The corneal reflex, also known as the blink reflex, is an involuntary blinking of the eyelids elicited by stimulation of the cornea. The purpose of this reflex is to protect the eyes from foreign bodies and bright lights (the latter known as the optical reflex)
The edge of cornea (limbus) is touched with a wisp of cotton, with the patient looking upward in the opposite direction
The nasociliary branch of the ophthalmic branch (V1) of the 5th cranial nerve (trigeminal nerve) sensing the stimulus on the cornea(afferent fiber).
The temporal and zygomatic branches of the 7th cranial nerve (Facial nerve) initiating the motor response (efferent fiber).
The centre (nucleus) in the pons of brain stem.
Use of contact lenses may diminish or abolish the testing of this reflex.
Response is brisk closure of both the eyes
Stimulation should elicit both a direct and indirect or consensual response (opposite eye). The reflex consumes a rapid rate of 0.1 second. The evolutionary purpose of this reflex is to protect the eyes from foreign bodies
Interpretation:
An absent corneal reflex may be due to
Sensory loss in Vi (e.g. neuropathy or ganglionpathy)
Weakness or paralysis of the facial muscles (myopathy)
Facial nerve (facial palsy, for example Bell's palsy)
Brain stem disease.
For a myopathy to cause a loss of the blink reflex the weakness has to be very severe, example chronic progressive external ophthalmoplegia (CPEO)
In endemic areas, the control of plague in humans is based
on the 2 main factors
·Reduction of the likelihood of being bitten by
infected fleas
·Exposure to infected droplets from either humans
or animals with plague pneumonia.
In the United States, residence and outdoor activity in
rural areas of western states where epizootics occur are the main risk factors
for infection.
How to assess the
potential risk of plague to human in specific area?
To assess potential risks to humans in specific areas,
surveillance for Y. pestis infection among animal plague hosts and vectors is
carried out regularly as well as in response to observed animal die-offs.
What are the personal
protective measures?
Personal protective measures is very essential include
avoidance of areas where a plague epizootic has been identified and publicized (e.g.,
by warning signs or closure of campsites).
Sick or dead animals should not be handled by the general
public.
Hunters and zoologists should wear gloves when handling
wild-animal carcasses in endemic areas.
General measures to avoid rodent fleabite during outdoor activity
are appropriate and include the use of insect repellant, insecticide, and
protective clothing.
General measures to reduce peridomestic and occupational
human contact with rodents are advised and include rodent-proofing of buildings
and food-waste stores and removal of potential rodent habitats (e.g., woodpiles
and junk heaps).
Flea control by insecticide treatment of wild rodents is an
effective means of minimizing human contact with plague if an epizootic is identified
in an area close to human habitation.
Control of rodents-Any attempt to reduce rodent numbers must
be preceded by flea suppression to reduce the migration of infected fleas to
human hosts. An oral F1-V subunit vaccine using raccoon poxvirus (RCN) as a
vector protects prairie dogs against Y. pestis injections and is being
investigated for efficacy in preventing disease in wild animals, hence
potentially reducing human exposure
Prevention of infection from suspected host
Patients in whom pneumonic plague is suspected should be
managed in isolation, with droplet precautions taken until pneumonia is excluded or effective
antimicrobial therapy has been given for 48 h.
The main infective risk
is posed by patients in the final stages of disease who are coughing up sputum
with plentiful visible blood and/or pus.
Cotton and gauze masks were protective in these circumstances.
Current surgical masks
capable of barrier protection against droplets, including large respiratory
particles, are considered protective; a particulate respirator (e.g., N95 or
greater) is not required.
Antimicrobial Prophylaxis
Postexposure
antimicrobial prophylaxis for 7 days is
recommended following household, hospital, or other close contact with persons
with untreated pneumonic plague. (Close contact is defined as contact with a
patient at <2 m.) In animal aerosolinfection studies, levofloxacin and ciprofloxacin
are associated with higher survival rates than doxycycline
Immunization studies with candidate plague vaccines in animal models show that neutralizing antibody provides protection against exposure but that cell-mediated immunity is so critical for protection and clearance of Y. pestis from the host.
There is 2 vaccine whole cell vaccine and live attenuated vaccine
A killed whole-cell vaccine used in humans as many disadvantages
Required multiple doses
Caused significant local and systemic reactions
It failed to give protection against pneumonic plague
This vaccine is not currently available in the United States.
A live attenuated vaccine
Live attenuated vaccine based on strain EV76 is still used in countries of the former Soviet Union but has significant side effects. Live attenuated vaccines closest to licensure are subunit vaccines comprising recombinant F1 (rF1) and various recombinantV (rV) proteins produced in Escherichia coli, that are combined either as a fusion protein or as a mixture, purified, and adsorbed to aluminum hydroxide for injection.
This combination will protects mice and various nonhuman primates in laboratory models of bubonic and pneumonic plague and has been evaluated in phase 2 clinical trials. Special ethical considerations with controlled clinical studies involving plague in humans make prelicensure field efficacy studies unlikely.
In the United States, the FDA is hence prepared to assess plague vaccines for human use under the Animal Rule, using efficacy data and other results from animal studies as well as antibodies and other correlates of immunity from human vaccine recipients
Live attenuated Y. pseudotuberculosis and Salmonella strains expressing Y. pestis–specific antigens found to be protective in laboratory animal models of bubonic and pneumonic type of plague and it can be also delivered by the oral route.
There is also a wide variety of other delivery mechanisms for Y. pestis antigens are being explored.
Antigens other than F1 and V that can be added to subunit vaccines are being investigated. Advances providing impetus for exploration of these antigens are the following
The recovery of F1-negative Y. pestis strains from natural sources
The observation that F1 antigen is not required for virulence in primate models of pneumonic plague
Carotid artery is felt between the anterior border of the
sternocleidomastoid muscle, above the hyoid bone and lateral to the thyroid
cartilage.
Precautions while palpating the carotid artery
The carotid artery
should be palpated gently and while the patient is sitting or lying down.
Stimulating its baroreceptors with low palpitation can provoke severe
bradycardia or even stop the heart in some sensitive persons.
A person's two carotid arteries should not be palpated at
the same time. Doing so may limit the flow of blood to the head, possibly
leading to fainting or brain ischemia.
An alternate expansion and recoil of an artery as the wave
of blood is forced through it by the contraction of the left ventricle.
Arterial pulse is
felt by palpating a superficial artery that has a bone behind it.
Counting pulse is an indirect measure to assess heart rate.
Normally pulse rate is equal to heart rate.
Assessment of Pulse;
Pulse Rate
Pulse rate is the number of contractions over a peripheral
artery in 1 minute.
Regulated by the autonomic nervous system through cardiac
sinoatrial node
Parasympathetic stimulation
will decrease heart rate
Sympathetic stimulation
will increases heart rate
The normal heart rate in adult is ( 60 – 100 beat/min.)
Tachycardia defined as
rapid pulse rate , greater than 100 beat /min.
Bradycardia is
defined as pulse rate below 60 beats /
min. in adults.
The pulse rate may fluctuate and increase with exercise,
illness, injury, and emotions. Girls with age 12 and older and women, in
general, tend to have faster heart rates than do boys and men
Athletes, such as runners, may have slow heart rates in the
40's and experience no problems.
What are the factors that contribute to increase in pulse
rate
Pain.
Fever.
Stress.
Exercise
.
Bleeding.
Decrease
in blood pressure .
Medications
as adrenalin, aminophylline
Age; as
age increases, the pulse rate gradually decreases.
Exercise;
the pulse rate normally increase with activity
Fever;
the pulse rate increases in response to the lowered blood pressure which results from peripheral vasodilatation
associated with elevated temperature and because of the increased metabolic
rate.
Factors that may slow the heart rate
Rest .
Increasing
age.
People
with thin body size .
Medication
as ( digitalis ).
Thyroid
gland disturbances .
Assessment of Rhythm of pulse:
Rhythm refers to the pattern of beats ,the interval between
each beat should be identical. Normal Rhythm of pulse indicate that beats are identical in force and
separated by equal intervals.
Abnormalities in pulse Rhythm: - An irregular pulse rhythm
is called arrhythmias.
Intermittent pulse: a type of irregular pulse where a
beat dropped either irregular or regular i.e. each 4 beats there is a dropped
beat or in the form of periods of normal rhythm broken by periods of abnormal
rhythm.
Bigeminal; It consists of two regular beats followed by a
longer than normal pause with no beat, and then two regular beats again
followed by a pause
Facial pulse: located on the mandible (lower jawbone) on a
line with the corners of the mouth (facial artery).
Temporal pulse: located on the temple directly in front of
the ear (superficial temporal artery)
The facial artery, about an inch forward of the angle of the
jaw.
The subclavian artery behind the inner end of the clavicle
against the first rib
The internal maxillary artery- in front of and slightly
below the ear
Pulse in the upper limb
Axillary pulse: located inferiorly of the lateral wall of
the axilla
Brachial pulse: located on the inside of the upper arm
near the elbow, frequently used in place of carotid pulse in infants (brachial artery) .The brachial artery, on
the inner aspect of the upper arm, about halfway between the shoulder and the
elbow.
Radial pulse: located on the lateral of the wrist (radial
artery). It can also be found in the anatomical snuff box. At the wrist, is
the most commonly used for palpating the pulse rate, because it is easily
accessible and it can pressed against the radius bone
Ulnar pulse: located on the medial of the wrist (ulnar
artery).
Pulse in Lower limb
Femoral pulse: located in the inner thigh, at the
mid-inguinal point, halfway between the pubic symphysis and anterior superior
iliac spine (femoral artery).
Popliteal pulse: Above the knee in the popliteal fossa,
found by holding the bent knee. The patient bends the knee at approximately
124°, and the physician holds it in both hands to find the popliteal artery in
the pit behind the knee (Popliteal artery).
Dorsalis pedis pulse: located on top of the foot,
immediately lateral to the extensor of hallucis longus (dorsalis pedis artery).
Tibialis posterior pulse: located on the medial side of
the ankle, 2 cm inferior and 2 cm posterior to the medial malleolus (posterior
tibial artery). It is easily palpable over Pimenta's Point.
How to check your pulse?
You feel the beats by firmly pressing on the arteries, that
is located close to the surface of the skin at certain points of the body.
Place the tips of your index and middle fingers just
proximal to the patients wrist on the thumb side, orienting them so that they
are both over the length of the vessel.
Push lightly at first, adding pressure if there is a lot of
subcutaneous fat or you are unable to detect a pulse. If you push too hard, you
might occlude the vessel and mistake your own pulse for that of the patient.
Measure the rate of the pulse (recorded in beats per
minute).
Count for 30 seconds and multiply by 2 (or 15 seconds x 4).
If the rate is particularly slow or fast, it is probably
best to measure for a full 60 seconds in
order to minimize the error.
Pulse: Regularity.Is
assessed by examining the time between beats ,if it is constant it is
regular
To delineate the upper border of liver dullness, you should percuss the anterior chest wall along right MCL from above downwards. Normally the upper border of liver dullness is present in right 5th ICS at MCL Lowered or obliterated of liver dullness is noted in
Emphysema.
Pneumothorax (right sided).
Perforation of abdominal hollow vtscus e.g. perforation of peptic ulcer.
Cirrhosis of liver (liver becomes small).
Visceroptosis of liver.
Elevated liverdullness :
Amoebic or pyogenic liver abscess.
Subdiaphragmatie abscess (right).
Pleural effusion (right).
Basal pneumonia (right).
Increased intraabdominal tension due to ascites or pregnancy.
The upper border of liver dullness is present in right 7th and 9th ICS when percussed along
midaxillary and scapular line respectively.
This is a direct percussion (clavicle acts as pleximeter finger): percussion is done by right middle finger.
Over the most prominent part of clavicle, or
Over the medial I /3 rd ol the clavicle, just lateral to its expanded medial end.
During percussion, stretch the overlying skin downwards with the left thumb so that the percussing finger does not slip over the clavicle. It is a light percussion.
