CEREBRAL PHYSIOLOGY

A SORE STORY : THE PROPELLORS OF #INFLAMMATION

🔥The process of inflammation is maintained by 3 important mechanisms:

✔️Vasodilation 

✔️Increased capillary permeability 

✔️Migration of leucocytes

🔥WHO IS DOING THESE?

▪️PLASMA DERIVED MEDIATORS 

✔️BRADYKININ --> Vasodilation & Increased capillary permeability 

✔️COMPLEMENT MEDIATORS --> Mast cell degranulation --> Vasodilation & Increased capillary permeability + activate neutrophils and phagocyte migration 

✔️COAGULATION: Forms a protective clot over the injured area

✔️ FIBRINOLYSIS: Activates neutrophils & macrophages by Fibrin Degradation Products (FDP)

▪️CELL DERIVED MEDIATORS

✔️HISTAMINE (from basophils and mast cells) --> Vasodilation & Increased capillary permeability 

✔️LEUKOTRIENES (from basophils and mast cells) --> chemotaxis of granulocytes 

Ⓜ️NEMO> " leukoTRYenes TRY to catch granulocytes"

✔️TUMOR NECROSIS FACTOR (cytokine from macrophage) --> activates endothelial cells , enhances phagocytosis 

Ⓜ️NEMO> "TN(F)™ = F for 'Fagocytosis' TM= TNF is from Macrophages "

✔️CHEMOKINES are chemotactic #cytokines

✔️NITRIC OXIDE (from endothelial cells and macrophages) is a powerful vasodilator and smooth-muscle relaxant.

#anesthesia , #anaesthesia , #pathology , #exams , #MedicalStudents , #MedicalExams

The Life of P.I. (PERFUSION INDEX)🐾

🚤 Reduction of plethysmographic pulse wave amplitude (PPWA) has been proven to be a reliable method for detecting the IV injection of an exogenous vasopressor ( for e.g. The adrenaline in epidural test dose)

🚤 Currently, a numerical value has been added to new pulse

oximeters indicating the PPWA, termed the perfusion index (PI), to augment its clinical applicability.

🚤i.e. PI is the numerical value of the amplitude of the

plethysmographic pulse wave that is displayed on

many pulse oximeters.

🚤 Using pulse oximetry, a variable amount of light is absorbed by pulsating arterial flow (AC) and a constant amount of light is absorbed by nonpulsating blood and tissue

(DC). The pulsating signal indexed against nonpulsating signal and expressed as ratio is commonly referred to as the perfusion index

🚤 It depends on the distensibility of the vascular wall and the intravascular pulse pressure. Usually the effect of autonomic impulses upon distensibility is so strong that it predominates the opposite effect of pulse pressure.

🚤 Decreases in PI resulting from pain and other stressful stimuli are due to vasoconstriction of the finger arterial bed rather than changes in the pulse pressure

Reference: The Efficacy of Perfusion Index as an Indicator for Intravascular Injection of Epinephrine-Containing Epidural Test Dose in Propofol-Anesthetized Adults, Anesth Analg 2009;108:549 –53) 

ROBOTIC🤖 PROSTATECTOMY: #Anesthesia CONCERNS

🏈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.

Circle of Willis : #ShortNote ❗️

⭕️The #CircleofWillis is a vital arterial structure on the ventral surface of the brain that joins the two internal carotid arteries (ICAs) (two-thirds of the supply) with the two vertebral arteries to supply the contents of the cranium 

⭕️The vertebral arteries enter the cranial cavity through the foramen magnum and join to become the basilar artery, which supplies blood to the posterior portion of the circle of Willis. 

⭕️The internal carotid arteries enter the skull through the carotid canals and supply the anterior circulation of the brain.

⭕️After entering the skull, the ICA branches into two main vessels: the Anterior Cerebral Artery (ACA) and Middle Cerebral Artery (MCA).

⭕️The MCA supplies the lateral surface of the brain, traveling in the Sylvian fissure

⭕️The ACAs also originate from the ICA and run anterior and medially towards the midline, coursing over the corpus callosum, between the hemispheres in the longitudinal fissure, and supplying the medial aspect of the hemispheres as far back as the splenium. The anterior cerebral arteries are joined together by a single anterior communicating artery(ACom)

⭕️An ACA #stroke can result in paralysis or sensory loss of the legs, whereas a MCA stroke can result in loss of paralysis or sensory loss of the face and/or arms. A MCA stroke of the dominant hemisphere may injure the language centers and produce aphasia.

⭕️The two vertebral arteries lie on either side of the medulla and join anteriorly at the caudal border of the pons to form the basilar artery. 

⭕️The vertebral arteries give off the posterior inferior cerebellar artery(PICA), before joining to form the basilar artery

⭕️Another important single artery that is created by the merger of the two vertebral arteries is the anterior spinal artery.

⭕️The basilar artery gives rise to a number of important paired branches. Posterior to anterior, these are:  anterior inferior cerebellar artery(AICA), superior cerebellar artery(SCA).

⭕️The vertebral arteries supply the medulla via small, penetrating branches. 

⭕️The basilar artery supplies the pons through small penetrating vessels.

⭕️PICA supply the inferior surface of the cerebellum, as well as the lateral medulla

⭕️AICA supplies the anterior portions of the cerebellum and the lateral pons.

⭕️SCAs supply the cerebellum and lateral midbrain

⭕️The basilar artery gives rise to the posterior cerebral arteries (PCAs), which join the anterior part of the circle of Willis via the posterior communicating arteries(PCom). PCAs supply the occipital lobe and lateral midbrain 

⭕️The thalamus is supplied by perforators that originate from the tip of the basilar artery and the proximal PCA

⭕️Basilar artery strokes usually are fatal because they cause the loss of cardiac, respiratory, and reticular activating function. Patients who survive may have a clinical syndrome known as locked-in syndrome in which the patient cannot move as the ventral brainstem tracts (motor) are destroyed, but the sensory tracts (more dorsal) may be left intact. These patients are unable to move, speak, or communicate with the world, except by blinking and possibly through upgaze.

N.B.: VENOUS DRAINAGE

🔻The superior sagittal sinus lies along the attached edge of the falx cerebri, dividing the hemispheres, and usually drains into the right transverse sinus. 

🔻The inferior sagittal sinus lies along the free edge of the falx and drains via the straight sinus into the left transverse sinus (The straight sinus lies in the tentorium cerebelli.) 

🔻The transverse sinuses merge into the sigmoid sinuses before emerging from the cranium as the internal jugular veins.  

🔻Deeper cranial structures drain via the two internal cerebral veins, which join to form the great cerebral vein (of Galen). This also drains into the inferior sagittal sinus.  

🔻The cavernous sinuses lie on either side of the pituitary fossa and drain eventually into the transverse sinuses.

#Anatomy , #NeuroAnatomy , #BloodSupplyOfBrain , #Neurology , #NeuroAnesthesia , #NeuroSurgery , #NeurologyICU , #ICU

Paravertebral blocks

• A paravertebral block is essentially a unilateral block of the spinal nerve, including the dorsal and ventral rami, as well as the sympathetic chain ganglion. These blocks can be performed at any vertebral level. However, they are most commonly performed at the thoracic level because of anatomic considerations.
• They provide analgesia for ✔️Unilateral thoracic pain ✔️Rib fracture ✔️Refractory angina✔️Hyperhydrosis etc
• Usually a single level injection may cover less than four dermatomes
• Can be given under USG guidance or using a landmark technique 
• Point to be marked at a point 25 mm lateral to the spinous process of the level to be blocked
• After local anesthetic infiltration an 18 G epidural catheter is inserted to a depth, not greater than 35 mm till transverse process are hit (they are fairly superficial) and then the needle should be walked off the transverse process caudally, until it is 10mm deeper than the depth at which bone was initially contacted. (cranial walking of the needle increases the chance of pneumothorax)
• A loss of resistance to injection when the costotransverse ligament is passed is a clue to achieving of correct needle position,; but this is not as marked as the loss of resistance achieved during epidural insertion.
• If using a peripheral nerve stimulator, contraction of intercostal muscle or transverse abdominis may be elicited
• 3-5 mL of ropivacaine or levobupivacaine can be used per level. Addition of clonidine may prolong the blockade

reference: Deegan CA, Murray D, Doran P et al. Effect of anaesthetic technique on oestrogen receptor-negative breast cell cancer function in vitro. Br J Anaesth. 2009; 103(5): 685–690. Tighe SQM, Greene MD, Rajadurai N. Paravertebral block. Contin Educ Anaesth Crit Care Pain. 2010; 10(5): 133–137.

WHEN VENTILATOR GIVEs ALARM & SHOWS 'PATIENT-DEMAND IS HIGH' : #TroubleshootingVentilator

⁉️Check for causes: 

✔️Increased airway resistance- if so give bronchodilators

✔️Anxiety--> increased RR + muscle tension--> increased airway resistance  --> increased demand: Optimise sedation 

✔️Check for leaks in circuit and correct

✔️If flow rate seems too low: Set higher inspiratory flow rate or reduce inspiratory time especially if patient is showing tachypnea

✔️If Tidal volume or RR set too low: Increase it

🌵Double triggering or breath stacking can happen if inspiratory time set is lower compared to that of the patient and ventilatory demand is high: Try increasing the inspiratory time or change to pressure control modes

Mechanical Ventilation Facts

LOW FLOW #Anesthesia

🌧Low flow anesthesia allows for economy of volatile anesthetics, makes possible heating and humidification of gases and reduces environmental pollution 

🌧Sodalime contains 94% Calcium hydroxide, 5% Sodium hydroxide snd also Potassium hydroxide, Silica and dying agent

🌧 CO2 + 2NaOH --> Na2CO3 + water + heat

      Na2CO3 + Ca(OH)2 --> 2NaOH + CaCO3

..this sequence gets back Sodium hydroxide, back in the game💁♂️

🌧 1 Kg of Sodalime can absorb >120 L of CO2

🌧 Carbon monoxide which is a byproduct of protein metabolism can accumulate in the system, but levels are <4%

🌧 If there is intoxication by alcohol or poisoning by Carbon monoxide or severe diabetic ketosis, alcohol or CO or acetone from the expired gases, will recirculate and accumulate inside the system; so low flow anesthesia is contraindicated in such states

🌧 Prolonged anesthesia with sevoflurane may generate Compound A inside the system, which can cause acute tubular necrosis in rats at concentrations around 250 ppm, a dose that is nearly 200 times seen in clinical practice. So any proteinuria, glycosuria or enzymuria which does develop in such a context has not been shown to have any clinical significance, even in patients with proteinuria

Reference: Al-Shaikh B, Stacey S. Essentials of Anaesthetic Equipment, 2nd edn. Edinburgh: Churchill Livingstone, 2002; pp. 74–9 . Nunn G. Low-flow anaesthesia. Contin Educ Anaesth Crit Care Pain 2008; 8: 1–4. 

SJOGRENS SYNDROME-anesthesia implications ➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖

🏳️🌈Preoperative abnormalities

1. Symptoms of the sicca syndrome include dryness of the eyes and skin.

2. Check for associated RA, SLE, scleroderma, the polymyositis, polyarteritis nodosa, chronic active hepatitis, and Grave's disease.

3.Lung / airway : desiccation of the nose and bronchial tree, obstructive airways disease, interstitial lung disease

4.sensory / motor neuropathy may occur and CNS lesions have been described.

5.The patient may be taking corticosteroids or occasionally immunosuppressive agents.

🏳️🌈Anaesthetist's concerns

1. Sometimes gross swelling of the salivary glands may make mask anaesthesia difficult.

2.The problems of pulmonary disease, if present.

3.The dry eyes are susceptible to damage during anaesthesia.

4.Allergy to antimicrobial agents, particularly penicillin, cephalosporins and trimethoprim

Management

1. careful assessment of the primary disease, and of any pulmonary involvement.

2. Drying agents should be avoided if possible.

3. The eyes should be protected with pads.

4. Anaesthetic gases should be humidified.

5. Steroid supplements may be required.

6. Care should be taken when prescribing antimicrobial agents

#anesthesia , #anaesthesia , #anesthesiology , #anaesthesiology , #PerioperativeCare , #comorbidities , #PreAnestheticCheckup , #PAC

BIOSTATISTICS FOR MEDICAL STUDENTS : TYPES OF DATA

POSTOPERATIVE VISUAL LOSS

👀 Corneal abrasion is the most common ocular complication after general anesthesia

👀 Ischemic Optic neuropathy (ION) and Central Retinal Artery Occlusion (CRAO) are the commonest causes for postoperative visual loss

👀 ISCHEMIC OPTIC NEUROPATHY (ION)

🌵More common among the two

🌵Most often seen after prolonged surgery in prone position 

🌵Venous congestion--> Raised Intra Ocular Pressure (IOP) due to Raised Intra Orbital Pressure --> Intra Orbital ‘Compartment Syndrome’

🌵Hypotension, Diabetes, Vascular disease, Smoking etc also may be important in the etiopathogenesis

🌵Treatment:

➖ Reduce optic nerve edema as it passes through posterior scleral foramen with steroids and mannitol 

➖ Optimal oxygen delivery by ensuring normal blood pressure and hematocrit  

➖ Clear all obstruction to venous drainage 

🌵Chance of visual recovery is less

👀 CENTRAL RETINAL ARTERY OCCLUSION (CRAO)

🌵 External pressure on eye and embolism are risk factors 

🌵 An echocardiogram and carotid ultrasound may help us to find an embolic source

Reference: White E, David DB. Care of the eye during anaesthesia and intensive care. Anaesth Intens Care Med. 2007; 8(9): 383–386.

SUGAMMADEX & DRUG INTERACTIONS

Sugammadex acts by forming a complex with steroidal Neuro Muscular Blocking Agents such as rocuronium and vecuronium and reduces their concentrations in the neuromuscular junction. 

Because of its inert structure, direct drug interactions are rarely expected with sugammadex. Two types of drug interactions may occur with sugammadex by displacement or capturing.

Drugs interacting with sugammadex by displacement : toremifene, fusidic acid, and flucloxacillin, could potentially affect the efficacy of sugammadex due to rocuronium 

or vecuronium being displaced from sugammadex.

Capturing interactions may occur if sugammadex binds with other drugs (i.e., hormonal contraceptives), and reduces their free plasma concentration. In addition, sugammadex might have decreased efficacy for rocuronium or vecuronium due to it binding with another 

drug.

Cyclodextrins have been reported to form inclusion complexes with other compounds.

In an in vitro experimental model of functionally innervated human muscle cells Rezonja et al. found that dexamethasone led to a dose-dependent inhibition of sugammadex reversal; but Ersel Gulec et al, who investigated the clinical relevance of the interaction between dexamethasone and sugammadex in humans failed to demonstrate any inhibitory effect of dexamethasone (0.5 mg/kg) on the reversal time of sugammadex in children.

N.B.(DO YOU KNOW?): It is clearly demonstrated that dexamethasone attenuates rocuronium-induced neuromuscular blockade when administered 2 to 3 hours before the induction of anesthesia; but not when dexamethasone is given at induction

Reference: The Effect of Intravenous Dexamethasone on Sugammadex Reversal Time in Children Undergoing Adenotonsillectomy; Ersel Gulec, Ebru Biricik, Mediha Turktan, Zehra Hatipoglu and Hakki Unlugenc, April 2016 • Volume 122 • Number 4, anesthesia-analgesia

ANTIDEPRESSANTS; AS ANALGESIC Vs AS ANTIDEPRESSANT

💪🏼The tricyclic antidepressants prevent the reuptake of monoamines, including serotonin and noradrenaline, as both pathways are important in the pain propagation. So the mixed reuptake drugs work better than more selective drugs like SSRIs

💪🏼But serotonin-noradrenaline reuptake inhibitor antidepressants (SNRIs), for example, venlafaxine & duloxetine and the atypical antidepressant group, such as bupropion and mirtazapine are also effective for some chronic pain conditions and are increasingly used because of their improved tolerability

💪🏼The superiority of tricyclics, particularly clomipramine and amitriptyline, in the management of pain may be also explained by their additional action on sodium channels blockade ( which is an action that SNRIs do not exhibit.)

💪🏼The dose of amitriptyline to treat pain is much lower when compared to that needed to treat depression 

💪🏼The analgesic action has a faster onset, whereas antidepressant action takes weeks to start

💪🏼The sedative action of tricyclic antidepressants are helpful in treating the sleep disturbances associated with neuropathic syndromes. Nortriptyline is less sedative than amitriptyline.

#antidepressants , #analgesics , #PainManagement , #ChronicPain 

Reference: Medscape, Pharmacogenetics and Analgesic Effects of Antidepressants in Chronic Pain Management

Frédérique Rodieux; Valérie Piguet; Patricia Berney; Jules Desmeules; Marie Besson, Personalized Medicine. 2015;12(2):163-175. 

Ryder S A, Stannard C F. Treatment of chronic pain: antidepressant, antiepileptic and antiarrhythmic drugs. Contin Educ Anaesth Crit Care Pain 2005; 5: 18–20 . 

A TRAVELOGUE: The long journey of #Insulin

 ✔️Insulin is produced by beta cells of islets of Langerhans. 

✔️It is produced from the pro hormone, 'preproinsulin'® in endoplasmic reticulum. A portion of the structure is cleaved off✂️ and the remaining portion is folded with the help of C-peptide to form 'proinsulin'® 

✔️The C-peptide portion is then removed✂️ to form Insulin 

✔️This active 💪🏼Insulin is transported 🚛 via Golgi apparatus to cytoplasmic granules for exocytosis💦 into plasma

✔️Insulin then binds with its receptor on Insulin sensitive❣️ cells

 ✔️Insulin receptor 🎛 is a tetramer consisting of 2 alpha & 2 beta units. 

✔️Insulin binds to the alpha unit on the cell membrane, while the beta unit, which spans the cell membrane activates🔥 , tyrosine kinase™ and the second messenger system

✔️This activates🔥 cytoplasmic vesicles containing transport molecules🚤

✔️The vesicles fuse with the cell membrane to incorporate the transport molecules🚤 into the cell membrane, which facilitate the transport of glucose into the cell.

Ⓜ️NEMO> MECHANISM OF ACTION: INSULIN Vs GLUCAGON 

🔻Insulin binding to the receptor activates an intracellular second-messenger system via tyrosine kinase. 

🔻Glucagon binding to its receptor activates a G-protein second-messenger system via adenylyl cyclase.

"Insulin is TricKy"

"Glucagon is ACcurate"

#DiabetesMellitus , #endocrinology , #physiology , #pharmacology , #biochemistry , #MedicalExam , #mnemonic , #anesthesia

BUSINESS HACKS: DEALING WITH PEOPLE IN BUSINESS

Medical Etymology : Terms & Root words

➰ Internist - Internus = inside (Latin)

➰Gynecologist- Gyne= woman , Logos = Science (Greek)

➰Obstetrician- Obstetrix = midwife (Latin), ician = expert

➰ Pediatrician - paidos= child , iatreia= medical healing , ician= expert (Greek)

➰Dermatologist - derma= skin (Greek)

➰Ophthalmologist- ophthalmos = eye , logos = science (Greek)

➰Anesthesia- an= without, aisthesis = sensation --> anaisthesia (Greek)

➰Neurologist - neuron = nerve , logos = science (Greek)

➰Geriatrics - geras = old age , iatreia = medical healing (Greek) 

➰ Psychiatry - psyche= mind , iatreia = medical healing (Greek) 

➰Cardiologist - kardia= heart , logos= science (Greek)

➰Orthopedist - orthos= straight, paidos= child (Greek) At the time of coining this word, correction of spinal curvature was a main concern among practitioners of Orthopedics

➰Orthodontist- orthos= straight , odontos= tooth(Greek)

HOMOCYSTINURIA : #Anesthesia IMPLICATIONS

⏫ There is increased(⏫) levels of homocystine and methionine in blood and urine due to the deficiency of Cystathionine B synthetase which catalyses the conversion of homocystine and serine into cystathionine

⏫ Raised cystine levels reduce the resistance of endothelium against thrombosis, reduces the activity of the vasodilator nitric oxide (NO) and increase platelet aggregation. So there is high incidence of thromboembolism. We have to ensure good hydration, good cardiac output,early mobilisation and should provide mechanical +/- pharmacological thromboprophylaxis. Many patients will be on anticoagulation. If untreated 50% of patients will have thromboembolic complications and the mortality is about 20% before the age of 30 years.  So both modification of the dosing of anticoagulants ( especially if regional anesthesia is planned) if patient is receiving them and providing prophylaxis against DVT are important elements of perioperative care. The incidence of thrombotic complications are more in pregnant patients. 

⏫ Blood viscosity and platelet adhesiveness can be reduced by dextran, and the prior administration of pyridoxine

⏫ Reduced cystine results in weak collagen and fragmentation of elastic tissue of large arteries. There is high incidence of vascular diseases like Cerebrovascular diseases, Coronary Artery Disease, Peripheral Vascular Diseases

⏫ Patients may have increased insulin levels resulting in hypoglycemia. Dextrose infusion will prevent hypoglycaemia.

⏫ Acute psychiatritc symptoms, delirium etc have been reported and the altered availability of homocysteine, methionine and cystiene which are having glutamate agonist properties, has been postulated as a factor which promotes this.

⏫ Regional anaesthesia has certain theoretical disadvantages. Penetration of a large epidural blood vessel might initiate thrombosis, as may the accompanying venous stasis of the lower limbs.

Reference: ANAESTHESIA DATABOOK, A Perioperative and Peripartum Manual, 3RD EDITION

Rosemary Mason

#anaesthesia , #dvt , #biochemistry ,

A FEW CLUES IN INTERPRETING AN ISOLATED PROLONGATION OF ACTIVATED PARTIAL THROMBOPLASTIN TIME (aPTT)

👆🏿aPTT tests the intrinsic and common pathways of coagulation 

👆🏿Though it is included commonly as a part of coagulation profile assessment, it's primary uses are to detect coagulation factor deficiency and titration of heparin therapy

👆🏿An isolated elevation of aPTT may indicate 

➖deficiency of Factor VIII or IX or XI or XII

➖acquired clotting factor inhibitors 

➖presence of Lupus anticoagulant 

👆🏿N.B.:- Factor VIII deficiency is Haemophilia A, Factor IX deficiency is Haemophilia B and Factor XI deficiency is Haemophilia C

👆🏿If factor levels are >30% of normal, aPTT may remain normal, for e.g. in mild von Willebrand disease [raised aPTT + prolonged Bleeding Time (BT)], in mild hemophilia etc

Reference: Martlew V. Peri-operative management of patients with coagulation disorders. Br J Anaesth. 2000; 85(3): 446–455.

MULTIPLE SCLEROSIS- ANESTHESIA IMPLICATIONS

# Most often, postop exacerbation, if it occurs is due to surgical complications like fever and infections

# Even minor increases in body temperatures are not tolerated well

# With the use of Suxamethonium, there is a risk of hyperkalemia

# Both resistance and prolongation of NMBA response are seen

# Complications have been reported with spinal anesthesia (Weak myelin sheath and direct neurotoxicity from LAs have been suggested as reason for this)

# Epidural is safe in this regard (As in epidural technique, there will be a lower concentration of LA in white matter)

# We should explain the chance of exacerbation of symptoms before any form of regional anesthesia

#multiplesclerosis , #anesthesia , #anaesthesia

A FEW FACTS ABOUT COAGULATION FUNCTION, IT’S MONITORING & #RegionalAnesthesia IN OBSTETRIC PATIENTS

🏳️🌈 During routine epidural or spinal anaesthesia, accidental puncture of epidural veins occurs in 1–18% of patients

🏳️🌈The incidence after epidural techniques is estimated to be in the order of 1:150,000 after epidural placement and 1:220,000 after spinal injection in the general population

🏳️🌈removal of epidural catheters posed an equal risk to insertion ( Van- dermeulen et al)

🏳️🌈Surgery on spinal haematoma should ideally be performed within 8–12 h of the identification of symptoms in order to improve the chances of recovery. 

🏳️🌈The overall risk of death in those having general anaesthesia for caesarean section was quoted in 2007 as being just over 1:25,000.

🏳️🌈The levels of factors VII, VIII and fibrinogen increase and those of anticoagulation factors decrease, causing augmented coagulation and decreased fibrinolysis.

🏳️🌈There is no evidence to support routine full blood count (FBC) or coagu lation tests in women before the performance of a regional block in those who have had  

🏴normal FBC results

🏴no bleeding history

🏴no signs or symptoms of liver disease

🏴no signs or symptoms of pre-eclampsia, abruption or clinical signs of disseminated intravascular coagulation

🏴no recent anticoagulant treatment.

🏳️🌈In women with known thrombocytopaenia, a Full Blood Count (FBC) should be checked within 24 h of a regional procedure. 

🏴In women with mild to moderate pre-eclampsia, the course of the disease can be unpredictable and so  FBC be checked within 6 h. In addition, coagulation tests should be performed if platelets are <100000/mcL or if there is abnormal liver function. 

🏴In severe disease, FBC and clotting should be checked immediately before a procedure, as platelet levels in particular can decline rapidly. 

🏴Women with pregnancy-induced hypertension alone do not require an FBC before a regional procedure

🏳️🌈Activated partial thromboplastin time ratio (APTTR) and international normalised ratio (INR) are slightly decreased in late pregnancy.

🏳️🌈In a patient who receives LMWH, if he/she is simultaneously taking NSAID+Aspirin, there is an increased risk if last dose of LMWH is between 12-24 hours; it further increases if last dose is <12 hours 

🏳️🌈In patients with pre-eclampsia and platelet count between 75000-100000/mcL, there is an increased risk even if coagulation tests are normal; but it increases further if the counts has not been stable (= decreasing platelet count)

#obstetrics , #anesthesia , #coagulation , #anaesthesia

Reference: Abnormalities of Coagulation and Obstetric Anaesthesia, Hilary Swales, AAGBI Core Topics in Anaesthesia 2015

🔃COMPATIBILITY IN BLOOD TRANSFUSIONS🔃: RBC Vs FFP Vs PLATELETS

COMPATIBILITY: RBC TRANSFUSION 

In red cell transfusion, there must be ABO and RhD compatibility between the donor’s red cells and the recipient’s plasma. 

All healthy normal adults of group A, group B and group O have ANTIBODIES IN THEIR PLASMA against the red cell types (antigens) that they have not inherited

Among the ABO blood groups: 

Group A individuals have antibody to group B

Group B individuals have antibody to group A

Group O individuals have antibody to group A and group B

Group AB individuals do not have antibody to group A or B. So,

1 Group O individuals can receive blood from group O donors only ( as the antibodies against A or B in their plasma will react with any A or B antigens which enter the circulation)

2 Group A individuals can receive blood from group A and O donors 

3 Group B individuals can receive blood from group B and O donors

4 Group AB individuals can receive blood from AB donors, and also from group A, B and O donors ( as their plasma don't have any antibodies against any antigens)

RhD RED CELL ANTIGENS AND ANTIBODIES

Individuals very rarely make antibodies against these antigens, unless they have been exposed to them (‘immunized’) by previous transfusion or during pregnancy and childbirth.

A single unit of RhD positive red cells transfused to an RhD negative person will usually provoke production of anti-RhD antibody. This can cause: in a subsequent pregnancy, rapid destruction of RhD positive red cells.

Haemolytic disease of the newborn (HDN):

An Rh D-negative mother may first encounter the D antigen while being pregnant with an Rh D-positive child, or by receiving a blood transfusion of Rh D-positive blood. Now the mother's immune response to the fetal D antigen is to form antibodies against it (anti-D.) The fetal red cells are haemolysed, causing severe anaemia. HDN due to ABO incompatibility is usually less severe than Rh incompatibility.

PLASMA TRANSFUSION: COMPATIBILITY 

In plasma transfusion, group AB plasma can be given to a patient of any ABO group because it contains neither anti-A nor anti-B antibody. 

1 Group AB plasma (no antibodies) can be given to any ABO group patients

2 Group A plasma (anti-B) can be given to group O and A patients 

3 Group B plasma (anti-A) can be given to group O and B patients 

4 Group O plasma (anti-A + anti-B) can be given to group O patients only

FFP does not need to be Rh-compatible  (However, the unit will still be labelled as Rh +ve or Rh −ve); anti-D prophylaxis is not necessary in Rh D-negative recipients of Rh D-positive FFP

PLATELET TRANSFUSION: COMPATIBILITY 

The Platelet Concentrates( PCs ) transfused must be ABO-identical, or at least ABO-compatible, in order to give a good yield. ( ( Ideally, ABO identical units should be used but, in an emergency, ABO non-identical units can be used, although the improvement seen in platelet count post-transfusion may be less.)

Group O PC can be used for patients with blood groups A, B, and AB ONLY IF,  they are resuspended in additive/preservative solutions, or if negative for high titre anti-A/A,B 

ABO-incompatible PCs have reduced efficacy and, preferably, should not be used 

 

Rh-negative patients, in particular women of childbearing age, should receive, if possible, RhD-negative PC 

 

In the case of a transfusion of a RhD-positive PC to a RhD-negative women of childbearing age, 250 UI (50 μg) of anti-D immunoglobulin should be administered, a dose able to cover the transfusion of five therapeutic doses of PC in 6 weeks 

ACUTE EMERGENCY : COMPATIBILITY 

During an acute emergency, the blood bank may send group O (and possibly RhD negative) blood, especially if there is any risk of errors in patient identification. This may be the safest way to avoid a serious mismatched transfusion, in such situations. 

Reference: The Clinical Use of Blood, Handbook, WHO,

 Recommendations for the transfusion of plasma and platelets Giancarlo Liumbruno, Francesco Bennardello, [...], and as Italian Society of Transfusion Medicine and Immunohaematology (SIMTI) Working Party

Succinylcholine aka Suxamethonium

 ⚗️Two molecules of acetyl choline joined together by the acetyl group forms Succinylcholine 

⚗️ It can be presented as chloride, bromide or iodide salt

⚗️ When presented as the chloride salt, it's a solution with concentration 50 mg/ mL

⚗️ When presented as bromide or iodide salts, they are powders, with more stability, shell life and suited for warm climates; but has to be reconstituted before use

⚗️ pH of the solution is around 4

⚗️ So they are destroyed by mixing it with alkaline solutions (e.g. Thiopentone )

Reference: Kestin I. Suxamethonium. Update in Anaesthesia 1992; 1: article 7.  Peck T, Hill S, Williams M. Pharmacology for Anaesthesia and Intensive Care, 3rd edn. Cambridge: Cambridge University Press, 2008; pp. 179–84 .

Visual Analogue Scale & Statistical Concerns

🔸A frequently used tool in anaesthesia research is the 100 mm visual analogue scale (VAS). 

🔸This is most commonly used to measure postoperative pain, but can also be used to measure a diverse range of (mostly) subjective experiences such as preoperative anxiety, postoperative nausea, and patient satisfaction after ICU discharge. 

🔸Because there are infinite possible values that can occur throughout the range 0-100 mm, describing a continuum of pain intensity, most researchers treat the resulting data as continuous. 

🔸If there is some doubt about the sample distribution, then the data should be considered ordinal.

🔸When small numbers of observations are being analysed (say, less than 30 observations), it is preferable to consider VAS data as ordinal. 

🔸For a number of practical reasons, a VAS is sometimes converted to a 'verbal rating scale', whereby the subject is asked to rate an endpoint on a scale of 0-10 (or 0-5), most commonly recorded as whole numbers. In this situation it is preferable to treat the observations as ordinal data.

🔸There has been some controversy in the literature regarding which statistical tests should be used when analysing VAS data. 

🔸Mantha et al surveyed the anaesthetic literature and found that approximately 50% used parametric tests. 

🔸Dexter and Chestnuts used a multiple resampling (of VAS data) method to demonstrate that parametric tests had the greater power to detect differences among groups. 

🔸Myles et al have recently shown that the VAS has properties consistent with a linear scale, and thus VAS scores can be treated as ratio data. This supports the notion that a change in the VAS score represents a relative change in the magnitude of pain sensation. This enhances its clinical application.

Reference: Statistical Methods for Anaesthesia and Intensive Care, Paul S Myles and Tony Gin

WHY ‘WORK HERE ONLY IF YOU WANT’ IS A BAD POLICY IN HEALTHCARE

🙍🏽♂️Some studies indicate that  the cost of turnover can average 150% of the employee's annual salary. 

🙍🏽♂️A staff, say an ICU nurse,  gets moulded, for the work pattern of  a particular ICU,  AFTER KEEN OBSERVATION OF 

🔃the course of various diseases that is commonly admitted in that ICU

🔃the pattern of other staff’s responses to various emergency situations which happens there commonly 

🔃the usual prescription pattern of the doctors there 

🔃the way of communication to caretakers followed in that ICU

🔃the medicolegal issues unique to that ICU etc. 

…FOR A LONG PERIOD OF TIME

🙍🏽♂️Many patients avoid a hospital because of inappropriate care resulting from ’too volatile’ staff pool (e.g. lack of awareness of a new nurse about patient’s requirements in a particular ward, a new doctor who doesn't communicate with nursing team unlike the previous person which may translate into poor awareness of the nursing team about the management plan and less confidence in them while talking to the caretakers etc)

🙍🏽♂️When employees leave, their duties are shifted to the remaining personnel who feel obligated to shoulder the additional burden. This decreases the quality of work by the remaining staff, till a replacement comes.

🙍🏽♂️All patients prefer to be cared for by the same members of a healthcare team each time they require treatment because of the already established relationships between the patient and the treating team ( This may be more obvious in case of doctors; but in reality this is equally important in case of all other performing staffs. For e.g. Seeing the same well behaving and caring front reception staff every time, will boost the level of comfort in the patient as soon as he or she enters the hospital and will add to the reputation about the hospital )

🙍🏽♂️Such relationships are important in the success of the institution,  especially in the present scenario where the same treatment/care can be received from various similar healthcare facilities 

🙍🏽♂️Creating an organizational environment that is dedicated to the retention of talented personnel is the first step in reducing employee turnover. 

🙍🏽♂️Determining why employees are leaving an organization is an important part of developing an effective strategy. One way this information can be obtained is by conducting detailed exit interviews. 

🙍🏽♂️Some employees may truly enjoy their jobs, but eventually decide that the challenges associated with completing their assigned responsibilities are simply too much to bear. For example, nurses may be drowning in mundane paperwork that never seems to end. This could result in nurses feeling unsatisfied and unrewarded for their work. A solution to this challenge could be to implement a new digital technology that streamlines the paperwork process. Or, you could hire additional clerks to transfer some of the overwhelming responsibility away from the nurses.

🙍🏽♂️A strategy for retainment is to provide various opportunities for your employee’s to learn or improve within their field. Along with that, if your employees know that their hard work will eventually pay off in the form of a promotion, they are far more likely to stay with your organization in the long-run.

🙍🏽♂️With a strong reputation, a particular hospital  can better attract the best new employees and better retain the current employees. Such information regarding reputation will silently flow between healthcare professionals working in various hospitals and whenever a crisis develops in their present workplace, they will be tempted to move to such hospitals with good reputation. 

🙍🏽♂️In the long term, such a policy will result in the hospital retaining a pool of good doctors, nurses and other staffs and will help the institution stand strong in adversities and help it retain a big pool of very loyal ‘customers’(=patients) 

Reference: Radiol Manage. 2004 Jul-Aug;26(4):52-5.Employee retention: an issue of survival in healthcare. Collins SK1, Collins KS., Healthcare Recruiters International: 4 Ways to Increase Healthcare Employee Retention

A FEW PROSPECTIVE TECHNIQUES TO MEASURE ANALGESIA INTRA-OPERATIVELY

🤖Current electroencephalogram (EEG)-derived measures like BIS, provide information on cortical activity and hypnosis but are less accurate regarding subcortical activity, which is expected to vary with the degree of antinociception. 

🤖Efforts to develop methods for monitoring these subcortical activities produced a few indices, which may provide some use intra-operatively 

🤖Recently, the neurophysiologically based EEG measures of cortical input (CI) and cortical state (CS) have been shown to be prospective indicators of analgesia/anti-nociception and hypnosis, respectively. Composite Cortical State (CCS) is an alternate measure of CS.

🤖Composite Variability Index (CVI) is another recently developed EEG-derived measure of antinociception  based on a weighted combination of BIS and estimated electromyographic activity.

🤖CCS and BIS show strong correlations, suggesting that they behave similarly as indicators of hypnosis.

Reference: Comparisons of Electroencephalographically Derived Measures of Hypnosis and Antinociception in Response to Standardized Stimuli During Target-Controlled 

Propofol-Remifentanil Anesthesia, Mehrnaz Shoushtarian, Marko M. Sahinovic, Anthony R. Absalom, Alain F. Kalmar, Hugo E. M. Vereecke, David T. J. Liley and Michel M. R. F. Struys, anesthesia-analgesia, February 2016 • Volume 122 • Number 2

☹️FIBROMYALGIA- AN OVERVIEW 🙍🏻♂️

🦂Is a common chronic pain condition, characterised by 

🖌Pain ( Spontaneous, widespread , diffuse, worse in the morning, hypersensitivity to all painful stimuli, >3 months duration, 11 out of 18 defined tender points produce tenderness on digital palpation)

🖌 Sleep disturbances

🖌 Fatigue 

🦂Pathophysiology may include 

🖌dysfunction of descending inhibitory pathways 

🖌abnormal neurotransmitter release

🖌central sensitisation etc

🦂Tricyclic antidepressants ( like Amitriptyline 5-10 mg ) may be effective in fibromyalgia as they reduce pain & fatigue and improve sleep

🦂Other therapies used:

🖌 Pregabalin

🖌Gabapentin

🖌Newer MAO inhibitors like pirlindole

🖌TENS

🖌Acupuncture 

🖌Intravenous lignocaine

🖌Injection of trigger points

🖌Cognitive Behavioural Therapy

🖌Warm bath

🖌Complimentary therapies

#pain , #fibromyalgia , #PainManagement

Reference: Dedhia JT, Bone ME. Pain and fibromyalgia. Contin Educ Anaesth Crit Care Pain. 2009; 9(5): 162–166.

PIN INDEX AND COLOUR CODING

ANESTHETIC CONCERNS IN TRANS SPHENOIDAL PITUITARY SURGERIES

🐨 Pituitary tumours can be hypo or hyper secretory : so they may exhibit Cushingoid status or cortisol deficiency. Accordingly the anesthetist has to look for diseases which are associated with these conditions

🐨 During the Pre Anesthetic Check up (PAC), we should screen for the presence of factors affecting airway management, like

✔️ Macroglossia

✔️ Soft tissue hypertrophy

✔️Obstructive Sleep Apnea (OSA)

And also for other associations like

✔️ DM

✔️ Systemic Hypertension 

✔️ Ischemic Heart Disease

✔️ Heart failure

✔️ Pulmonary Hypertension 

 🐨 If there is cortisol deficiency ( can be diagnosed by short synacthen test) glucocorticoid supplementation should be continued peri-operatively.

🐨 The trans nasal trans sphenoidal approach offers better visibility and lesser incidence of postoperative Diabetes Insipidus (DI). NB: Both DI and SIADH can occur as postoperative complications; but incidence of DI is much higher (upto 50%) compared to that of SIADH.

🐨Trans nasal surgery requires oro-tracheal intubation, insertion of a throat pack to prevent blood going to trachea and stomach and infiltration of the nasal mucosa with local anesthetic and vasopressor ( by surgeon )

🐨 Establishment of an arterial line will help to intervene promptly during hemodynamic fluctuations that happens with infiltration or intense surgical stimulation 

🐨 Surgeon may request various 'helps' from the anesthesiologist to make the suprasellar part of the tumor prolapse down into the sella, like:

✔️ Insertion of a lumbar drain and letting out of CSF

✔️ Maintenance of hypercapnea (upto 60 mm of Hg)

✔️ Fluid administration

🐨 As the patient is positioned with upper part of trunk and head elevated, there is chance for venous air embolism

🐨 Use of short acting drugs facilitate a rapid and smooth emergence which will help in neurological assessment 

🐨 Presence of blood in pharynx, nasal packs and preexisting OSA, pose additional problems in managing the airway

🐨 We can't apply a nasal CPAP mask in such cases as it can cause pneumocephalus, meningitis and air embolism

Reference: Lim M, Williams D, Maartens N. Anaesthesia for pituitary surgery. J Clin Neurosci. 2006; 13(4): 413–418.

HOW Hb S BECOMES A VILLAIN IN SICKLE CELL DISEASE (SCD) ❓

✔️ Inherited as Autosomal Dominant (Ⓜ️NEMO> Sickle Cell Disease is a SAD disease; S=SCD, AD=Autosomal Dominant)

✔️ A single DNA base change ( Beta chain) causes SCD

✔️ DNA base change is Adenine for Thymine & the resultant amino acid change is Valine for Glutamic Acid ( Ⓜ️NEMO> Addition of bases other than Thymine results in Valueless Goods )

✔️ Thus Hb S is produced. As Valine is hydrophobic, the deoxygenated Hb is less water soluble and gets precipitated & polymerized inside the RBC

✔️ This polymerization slightly reduces the overall affinity for O2; otherwise the affinity for O2 is same for Hb A and Hb S

✔️ These changes also make the RBS more rigid and contributes to sickling and microvascular occlusion

✔️ Regarding hypoxaemia, HbS will precipitate at a PO2 of 5–6 kPa (37-45 mm of Hg). As venous PO2 lies in this range, in case of homozygous individuals having only abnormal Hb will have continuous sickling

✔️ Patients with sickle cell trait experience sickling at much lower partial pressures (2.5–4 kPa / 19-30 mm of Hg )

✔️ Sickledex test produces a turbidity and becomes positive even with a very small amount of Hb S: so it CAN NOT differentiate between homo & heterozygous states

Reference: Smith T, Pinnock C, Lin T. Fundamentals of Anaesthesia, 3rd edn. Cambridge: Cambridge University Press, 2009; pp. 234–5 

#Anesthesia , #hematology , #medicine , #SickleCellDisease

INTRACRANIAL PRESSURE (ICP) & IT'S MEASUREMENT

🔸The ICP waveform is a modified arterial pressure tracing

🔸 It has 3 peaks: P1, P2 & P3

🔸 P1 is a result of transmitted pressure from choroid plexus

🔸 The amplitude of P2 changes with brain compliance. If compliance is poor, amplitude will be high ( can even exceed that of P1) and vice versa

🔸P3 represents the dicrotic notch

🔸 Lundberg (A) or Plateau waves are steep rise of ICP to over 50 mm of Hg and lasting for 5-20 minutes; then it falls abruptly. Are always pathological and indicates significantly reduced compliance

🔸 Lundberg (B) waves are oscillations occurring every 1-2 minutes where ICP rises to over 20-30 mm of Hg from baseline in a crescendo manner. They are supposed to be result of altered cerebral (B)lood volume and altered tone of cerebral (B)lood vessels 

🔸 Lundberg (C) waves are oscillations whose amplitude is less than that of B waves and are supposed to result because of interactions between cardiac and respiratory (C)ycles. They occur also in healthy individuals 

METHODS OF MEASUREMENT OF ICP

 Intraventricular catheter - ventriculostomy represents the "gold standard" for pressure measurement

 

✔️Normally placed in the frontal horn of lateral ventricle 

✔️Allows therapeutic CSF drainage 

✔️Creates a pathway for infection 

✔️Potential for accidental venting of CSF

✔️Possible subdural haemorrhage or upward brain herniation 

✔️ Catheter obstruction & ventricular haemorrhage may occur 

 Subdural bolt 

✔️ "Richmond Screw" or "Leeds device" inserted through a burr hole & an opening in the dura & arachnoid remains intact

 

✔️connects via a fluid couple to a transducer 

✔️ less invasive 

✔️ may underestimate high ICP and damping is a problem

 Subdural catheter 

✔️ Usually subdural space over frontal lobe of non-dominant hemisphere is selected

✔️ Prone to signal damping and calibration drift 

✔️ Potential risk of infection 

✔️ Doesn't require penetration of brain tissue

 Intracerebral transducer 

✔️Inability to check zero calibration & drain CSF 

✔️ Risk of infection

✔️Less reliable

🔸The incidence of infection ~ 2-7% with monitoring ≥ 5 days

🔸The risks are slightly greater with dural penetration 

🔸The zero reference point of the transducer is usually taken as the external auditory meatus 

🔸 Rather than the waveform type, the important factors appear to be the degree and duration of ICP elevation