Retinoblastoma

Posted by e-Medical PPT Friday, October 20, 2017 0 comments

Most common primary, malignant, intraocular tumour of childhood  (1:20,000)
No sexual predilection
Presents before age of 3 years (average 3 months)
Heritable (40%) or non-heritable (60%)
Predisposing gene (RPE 1) on 13q14

Presentations of retinoblastoma
 Leukocoria - 60%
 Strabismus - 20%
 Secondary glaucoma
 Anterior segment invasion
 Orbital inflammation
 Orbital invasion

Poor Prognostic Factors in Retinoblastoma
Optic nerve involvement
Choroidal invasion
Large tumour
Anterior location
Poor cellular differentiation
Older children 
                              Retinoblastoma PPT

Ectopia Lentis

Posted by e-Medical PPT Wednesday, October 18, 2017 0 comments

Causes of Ectopia Lentis
1. Acquired -Trauma,Stretched zonules,Anterior uveal tumours,Degenerate eye
2. Isolated familial ectopia lentis
3. Associated with systemic syndromes
Marfan syndrome
Weill-Marchesani syndrome
Homocystinuria

Ocular features of Marfan syndrome
Upward subluxation
Angle anomaly and glaucoma
Retinal detachment
Cornea plana
Blue sclera

Weill-Marchesani syndrome
Microspherophakia
Usually anterior lens subluxation
Angle anomaly and glaucoma

Homocystinuria
Ocular features
Downward lens subluxation
Disintegration of zonule

                      Ectopia Lentis PPT

Complications of Cataract Surgery

Posted by e-Medical PPT Tuesday, October 17, 2017 0 comments

Operative complications
Vitreous loss
Posterior loss of lens fragments
Suprachoroidal (expulsive) haemorrhage

Early postoperative complications
Iris prolapse
Striate keratopathy
Acute bacterial endophthalmitis

Late postoperative complications
Capsular opacification
Implant displacement
Corneal decompensation
Retinal detachment
Chronic bacterial endophthalmitis


Iris prolapse
Cause
Usually inadequate suturing of incision
Most frequently follows inappropriate management of vitreous loss
Treatment
Excise prolapsed iris tissue
Resuture incision

Striate keratopathy
Corneal oedema and folds in Descemet membrane
Cause
Damage to endothelium during surgery

Acute bacterial endophthalmitis
Common causative organisms
Staph. epidermidis
Staph. aureus
Pseudomonas sp...

Benign Eyelid Lesions

Posted by e-Medical PPT Monday, October 16, 2017 0 comments

Nodules
Chalazion -Painless, roundish, firm lesion within tarsal plate
Acute hordeola -Tender swelling within tarsal plate
Molluscum contagiosum -Painless, waxy, umbilicated nodule
Xanthelasma
 Common in elderly or those with hypercholesterolaemia
 Yellowish, subcutaneous plaques containing cholesterol and lipid
 Usually bilateral and located medially

Cysts
Cyst of Moll
Cyst of Zeiss
Sebaceous cyst
Hidrocystoma

Tumours
Viral wart
Keratoacanthoma
Naevi
Capillary haemangioma
Port-wine stain
Pyogenic granuloma
Cutaneous horn
                   Benign Eyelid Lesions PPT

ACQUIRED CATARACT

Posted by e-Medical PPT Sunday, October 15, 2017 0 comments

ACQUIRED CATARACT
1. Classification of age-related cataract
Morphological
According to maturity
2. Other causes of cataracts
Diabetes
Myotonic dystrophy
Atopic dermatitis
Trauma
Drugs
Secondary (complicated)
3. Surgery
Large incision extracapsular extraction
Phacoemulsification

Classification of Age-related Cataract According to Morphology
1. Subcapsular Cataract
2. Nuclear Cataract
3. Cortical Cataract
4. Christmas tree Cataract...

Pathophysiology of hypercapnic and hypoxic respiratory failure

Posted by e-Medical PPT Thursday, May 14, 2015 0 comments

Respiratory Failure inadequate blood oxygenation or CO2 removal A syndrome rather than a disease
Hypoxemic PaO2 < 60 mmHg Hypercapnic PaCO2 > 45 mmHg

Hypercapnic respiratory failure
Decreased minute ventilation †
CNS disorders „
Stroke, brain tumor, spinal cord lesions, drug overdose †
Peripheral nerve disease
„ Guillain-Barresyndrome, botulism,
myasthenia gravis †
Muscle disorders
„Muscular dystrophy, respiratory muscles fatigue
Chest wall abnormalities „
Scoliosis, kyphosis, obesity †
Metabolic abnormalities „
Myxedema, hypokalemia †
Airway obstruction „Upper airway obstruction, Asthma, COPD

Ventilatory demand depends on
O2 demand
CO2production
dead space and minute ventilation

Ventilatory supply depends on
Respiratory drive
Muscle /neuron function
Respiratory mechanics

Use of One-Lung Ventilation for Thoracic Surgery

Posted by e-Medical PPT Tuesday, May 12, 2015 0 comments

Objectives
Indication/contraindication of OLV
Physiology changes of OLV
Selection of the methods for OLV
Management of common problems associated with OLV, especially hypoxemia

One-lung ventilation, OLV, means separation of the two lungs and each lung functioning independently by preparation of the airway
OLV provides:
Protection of healthy lung from infected/bleeding one
Diversion of ventilation from damaged airway or lung
Improved exposure of surgical field
OLV causes:
More manipulation of airway, more damage
Significant physiologic change and easily development of hypoxemia

Indication
Absolute
Isolation of one lung from the other to avoid spillage or contamination
Infection
Massive hemorrhage
Control of the distribution of ventilation
Bronchopleural fistula
Bronchopleural cutaneous fistula
Surgical opening of a major conducting airway
giant unilateral lung cyst or bulla
Tracheobronchial tree disruption
Life-threatening hypoxemia due to unilateral lung disease
Unilateral bronchopulmonary lavage...

Control of Respiration

Posted by e-Medical PPT Saturday, May 9, 2015 0 comments

Ventilation is constantly adjusted to maintain the homeostasis of bld gases and arterial ph
Variations of pao2 <3-4 mm hg and even less for paco2
To expend minimal energy in the work of breathing

Sensors
peripheral chemoreceptors
central chemoreceptors
pulmonary receptors
chest wall and muscle receptors

Peripheral chemoreceptors
carotid bodies
aortic bodies (significance ?)
bifurcation of common carotid
blood supply-external carotid
venous drain-int jugular
nerve supply- ix  nerve

Carotid body
rich blood supply(2l/100g/min)
utilizes dissolved o2 from blood unlike other tissues
senses changes in pa o2
hence not affected by conditions in which pao2  (n)
mild anemia
co poisoning..

Ventilation‐perfusion in health & disease

Posted by e-Medical PPT Thursday, May 7, 2015 0 comments

Distribution of ventilation Distribution of ventilation
•Spatial & anatomical variation
•Rate of alveolar filling
•Rate of alveolar emptying

Clinical relevance Clinical relevance
Perfusion is poor & pulsatile at apex
Pa& Pv proportionately increases from top to bottom
PA changes minimally with gravity
Pressures are max at bottom
Pulmonary edema starts at bottom
Redistribution of blood flow to apex –antler’s horn

Understanding V/Q relationships Understanding V/Q relationships
Consider lung as single unit
– Relationships between PAO2, PACO2, alveolar ventilation & pulmonary blood flow
–Alveolar gas equation
Consider lung as multiple units of varying V/Q
–Clinical consequences in health & disease

Alveolar PO and PCO Alveolar PO2 and PCO2
Determined by the ratio between ventilation and blood flow: V/Q
PO2and PCO2 are inversely related through alveolar ventilation
Increasing V/Q produces higher PAO2and lower PACO2
Decreasing V/Q produces lower PAO2and higher PACO2

Lung in extreme environments

Posted by e-Medical PPT Monday, May 4, 2015 0 comments

Introduction
Lung -First barrier between the body and its surrounding atmosphere.
Variousactivitiesexposehumanstodifferentenvironmentsinwhich Various activities expose humans to different environments in which the stresses are beyond our physiologic capabilities.
Extreme environments & the lung
Underwater
High altitude
Space

Extreme cold

Lung physiology in diving
Diving -Exposure to higher than normal ambient pressure.
Compression, isobaric, and decompression phases.
One atmosphere -760 mm Hg or 101.3 kPa.
One bar corresponds to a pressure of 750 mm Hg, 100 kPa, or 10 msw(Metres of sea water).
Depth of 30 msw-pressure of 4 bars
100 mswpressure equivalent of 11 bars.
4 bars / 30 msw, the fractional concentration of oxygen is still 0.21 but the partial pressure is 84 kPa

Pulmonary baro trauma(PBT)
Exposure to abrupt pressure changes. posuetoabuptpessuecages
IndividualsatriskofPBT-Astronauts,aviators, Individuals at risk of PBT Astronauts, aviators, compressed air workers, and divers.
Diving related PBT –Second among all causes of SCUBA diving fatalities.
PBT during descent of apnoeadive -Lung gg squeeze
PBT during ascent


Measurement of Lung Volumes and Airway Resistance

Posted by e-Medical PPT Sunday, May 3, 2015 0 comments

Introduction
lung volumes measured by spirometry are useful for detecting, characterising & quantifying the severity of lung disease
€Measurements of absolute lung volumes, RV, FRC g,, & TLC are technically more challenging --->limiting use in clinical practice
€Precise role of lung volume measurements in the assessment of disease severity, functional assessment of disease severity, functional disability, course of disease and response to treatment remains to be determined
Lung volume are necessary for a correct physiological diagnosis in certain clinical conditions
€Contrast to the relative simplicity of spirometric volumes variety of disparate techniques have volumes variety of disparate techniques have been developed for the measurement of absolute lung volumes
€Various methodologies of body plethysmography, nitrogen washout, gas dilution, and radiographic imaging methods

Basic Lung Volumes
Tidal Volume
The amount of gas inspired or expired with each breath
€Inspiratory Reserve Volume
Maximum amount of additional air that can be inspired from the end of a normal inspiration
€Expiratory Reserve Volume
The maximum volume of additional air that can be expired from the end of a normal expiration
€Residual Volume
The volume of air remaining in the lung after a maximal expiration
ƒThis is the only lung volume which cannotbe measred ith a spirometer

Physiology of ventilation & work of breathing

Posted by e-Medical PPT Saturday, May 2, 2015 0 comments

Goals of respiration
1.Ventilation
2.Diffusion of O2& CO2
3.Transport of O2& CO2
4.Regulation of respiration

Ventilation
Movement of air in & out of lungs the
    airways
    respiratory muscles
    dead space ventilation
Measurement of ventilation
The work of breathing
Importance in the ICU

Importance in the ICU
Measurement of WOB in ICU not routine
Until recently performed by physiologists>clinicians
Most ICU pts. are extubated < 96 hrs using standard weaning criteria
“advantages” of measuring WOB
  ensure pt.-vent synchrony
  aid to weaning
  comparison of diff. modes of MV

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