Thursday, February 4, 2016
Wednesday, February 3, 2016
FRONTO TEMPORAL (PTERIONAL ) CRANIOTOMY
Allows access to most aneurysms on lateral and anterior Circle of Willis vessels.
Internal Carotid : Paraclinoid / Superior hypophyseal artery
Internal Carotid : Ophthalmic artery
Posterior Commununicating Artery
Anterior Choroidal artery
Internal Carotid Bifurcation
Middle Cerebral Artery
Anterior Commununicating Artery
PTERIONAL / SUBTEMPORAL APPROACH
Upper Basilar Artery
Superior Cerebellar Artery
Posterior Inferior Cerebellar Artery
COMBINED SUBTEMPORAL AND SUBOCCIPITAL APPROACH
Tuesday, February 2, 2016
ANTI INFLAMMATORY PROPERTIES
✨BETTER THAN NAPROXEN :
✨FEWER SIDE EFFECTS
✨GREATER THAN IBUPROFEN
✨HIGH RISK OF RASH
✨DIARRHOEA & HEMOLYTIC ANEMIA
✨LOW G.I.; BUT HIGH C.V. EFFECTS
Medicines Optimisation Academy
British National Formulary
✔️Plasma sterilization requires an array of equipments
A chemical processor (to derive the plasma)
A closed chamber and deep vacuum ( for the creation of low temperature plasma)
A source of electromagnetic energy ( to create an electromagnetic field)
Hydrogen peroxide or a mixture of Hydrogen peroxide + per acetic acide can be used as the chemical disinfectant
✔️The electromagnetic field interacts with the chemical disinfectant to induce the plasma
✔️The resulting UV radiation causes rapid destruction of vegetative organisms including spores
✔️Examples of commercial plasma sterilizers : Sterrad 100S , Plazlyte
✔️Useful for sterilization of surgical instruments having long and narrow lumens
( e.g. Those used in urologic, laparoscopic and arthroscopic surgeries )
Hospital Associated Infections; Epidemiology, Prevention and Control , Nita Patwardhan
Friday, January 29, 2016
APPROACH TO PATIENTS WITH INTRACRANIAL ANEURYSM PERIOPERATIVELY; A FEW ANESTHETIC AND SURGICAL PRINCIPLES
✔️Risk factors for an aneurysmal SAH (aSAH) include female sex, African American ethnicity, first-degree relative with SAH, low HDL cholesterol level, hypertension, obesity, alcohol abuse, and tobacco use.
✔️For diagnosis,CT has the highest sensitivity during the first 3 days after the onset of bleeding; MRI has better sensitivity than CT after 3 days . Lumbar puncture can also confirm clinical suspicions of SAH.
✔️Risk of rebleeding is highest within the first 12 hours of initial rupture.
✔️Cerebral ischemia caused by rebleeding and cerebral vasospasm is the major cause of morbidity and mortality after aSAH. ( Hypovolemia and increased ICP heighten the chance of cerebral vasospasm )
✔️Vasospasm and DCI (Delayed Cerebral Ischemia ) are common after SAH and occur most frequently 7-10 days after aneurysm rupture.
✔️Induced hypertension to treat DCI is recommended if cardiac status allows and baseline blood pressure is not elevated.
✔️Early rebleeding has worse outcomes than later rebleeding
✔️General recommendations call for SBP <160 mmHg because of the risk of rebleeding; by administering nicardipine, labetalol, and esmolol to control hypertension when needed; and avoiding sodium nitroprusside.
✔️Although Nimodipine has not been shown to improve cerebral vasospasm by angiogram, it has decreased delayed ischemia and improved neurologic outcomes. Verapamil has been shown to improve neurologic outcomes without increasing ICP.
✔️Hemodynamic augmentation focus has shifted away from traditional triple H therapy toward maintenance of normovolemia and induced hypertension
✔️The Neurocritical Care Society recommends vasopressor therapy to augment blood pressure when necessary. Commonly used vasopressors include phenylephrine, norepinephrine, and dopamine.
✔️For a symptomatic vasospasm unresponsive to hypertensive augmentation, the AHA has deemed cerebral angioplasty and/or selective intraarterial vasodilator therapy reasonable.
✔️In the presence of vasospasm, intraaortic balloon pump therapy has been shown to successfully improve cardiac function and cerebral blood flow for patients with SAH and to reverse vasospasm-induced DCI
✔️️Erythropoietin has shown some promise in lowering the incidence of vasospasm and delayed cerebral ischemia
✔️Albumin has been shown to improve cerebral perfusion, has neuroprotective properties and minimal effect on coagulation
✔️Administering normal saline intravenously can help attenuate hyponatremia while maintaining appropriate normovolemia. Vasopressin is not commonly used as a vasopressor for patients with SAH because hyponatremia is seen associated with SAH and vasopressin has ability to further deplete blood sodium levels
✔️In the immediate post hemorrhage period , clinicians should consider using a short course (3-7 days) of anticonvulsant therapy prophylactically, while weighing the risks, including possible worse cognitive outcomes ( e.g. Phenytoin may worsen outcomes Ref: J Neurosurg Anesthesiol. 2011 Jan;23(1):35-40. doi: Adenosine-induced transient asystole for intracranial aneurysm surgery: a retrospective review.Guinn NR1, McDonagh DL, Borel CO )
✔️Elevated troponin levels ( not ECG changes) have been associated with increased mortality and disability at discharge. Because of possible cardiac dysfunction and its negative effect on outcomes, treatment of cardiac insufficiency should be considered. If cardiac dysfunction and/or myocardial injury are present, therapies like triple H therapy for vasospasm, must be weighed for their benefit vs risk
✔️When aneurysm obliteration is delayed, antifibrinolytic drugs such as aminocaproic acid or tranexamic acid have been shown to reduce the incidence of rebleeding
✔️Papaverine has been shown to reverse arterial narrowing, but it has not been shown to improve outcomes and its use is not recommended.
✔️The latest guidelines from the AHA/American Stroke Association recommend endovascular coiling as the preferred method of treatment for ruptured aneurysms that are amenable to both clipping and coiling. However, middle cerebral artery aneurysms are sometimes difficult to treat with coiling, so clipping might be a better option.
✔️The Neurocritical Care Society recommends maintaining hemoglobin between 8-10 g/dL and maintaining higher levels (up to 12 g/dL) for patients at risk for DCI
✔️Monitoring of cerebral function via cortical somatosensory evoked potentials (SSEPs) and brainstem auditory evoked potentials (BAEPs) can guide surgical cessation or application of temporary vascular occlusion (clipping) and can guide adjustment of blood pressure management for perfusion augmentation if cerebral ischemia is detected.
✔️During temporary clipping, induced hypertension may be requested and considered to increase cerebral perfusion pressure for the duration of the clipping, especially if the temporary clipping is to be longer than 120 seconds. Brief periods of temporary clipping of aneurysms have been shown not to affect outcomes, but the duration should not be greater than 15-20 minutes.
✔️Mannitol, Frusemide and Cerebrospinal fluid volume management via ventricular drains can facilitate creation of slack brain. ( N.B: abrupt ICP decreases and brain sagging can lead to rebleeding, reflex hypertension, bradycardia, and possible asystole, as well as significant clinical deterioration postoperatively.Acute volume drainage should not exceed 20-30 mL)
✔️Mild hyperventilation (30-35 mmHg PaCO2 with intact dura and 20-30 mmHg with open dura) can be employed to facilitate a reduction in brain-blood volume via cerebral vasoconstriction in patients with intact CO2 cerebrovascular activity
✔️Induced hypotension is not recommended, and the degree and duration of hypotension should be minimized because of the increased risk of neurologic deficits
✔️The Neurocritical Care Society recommends blood glucose levels <200 mg/dL and >80 mg/dL, compared to the old recommendation of levels <129 mg/dL.
Anesthetic Management of Patients with Intracranial Aneurysms
Alaa A. Abd-Elsayed, MD, MPH, Anthony S. Wehby, RN, MSN, and Ehab Farag, MD, FRCA
Connolly ES, Jr, Rabinstein AA, Carhuapoma JR, et al. Guidelines for the management of aneurysmal subarachnoid hemorrhage: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2012 Jun;43(6):1711–1737.
Rabinstein AA, Lanzino G, Wijdicks EF. Multidisciplinary management and emerging therapeutic strategies in aneurysmal subarachnoid haemorrhage. Lancet Neurol. 2010 May;9(5):504–519
Priebe HJ. Aneurysmal subarachnoid haemorrhage and the anaesthetist. Br J Anaesth. 2007 Jul;99(1):102–118.
✔️Can be measured by Fick Principle
✔️This states that the uptake/ release of a substance e.g. O2 (Vo2) by an organ is the product of the blood flow (Q) through that organ and the arteriovenous difference in content (Cao2-Cvo2)
✔️This is applied using Kety-Schmidt technique where 10% Nitrous oxide is inhaled for 10-15 minutes, and the jugular venous concentration is measured and assumed to be the same as the brain concentration
✔️Once CBF is determined, additional values like CMRO2 and vascular resistance may be derived.
✔️N2O offers significant advantages over other agents used for the measurement of CBF in that it is safe, stable, cheap, readily available and has a partition coefficient unaffected by varying levels of lipid and water and hence is unlikely to change with age or cerebral oedema.
✔️CBF calculated by this technique represents the mean blood flow from the area of the brain draining into the particular jugular venous bulb being sampled: i.e. the ipsilateral cerebral hemisphere. Therefore, the Kety–Schmidt method of CBF measurement is unable to discriminate between grey and white matter and is insensitive to regional changes in flow.
Ref: Textbook of Neuroanaesthesia and Critical Care, Basil F Matta
Of patients who have SAH from ruptured aneurysm, 5% to 10% will have one or more first-order relatives who have also had a ruptured aneurysm.
The inheritance is probably dominant with variable penetrance.
Conditions associated with intracranial aneurysms include 〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰
polycystic kidney disease (5% of aneurysms series, 33% of polycystic kidney series)
coarctation of the aorta (1% of aneurysm patients, 5% of coarctation patients, all of whom are hypertensive)
sickle cell disease
drug abuse (cocaine: generalized vasoconstriction and hypertension; intravenous use: mycotic aneurysms)
hypertension (30% to 40% of patients with SAH).
hereditary hemorrhagic telangiectasia
Ref: Handbook of Neuroanesthesia, 4th Edition, p:144
Thursday, January 28, 2016
Sterilant of choice for sterilizing heat labile medical equipment
e.g. plastic and rubber items, blankets,crude drugs and powders,glass ,metal, paper,fabrics
Also used for sterilizing heart-lung machines, respirators, sutures
Extremely penetrant, non corrosive,effective
Toxic, irritant, mutagenic and a suspected carcinogen
Explosive, except when mixed with other gases like Carbon dioxide or Nitrogen in the ratio 1:10 (require expensive equipment)
Usually used at 55-60 degree at about 33% humidity
Items to be sterilized should be clean and packaged with polythene or polypropylene (don't use nylon)
The sterilizing process should be monitored by spore tests +/- indicator tests
As ETO and its residues are toxic and irritant, materials exposed should be thoroughly aerated before use. Aeration at 55 degree greatly enhances elution of ETO
Control limit of exposure of individuals at work is 1 ppm ETO over an 8 hour time weighted averaged period
Irradiated articles should not be subsequently treated with ETO, unless they are known to be safe after such treatment
Hospital Associated Infections; Epidemiology, Prevention and Control , Nita Patwardhan , p:71-72
<Ⓜ️nemo : "POOR PreDICTOR"
P͞͞O͞͞O͞͞R͞͞ neurologic condition at hospital admission, a function of rate and volume of bleed
D͞͞epressed level of consciousness after initial bleed
I͞͞ncreased blood pressure
C͞͞irculation affected: if Basilar
T͞͞hick clot in the brain substance or ventricles on initial computed tomographic scan
Friday, January 22, 2016
Its a Neurokinin-1 receptor antagonist . NK-1 receptors are highly concentrated in the vomiting center of the brain and bind a neurokinin termed substance P; activation of NK-1 receptors by substance P plays a central role in eliciting chemotherapy-induced nausea and vomiting
Blocking the interaction of substance P at the NK-1 receptor, NK-1 receptor antagonists improve the management of nausea and vomiting
Comes in Tablet form (90 mg)
Indication: In combination with other antiemetic agents, to prevent nausea and vomiting associated with emetogenic cancer chemotherapy
Especially useful in preventing delayed phase chemotherapy induced nausea and vomiting
Highly emetogenic chemotherapy
Day 1: Rolapitant 180 mg PO 1-2 hr before chemotherapy PLUS dexamethasone 20 mg PO 30 minutes before chemotherapy PLUS 5HT-3 antagonist
Days 2-4: Dexamethasone 8 mg PO BID
Moderately emetogenic chemotherapy
Day 1: Rolapitant 180 mg PO 1-2 hr before chemotherapy PLUS dexamethasone 20 mg PO 30 minutes before chemotherapy PLUS 5HT-3 antagonist
Days 2-4: 5HT-3 antagonist
Contraindicated with the use of thioridazine ( risk of arrhythmias due to increased thioridazine levels)
Safety not established for pediatric use and in pregnancy
Decreased appetite (9%), Neutropenia (7-9%)
Rolapitant vs Aprepitant
Rolapitant has been studied as a one-time dose on day 1 of chemotherapy, while aprepitant is recommended to be given on days 1 through 3. Rolapitant does not inhibit CYP 2C9 or 3A4 enzymes, whereas aprepitant induces CYP 2C9 and 3A4 and moderately inhibits 3A4.3,4 As a result, aprepitant can interfere with warfarin, hormonal contraceptives, and certain chemotherapy, among other drugs.
Ref: WHO DRUG INFORMATION, VOL 29, number 3, 2015
Medscape Reference , http://reference.medscape.com/drug/varubi-rolapitant