severe

9-12 moderate

13-15 mild

Patients with a GCS less than 9 should be considered to have losttheir protective airway reexes and so should be intubated early. Rapidsequence induction should be used, with consideration given to use oopioids such as alentanil to minimise the rise in intracranial pressureassociated with intubation. Until proven otherwise, such patientsshould be assumed to have sufered a cervical spine injury, with 3-pointimmobilisation and in-line stabilisation perormed during intubation.

Tis patients C shows a large right subdural haematoma withsignicantmidlineshiftindicativeofasevereheadinjury.

Case 3

Subdural haematomas are located between the dura mater lining the

brain and the brain itsel, with a convex outer edge and a concaveinner border. Tey are usually venous in origin.

A

BD

C

Figure 4. The CT o patient 2 shows a large subdural haematoma (A) with

midline shit (B), efacement o the right lateral ventricle (C) and air within

the cranial cavity (D) indicating likely cranial racture


Headinjuriescanalsobeclassiedradiologicallybytheirappearanceon a C scan.

Grade CT appearance

I Noevidenceofanysignicantbraininjury

II Nomidlineshiftor25ml

III Midlineshift>4mmcompressionorabsenceofbasalcisterns.

Nohighormixed-densitylesions>25ml

IV Midline shif t>5mm,compressionorabsenceofbasalcisterns.

ismanshouldbediscussedwithaneurosurgeonasdenitivemanagement should include drainage o the haematoma. Tis mayinvolve transer to a tertiary centre with neurosurgical acilities. Whilstawaiting transer to theatre or another centre, there are several aspectsto his care that can be optimised to limit secondary brain injury , bymaintaining cerebral perusion pressure above 70mmHg.

REMEMBER: CPP = MAP ICP

(CPP=Cerebralperfusionpressure,MAP=Meanarterialpressure,ICP=Intracranialpressure)

NormalICP is 5-12mmHg. In ahead injuredpatientit is

reasonable to assume it is 20mmHg and so a mean arterial pressureo 90mmHg is needed to achieve a CPP o 70mmHg.

Bloodpressureshouldbemonitoredregularly,andinvasivelyifpossible.

Ifthoracicandlumbarspinehavebeenclearedthenpatientshouldbe 30 head up to improve cranial venous drainage.

Endotrachealtubesshouldbetapedinplaceratherthantiedtoprevent ties obstructing venous drainage.

PaCO2

should be maintained in the low normal range(4.5-5kPa).

Maintainnormoglyacemia.

Maintainoxygensaturations>95%.

Anyseizuresshouldbecontrolled(e.g.18mg.kg-1 phenytoin)

A brie period o hyperventilation (to lower the PaCO2) and/or

mannitol 0.5g.kg-1 IV can be used to control acute surges in ICP.Hyperventilation should not be sustained as cerebral vasoconstrictionmay lead to urther ischaemia.

FURTHER READING

AliB,DrageS.Managementofheadinjuries.Anaesthesia Tutorial o the

WeekNo46(March2007).Availableat:http://totw.anaesthesiologists.org/2007/03/12/management-of-head-injuries-46/

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