EVALUATION Clinical – History & Physical Laboratory Hemodynamic - All parameters are indirect,...
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Transcript of EVALUATION Clinical – History & Physical Laboratory Hemodynamic - All parameters are indirect,...
EVALUATIONEVALUATION
Clinical – History & PhysicalLaboratoryHemodynamic- All parameters are indirect, nonspecific
measures of volume - Serial evaluations necessary ≈ fluid therapy- Modalities should complement one another
PHYSICALPHYSICAL
Most reliable preoperativelySkin turgor, hydration of mucous
membranes, fullness of peripheral pulse, capillary refill, resting HR & BP and changes from the supine to sitting or standing position, urinary excretion and fontanels in babies.
LABORATORYLABORATORY Serial hematocrits Arterial blood pH Urinary specific gravity/osmolality >1.01/450
mOsm/kg Serum blood urea nitrogen (BUN)-to-creatinine
ratio > 10:1
Indirect indices of volume, esp intraoperatively Only X-ray signs reliable measures of volume
overload – Kerly B lines or intestitial markings
HEMODYNAMICHEMODYNAMIC CENTRAL VENOUS PRESSURE (CVP) Cardiac output is based on the Frank starling mechanism
where force of contraction is determined by the initial fiber length and the contractility of cardiac muscle to determine stroke volume
We do not measure stroke volume, so pressure is used as a surrogate
The placement of a central venous catheter with its tip at junction SVC & RA provides measurable parameter of volume status or preload of patient
PULMONARY ARTERY PRESSURE In the normal individual CVP measurement provides a
reasonably accurate estimate of the filling pressures of both R & L atria. In some situations not, and infusion of fluids or inotropic agents titrated against CVP may not result in optimum cardiac function
LV failure with pulmonary oedema Interstitial pulmonary oedema of any cause Chronic pulmonary disease Valvular heart disease
PULSE PRESSURE VARIATIONPULSE PRESSURE VARIATION
Ventilation causes changes in intrathorasic pressure, influences cardiac filling
Responsible variation in BP during ventilation Identify highest and lowest BP Subtract highest DBP from highest SBP and
lowest DBP from lowest SBP Render pulse pressure variation Divide diff btw HPP & LPP by mean X 100
Highest SBP = 100 mmHgHighest SBP = 100 mmHgHighest DBP = 60 mmHgHighest DBP = 60 mmHgLowest SBP = 90 mmHgLowest SBP = 90 mmHgLowest DBP = 55 mmHgLowest DBP = 55 mmHg
HPP = 100 – 60 = 40 mmHgHPP = 100 – 60 = 40 mmHgLPP = 90 - 55 = 35 mmHgLPP = 90 - 55 = 35 mmHg
Difference btw HPP & LPP = 40 – 35 = 5 mmHgDifference btw HPP & LPP = 40 – 35 = 5 mmHgMean PP = (40+35) / 2 = 37.5 mmHgMean PP = (40+35) / 2 = 37.5 mmHg
therefore the PPV = (5/37.5) x 100 = 13.3%therefore the PPV = (5/37.5) x 100 = 13.3%> 12% indication of hypovolaemia ~ respond fluid> 12% indication of hypovolaemia ~ respond fluid
volume, < 8% non-responders, 8-12 grey areavolume, < 8% non-responders, 8-12 grey area
INTRAVENOUS FLUIDS
Crystalloids, Colloids or both Crystalloids ~ aqueous sol low-molecular-weight
ions (salts) ± glucose Colloids ~ high-molecular-weight sub :- Protein colloids – Albumin :- Non protein colloids – gelatins (haemaccel, gelofusin) hydroxyethylstarchs (voluven, venofundin) sugars (dextrans)
Replacing intravascular volume deficit with crystalloids ~ 3X volume needed using colloids
Intravascular fluid deficits ~ more rapidly corrected using colloid solutions
Surgical patients ~ extracellular fluid deficit > intravascular deficit
Rapid administration of large amounts of crystalloids (>4-51) more frequently associated with significant tissue oedema
Intravascular ½ life crystalloids 20-30 min, colloids ½ life 3-6 hours
PERIOPERATIVEPERIOPERATIVEFLUID THERAPYFLUID THERAPY
Replacement: pre-existing deficits, maintenance requirements and surgical wound losses
Maintenance fluid requirements
Weight Rate
For the firs 10 kg 4ml/kg/h
For the next 10-20 kg Add 2ml/kg/h
For each kg above 20 kg Add 1mi/kg/h
70 kg person fasting for 8h amounts to:
(40 + 20 + 50) ml/h X 8h = 880 ml
BLOOD
VolumeOxygenationClotting
Prem 95ml / kgNeonate 90ml / kg> 3month 80ml / kg> 1y 70ml / kgMABL = EBV × ( I Hct – F Hct) /
Mean Hct
Mean Hct = ( I Hct + F Hct ) / 2
Whole blood = ( F Hct – I Hct) × Kg × 2.5
Packed RBC = (F Hct – I Hct) × Kg × 1,5
DO2 = CO × CaO2
= (70 × 72) × [ (Hb × 1,34 × SaO2 ) +
(0,031 × PaO2) ]
= 5 × 200ml
= 1000ml/min Extraction ~ 200ml/min
COMPLICATIONS OF COMPLICATIONS OF BLOOD TRANSFUSIONSBLOOD TRANSFUSIONS
HEMOLYTIC REACTIONSInvolves specific destruction of transfused RBC byrecipient’s antibodies, less common – hemolysisrecipient’s RBC due to transfusion of antibodies
ACUTE HEMOLYTIC REACTIONSFatal 1:100000In awake patients – chills, fever, nausea, chest and flank pain.In anaesthetized pts -↑ temp, ↑HR, hypotension,hemoglobinuria and diffuse oozing in surgical field. Disseminated intravascular coagulation & renal shutdown Severe with as little as 10-15ml ABO-incompatibility
MANAGEMENT OF MANAGEMENT OF REACTIONREACTION
Hemolytic reaction suspected ~ stop transfusionRecheck identity bracelet against blood slipDraw blood for Hb, compatibility, platelet count
& coagulation studiesUrinary catheter inserted & urine checked for HbOsmotic diuresis initiated with mannitol & iv
fluidsPresence of rapid blood loss – Platelets & FFP
DELAYED HEMOLYTIC REACTIONS
Following ABO & Rh-compatible transfusion, 1 – 1.6% chance antibodies against Kell, Duffy, Kidd etc antigens
Extravascular hemolysisMild – malaise, jaundice & fever 2-21 days
afterTreatment primarily supportive
NONHEMOLYTIC REACTIONS
Sensitization of the recipient to donor white cells, platelets or plasma proteins
Febrile reactions Urticarial reactions Anaphylactic reactions Noncardiogenic pulmonary oedema Graft-Versus-Host disease Posttransfusion purpura Immune suppression
ANAPHYLAXISANAPHYLAXIS
Definition: Allergic condition which results from an antibody-antigen reaction rapidly after the antigen entered the systemic circulation.
Signs:Resp: Bronchospasm, laryngeal oedemaCVS: Circulatory collapse – hypotensionSkin: Wheel & flare
ManagementInitial Therapy
- Stop drug- Call for help - Airway management- Feet elevation- Drug Rx Adrenaline:
0.5 – 1mg IMI/10min 50 – 100μg IVI/ 1min (hypotension)
Secondary Therapy- Antihistamines- Corticosteroids- Catecholamine infusion Adrenaline 0.05 – 0.1 μg/kg/min- Blood gas acidosis consider
Bicarbonate 0.5-1 mmol/kg- Airway evaluation before extubation- Bronchodilators in persistent
bronchospasm
Investigations:-Only after emergency treatment has been completed- Dx on clinical grounds- Bloods: Serum tryptase concentration
1 hour after reaction 10ml red top centrifuge and store @ -20ºC until send to Lab
- Patient and GP must be alerted toward the reaction and drug causing it.
Potentially
OBESITY
BMI – Body Mass Index is the weight (kg) divided by the square of the height (m)Normal range 18-25Overweight >27Obese >30Morbid obesity >35Massive morbid obesity >40? modeling not <18
Broca Index - normal weight (kg) = height (cm) minus 100 for males or 105 for females- children weight (kg) = 10 + 2 age
Distribution – truncal, buttocks Respiratory - Difficult intubation - FRC - work of breathing, chest compliance - risk of aspiration: gastric volume,
: Hiatus hernia
:intra- abdominal pressure
- Obstructive sleep apnea esp after GA or
opioids, PCA ~ safer Nocturnal CPAP nasal oxygen mask Apnea monitor
Cardiovascular - blood volume and CO Difficult: IV access
: BP measurement (cuff size –20% > arm
diameter ) arterial line PCA better than IM opiods Tromboprophylaxis & mobilization post-op Medical conditions – Diabetes mellitus, Cushing’s
syndrome, hypothyroidism, syndromes (Prader-Willi or Lawrence-Moon-Biedl)
Table max 150kg
LARYNGOSPASMLARYNGOSPASM
Definition – Acute glottic closure by the vocal cords
Presentation – Crowing or absent inspiratory sounds and marked tracheal tug
Differential diagnosis - Bronchospasm - Laryngeal trauma / airway oedema - Recurrent laryngeal nerve damage - Tracheomalacia - Inhaled foreign body - Epiglottitis or croup
Management Avoid painful stimuli Remove irritants from airway 100% oxygen CPAP mask, jaw thrust ? Deepen anaesthesia Intractable: Muscle relaxation and intubation
PACEMAKERS
Indications – Third degree heart block
Mobitz type II block
Trifassicular block: RBBB
: Left ant/post hemiblock
: First degree heart block
Sick sinus syndrome
Symptomatic bradycardia
Post MI, HOCM, torsade de pointes
Pacemaker codePacemaker code Position 1- chamber(s) paced Position 2- chamber(s) sensed Position 3-response to a sensed elect. Signal Position 4- rate modulation Position 5- multi-site pacing
Pacemaker codePacemaker code
1 2 3 4 5Chamber paced
Chamber sensed
Response Rate modu lation
Anti-tachycardia
A=atrium
V=ventricle
D=dual
0=none
A=atrium
V=ventricle
D=Dual
0=none
I=inhibit
T=trigger
D=dual
0=none
R=rate mod
P=pacing
S=shock
D=dual
ICD codeICD code
1 2 3 4Shock chamber
Chamber anti-tachy pacing
How tachy is sensed
Pacemaker code
0=none
A=atrium
V=ventricle
D=dual
0=none
A=atrium
V=ventricle
D=dual
E=intracardiac electrogram
H=haemodynameans
above
Anaesthetic implications
- Follow up clinic, function- Pre-op ECG : Absence of all spikes may represent
appropriate sensing or total failure!- Loss of capture : Hypokalaemia After defibrillation MI over lead Toxic levels of local anaesthetic Lead dislodgement - Bipolar diathermy safe- MRI