0
[postlink]http://tube.medchrome.com/2014/08/how-much-sleep-do-we-need-in-day.html[/postlink]
[starttext] Sleep is a necessity of body homeostasis. Inadequate sleep or sleep lapse can cause tremendous amount of consequence on brain and bodily performance. How many hours of sleep per day is required is a big question. The requirement is variable but on an average a normal human needs an 8 hour sleep. The video given below is self explanatory.

The hazards of Sleep deprivations- Read symptoms and signs of sleep deprivation.

 [endtext]

http://www.youtube.com/watch?v=SVQlcxiQlzIendofvid 

How much sleep do we need in a day?

0
[postlink]http://tube.medchrome.com/2011/05/tracheotomy-procedure-animation.html[/postlink]
[starttext]Tracheotomy and tracheostomy are surgical procedures on the neck to open a direct airway through an incision in the trachea (the windpipe). It is performed in emergency situations, in the operating room , or at bedside of critically ill patients. This procedure, technically called a cricothyroidotomy, should be undertaken only when a person with a throat obstruction is not able to breathe at all-no gasping sounds, no coughing-and only after you have attempted to perform the Heimlich maneuver three times without dislodging the obstruction.

Procedure
  1. Find the person's Adam's apple (thyroid cartilage).
  2. Move your finger about 1 inch down the neck until you feel another bulge. This is the cricoid cartilage. The indentation between the two is the cricothyroid membrane, where the incision will be made.
  3. Take the razor blade or knife and make a 1/2 inch horizontal incision. The cut should be about half an inch deep. There should not be too much blood.
  4. Pinch the incision open or place your finger inside the slit to open it.
  5. Insert your tube in the incision, roughly one-half to one inch deep.
  6. Breathe into the tube with two quick breaths. Pause 5 seconds, then give 1 breath every 5 seconds.
  7. You will see the chest rise and the person should regain consciousness if you have performed the procedure correctly. The person should be able to breathe on their own, albeit with some difficulty, until help arrives.

The term tracheostomy is sometimes used interchangeably with tracheotomy. Strictly speaking, however, tracheostomy usually refers to the opening itself while a tracheotomy is the actual operation.
[endtext]

http://www.youtube.com/watch?v=d_5eKkwnIRsendofvid

Tracheotomy Procedure with Animation tutorial

0
[postlink]http://tube.medchrome.com/2014/06/blackhead-or-comedone-removal-or.html[/postlink]
[starttext] Comedones are also called whiteheads and blackheads. Blackheads are open comedones, and whiteheads are closed comedones. Many people have them in their skin, but this severity of blackheads?
Watch this blackhead removal using special instrument. This video shows removal of big black heads from nasal area of an old patient, that slip out like live worms [endtext]
http://www.youtube.com/watch?v=KCKh0-vTRAEendofvid

Blackhead or comedone: Removal or extraction

0
[postlink]http://tube.medchrome.com/2010/11/nasal-myiasis-maggots-in-your-nose.html[/postlink] [starttext]This post includes a video of maggots in nose and the removal of maggots using ether.

Myiasis is the infestation of tissue with fly larvae, commonly referred to as maggots. Maggots infest nose, nasopharynx and paranasal sinuses causing extensive destruction and obvious deformity.

Treatment:
  1. Visible maggots should be picked up with forceps
  2. Instillation of chloroform water/ether and oil (liquid paraffin) kills them
  3. Nasal docuhe with warm saline is used to remove slough, crusts and dead maggots
  4. Avoid contact of the patient with flies by use of mosquito nets
  5. Nasal hygiene for prevention
For complete information about nasal myiasis: http://medchrome.com/minor/ent/nasal-myiasis-maggots-in-nose/

[endtext]
http://www.youtube.com/watch?v=UbYyOxbBAnkendofvid

Nasal Myiasis Removal Video

0
[postlink]http://tube.medchrome.com/2013/11/pulsus-paradoxus-correct-technique-of.html[/postlink]
http://www.youtube.com/watch?v=jTsjCZ9QxW8endofvid [starttext]

Systolic blood pressure normally falls during quiet inspiration in normal individuals. It is the accentuation of normal physiology where there is an inspiratory fall in systolic blood pressure more than 10 mmHg.

Pulsus paradoxus is defined as a fall of systolic blood pressure of more than 10 mmHg during the inspiratory phase. [Eur Respir J. 2012 Dec 6. Pulsus paradoxus. [Hamzaoui O Et Al]



Measurement:
1.Inflate the cuff beyond the point where you hear any Korotkoff sounds.
2.Slowly deflate the cuff until you start hearing any sounds. At the highest BP when you hear sounds intermittently (rather than with every heart beat), note the blood pressure. (This corresponds to the higher systemic blood pressure which is occurring during expiration).
3.Keep slowly deflating the cuff until you reach the highest BP in which you hear sounds every beat.
4.The difference between #2 and #3 is the “pulsus paradoxus.” If it is >10 mmHg, it is considered significant.

Cardiac causes
Cardiac tamponade
Pericardial effusion
Constrictive pericarditis
Restrictive cardiomyopathy
Pulmonary embolism
Acute myocardial infarction
Cardiogenic shock

Extracardiac pulmonary causes
Bronchial asthma
Tension pneumothorax

Early recognition of pulsus paradoxus can help to diagnose rapidly cardiac tamponade, assess the severity of acute asthma as well as its response to therapy. Its essential to have good clinical skill inspite of development of newer technology [endtext]

Pulsus Paradoxus- Correct technique of measurement

0
[postlink]http://tube.medchrome.com/2013/09/schirmers-test-i-ii-dry-eye-screening.html[/postlink]
[starttext]Indication: Evaluation of dry eye (Measures aqueous tear production)

Types:
1. Schirmer 1 (without anesthetic): measures baseline and reflex secretion
  • function of main lacrimal gland, whose secretory activity is stimulated by the irritating nature of filter paper
2. Schirmer 2 (without anesthetic): measures baseline secretion
  • function of accesory lacrimal glands (the basic secretors)
Materials required: 5 X 35 mm of Schirmer's strip or Whatman filter paper no. 41

Procedure:
  1. The eye is gently dried of excess tears
  2. The schirmer strip is folded 5 mm from one end and kept in the lower fornix at the junction of lateral 1/3 and medial 2/3 (do not touch cornea or lashes)
  3. The patient is asked to close the eyes.
  4. Tears in the conjunctival sac will cause progressive wetting of the paper strip.
  5. After 5 minutes, the filter paper is removed and the distance between the leading edge of wetness and the initial fold is measured, using a millimeter ruler.
Interpretation:
Normal: >15 mm
Mild-moderate Keratoconjunctivitis sicca (KCS): 5-10 mm
Severe KCS: <5 mm
<10 mm is considered abnormal in Schirmer 1 and < 5 mm in Schirmer 2
Causes of KCS:
  1. Idiopathic
  2. Congenial alacimia
  3. Xerophthalmia
  4. Lacrimal gland ablation
  5. Sensory denervation
  6. Collagen vascular disease: Sjogren syndrome, SLE, RA
[endtext]
http://www.youtube.com/watch?v=FX0uS9iMCXMendofvid

Schirmer's test I & II: Dry Eye Screening

0
[postlink]http://tube.medchrome.com/2011/04/how-to-draw-brachial-plexus-video.html[/postlink]
[starttext]
1. Write the Root values C5, C6, C7, C8 and T1 leaving almost equal space between the 2 consecutive points.

2. Join C5 and C6 like in the video to get image similar to greater than sign. Join C8 and T1 in the same manner. Leave C7 alone in between.

3. As demonstrated in the video, from green, blue and orange figures obtained from step 2, extend 3 curved parallel lines that drop into the same imaginary horizontal line.

4. From the end of the green line extend a line (brown) to the orange line slightly above the end of the orange line as shown in the picture below.

5. In between the green and blue line draw a cross touching both lines. Draw a branch from orange line on the blue line such that it meets the green line of the cross.

6. For branches and labelling, follow the video or picture.

Mnemonic: Real Teenager Drinks Cold Beer (R=Root, T=Trunk, D=Division, C=Cord and B=Branches)
[endtext]
http://www.youtube.com/watch?v=9E1eIAKLxNsendofvid

How to draw brachial plexus : Video

0
[postlink]http://tube.medchrome.com/2013/05/laryngeal-mask-airway-lma-insertion.html[/postlink]
[starttext]Originally designed for use in spontaneously breathing patients, it consists of a ‘mask’ that sits over the laryngeal opening, attached to which is a tube that protrudes from the mouth and connects directly to the anaesthetic breathing system. On the perimeter of the mask is an inflatable cuff that creates a seal and helps to stabilize it.

The use of the laryngeal mask overcomes some of the problems of the simple adjuncts:

  1. It is not affected by the shape of the patient’s face or the absence of teeth.
  2. The anaesthetist is not required to hold it in position, avoiding fatigue and allowing any other problems to be dealt with.
  3. It significantly reduces the risk of aspiration of regurgitated gastric contents, but does not eliminate it completely.

Relative contraindication: 

  1. Increased risk of regurgitation, for example in emergency cases, pregnancy and patients with a hiatus hernia. 

Technique for insertion of the standard LMA:

  1. The patient’s reflexes must be suppressed to a level similar to that required for the insertion of an oropharyngeal airway to prevent coughing or laryngospasm.
  2. The cuff is deflated and the mask lightly lubricated.
  3. A head tilt is performed, the patient’s mouth opened fully and the tip of the mask inserted along the hard palate with the open side facing but not touching the tongue.
  4. The mask is further inserted, using the index finger to provide support for the tube.
  5. Eventually, resistance will be felt at the point where the tip of the mask lies at the upper oesophageal sphincter.
  6. The cuff is now fully inflated using an air-filled syringe attached to the valve at the end of the pilot tube.
  7. The laryngeal mask is secured either by a length of bandage or adhesive strapping attached to the protruding tube.
  8. A ‘bite block’ may be inserted to reduce the risk of damage to the LMA at recovery.

[endtext] http://www.youtube.com/watch?v=rnTLqhd6cwkendofvid

Laryngeal Mask Airway (LMA) Insertion Technique

0
[postlink]http://tube.medchrome.com/2013/05/classification-of-seizure.html[/postlink]
[starttext] [endtext]Seizure is any clinical event caused by an abnormal electrical discharge in the brain, whilst epilepsy is the tendency to have recurrent seizures.

Classification:

A. Partial seizure: Focal, only part of cortex involved

  1. Simple: No loss of consciousness (LOC), no postictal state
  2. Complex: Postictal state present, LOC may or may not be present

B. Generalized seizure: Always associated with LOC, whole cortex is involved

  1. Absence (petit mal): Brief episode of nonresponsiveness to external or internal stimuli; motor tone is preserved
  2. Tonic–clonic (grand mal): Generalized convulsion - brief tonic phase (stiffening) followed by clonic phase (rhythmic jerking) 

http://www.youtube.com/watch?v=6zXFUIjY5xUendofvid

Classification of Seizure

0
[postlink]http://tube.medchrome.com/2013/01/intubation-procedure-video.html[/postlink]
[starttext]Indications:
1. Maintenance of a patent airway:

  • When an awkward intraoperative position is required (eg. lateral decubitus, prone, sitting)
  • When the airway is inaccessible (eg. during head and neck operations)
  • When difficulties with the face mask are anticipated (eg. in grossly obese or edentulous patients or those with unusual facial features).

2. Protection of the airway: from contamination by blood, pus, debris, or stomach contents

3. Controlled ventilation

Technique of laryngoscopy and Tracheal intubation:

1. Position: The patient is positioned supine with the head resting on a pillow, in the so-called 'sniffing the morning air position' (flexion of the lower cervical spine and extension of head at atlanto-occipital junction). The position aligns the oral, pharyngeal and laryngeal axis so that the pathway from the lips to the glottis is nearly a straight line.

2. Laryngoscopy: The laryngoscope is held in the left hand, whilst the right hand is used to stabilize the head and open the mouth. The laryngoscope is inserted into the right side of the patient's mouth avoiding the incisor teeth and pushing the tongue to the left. The tip of the blade is advanced in the midline over the back of the tongue until the epiglottis comes into view. The tip of Macintosh laryngoscope blade should be positioned above the epiglottis, into the vallecula (the space between the base of tongue and the epiglottis). The tongue and pharyngeal soft tissues are then lifted, pulling the epiglottis up without directly touching it, exposing the glottic opening. You should use your arm and shoulder to lift the laryngoscope handle in an anterior and forward direction (along the long axis of handle containing the batteries). The tendency to lever the laryngoscope against the upper incisor teeth or upper gum should be avoided to prevent trauma.



The Miller blade, which is straight, is less commonly used. The tip of Miller blade is passed beneath the laryngeal surface of the epiglottis and the epiglottis itself is then lifted to expose the vocal cords. There is more risk of trauma to the epiglottis and stimulation of the laryngeal surface of the epiglottis.

3. Intubation: The size of the tracheal tube used depends on the patient's age and body build. Usually an 8mm internal diameter cuffed tube is used for women and a 9mm tube for men. The tube is held in the right hand as one would hold a pencil and advanced through the oral cavity through the right corner of the mouth and then through the vocal cords. External pressure on the cricoid or thyroid cartilage may be required to help visualize the laryngeal inlet. The proximal end of the tube cuff is placed so that the cuff is below the vocal cords, and the length markings on the tube are noted in relation to the patient's lips. The cuff is inflated to obtain a seal in the presence of 20-30 cm H20 pressure of gas in the breathing system.



4. Verification of position of tube: The next step is to verify the position of the tracheal tube. The best method to determine the position of the tube is by detection of carbon dioxide in expired gas. It is possible for gas in the stomach to contain carbon dioxide but this will only be present in the first few 'breaths'. Visulaization of the end of the tube advancing through the vocal cords is also taken as a sign of correct palcement. However, tubes may be displaced after 'correct' insertion. Auscultation of both lung fields in the axilla and over the stomach may also be used to confirm correct placement, but is less reliable. Asymmetrical breath sounds may indicate that the tip of the tube lies in one or other of the main bronchi (usually the right_. The tube should be withdrawn until breath sounds are heard bilaterally.

Complications of orotracheal intubation include:

  • Injury to lips, tongue or teeth
  • Injury to larynx (especially the arytenoid cartilages and the vocal cords)
  • Tracheal mucosa tear
  • Sympathetic stimulation

Attempting laryngoscopy or tracheal intubation in lightly anesthetized patients who are not fully relaxed can result in laryngospasm, coughing and bronchospasm. The laryngoscope should be removed, face-mask ventilation should be continued and anesthesia deepened or more muscle relaxant given to achieve adequate conditions. A peripheral nerve stimulator can be used to ensure complete neuromuscular blockade before commencing laryngoscopy and intubation.[endtext]
http://www.youtube.com/watch?v=BRjN3kQZLRIendofvid

Intubation procedure: Video

0
[postlink]http://tube.medchrome.com/2013/04/brushing-technique-bass-and-modified.html[/postlink]
[starttext]There are 5 commonly used brushing techniques: Bass or modified bass, Charters, Modified Stillman, Rolling stroke and Modified stroke. While the rolling technique is commonly used by the children, Bass or modified bass is the commonest technique for the adults. 

Bass: 
  1. Hold the toothbrush sideways against your teeth with some of the bristles touching your gums.
  2. Tilt the brush so the bristles are at 45 degree angle and pointing at your gum line.
  3. Move the brush back and forth, using short strokes. The tips of the bristles should stay in one place, but the head of the brush should wiggle back and forth. You also can make tiny circles with the brush. This allows the bristles to slide gently under the gum. Do this for about 20 strokes or 20 circles. 
  4. Repeat for every tooth, on the insides and outsides.
  5. The toe bristles of the brush can be used to clean the lingual (tongue) surface of the anterior teeth.


Modified Bass:
  1. Follow all the steps of the Bass technique.
  2. After the vibratory motion has been completed in each area, sweep the bristles over the crown of the tooth, toward biting surface of the tooth.
Importance of these methods:
  1. Most effective in cleaning cervical 1/3 & beneath gingival margins
  2. Suitable for everyone – Periodontally healthy & periodontally disease
  3. Periodontal maintenance
  4. Cleanses sulcus (space between tooth and gums)[endtext] http://www.youtube.com/watch?v=LqCpZm6s_dEendofvid

Brushing technique: Bass and Modified Bass Methods

1
[postlink]http://tube.medchrome.com/2013/04/inferior-alveolar-nerve-block.html[/postlink]
[starttext]Inferior Alveolar Nerve Block (IANB) is a technique for dental anesthesia used to produce anesthesia of the mandibular teeth, gingival tissues of the mandible and the lower lip.


Nerves Anesthetized

  • Inferior alveolar (CN V3 branch)
  • Incisive
  • Mental
  • Lingual

Areas Anesthetized

  1. Mandibular teeth to the midline
  2. Body of the mandible, inferior portion of the ramus
  3. Buccal mucoperiosteum, mucous membrane anterior to the mental foramen (mental nerve)
  4. Anterior two thirds of the tongue and floor of the oral cavity (lingual nerve)
  5. Lingual soft tissues and periosteum (lingual nerve)

Indications

  1. Procedures on multiple mandibular teeth in one quadrant
  2. When buccal soft tissue anesthesia (anterior to the mental foramen) is necessary
  3. When lingual soft tissue anesthesia is necessary

Contraindications
  1. Infection or acute inflammation in the area of injection (rare)
  2. Patients who are more likely to bite their lip or tongue, for instance, a very young child or a physically or mentally handicapped adult or child



Advantages

  • One injection provides a wide area of anesthesia (useful for quadrant dentistry).

Disadvantages

  • Wide area of anesthesia (not indicated for localized procedures)
  • Rate of inadequate anesthesia (31% to 81%)
  • Intraoral landmarks not consistently reliable
  • Positive aspiration (10% to 15%, highest of all intraoral injection techniques)
  • Lingual and lower lip anesthesia, discomfiting to many patients and possibly dangerous (self-inflicted soft tissue trauma) for certain individuals
  • Partial anesthesia possible where a bifid inferior alveolar nerve and bifid mandibular canals are present; cross-innervation in lower anterior region

Symptoms

  1. Tingling or numbness of the lower lip (mental nerve)
  2. Tingling or numbness of the tongue (lingual nerve)

Signs

  1. Using an electrical pulp tester (EPT) and eliciting no response to maximal output (80/80) on two consecutive tests at least 2 minutes apart serves as a “guarantee” of successful pulpal anesthesia in nonpulpitic teeth. 
  2. No pain is felt during dental therapy.

Precautions

  1. Do not deposit local anesthetic if bone is not contacted. The needle tip may be resting within the parotid gland near the facial nerve (cranial nerve VII), and a transient blockade (paralysis) of the facial nerve may develop if local anesthetic solution is deposited.
  2. Avoid pain by not contacting bone too forcefully.


Text from: Handbook of Local Anesthesia (Malamed)
[endtext] http://www.youtube.com/watch?v=39kPPBbrM1cendofvid

Inferior Alveolar Nerve Block: Anatomical consideration and Technique

0
[postlink]http://tube.medchrome.com/2013/04/stages-and-process-of-wound-healing.html[/postlink]
[starttext]

1. Haemostasis (immediate): In response to exposed collagen, platelets aggregate at the wound and degranulate, releasing inflammatory mediators. Clotting and complement cascades activated. Thrombus formation and reactive vasospasm achieve haemostasis

2. Inflammation (0-3 days): Vasodilatation and increased capillary permeability allow inflammatory cells to enter wound, and cause swelling. Neutrophils amplify inflammatory response by release of cytokines; reduce infection by bacterial killing; and debride damaged tissue. Macrophages follow and secrete cytokines, growth factors, and collagenases. They phagocytose bacteria and dead tissue and orchestrate fibroblast migration, proliferation, and collagen production.

3. Proliferation (3 days-3 weeks): Fibroblasts migrate into the wound and synthesize collagen. Specialized myofibroblasts containing actin cause wound contraction. Angiogenesis is stimulated by hypoxia and cytokines and granulation tissue forms

4. Remodelling (3 weeks-1 year): Re-orientation and maturation of collagen fibres increases wound strength.

Text taken from Oxford Handbook of Clinical Surgery
Points to remember:
Maximum collagen production occurs at 20 days
Maximum wound strength at 3 to 6 months
[endtext]  http://www.youtube.com/watch?v=u7Ryg9nVFLIendofvid

Stages and process of Wound healing

0
[postlink]http://tube.medchrome.com/2013/04/stages-of-fracture-healing.html[/postlink]
[starttext]

1. Inflammation: Bleeding from fracture site and surrounding soft tissues creates a hematoma, which provides a source of hematopoietic cells capable of secreting growth factors. Subsequently fibroblasts, mesenchymal cells, and osteoprogenitor cells are present at the fracture site, and granulation tissue forms around the fracture ends. Osteoblasts, from surrounding osteogenic precursor cells, fibroblasts, or both proliferate.

2. Repair: Primary callus response occurs within 2 weeks. If the bone ends are not in continuity, bridging (soft) callus occurs. The soft callus later is replaced, via the process of enchondral ossification, by woven bone (hard callus). Another type of callus, medullary callus, supplements the bridging callus, although it forms more slowly and occurs later. The amount of callus formation is indirectly proportional to the amount of immobilization of fracture.

3. Remodeling: This process begins during the middle of the repair phase and continues long after the fracture has clinically healed (upto 7 years). Remodeling allows the bone to assume its normal configuration and shape based on the stresses to which it is exposed (Wolff's law). Throughout the process, woven bone formed during the repair phase is replaced with lamellar bone.

Text source: Miller Review of Orthopaedics
[endtext]
http://www.youtube.com/watch?v=VZF3xicLtTwendofvid

Stages of fracture healing

0
[postlink]http://tube.medchrome.com/2013/02/outbreak-investigation-basics.html[/postlink]
[starttext]Epidemic or outbreak is a significant rise of level of disease above the normal endemic level (expected level of disease in community). The steps in outbreak investigation are:



1. Prepare for fieldwork in advance: Literature review, decide role, team, equipments

2. Establish the existence of an outbreak:

  • Compare with previous weeks, months or years of same geographic area and time period
  • Excess may not be outbreak. It may be due to population change, media attention, improved screening, change in case definition, etc.

3. Verify the diagnosis, if possible

4. Define, identify and collect data on all cases

a. Case definition:

  • Must include personal information, place information, time information and clinical information
  • Types:
  • Possible (Suspected): Broadest definition
  • Probable
  • Confirmed (Definite): Tightest definition (A clinically compatible case that is not laboratory confirmed and is not epidemiologically linked to laboratory-confirmed cases)
  • Broad definition is needed in the beginning, so that cases aren't missed. It can be tightened later.

b. Identify all possible cases: surveillance data

c. Collect data on all possible cases: in relation to person, place, time and clinical features

5. Perform descriptive epidemiology

  • Person
  • Place (Spot map)
  • Time (Epidemic curve)

6. Develop a hypothesis

  • Include: What is known about likely pathogen, who is at risk, likely exposures, mode of transmission
  • Should be testable

7. Evaluate hypothesis

  • Comparative method: all cases having same symptoms, lab confirmation, etc.
  • Analytic method: attack rates, case fatality rates, relative risks, odds ratio, statistical significance testing (chi-square, p-value)

8. Refine hypothesis and execute additional studies if required

9. Immplement control and prevention measures

10. Communicate findings and prepare a report

A very good pictorial guide: http://dse.healthrepository.org/bitstream/123456789/80/1/Obi%20Guide.jpg

Some terms:

  • Index case: First person to come to attention to public health authorities
  • Primary case: Acquiring disease from an exposure
  • Secondary case: Acquiring disease from exposure to primary case

[endtext]
http://www.youtube.com/watch?v=ug_JVEEV_TMendofvid

Outbreak Investigation Basics

0
[postlink]http://tube.medchrome.com/2013/02/physiology-and-effects-of-alcohol-on.html[/postlink]
[starttext]Alcohol can be regarded as a drug as it can cause physiologic addiction in all who consume it and may result in intoxication, tolerance or withdrawal.

Absorption and Elimination of alcohol:
  1. 20% in stomach and 80% in small intestine
  2. Can be detected in blood within 2-3 minutes of swallowing a few sips of whisky or beer
  3. A single bolus of alcohol taken into an empty stomach will be completely absorbed into portal bloodstream within 30-90 minutes
  4. As soon as alcohol enters the bloodstream, liver and kidneys will begin to eliminate
  5. 90% is eliminated by liver and 10% by kidneys, sweat and breath
  6. Chronic alcoholics with induced liver Cyt. P450 (until their liver fails) can metabolize alcohol at an abnormally high rate
  7. Normal rate of elimination for non-alcoholic: 10 to 25 mg/100ml/hr

Blood Alcohol Concentration (BAC): BAC expressed as mg/dl or mg% is the most useful measurement of alcohol, because the rapid equilibrtion of alcohol across Blood brain barrier (BBB) means that BAC reflects the concentration of alcohol currently affecting the brain.

Mathematically, BAC = Total amount of alcohol in body/ Total amount of body water

The factors increasing BAC are:

1. Decreased body water
  • Low body weight
  • Appreciable adiposity
  • Female gender
2. Faster absorption
  • Rapid drinking
  • Empty stomach
  • Food physically obstructs the contact of alcohol molecules with gastric mucosa
  • Food delays emptying through the pylorus
  • Optimum concentration of alcohol (around 20%)
  • Week drinks like beer have poor absorption
  • Strong spirits (>40% concentration) irritate gastric mucosa resulting in excess secretion of mucus (barrier), cause pyloric spasm and reduce gastric motility
  • Gastrectomy, Gastrojejunostomy
Effects of Alcohol on Brain:

Alcohol depresses the nervous system and any apparent initial excitant effect is due to suppression of inhibition by the cerebral cortex. It begins to act at lowest concentration upon the higher centers and it affect the lower centers of CNS only when BAC becomes higher. The correlation of BAC and physiologic effects have been correlated below:
  • 0 to 50 mg%: No significant effect or mild euphoria
  • 50 to 100 mg% (Cerebral cortex): Talkativeness, More self confidence, Reduced social inhibitions, Slight sensory disturbance, Poor judgement
  • 100 to 150 mg% (Limbic system): Exaggerated emotions and memory loss
  • 150 to 300 mg% (Cerebellum): Incoordination, unsteadiness, slurred speech, ataxia (Obvious drunkenness)
  • 300 to 400 mg+ % (Hypothalamus and Medulla): Stupor, Increased BP, Decreased temperature, Bradycardia, Respiratory depression, Coma, Death 
A person is likely to appear more uninhibited in a student party than in a very formal function given the same level of alcohol.
[endtext]

http://www.youtube.com/watch?v=zXjANz9r5F0endofvid

Physiology and Effects of Alcohol on Brain

0
[postlink]http://tube.medchrome.com/2013/02/postmortem-brain-dissection-autopsy.html[/postlink]
[starttext]A. Opening the Skull:
  1. Separate the hair and incise the scalp across the vertex from one mastoid process just behind the ear to another.
  2. Reflect the scalp forwards and backwards past the hairline. Note injury to skull or deeper tissues of scalp.
  3. Cut temporalis and masseter muscles on either side.
  4. Cut the calvarium with the saw in a slightly "V" shaped fashion. Remove the skull cap by inserting and twisting chisel at the sawline.
  5. Examine meninges and note extradural or subdural hemorrhage if any.

B. Removing the Brain:
  1. Open superior longitudinal sinus. Examine for antemortem thrombus.
  2. Cut dura along the sawline of skull and reflect towards the midline. Inspect the surface of brain.
  3. Retract the frontal poles and cut anterior attachments of falx cerebri (i.e cribiform plate).
  4. Elevate olfactory bulbs by inserting fingers between the frontal lobes and skull and drawing them backwards, retract the brain and cut: optic nerves, carotid arteries and other nerves.
  5. Retract brain medially and cut tentorial attachments along the petrous ridges.
  6. Retract brain posteriorly and cut remaining cranial nerves as close to bone as possible, vertebral arteries and spinal cord as distally as possible within the spinal canal.
  7. Retract cerebellum and brainstem. Support brain and cut remaining dural attachment with scissors. Remove the brain from the cranial vault.

C. Dissecting the brain:
  1. Brain can be fixed in 10% formalin to dissect later or it can be dissected at the moment.
  2. Remove brainstem and cerebellum by thin knife section across the the cerebral peduncle in a planes perpendicular to the brainstem and aqueduct. 
  3. Perform serial cross-section of the brainstem along the same plane and inspect for substantia nigra in medulla.
  4. Cerebellum may be sectioned in a plane parallel to the long axis of brainstem. Observe the vermis and dentate nucleus.
  5. Carefully inspect for surface vessels, cranial nerves, midline structures i.e. cingulate gyri, unci, mammilary body, pineal recess and the remaining part of brainstem.
  6. Use serial coronal section at about 1 cm interval for the dissection of cerebral hemispheres. Examine the corpus callosum, thalamus, internal capsule and basal nuclei.
[endtext]

http://www.youtube.com/watch?v=Otq74eW4ouEendofvid

Postmortem brain dissection (Autopsy)

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[starttext]A. Removal of Heart from the Body:
  • Check the pericardium, open it and explore the pericardial cavity.
  • Check the anatomy of great arteries before transecting them about 3 cm above the aortic and pulmonary valves.
  • Check and transect the pulmonary veins. Transect the superior venacava about 2cm above the junction of the crest of right atrial appendage and superior venacava (to preserve the sinus node). Transect the inferior venacava close to the diaphragm.
  • Remove the heart from the body.

B. Evaluation of coronary arteries:

Before beginning the dissection of heart, serial transverse transection at about 3mm intervals along the course of the main coronary arteries i.e. Left anterior descending artery, Right coronary artery and Left circumflex artery is performed using scalpel to visualize their patency. The obstruction of the coronary arteries can range from mild/grade I (>25%) to severe (70%) to critical/grade IV (>90%).


C. Dissection of Heart:

Many older methods (4 chamber method, Long axis method, Base of heart method, Window method, etc.) are impractical for routine diagnostic pathology. Only the inflow-outflow and short-axis (bread-slice) methods have withstood the test of time. Here we describe, the inflow-outflow method in which the heart is opened according to the direction of blood flow:

1. Right:
  • Open right atrium using scissors, from the inferior venacava (IVC) to the right atrial appendage. Spare superior venacava and SA node. Examine the atrial cavity and septum along with the atrioventricular valves.
  • Both the inflow and outflow cuts for the right ventricle are made about 0.5 cm from the ventricular septum, with either scissors or a knife from the right atrium to the ventricular apex through the tricuspid valve and then from apex to the pulmonary artery.
2. Left:
  • Open left atrium from a point between the right upper and lower pulmonary vein orifices to the tip of left atrial appendage.
  • In contrast to the right ventricle, the left ventricular inflow tract is opened not along the septum but rather along lateral wall between the mitral papillary muscles from the left atrium to the left ventricular apex.
  • From the left ventricular apex to the aortic valve, the outflow cut follows the junction, generally forming a gentle inverted S-shaped cut.
A combined approach of Inflow-outflow method and short-axis method can also be used as it allows for examination of infarcts along with ventricular chambers.


D. Measurements:
  • Total heart weight: 200gm-450gm normally (average 300 gm)
  • Circumference of atrioventricular valves (before opening ventricles): Normally, tricuspid valve admits 3 fingers and mitral valve admits 2 fingers
  • Wall thickness: Ventricles and septum (Thickness of normal left ventricle and right ventricle is less than 1.5 cm and 0.5 cm respectively). Wall thickness is measured at the level of papillary muscles.
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Postmortem Dissection of Heart (Autopsy)