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Wednesday, February 4, 2015

ANESTHETIC MANAGEMENT OF PATIENT, WITH HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY

Tachycardias from emotion, exercise and pain, and drugs such as digoxin and beta stimulators, will all increase the outflow tract gradients and may considerably reduce the cardiac output to essential organs, such as the myocardium and brain.Preoperative beta blockers should be maintained.(Patients are often already taking beta blockers to prevent tachycardias.)

Hypotension from blood loss, regional anaesthesia, or vasodilator drugs, cause similar reductions in cardiac output and can worsen obstruction.Drugs and techniques that cause vasodilatation and hypotension must be avoided,contraindicated. However, with the greater ability to control the onset of epidural and by the use of continuous infusions and opiates, it has been suggested that regional blocks are no longer contraindicated. Hypotension should be treated by restoring vascular volume. If vasopressors are required, an alpha1agonist, such as phenylephrine or methoxamine, is the most suitable.

An adequate preload should be given and blood loss should be replaced promptly.

Monday, January 26, 2015

KNOWN SECRETS!-PREANESTHETIC CHECK

Y1. Two cardinal symptoms of cardiac illness are exercise intolerance and chest pain
2.Systemic illness in : ASA 2- not incapacitating , ASA 3- incapacitating, ASA 4- life threatening
3. Take history of syncope, seriously, as it may point towards undetected significant CVS issues.
4. Cardiac catheterisation is indicated in whom, a non invasive test is strongly positive or whose symptoms are unequvivocal.
5. Postponing of surgery is considered, ONLY IF, BP is consistently >180/110 mm of Hg
6. Preoperative administration of bronchodilators and topical application of local anesthetics , are some strategies practiced to reduce bronchospasm at induction, in asthmatic patients.
7.  TOTAL LUNG CAPACITY: reduced in RLD and increased in OLD
FORCED VITAL CAPACITY(4-5L): reduced in both OLD and RLD
FEV1(75% of FVC): reduced in both OLD and RLD
FEV1/FVC(>75%): reduced in OLD
PEFR(450-650L/min):<120L/min if severe obstruction
MVV(70-100L/min): index of total cardiorespiratory function
(OLD-Obstructive Lung Disease, RLD-Restrictive Lung Disease, F-Fibrosis)
8. Mallampati score
G1-all structures visible
G2-uvula obscured by base of tongue
G3-only soft palate
G4-only hard palate
Thyro Mental Distance >6.5cm is normal
Mallampati score + TMD provides a positive predictive value of upto 100%
9. Volatile agents other than halothane also may cause jaundice
10. Non Alcoholic Steato Hepatitis (NASH-comprises obesity, T2 DM and elevated blood lipids) is an advanced form of Non Alcoholic Fatty Liver Disease (NAFLD). Incidence of NAFLD is rising in the western world.
11. Child Pugh Grade B patients should be optimised preoperatively. Grade C patients should not undergo elective surgery if possible.
12. Look for the development of Hepatorenal syndrome in the jaundiced patient, document it, and consider prophylactic measures like mannitol administration.
13. Cirrhotic patients are at risk of hypovolemia and so, consider CVP monitoring.
14. Anticipate higher incidence of PONV in E.N.T. and Gynecological surgeries. If more than one among the following risk factors is present, a prophylactic antiemetic should be administered: 1) female gender 2) non smoker 3) h/o PONV or motion sickness 4) predicted opioid use
15. The obese patient is at risk of perioperative hypoxia, because of (a) hypoventilation and (b) restriction of diaphragmatic excursion. Volume of epidural space will be less, reducing drug requirement. NIBP cuff may overestimate BP; so consider IBP, if required.
16. If planning to give transfusion, complete it 24 hours prior to surgery
17. DVT PROPHYLAXIS :
Low risk- Compressive stockings/ Pneumatic Compression Device
Medium risk- +LMWH (e.g.20-40 mg ENOXOPARIN s/c )
High risk- +LMWH. Maintain anticoagulation with Warfarin.
18. Patients of African or Afro-Caribbean descent should be screened for Sickle cell disease, using a Sickledex test.
19. Malignant hyperthermia, is a preventable cause of anesthetic death. Ask for family history; the standard test is the in vitro sensitivity of striated muscle to caffiene and halothane.
20. Clonidine reduces requirements for volatile anesthetics.
21. The amnesia produced by benzodiazepines is anterograde and lasts for about 10 mins,  if given i.v. , but much longer after oral doses
22. Benzodiazepines potentiate propofol.
23. The dose of Flumazenil, the benzodiazepine antagonist, is 100-200 microgram iv, followed by 100-400 microgram/hr. S/E: tachycardia,  hypertension, seizures
24. Lorazepam : Oral dose 1-4 mg (30-50 ug/kg).  Duration : 4-24 hours.  Produces appreciable anterograde amnesia. Abolishes vasoconstriction that accompanies fear.
25. Diazepam: Oral dose : 10-20 mg,  duration : 4-8 hours,  When given in combination with metoprolol, its anxiolytic effect is greatly enhanced.
26. Patients with alcoholic liver disease are very sensitive to promethazine. Promethazine has antihypertensive property.
27. Complete vagal block requires a dose of 3 mg of atropine.
28. Atropine should be avoided in small children with pyrexia or sepsis ; may result in overdose and febrile convulsions can occur
29. Patients with Downs syndrome may show resistance to parenteral atropine
30. Antisecretory effect of atropine,  is much more pronounced, if given as i.m. 1 hour before,  than immediately before induction as i.v.
31. Hyoscine,  glycopyrrolate and atropine increases chances of regurgitation by relaxing cardiac sphinctor of stomach. 
32. Atropine crosses the placenta and can protect foetus from vagal reflexes.
33. Hyoscine butylbromide is a gi or urinary antispasmodic at doses, of 10-30 mg oral/i.v.
34. Hyoscine hydrobromide is a mild respiratory stimulant and an antiemetic at doses of 0.3-0.6 mg im.
35. Glycopyrronium bromide (dose: 0.2-0.4 mg  /  4-8 ug/kg) is a better, antisecretory agent than atropine and emergence is faster, than after giving atropine; is effective in  preventing bradycardia after suxamethonium; but has no antiemetic effect.
36. The treatment of Central anticholinergic syndrome is with Physostigmine salicylate (2mg iv); it can also be used to modify the psychotic side effects of ketamine.
37. For major surgery,  Lithium should be stopped 2 days prior, as it will potentiate NDMR; if case is posted as emergency, may have to consider regional anesthesia or suxamethonium. Hydrate well and take care of fluid, and electrolyte balance.
38. NON SELECTIVE MAO INHIBITORS :
# May react with pethidine, morphine and fentanyl and can cause fits, coma, muscle twitching, hypertension, ataxia and ocular paralysis. Deaths have occurred. Chlorpromazine (25 mg) has found to be effective, in treating this. Regional anesthesia,  NSAIDs and a combination of chorpromazine and codeine are choices for postoperative analgesia. Severe hypertension and even death may occur with administration of vasopressor drugs (even with adrenaline contained in local anesthetic preparations). Treatment is with phentoamine. So non specific MAO inhibitors should be stopped,  2 weeks prior to surgery.
39. SELECTIVE MAO INHIBITORS:
# The specific,  reversible MAO-A inhibitors (moclobemide) and MAO-B inhibitors ( Selegiline,  used in treatment of Parkinsonism) are less dangerous and can be continued upto the day before surgery; but caution is still needed; avoid pethidine and sympathomimetic agents
40. SSRIs may prolong the action of warfarin; fluvoxamine an SSRI, may reduce the metabolism of ropivacaine; otherwise SSRIs are relatively safe in the perioperative period.
41. To avoid the recurrence of severe Parkinsonism, dysphagia and the risk of aspiration pneumonia, antiparkinsonian drugs like levodopa should be continued upto the time of surgery.
42. During the perioperative period, in response to the stress, cortisol secretion from the adrenal cortex may rise upto 500 mg/day from the normal value of ~25 mg/day. This response cannot occur in patients on corticosteroid therapy, due to adrenal suppression. Even a one week course of steroids or inhaled steroids can cause this suppression. But <10 mg prednisone per day or equivalents,  has no effect. For higher dose therapy,  it requires extra hydrocortisone e.g. 25 mg at induction,  followed by 25 mg 6 hourly for 24-48 hours (48 hours for major surgeries). i.m. route gives more sustained release.
43. Combined Oral Contraceptive Pills, if possible,  should be discontinued 4 weeks before major elective surgery or leg surgery, and started again at the first menstrual period, following an interval of 2 weeks after the surgery, if the patient is fully mobile. If this is not feasible, prophylactic heparin/LMWH should be considered. Risk for DVT is higher in case of pelvic/cancer/orthopaedic surgeries, old age, smoking, obesity and factor V Leiden mutation.

Sunday, October 26, 2014

ANESTHESIA FOR ESOPHAGEAL SURGERIES

Approaches: Ivor Lewis (laparotomy and right thoracotomy, transhiatal (abdominal and neck incisions), left thoraco abdominal approach

Concerns:

Preoperative Chemotherapy
1. Less distinct tissue planes and increased bleeding
2. Bleomycin : pulmonary toxicity ; worsened by high oxygen concentrations
3. Doxorubicin: acute dysrhythmia, chronic cardiomyopathy

Incomplete Obstruction
1. Recurrent aspiration pneumonitis- decreased pulmonary reserve
2. Retained food products @ induction - increased risk of aspiration

History of smoking, alcoholism
1. Associated COPD
2. Alcoholic cardiomyopathy
3. If on antiplatelets for CAD, use of epidural may be contraindicated

Evaluation

1. CBC: check for infections
2. PFT-ABG-FLOW VOLUME LOOPS
3. CT/MRI- bronchoscopy; if required, to evaluate for presence of tracheal or bronchial compression
4. ECG, ECHO

Special points on Anesthetic technique

1. In thoracic or thoraco abdominal approach, placement of a DLT is indicated to provide OLV. If difficult airway, single lumen can be inserted first and then changed using a tube exchange catheter.
2. Surgeries involving only cervical or endoscopic approach don't require epidural
3. If epidural is planned placement and testing before induction is recommended
4. Significant third space loss : close monitoring of BP and Urine output
5. Transient compression of myocardium can produce dysrhythmia and hypotension : IBP will be helpful
6. PEEP- low tidal volume - low ventilator pressures can be lung protective strategies in OLV
7. Avoid excess fluids: anastamotic edema, pulmonary edema
8. Patients with significant intraoperative fluid shifts may develop airway edema- avoid premature extubation
8. If patient requires prolonged postoperative ventilation, DLT can be exchanged with single lumen tube, before shifting to icu.
9. Arrange platelets, ffp, cryoprecipitate etc.
10. CVP cannulation site should be determined by surgical approach
11. Prevent hypothermia
12. Take necessary precautions to avoid position related injuries; check radial pulse after placement of axillary roll. Can place pulseoximeter probe on down arm to check perfusion
13. Ensure normal potassium ( dysrhythmias)
14. Hypoxia during OLV : PEEP to ventilated lung, CPAP to non ventilated lung, return to double lung ventilation
15. Adequate BP is necessary for maintaining integrity of the anastamosis

16. POSTOPERATIVE

a. Recovery in head up position, ig risk of aspiration high
b. High index of suspicion for pneumothorax
c. Hoarseness = RLN injury
d.  SVT: adenosine. 6 mg iv push and repeat if needed to 12 mg ; AF - DC cardioversion, beta blockers, Amiodarone,  CCBs, pacing
e. DVT prophylaxis

Friday, September 12, 2014

Magnesium Sulphate therapy in preeclampsia


Continuous Intravenous Infusion
Magnesium sulfate 4-g to 6-g loading dose diluted in 100 mL fluid  administered intravenously over 15 minutes, followed by continuous intravenous infusion at 1 to 2 g per hour. Discontinue 24 hours after delivery or last seizure.
If convulsions persist after 15 min, give up to 2  gram more intravenously as a 20% solution at a rate not to exceed 1g/min. If the woman is large (> 70 kg) then an additional 2 grams may be given slowly
Only give the next IM dose, or only continue the IV infusion if:
Respiratory rate > 16/min
Urine output > 25 ml/h
Patellar reflexes are present
If urine output < 100 ml in 4 h and there are no other signs of magnesium toxicity, reduce the IV infusion to 0.5 g/h.
If patellar reflexes are depressed and respiration is normal, withhold further doses of magnesium sulfate until the reflexes return and request magnesium level.
If there is concern about respiratory depression , stop magnesium, give oxygen by mask and give:
Calcium gluconate (10mL of 10% solution over 10 minutes)
ACOG TASK FORCE 2013
... For women with severe preeclampsia, the administration of intrapartum and postpartum magnesium sulfate to prevent eclampsia is recommended.  For women with preeclampsia undergoing cesarean delivery, the continued intraoperative administration of parenteral magnesium sulfate to prevent eclampsia is recommended.

Saturday, September 6, 2014

ACUTE FATTY LIVER OF PREGNANCY : ANESTHESIA IMPLICATIONS


Presentation : Any pregnant patient in the late second or third trimester who has elevated liver enzyme levels, especially in the presence of hypoglycemia. Also if patient presents with altered mental status and altered liver function in the postpartum period.

Preop optimisation : early recognition of liver dysfunction and aggressive resuscitation and treatment of hypoglycemia, DIC, and other associated complications.

Check the drug chart of the patient.  Avoid / reduce dose of medications with substantial hepatic metabolism to prevent worsening encephalopathy

Consider reversal agents if the patient has received narcotics (ie, morphine)

If cesarean section is required, coagulopathy and thrombocytopenia should be corrected before surgery when possible

Anesthetist should be prepared for massive blood loss (eg, 2 large-bore intravenous catheters, blood products in room, fluid warmer and level 1 transfuser available, arterial line, and central line available).

Choice of anesthesia:
General anaesthesia may worsen or confuse the clinical appearance of encephalopathy.  Regional techniques, however, may not be appropriate in those patients with worsening coagulation, and waiting for correction of any coagulopathy could lead to further deterioration in clinical condition.  Regional anaesthesia can also cause hypotension and decrease hepatic blood flow.

If epidural analgesia is used for vaginal delivery, the epidural should be left in place until correction of coagulopathy.

High index of suspicion for epidural hematoma should be maintained :
Hourly neurological examinations and early surgical consultation should be made if deficits are identified.

Anaesthesia for Myelomeningocele Repair; Precautions to be taken

The timing of surgery, usually in the first 48 hours after birth, is important because an increased infection rate is associated with delayed surgery

Check electrolytes, RFT

Check for associated anomalies like Chiari II malformation, scoliosis, renal anomalies, congenital heart disease and short trachea (Take care to avoid endobronchial intubation)

Positioning of a baby with a huge lumbar mass, will require thick sheets under the shoulder and similar head rings, for intubation. If it is associated with a Hydrocephalus, it can further complicate the airway management.

Take care in prone position to avoid undue pressure over body parts..facial oedema can occur postoperatively

Warmer should be arranged to avoid hypothermia; control the O.R. temperature

Respiratory complications : hypoventilation, sleep apnoea, bronchospasm, laryngospasm, prolonged breath holding as a result of structural derangement of  medullary respiratory control

Cardiovascular complications: bradycardia, hypotension and tachycardia. Brainstem compression and coning causes most of the  cardiac complications including cardiac arrest when Chiari malformation is  associated with MMC.

Delayed recovery has to be anticipated...so arrange for postop ventilation ( Respiratory centre dysfunction, due to brainstem compression, if there, will again, increase the chance of requirement for post op ventilation)

Check for swallowing, gag reflex before extubation. Extubation should be performed only when the child is awake and breathing well.

Monday, August 25, 2014

DIAGNOSIS OF AMNIOTIC FLUID EMBOLISM

Lower mortality can be achieved (27-37%), when early duagnosis made, and aggressive treatment implemented

Typical : Patient healthy prior to the onset of symptoms

ONSET: During or within 30 mins of labor ,cs ,dilatation and evacuation

Most important features :
DYSPNOEA-HYPOTENSION-DIC

OTHERS: Foetal distress, Seizures, Pulmonary edema, Uterine atony, Bronchospasm, Transient hypertension, Cough, Headache

Friday, August 15, 2014

Pneumoperitonium and CVP


".. Anesthesia and the Trendelenburg position increased the CVP, PCWP and pulmonary arterial pressures and decreased cardiac output. Pneumoperitoneum increased these pressures further mostly in the beginning of the laparoscopy, and cardiac output decreased towards the end of the laparoscopy. The risk of systemic CO2-embolus was increased during laparoscopy."

Ref: Acta Anaesthesiol Scand. 1995 Oct;39(7):949-55.

Thursday, August 14, 2014

Supraclavicular Nerves

See the supraclavicular n., dat divides into medial n lateral br.s, supplies skin over deltoid..and skin over anterior chest

Lesser occipital, greater auricular, transverse cervical and supraclavicular nerves contribute to Superficial Cervical Plexus

Emerge from behind the midpoint of sternocleidomastoid

Blocking the superficial plexus

Short bevelled needle inserted posterior to midpoint of sternocleidomastoid

Injection immediately deep to superficial cervial fascia

Infiltration along posterior border of sternocleidomastoid superiorly and inferiorly

You can do it with USG also. Just behind SCM at its mid point most of the time EJV crosses. It's an added block to BPB in surgeries like clavicle fixation, AC joint fixation,shoulder repair etc

15 ml of lignocaine 1.5% or ropivacaine 0.75%

Complications
External or internal jugular vein injection

Femur fractures

SURGERIES AND BLOOD LOSS
Displaced # NOF: Hemiarthroplasty
Undisplaced # : Closed Reduction n Percutaneous Pinning
Intertrochanteric #,Sub trochanteric #: Dynamic Hip Screw
Shaft#: Intra Medullary Nailing
Expected bloodloss
Undisplaced..<100 ml
Displaced...250-500
Intertrochanteric 500+
Distal femur,shaft,im nail 750+