Category Archives: Anesthesia for specific procedures

VIVA SCENE: ALL IMPORTANT PAEDIATRIC CASES IN ONE PLACE

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1. PYLORIC STENOSIS (PROTOTYPE CASE; ANY OTHER CASE, MAKE THIS A TEMPLATE AND ADD SPECIFIC POINTS RELEVANT FOR THAT CONDITION)

Most common cause of intestinal obstruction in infancy

Due to hypertrophy of circular pyloric muscle

Presentation: 4-6 weeks of age

Persistent projectile vomiting

There is obstruction at the level of pylorus: so bicarbonate rich fluid from intestine cannot mix with gastric secretions

So the vomiting causes metabolic alkalosis and hypokalemia due to loss of acidic gastric juice alone
The large bicarbonate load is in excess of kidney’s absorptive capacity and the urine becomes alkaline initially
Later when the fluid and electrolyte loss result in dehydration, the renin angiotensin system is activated and result in aldosterone secretion which tries to preserve sodium at the expense of K and Cl ions

This result in production of paradoxical acidic urine and worsening of metabolic alkalosis and hypokalemia

An attempt to compensate it through hypoventilation is initiated; but it will be insufficient and also this will trigger the hypoxic drive!

Hypoglycemia, hemoconcentration, mild uremia and unconjugated hyperbilirubinemia may be seen.
ANAESTHETIC CONCERNS

Pyloric stenosis is not an emergency

The DYSELECTROLYTEMIA and ACID BASE IMBALANCE should be corrected before taking up for surgery.

Increased chance for regurgitation, altered physiology and anatomy, altered drug dosages, difficult venous access, anxious parents are other concerns

There should be an experienced paediatric anaesthesiologist for the conduct of anaesthesia
P.A.C. AND EVALUATION

LOCATION: Needs resuscitation in a paediatric ICU or ward

INVESTIGATIONS: CBC, Blood sugar, RFT, LFT, group and hold, serial ABGs to know the effectiveness of resuscitation and decide on the dose of K administration. 3 mmol/kg/24 hour potassium should be added to maintenance fluids

HISTORY: From the parent; vomiting frequency, amount of feeds taken, diarrhoea, frequency of wetting of the nappy, fever, altered sensorium

EXAM: ?Dry mucus membrane ?Dry eyes (5% dehydration) ?Sunken fontanelle ?cool peripheries ?oliguria(10%) ?Hypotension ?Tachycardia ?Altered Sensorium (10%) ?prolonged capillary refill time

Naso Gastric tube insertion and 4 hourly aspiration of residue

FLUID RESUSCITATION:

  • For fluid resuscitation : use glucose‑free crystalloids that contain sodium in the range 131–154 mmol/litre, with a bolus of 20 ml/kg over less than 10 minutes. PlasmaLyte, 0.9% Saline ad Ringer Lactate

MAINTENANCE FLUIDS:

  • Calculate routine maintenance IV fluid rates using the Holliday–Segar formula (4 ml/kg/hr for the first 10 kg of weight, 2 ml/kg/hr for the next 10 kg and 1 ml/kg/hr for the weight over 20 kg).
  • This solution would preferably be enriched with glucose 5% (50 ml glucose 50% in 500 ml fluid) in order to provide an adequate caloric supply as recommended (4 to 8 mg glucose/kg/min). In addition, the osmolarity of such a solution makes it possible to be administered on a peripheral venous access.
  • Intraoperative: also will assess for blood loss; the maximum speed of transfusion should be 10ml/kg/hour (if no cardiac failure). Estimated blood volume x ( Desired Hct – Current Hct / Hct of the RBC ) will give the volume of PRBC to be transfused. (N.B.: As a general guide in laparotomies 10 ml/kg/ hour would be needed to compensate for evaporative losses). FFP if needed: 10-15 ml/kg

TARGETS:

  • Normovolemia
  • 1-2 ml/kg/hr of urine OR at least 2 wet nappies
  • Chloride > 95 mmol/L
  • pH <7.5
  • Base excess <6 mmol/L or bicarbonate < 30 mmol/L

CONDUCT OF ANAESTHESIA

  • Ensure that the child is adequately resuscitated
  • Procedure may take 30-60 mins
  • Paediatric anaesthetist
  • Ensure the availability of drugs-equipments for anaesthesia induction, maintenance and resuscitation
  • Attach monitors: ECG, SpO2 and NIBP(AAGBI standards)
  • 4 quadrant aspiration via Ryles tube
  • Preoxygenation for 3 mins
  • Modified rapid sequence induction with cricoid pressure
  • Propofol, Fentanyl and succinyl choline/ rocuronium 1 mg/kg
  • Straight bladed laryngoscope. Insert an uncuffed ETT of size 3.5 mm ID; I will also keep size 3 and 4
  • Ensure proper placement: 5 point auscultation and checking capnography trace
  • Release cricoid pressure and secure the tube
  • Hand ventilate the child before connecting to a ventilator (ventilation guided by ETCO2 values)
  • Paediatric mode; Pressure Controlled Ventilation
  • O2, Air and sevoflurane maintenance
  • Can consider an epidural for intra and postoperative analgesia (C/I Sepsis, coagulopathy)
  • Local anesthetic can be infiltrated by the surgeon; Ropivacaine or levobupivacaine; dose < 2mg/kg
  • Paracetamol iv (child <10 kg–> 7.5 mg/kg 6 hourly; max 30 mg/kg/day) OR
  • Paracetamol suppository 30 mg/kg loading dose followed by 20 mg/kg 6-8 hourly: max 60 mg/kg/day; continue postoperatively
  • Fentanyl 1microgram/kg iv boluses hourly is less cumulative and more predictable than morphine
  • If well hydrated with good renal perfusion: NSAIDs Ibuprofen 3 mg/kg three times daily or diclofenac per rectal 1 mg/kg/dose suppositories
  • Monitor urine output
  • Antiemetics: ondansetron 0.15 mg/kg
  • Extubation in lateral position
  • Risk of post operative apnoea: SpO2 monitoring with apnoea alarm
  • Regular and PRN analgesics in postoperative period

OTHER INTRAOPERATIVE CONCERNS

  • Strategies to avoid excessive heat loss, optimal analgesia and depth of anaesthesia, optimal fluid therapy
  • Constant monitoring of heart rate, oxygen saturation,EtCO2, blood pressure, body temperature, urine output
  • Check blood sugar to avoid hypoglycemia
  • To prevent hypothermia: Increase the ambient temperature of the OR prior to and during the surgery, body warmer, bubble wraps and plastic drapes to cover the body, cover the head, warm the iv fluids, HME to reduce heat loss from the respiratory system

PAIN EVALUATION IN PAEDIATRICS

  • Evaluated with the support of the parents
  • Using a combination of physiological and behavioural markers in neonates and infants
  • e.g. facial expression, sleeplessness, cry, body movements, posture, increased clinginess, loss of appetite, screaming, reluctance to move, CVS & RS changes
  • Neonate and Infant: Neonatal Pain Agitation and Sedation Score (N-PASS), Neonatal and Infant Pain Scale (NIPS), Face, Legs, Activity Cry and Consolatility scale (FLACC), Objective Pain Score
  • Pre-school and school children can be evaluated by scales like Faces scale ( Happy to crying faces
  • Adolescents: Visual Analogue Scale

POSTOPERATIVE CARE

  • In a high dependency unit or Paediatric Intensive Care unit
  • Will watch for respiratory depression and respiratory compromise, ?shock, pain levels, surgical complications, signs of loss of blood volume
  • Send sample for full blood count and serum electrolytes
  • Continue IV fluids

2.INTUSSUSCEPTION

  • Small bowel telescoping; most common cause of intestinal obstruction in first year of life; other diseases like Meckel’s diverticulum, lymphoma etc can present as intussuception.
  • HISTORY:Present with paroxysmal abdominal pain- child may hold legs to abdomen and red currant jelly like stools. Vomiting and dehydration can cause shock. Abdominal distension can compromise respiration. Infection, infarction,bleeding, perforation, Sepsis-shock etc also can occur.
  • EXAMINATION:Abdomen-guarding. Sausage shaped mass on the right side.
  • INVESTIGATION: Abdominal Ultra sound. X ray abdomen: ?obstruction ?perforation. Air enema can be therapeutic also but contraindicated if having perforation or peritonitis or if in shock.
  • If in shock–> resuscitate and take for laparotomy. A
  • ny repiratory compromise due to distension–> consider the need for mechanical ventilation

3.OESOPHAGEAL ATRESIA (OA) & TRACHEO OESOPHAGEAL FISTULA (TOF)

  • Defective embryonic development of oesophagus and trachea
  • Mostcommon types are 1. isolated OA with distal TOF 2. isolated OA and 3. isolated TOF
  • PAC: ask for SYMPTOMS: Repeated episodes of coughing,chocking and cyanosis worsened by feeding, resitance to pass a nasogastric tube; evaluate for associated congenital anomalies- VACTERL: Vertebral Anal Cardiac Tracheo Esophageal Renal Limb anomalies; problems of prematurity- lung disease, retinal problems, impaired glucose regulation
  • OPTIMISATION: The ligation of a TEF is urgent, but not emergent, except in the setting of respiratory insufficiency severe enough to require ventilatory support. Use IV fluids with glucose to avoid hypoglycemia and to achieve euvolemia. Use specialised suction called Replogle suction to clear the upper part of the oesophagus. Avoiding feeding. Upright positioning of the infant to minimize gastroesophageal reflux. Administration of antibiotic therapy to treat sepsis or aspiration pneumonia. Uncomplicated surgery can be done within 24 hours of birth, to reduce the chance of aspiration of pooled secretions.
  • ANAESTHESIA TECHNIQUE (See above) Specific points for TOF: Under monitoring with pulseoximeter, suction the upper pouch–>Preoxygenation with 100 % O2; avoid vigorous bag and mask ventilation; else the air will pass via TOF into stomach causing distension and splinting of the diaphragm–> An awake technique with titration of small doses of fentanyl (0.2 to 0.5 mcg/kg) allows intubation of the trachea without excessive hemodynamic stimulation or depression. OR an inhalational anesthetic with or without muscle relaxation and with cautious, gentle positive pressure ventilation as needed (Ref: Smith’s anaesthesia for infants & children 8/e) –> place ETT–> allow child to breath spontaneously–>examine airway with a rigid bronchoscope and establish the exact anatomy–> replace and position ETT in a way to occlude the TOF–> once the ETT is placed in the correct position, NMBA can be given. Consider IBP and central venous access based on individual case. Child usually in Right lateral position; take care to maintain the iv access safely.

4.CONGENITAL DIAPHRAGMATIC HERNIA (CDH)

  • Repair is not an emergency procedure. Usually delayed for 24-48 hours for the pulmonary resistance to come down. Baby should be resuscitated first. Delivery should take place as close to term as possible to achieve maximum lung maturity. ABG, Chest x-ray and Echo shold be done. Do an oroogastric suction to clear the part of the bowel in the chest. Intubatin and ventilation should aim to reduce barotrauma with smaller tidal volumes and permissive hypercapnea.

5.EXOMPHALOS & GASTROSCHISIS

  • Due to failure of the migation of the gut into the abdominal cavity during fetal development, there is a herniation of the abdominal contents with a covering sac through a midline defect in the abdominal wall and other congenital anomalies may accompany. Whereas gastroschisis is an isolated anomaly where the gastric contents without any covering sac herniates through a defect in the abdominal wall but not in the midline.
  • There is chance of infection and extensive loss of heat and moisture from the exposed bowel; so it should initially be covered with a non porous material and extreme priority shoud be given for the eveluating the fluid loss and replacement and also for establishing normothermia
  • Primary closure or if respiratory compromise is not allowing it, a staged closure may be necessary

6. INGUINAL HERNIA / REGIONAL TECHNIQUES

  • Mask or IV induction with general anesthesia (with or without endotracheal intubation); spinal anesthesia as a primary anesthetic; caudal anesthesia or analgesia. Muscle relaxation is not necessary but may be a valuable adjunct for decreasing anesthetic requirements and providing optimal surgical conditions.

  • Equipment: Low compression volume anesthesia breathing circuit (circle absorption system vs. Mapleson D ). Monitoring: Standard noninvasive monitoring

  • Maintenance: 1. Inhalation agent plus local infiltration or ilioinguinal-iliohypogastric block on the surgical field OR maintenance caudal analgesia, allow the avoidance of opiates. Neuromuscular blockade with nondepolarizing agent, if chosen. 2. Volume support with judicious amounts of crystalloids.(See 1.) Blood loss is minimal.

  • Emergence and Perioperative Care: 1. Vigilance regarding perioperative abnormalities of control of breathing: periodic breathing/apnea; laryngospasm/bronchospasm; bradycardia; hypoglycemia; continuously monitor with a pulseoximeter. 2. Pain management. (See:1)

Regional anaesthesia:

  • SPINAL ANAESTHESIA: For neonates and infants, a 1 inch 22-gauge spinal needle is inserted at the L4-5 interspace. 0.5 to 0.6 mg/kg of either isobaric or hyperbaric bupivacaine will provide an average of 80 minutes of surgical analgesia for infants and young children who are less than 5 kg in weight. For infants or toddlers 5 to 15 kg, the dosage of hyperbaric bupivacaine or tetracaine is 0.4 mg/kg, and for children weighing more than 15 kg, the dosage of bupivacaine or tetracaine is 0.3 mg/kg . Isobaric ropivacaine has been studied in children for spinal anesthesia at a dosage of 0.5 mg/kg up to 20 mg.
  • CAUDAL BLOCK: The recommended concentration of bupivacaine for a singleshot caudal is 0.125% to 0.25%. An epinephrine dosage of 2.5 mcg/mL, or a concentration of 1:400,000 may be used as an additive for central blocks. Epinephrine will serve as a marker for intravascular injection and decrease systemic absorption of local anesthetic. Additionally, epinephrine may prolong the duration of a regional block. Preservative Free Ketamine, fentanyl, clonidine etc also can also be used as additives. See table: Smith 8/eScreen Shot 2019-08-25 at 11.48.27 am
  • ILIOINGUINAL /ILIOHYPOGASTRIC BLOCK: Can be given after induction, but before the incision; a blunt 22 or 25 gauge needle is inserted 1 cm superior and 1 cm medial to the anterosuperior iliac spine; the needle is initially directed posterolaterally to contact the inner superficial lip of the ileum, then withdrawn while injecting local anesthetic during needle movement. Once skin is reached, the needle is redirected toward the inguinal ligament (ensuring that the needle does not enter the ligament) and local anesthetic is injected after a pop is felt. Can perform under US guidance too. Can use 0.25 mL/kg of 0.5% levobupivacaine or 0.5% ropivacaine at 3 mg/kg. (Ref: Smith’s anaesthesia for infants & children 8/e)
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MEDIASTENAL TUMOURS & THE ANESTHESIOLOGIST: SPECIFIC POINTS

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  • A preoperative CT scan will show the site, severity, and extent of the airway compromise to assess the level and degree of obstruction.
  • Assess the vocal cord function preoperatively
  • Lung function tests to look for the extent of intrathoracic or extrathoracic obstruction.
  • ECHO to rule out pericardial effusion and cardiac compression.
  • Premedication with benzodiazepine is generally avoided if there is risk of airway compromise.
  • Airway equipment—rigid bronchoscopy and difficult airway trolley, jet ventilation, cardiopulmonary bypass (CPB) should be there as standby. Femoro femoral bypass is the most common setup.
  • COMPLICATIONS DUE TO MASS EFFECT OF THE TUMOUR:
  • Vascular compromise—SVC Obstruction ( SVCO ) and pulmonary vessel obstruction
  • Laryngeal nerve palsy
  • Dysphagia
  • STRIDOR and airway compromise may be an important symptom
  • Inspiratory stridor (laryngeal)—obstruction above the level of glottis
  • Expiratory stridor (tracheobronchial)—obstruction in the intrathoracic airways
  • Biphasic stridor—obstruction between glottis and subglottis or a critical obstruction at any level
  • Sometimes you may have to go for a microlaryngoscopy tube (MLT)
  • TAKE CARE:
  • Aim to avoid worsening of cardiac compression, airway occlusion, and SVC obstruction.
  • IV cannula in the lower extremity
  • Induction in sitting position (semi Fowler’s position)
  • Inhalational (preferred choice) or IV induction agent titrated to effect
  • Choose spontaneous ventilation with LMA
  • Awake fibreoptic technique if intubation is necessary with a reinforced smaller calibre and longer endotracheal tube
  • Postoperative airway obstruction due to airway oedema, tracheomalacia, and bleeding warrant the need for awake extubation in ITU. The following steps would aid in an uneventful extubation:
  • Test for leak around the endotracheal tube cuff.
  • Administer dexamethasone or chemo radiotherapy in sensitive tumours to shrink size of tumour.
  • Use adrenaline nebulisers.
  • Extubate over airway exchange catheters.
  • SVCO: challenges during anaesthesia
  • Need for supplemental oxygen
  • Orthopnoea—induction in the sitting-up position
  • IV cannula in the lower extremity
  • Airway oedema
  • Mucosal bleeding
  • Laryngeal nerve palsy
  • Haemodynamic instability due to decreased venous return
  • OTHER CONCERNS
  • General anaesthesia, causes loss of intrinsic muscle tone, decreased lung volumes, and decreased transpleural pressure gradient
  • Positive pressure ventilation, can precipitate severe hypotension and also increases intrathoracic tracheal compression
  • Coughing, as it can cause complete airway obstruction by positive pleural pressure, increasing intrathoracic tracheal compression
  • Following gas induction, the patient stops breathing and if you are unable to ventilate her: Follow difficult or failed intubation guidelines. But cricoid puncture and emergency tracheostomy are futile if the level of airway obstruction is at the intrathoracic tracheobronchial tree: Try a change in position—lateral, sitting up, or prone—to decrease the mechanical effect of the tumour. Avoid positive pressure ventilation for fear of luminal closure. Low-frequency jet ventilation with Sander’s injector or high-frequency translaryngeal jet ventilation with Hunsaker’s catheter is one option. CPB bypass and ECMO to restore oxygenation when other measures fail.
  • Following chemotherapy in ICU, if patient develops hyperkalemia, Tumour Lysis Syndrome should be there in the differential diagnosis
  • ALSO NOTE
  • During inspiration, the intrathoracic airways expand along with the expanding lungs. In contrast, the extrathoracic airways diminish in caliber during inspiration due to their intraluminal pressure being lower than the atmospheric pressure. The reverse happens during expiration.
  • Flow volume loop in upper-airway obstruction:
  • Fixed lesions [extrathoracic or intrathoracic] are characterized by lack of changes in caliber during inhalation or exhalation and produce a constant degree of airflow limitation during the entire respiratory cycle. Its presence results in similar flattening of both the inspiratory and expiratory portions of the flow-volume loop
  • Variable lesions are characterized by changes in airway lesion caliber during breathing. Depending on their location (intrathoracic or extrathoracic), they tend to behave differently during inhalation and exhalation.
  • In the case of an extrathoracic obstructing lesion, during inspiration, there is acceleration of airflow from the atmosphere toward the lungs, and the intraluminal pressure decreases with respect to the atmospheric pressure due to a Bernoulli effect, resulting in the limitation of inspiratory flow seen as a flattening in the inspiratory limb of the flow-volume loop. During expiration, the air is forced out of the lungs through a narrowed (but potentially expandable) extrathoracic airway. Therefore, the maximal expiratory flow-volume curve is usually normal.
  • Variable intrathoracic constrictions expand during inspiration, causing an increase in airway lumen and resulting in a normal-appearing inspiratory limb of the flow-volume loop. During expiration, compression by increasing pleural pressures leads to a decrease in the size of the airway lumen at the site of intrathoracic obstruction, producing a flattening of the expiratory limb of the flow-volume loop
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TOTAL BODY WEIGHT [TBW] , LEAN BODY WEIGHT [LBW], IDEAL BODY WEIGHT [IBW] &ADJUSTED BODY WEIGHT ; THEIR IMPLICATIONS IN Anesthesia AND CriticalCare

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Drug administration in obese patients is difficult because recommended doses are based on pharmacokinetic data obtained from individuals with normal weights

With increasing obesity, fat mass accounts for an increasing amount of TBW, and the LBW/TBW ratio decreases

TBW is defined as the actual weight

IBW is what the patient should weigh with a normal ratio of lean to fat mass

IBW can be estimated from the formula: IBW (kg) = Height(cm) − x ( where x = 100 for adult males and 105 for adult females).

LBW is the patient’s weight , excluding fat

Male LBW = 1.1(weight)-128(weight/height)^2 (Weight in Kg and Height in cm)

Female LBW = 1.07 (weight) -148 (weight/height)^2

Regardless of total body weight, lean body weight rarely exceeds 100 kg in men and 70 kg in women

Below IBW, TBW and LBW are similar.

Adjusted body weight (ABW) Takes into account the fact that obese individuals have increased lean body mass and an increased volume of distribution for drugs.

It is calculated by adding 40% of the excess weight to the IBW : ABW (kg) = IBW (kg) + 0.4 [TBW (kg)]

Drugs with weak or moderate lipophilicity can be dosed on the basis of IBW or more accurately on LBW. These values are not same in obese; because 20–40% of an obese patient’s increase in TBW can be attributed to an increase in LBW. Adding 20% to the ‘estimated IBW based dose’ of hydrophilic medication is sufficient to include the extra lean mass. Non-depolarizing neuromuscular blocking drugs can be dosed in this manner.

In morbidly obese patients, the induction dose of propofol can be calculated on IBW.

In case of midazolam, prolonged sedation can occur from the larger initial dose needed to achieve adequate serum concentrations. #TheLayMedicalMan

Remifentanil dosing regimens should be based on IBW or LBW and not on TBW.

When using succinylcholine in obese adults or adolescents, dosage should be calculated on TBW

The antagonism time of neostigmine has been shown to be independent of TBW and BMI. Therefore, TBW can be used to calculate the dose.

Ref:Association of Anaesthetists of Great Britain and Ireland. Peri-operative management of the obese surgical patient 2015. Anaesthesia 2015, 70, pages 859–876.

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ROBOTIC 🤖 PROSTATECTOMY: Anesthesia CONCERNS

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FACTS ABOUT THE SURGERY

There is a master console; surgeon sits here & controls the robotic surgical manipulator, once it has been docked

Robot is bulky and is positioned over the chest and abdomen

Patient is positioned in lithotomy with a steep Trendelenberg tilt

Needs immobility of the patient till the robot is undocked

Table position should not be altered until the surgical instruments are disengaged

Discharge may occur as early as within 24 hours after surgery

ADVANTAGES

Better continence & erectile function
Less pain and hence less analgesic requirements
Less blood loss
Shorter hospital stay

ANESTHESIA CONCERNS

Since immobility is very important, it can be established by continuous infusion of a non depolarizing muscle relaxant

As the procedure may take long time, it’s better to use agents with rapid offset

Because patient is positioned in steep head-down position

Ensure pressure points are protected adequately

Fluids are infused cautiously to reduce chances of cerebral and laryngeal oedema ( N.B.: Rule out cerebral oedema in case of delayed emergence )

As the position of the robot interferes with resuscitation, prior practice-drills and good communication are necessary to manage such a situation effectively

Epidural analgesia, if at all required, are used only postoperatively, as the steep head-down position will increase the risk of high block

Reference: Irvine M, Patil V. Anaesthesia for robot-assisted laparoscopic surgery. Contin Educ Anaesth Crit Care Pain. 2009; 9(4): 125–129.

#ProstateSurgery , #RoboticSurgery , #anaesthesia , #perioperative

KNOWN SECRETS! – COEXISTING ILLNESS AND ANESTHESIA

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1. The evaluation of risk factors, is for planning the anesthetic management, and will be of no use in predicting the outcome.
2. There is no justification for performing revascularisation purely to facilitate elective non cardiac surgery.
3. M.I. within the last 6 weeks, class iii-iv angina, decompensated heart failure, malignant arrhythmias, severe valvular heart disease, CABG/PTCA within the last 6 weeks constitute major Cardio Vascular risk factors for surgery.
4. Previous M.I. (>6weeks), class i-ii angina, compensated heart failure, T2 DM constitute intermediate C. V. risk factors.
5. Age > 70 years, uncontrolled systemic hypertension, arrhythmias, family h/o CAD, dyslipidemia, smoking, renal dysfunction, ECG abnormalities (LVH, RBBB/LBBB, ST segment anomalies) constitute minor C. V. risk factors.
6. Only emergency, life saving procedures should be performed during the first 6 weeks after a myocardial infarction (M. I.) and after CABG/PTCA with or without a coronary stent. The period between 6 weeks and 3 months are considered as a period of intermediate risk, when non urgent elective surgery should be postponed.
7. SURGICAL PREDICTORS OF INCREASED PERIOPERATIVE CARDIOVASCULAR RISK
(i) HIGH RISK (complication rate >5%)
#Emergency major to intermediate surgery, especially in elderly patients
#Aortic & major vascular surgery; and also peripheral vascular surgery
#Procedures involving: hemodynamic instability, long duration or large fluid/blood loss
(ii) INTERMEDIATE RISK (complication rate 1-5%)
#Carotid endarterectomy
#Head & neck surgery
#Abdominal/thoracic surgery
#Orthopaedic surgery
#Prostatectomy
(iii)LOW RISK (complication rate <1%)
#Endoscopic procedure
#Breast and superficial surgery
#Eye surgery
8. ACE inhibitors are withheld for 24 hours by some anesthetists.
9. Perioperative beta blockade should be continued for 72 hours postoperatively.
10. The gold standard for detecting intraoperative ischemia and assessing volume status & valvular function is TEE.
11. Most perioperative myocardial infarctions occur in the first 3 days postoperatively. Patients at risk for M.I. require effective analgesia and humidified oxygen therapy for atleast 72 hours after major surgery.
12. Severe hypertension (grade 3) has been associated with an increased incidence of perioperative hemodynamic instability, silent m.i. and arrhythmias; but evidence of a clinically significant increase in adverse outcome is lacking. The presence of endorgan damage due to hypertension is more important than the blood pressure per se.
13. Ideally the blood pressure should be maintained within 20% of the best estimate of preoperative pressure.
14. The treatment of arrhythmias produced by WPW syndrome includes Flecainide, Disopyramide, Procainamide and Amiodarone. Digoxin and Verapamil are contraindicated.
15. There is no evidence to suggest that, frequent ventricular ectopics or asymptomatic non sustained ventricuar tachycardia is associated with an increased incidence of perioperative M.I.
16. Sick sinus syndrome is associated with a high risk of thromboemboism and may be anticoaguated. If the patient is not having a permanent pacemaker, he/she needs a, temporary pacing wire inserted preoperatively.
17. Complete heart block, type ii second degree A-V block and lesser degrees of heart block, in the presence of symptoms or cardiac failure requires preoperative insertion of permanent or temporary insertion of pacemaker. Volatile agents prolong cardiac conduction and can worsen heart block. Atropine, Isoprenaline and facilities for external pacing should be kept ready.
18. ATRIOVENTRICULAR BLOCKS
(i) First degree block: P-R interval > 0.2 sec
(ii)Second degree block
Type I: progressive lengthening of PR interval, until conduction fails and a beat is dropped.
Type II: intermittent failure of AV conduction without preceding PR prolongation.
(iii) Third degree block
Complete dissociation of atria and ventricles as atrial impulses fails to be transmitted.
19. CHECKLIST FOR A PATIENT WITH PACEMAKER
a. Indication for pacemaker insertion
b. Mode of function of pacemaker
c. Functional status
d. Consider conversion of rate responsive pacemakers to fixed rate in the perioperative period.
e. Ensure use of only bipolar diathermy
f. If unipolar diathermy must be used, then the ground plate should be placed on the same site as the operating site, as far away from the pacemaker as possible. The frequency and duration of use should be minimised and the lowest possible current used.
g. MRI is contraindicated
h. Magnets should not be placed over pacemakers during surgery, as they have an unpredictable effect on the programming of modern pacemakers.
i. A backup pacing system, atropine, adrenaline, isoprenaline and a backup pacing system should be available, in case of pacemaker failure.
20. Anesthesia constitutes a significant risk in Hypertrophic Obstructive Cardiomyopathy. Patients will be having dynamic left ventricular outflow tract obstruction, often with secondary MR. They are prone to arrhythmias and sudden cardiac death. Look for an Ejection systolic murmur in auscultation and LVH in ecg. Confirmation is by ECHO. Avoid hypovolemia, vasodilatation and the use of catecholamines
21. Constrictive pericarditis poorly tolerate vasodilatation; especially at induction.
22. In valvular heart disease, antibiotic prophylaxis is especially required for dental surgeries and those involving instrumentation of upper respiratory tract and genitourinary system.
23. AORTIC STENOSIS
# Even an ejection systolic murmur in an asymptomatic patient also warrants careful preoperative examination/ ECHO, as symptoms tend to appear late in the disease only.
# Promptly treat tachycardia and AF.
# Maintain ventricular filling by avoiding hypovolemia and maintaining SVR.
# Vasodilatation may result in profound hypotension–> subendocardial ischemia and even sudden death.
# Aggressive treatment of hypotension is mandatory to prevent cardiogenic shock and/or cardiac arrest. Cardiopulmonary resuscitation is unlikely to be effective in patients with aortic stenosis because it is difficult, if not impossible, to create an adequate stroke volume across a stenotic aortic valve with cardiac compression.
24. AORTIC REGURGITATION
# Avoid vasoconstriction and bradycardia which increases the degree of regurgitation
# A mild tachycardia, moderate fluid loading, a degree of vasodilatation and avoidence of myocardial depression can improve the forward flow.
# Acute AR is a surgical emergency and may respond poorly to vasodilatation.
25. MITRAL STENOSIS
# Patients are prone to develop CCF and Pulmonary Edema.
# Atrial fibrillation is a trigger for acute deterioration; so should be treated preoperatively
# Avoid tachycardia, myocardial depression and excessive vasodilatation
# Hypovolemia compromises ventricular filling
# Fluid overload can easily precipitate pulmonary edema
# PCWP will be inaccurate in the presence of pulmonary hyperension. Avoid Nitrous oxide if there is evidence of pulmonary hypertension.
26. MITRAL REGURGITATION
# A mild tachycardia, a slight reduction in SVR and avoidance of myocardial depression are desirable.
# Avoid hypovolemia
27. There is little evidence that GA in ADULTS with URTI is associated with an increased risk of adverse respiratory events, although upper airway reactivity may be increased
28. In children with URTI, a higher incidence of adverse respiratory events have been demonstrated, but few of these adverse events result in postoperative sequelae. It has been suggested that surgery need not necessarily be postponed in children with mild URTI. Increased airway reactivity may persist for 4-6 weeks and if surgery is postponed, it should be for a period of at least 6 weeks.
29. In COPD, if the patient is having copious secretions, better to avoid anticholinergics, as it will impair the ability to clear secretions.
30. Even though regional anesthesia has the advantage of avoiding respiratory complications of GA, most patients, even those with quite severe COPD may be managed safely under carefully conducted GA.
31. Pressure Controlled Ventilation with a low respiratory rate and prolonged expiratory phase is suitable in COPD patients.
32. Epidural analgesia has been shown to decrease the incidence of postoperative pulmonary complications in thoracic and upper abdomnal surgery.
33. In patients with bronchial asthma, good depth of anesthesia, good muscle relaxation and i. v. Lidocaine can reduce the incidence of bronchospasm during intubation; topical lidocaine spray is not effective and may induce bronchoconstriction in some patients.
34. Circulatory disturbance during anesthesia and surgery may affect the absorption of subcutaneous insulin.

LAPAROSCOPIC MYOMECTOMY; INSIGHTS FOR THE ANESTHESIOLOGIST

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# Preoperative treatment with GnRH analogue to shrink the fibroid

# Surgeon may intraoperatively inject dilute Vasopressin ( 1 IU in 100 mL RL) to reduce bleeding. IV Vasopressin can cause raised BP, myocardial ischemia, arrhythmias etc

# Position: Dorsal lithotomy; steep Trendlenberg to move the bowel out of surgical field

# Surgical time :1-4 hours; EBL: 100-600 mL

# Complications:

Puncture of major vessel/ severe bleeding

Insufflation in the wrong place

Air Embolism

Need for conversion to laparotomy

Peroneal nerve damage from positioning

# Pain score : 4-6

ANAESTHETIC MANAGEMENT OF SURGICAL PROCEDURES UNDER ECMO

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The plastic components of the bypass circuit can sequester varying amounts of intravenous anesthetic agents resulting in unpredictable effects and side effects

Volatile anaesthetics are not usually available on ECMO circuits due to the difficulties in scavenging

Since anesthetic agents can alter preload and afterload, should be ready for volume replacement and administration of vasoactive agents

Should inform the perfusionist before changing the height of the surgical table, as this can alter the venous return to the ECMO circuit ( passive gravity assisted drainage)