What the Whites of your Eyes say about your Health

Abstract:

Medicine is an art. Some thinks that doctors always need modern investigations to diagnose diseases. That is not true. Almost all the diseases can be diagnosed only by taking a proper history and by carrying out a thorough physical examination.

Medicine is an art. Some thinks that doctors always need modern investigations to diagnose diseases. That is not true. Almost all the diseases can be diagnosed only by taking a proper history and by carrying out a thorough physical examination. Not only doctors but also fortune tellers, palm readers and people who tell about people’s lives have the knowledge and ability to gather information from what they see. There are certain parts of the body that give information more than any modern test can give. Your eyes play a leading role in that list.

Eyes of a person tell a lot about him. The eye is composed of several components. Each one of these components is very important to your vision. The white of the eye, also known as the sclera is one such part. The whites of the eyes tell a lot about your health. Most of the time, the color of the sclera is the most apparent change in relation to the underlying disease.

Muddy Sclera

Before going to know about the abnormal presentations of your eyes, you should know about the normal variations. Usually a healthy person has a pure white sclera, but not always. Some people sometimes can have light brown discoloration of their eyes. This is known as muddy sclera. Muddy sclera commonly occurs as a result of repetitive exposure to wind, dust and other physical and chemical insults. That does not indicate any serious underlying illness, but it says that you are carrying out a life that exposes you to a lot of dust, wind and sunlight.

Yellowish Discoloration

Yellowish discoloration of eyes, also known as icterus or jaundice always indicates an underlying disease. The eyes become yellow as a result of increased amount of bilirubin in your blood. Bilirubin is produced by breakdown of red cells. The initial molecules produced immediately after breakdown of red cells are called unconjugated bilirubin. Then these unconjugated bilirubin molecules are carried to the liver and the liver converts them in to conjugated bilirubin and excretes them in the bile. Any illness that increases red cell destruction or interferes with the above mentioned pathway results in increment of serum bilirubin levels. These excess amounts of bilirubin deposits in the sclera and make it look yellow. Some of the commonest causes of yellowish discoloration of eyes are hemolytic anemias (thalassemia, hereditary spherocytosis), hepatitis, Gilbert’s syndrome, Crigler Najjar syndrome, sclerosing cholangitis, carcinoma of bile duct, gall stones, carcinoma of the head of the pancrease etc.
Blue Sclera
Blue sclera is beautiful, but the underlying disease is not. People with diseases such as osteogenesis imperfect have blue sclera. Osteogenesis imperfect usually present at a very early age with recurrent bone fractures. The presence of blue sclera helps the physicians to come to a final diagnosis.
Bitot Spots
Bitots spots are characteristic of vitamin A deficiency. They appear as white or gray triangular or oval spots on the temporal side of the eye. Bitot spots are very rare nowadays because almost every child is given vitamin A supplements to help them maintain their tissue stores.

Scleritis and Episcleritis

Red eyes are sometimes due to scleritis or episcleritis. These two conditions are usually linked with connective tissue disorders such as rheumatoid arthritis. Sometimes they are associated with sero negative arthropathies such as ankylosing spondylitis.

Conjunctivitis

If your eyes have become red, teary and inflamed, you are having conjunctivitis. Conjunctivitis is inflammation of the sclera. It can be allergic conjunctivitis, viral conjunctivitis or bacterial conjunctivitis.

Subconjunctival Hemorrhage

Subconjunctival hemorrhage appears as a spot of bleeding. Sometimes it indicates base of skull fracture. Sometimes it is simply due to local trauma. The presence of posterior margin of the hemorrhage indicate that is only a local condition but if there is no posterior margin, it is most probably due to base of skull fracture.

Above mentioned are only an outline of most common disease conditions that causes changes in the whites of your eyes. There are many other rare disease conditions that give rise to changes in the sclera.

Use of Penicillin during Pregnancy

Abstract:

Before starting the article I would like to say that penicillin is not the ‘only’ safe antibiotic to use during pregnancy, because there are few other drugs that can be considered as safe during pregnancy.    

Before starting the article I would like to say that penicillin is not the ‘only’ safe antibiotic to use during pregnancy, because there are few other drugs that can be considered as safe during pregnancy.

Most drugs are contraindicated during pregnancy. This is because most of the drugs that are taken during pregnancy can cross the placenta and enter the fetus. Most of these drugs can act negatively on the fetus, and cause various abnormalities. They can result in morphological abnormalities, as well as growth and developmental abnormalities. Therefore use of any drug during pregnancy should be done with caution.

Drugs are given in order to cure a disease, but what if the patient is pregnant? She should be given medications. We can not keep her without giving any treatments just because she is pregnant. This is where the few drugs that are safe during pregnancy come in to play.

Antibiotics are a class of drugs that are given to cure various infections. As mentioned above most of the antibiotics too can be hazardous to the fetus, but the patient should be given antibiotics, if she acquires a serious infectious disease during pregnancy.  Otherwise the disease it self could be life threatening to the fetus as well as to the mother.

Penicillin plays a major role among the drugs that are safe during pregnancy. It is used in pregnancy without any fear, because there is no evidence of fetal harm from this drug. It is the treatment of choice if the mother acquires any of the following infectious diseases.

Syphilis – This is a disease cause by Treponema pallidum. Protein penicillin is prescribed for primary, secondary or early latent syphilis. It is given 1.2 MU daily, intramuscularly, for 12 days. It should be given for 21 days for later stages of syphilis. Even though this is considered as safe, it can also have some adverse effects. Penicillin causes the death of organisms. Sometimes these dead organisms can trigger the release of pro-inflammatory cytokines, which leads to a Jarish-Herxheimer reaction. As a result the symptoms can become worsen and fever may rise for about a day after starting the treatment. This can also trigger preterm labour, so the mother is admitted to the hospital before starting the treatment.
Group B streptococcus infections – This is an organism that belongs to the normal flora of the gut and the vagina of 20-40 % of the normal women. It can cause upper genital tract infections that could lead to septicaemia, which is detrimental to the mother. Its infections are fatal to the neonate too. Therefore it should be cured by antibiotics. Fortunately penicillin is a safe and effective drug in treating this condition. Penicillin is given intravenously at the time of delivery, after the diagnosis has been made by culture. It is not given in early pregnancy because of common occurrence of re-colonization.
Gonorrhoea – This is a disease caused by Neisseria gonorrhoeae. It is also treated successfully with penicillin.

Even though there are many incidences of penicillin resistance, it is still widely used because of its high effectiveness and safety.

None of the drugs can be considered as safest, but comparing with other drugs, we can say that penicillin is fairly safe.

Finally I would like to say that penicillin is not the only drug that is safe during pregnancy, as the topic implies. Other antibiotics that are considered as safe during pregnancy are Cephalosporin, Erythromycin, and Nitrofurantoin in first and second trimesters.

How Staphylococcus Aureus in Blood can cause Fatal Infections

Abstract:

The presence of bacteria in the blood is called bacteraemia. Blood is a sterile medium. Therefore there are not any bacteria in the blood under normal circumstances. So, presence of any organism can cause various diseases. Transient bacteraemia ca

The presence of bacteria in the blood is called bacteraemia. Blood is a sterile medium. Therefore there are not any bacteria in the blood under normal circumstances. So, presence of any organism can cause various diseases. Transient bacteraemia can occur in normal individuals after defecation and after brushing teeth. Usually these bacteria are removed from the blood stream by the spleen and liver, but sometimes, some of these bacteria get the chance to stay in organs like the heart, and in the ends of growing bones, and thereby avoid reaching the spleen and liver.

Staphylococcus aureus is one such bacterium that can stay in these organs, and cause serious diseases, which could be fatal if untreated. Infective endocarditis is a potentially fatal disease caused by staphylococcus aureus. It is responsible for 25% - 66.7% of infective endocarditis cases occurring world wide.
Intravenous drug users are at a high risk of developing infective endocarditis, because a lot of Staphylococcus aureus organisms enter the blood when they inject drugs into their body. These bacteria enter the blood stream and establish themselves in the damaged heart valves (especially in prostatic heart valves). They can produce adhesins, dextran and fibronecting binding proteins, which help them to attach to the heart valves.
The organism starts multiplying after attaching to the wall. This leads to attraction of more platelets and deposition of fibrin. So finally the organisms are covered with platelets. These growths are called vegetations and can be of several centimeters in size. Vegetations help organisms to hide from the body’s surveillance system. It takes about five weeks for this process to occur. These vegetations act as foci that continuously introduce bacteria to the blood stream. So these bacteria can spread to various organs and cause diseases in other organs too.

Staphylococcal infective endocarditis could be dangerous in several ways.  The local damage done to the heart valves can give rise to various cardiac problems, which can be life threatening. Sometimes the vegetations can dislodge from their site of origin and travel to different organs in the body. These emboli are septic and can cause serious illnesses throughout the body. There are also immune complexes formations in response to the presence of micro-organisms in the blood. Immune complexes are composed of microorganisms and antibodies and complement proteins. These immune complexes circulate in the blood. They can deposit in organs like kidneys and cause serious problems like kidney failure, which is a life threatening disease.

The patients with infective endocarditis may initially present with pyrexia of unknown origin. Heart murmurs are always detected in patients with this disease. Apart from those main symptoms, the patient may have loss of weight, loss of appetite nausea, vomiting, malaise and night sweats. On examination the doctor may find Osler nodes, splinter haemorrhages in nail beds and petechial lesions in the skin. Earlier this was invariably a fatal disease.  Now with the discovery of antibiotics, staphylococcus aureus infections can be treated successfully if identified earlier.
The disease is diagnosed by doing a blood culture. The condition is treated with antibiotics that are powerful enough to eradicate the organisms from the blood. This may take several weeks. Treating infective endocarditis caused by staphylococcus aureus is very hard, because of the emergence of antibiotics resistance strains, especially when the organism is hospital acquired. Therefore beta lactamase stable penicillin such as cloxacilline is given along with an aminoglycoside, rifampicin or fusidic acid. Vancomycin or teicoplanin is given if the patient is allergic to penicillin. They are also given to treat methicillin resistant staphylococci.

How can Breast Milk Transmit HIV

Abstract:

HIV (Human Immunodeficiency Virus) is a virus belonging to the retrovirus group. It infects cells expressing the CD4 antigen. These cells include T helper cells, monocytes, macrophages, Langerhan’s cells and dendritic cells.

HIV (Human Immunodeficiency Virus) is a virus belonging to the retrovirus group. It infects cells expressing the CD4 antigen. These cells include T helper cells, monocytes, macrophages, Langerhan’s cells and dendritic cells. The immune system gets progressively damaged and the CD4 positive cells count declines steadily. As a result the cells mediated immune response is lost, so the host becomes immuno-compromised. When the CD4+ cell count drops below a critical level, the patient is said to have AIDS (Acquired Immune Deficiency Syndrome). This favors infections with various opportunistic organisms. The AIDS patients die not due to the HI virus, but due to serious infections caused by other organisms.

HIV is transmitted from an infected person to another through body fluids like, blood, semen, vaginal secretions and breast milk, because these body fluids contain the virus. When an HIV infected woman gets pregnant, the next problem she faces is “Will my child also get HIV?” The child can acquire HIV from the mother during second or third trimesters of pregnancy, during delivery, or during breast feeding. There are successful intervention methods that can prevent vertical transmission of HIV during pregnancy and labour, but unfortunately we still do not have an effective way to prevent transmission during breast feeding.

The exact mechanism by which breast milk transmit HIV is not known, but  scientists have found out that the breast milk contains the virus. The breast milk contains both the cell free virus and the cell associated virus, but which of these is important in infecting the child is not known. The plasma virus concentration that is required for it to appear in the breast milk is also yet to be studied.

When the child drinks the mother’s milk, the virus enters the child’s gut, but the mechanism by which they cross the mucosa is not well understood. The virus can penetrate the mucosa especially when there is a breach in the submucosa. Trancytosis through M cells and enterocytes with specific receptors can also occur. Tonsils are the next place where the virus can enter the blood stream. As the frequency and duration of the breast feeding increases, the risk of the child to acquire the infection also increases.

If the mother has mastitis, there is a higher chance for the virus to appear in large numbers in the breast milk. This occurs as a result of vasodilatation of the blood vessels. As a result the child is exposed to a higher number of virus, making him more viable to acquire the infection.

As discussed above HIV infected mothers can transmit the virus to their children during breast feeding. Therefore, reduction of HIV infected females in the reproductory age group in is very essential.  

Sources: Medical Microbiology 2nd edition (Mims)
www.unfpa.org/.../276_filename_HIV_PREV_BF_GUIDE_ENG.pdf

Causes of Hepatomegaly

Abstract:

Hepatomegaly is  enlargement of the liver  detected during medical examination. Both palpation and percussion techniques are used during abdominal examination to assess the size of the liver. O

Hepatomegaly is enlargement of the liver detected during medical examination. Both palpation and percussion techniques are used during abdominal examination to assess the size of the liver. On percussion the normal liver span is 7 cm for women and 10.5 cm for men. Hepatomegally is diagnosed when the liver size is found to be 2 to 3 cm larger than the above mentioned values.
Enlargement of the liver can be an apparent enlargement or true enlargement which can be due to several disease conditions. The disease conditions can be classified as cirrhosis, inflammatory conditions, cysts, metabolic conditions, haematological conditions, tumors, venous congestion and biliary obstruction.

Diseases which can cause apparent enlargement of the liver are low lying diaphragm and Reidel’s lobe. The liver is situated just below the right hemidiaphragm. Chest pathologies such as pneumothorax, emphysema, chronic obstructive pulmonary disease etc. push the right hemidiaphragm down along with the liver. This is noted as hepatomegaly on abdominal examination. Reidel’s lobe is defined as downward tongue-like projection of the anterior edge of the right liver lobe to the right of the gallbladder. This condition is commonly seen in women and can be an accessory lobe or a normal variant, which may extend up to the right iliac fossa. On palpation and percussion this can also be detected as enlarged liver.
One of the commonest causes of hepatomegaly is early cirrhosis which is the final outcome of most of the liver pathologies. Some of the causes of cirrhosis are Hepatitis C, alcoholic liver disease, non alcoholic fatty liver disease, hepatitis B, autoimmune hepatitis, primary and secondary biliary cirrhosis, primary sclerosing cholangitis, haemochromatosis, Wilson’s disease,  Alpha-1 antitrypsin deficiency, Sarcoidosis, Type IV glycogen storage disease, Drug-induced liver disease etc.
Cysts which cause hepatomegaly are Hydatid cysts and cysts seen in patients with polysystic kidney disease. Hydatid cysts are caused by the larval stage of the tapeworm Echinococcus granulosus. The cysts can occur in many organs but the liver is commonly involved. These cysts increase in size at an average rate of approximately 1-1.5 cm/year. The disease manifests as hepatomegaly when these cysts enlarge up to a detectable size.
Metabolic diseases causing hepatomegaly are fatty liver, Amyloid and glycogen storage disease. Fatty liver can occur with (alcoholic fatty liver disease) or without (non-alcoholic fatty liver disease) alcohol consumption. It is caused by accumulation of triglycerides and other fats in the liver cells. The ultimate outcome of the disease can be liver inflammation and cell death. Its prevalence is increasing worldwide along with the increasing number of obese people.  Liver is a commonly affected organ in Amyloidosis and can rarely cause massive hepatomegaly. The next metabolic disease causing hepatomegaly is glycogen storage disease which is a disease characterized by defective metabolism of glycogen.

Haematological diseases causing hepatomegaly are leukaemia, lymphoma, myeloproliferative disorders, and thalassaemia. In leukaemia, extra-medullary infiltration by leukemic cells may cause hepatomegaly along with Lymphadenopathy and splenomegaly. In patients with thalassaemia hepatomegaly occurs due to engorgement of hepatic paranchymal and phagocytic cells with hemosiderin deposits.

Tumors causing hepatomegaly can be either primary or secondary. Liver is one of the commonest sites for secondary deposits, especially from malignancies from the gastro-intestinal tract. Venous congestion caused by heart failure, hepatic vein occlusion can also lead to enlargement of the liver. Biliary obstruction particularly caused by an extra-hepatic cause is also an important cause of hepatomegaly.

Since there are a lot of causes of hepatomegaly, careful history taking, examination and investigations plays a vital role in detecting the correct eatiology and planning the future management.

Cause for Left Side Abdominal Pain in Females

There are several pathologies which can cause left side abdominal pain in a female. They can be mainly divided in to two categories. They are pathologies limited to females and pathologies affecting both males and females. The pain can arise from any structure that is situated in the left abdomen. These structures include the abdominal wall, peritoneum, colon, small intestine, omentum, left kidney, left ureter, spleen, and pancreas. Sometimes pathologies in the left lung and the heart can also present as left side abdominal pain. All the above mentioned pathologies are common to both females and males. Pathologies restricted to females are those arising from the female reproductive organs. Female reproductive organs which can give rise to left side abdominal pain are left ovary, left fallopian tube, and the uterus.

Ovarian diseases causing left side abdominal pain are mid cycle pain, benign and malignant ovarian cysts, ruptured ovarian cyst, twisting of the ovary, chocolate cyst, and ovarian carcinoma.  Mid cycle pain occurs at the midpoint of the woman’s menstrual cycle. This occurs as a result of ovulation. During ovulation, the ovarian capsule is broken and the ovum is released in to the peritoneal cavity. This can cause little amount of bleeding which gives rise to abdominal pain. In a woman who has 28 day cycles, ovulation occurs at the 14th day. This is the middle of the menstrual cycle. So, pain arising at the middle of the menstrual cycle is referred to as mid cycle pain. As a rule, ovulation occurs in every woman 14 days prior to the next expected day of menstruation. If you are having left side abdominal pain on this particular day, it can be due to ovulation. This is a physiological phenomenon and therefore, does not require special treatment. If the pain is disturbing, you can take simple analgesics. Ovarian cysts and tumors are major causes of abdominal pain. When they occur in left ovary, they cause left side lower abdominal pain.   There are many types of ovarian cysts. Chocolate cysts arise from the presence of endometrial tissues in the ovary. These endometrial tissues undergo cyclical bleeding in to the ovary. As there is no pathway for blood to drain, they accumulate within the ovary, causing abdominal pain during menstruation. The accumulated blood looks exactly like chocolate, hence the name chocolate cyst.

Diseases of the fallopian tube causing abdominal pain are ectopic pregnancies, fallopian tube tumors, infection etc. Ectopic pregnancy occurs when the blastocyst implants within the fallopian tube. The embryo slowly grows and becomes larger. Finally, the fallopian tube ruptures when it cannot accommodate the enlarging embryo, giving rise to severe abdominal pain and circulatory collapse. This is a gynecological emergency and therefore need immediate surgical intervention.

Diseases of the uterus causing abdominal pain are fibroids, Braxton Hicks contractions during pregnancy, labour pain etc. There are several types of fibroid. They are sub-mucosal, intramural, sub-serosal, pedunculated and parasitic fibroids. They cause pain when they become very large. Pedunculated fibroids can give rise to severe pain if they become twisted. The blood supply to the fibroid is cut off when it gets twisted. This causes ischemia to the fibroid, which ultimately give rise to pain.

Two of the common diseases involving the pelvic cavity are pelvic inflammatory disease and endometriosis. Pelvic inflammatory disease is inflammation of the pelvic cavity and it can be either acute or chronic. This occurs mainly due to infection. Chlamydia and gonococci are the commonest organisms causing pelvic inflammatory disease. Endometriosis is the presence of endometrial tissue in places other than the endometrium of the uterus. Chocolate cyst is also a type of endometriosis. Same as in chocolate cyst, the endometrial tissues in all other places undergo cyclical bleeding and give rise to abdominal pain.

Above mentioned are the commonest causes of abdominal pain specific to females. Apart from that abdominal pain also occur due to other common pathologies such as bowel diseases (irritable bowel syndrome), urinary tract infections, urinary tract stones, pancreatitis, pneumonia, musculoskeletal pain, etc.  

Ankylosing Spondylitis

A 23 year old male patient was presented to the medical ward with one year history of joint pains. He was mainly complaining of large joint involvement. He complained of back pain, shoulder, elbow, hip and knee joint pains, but there was no small joint involvement. The pain was more in the morning and there was significant morning stiffness.  He was having the symptoms for a long period of time hasn't got any regular treatment up until now.

On examination, he had restricted movements of his spine, but there were no joint deformities. Schoeber's test was positive indicating the presence of significant spinal stiffness. Schoeber's test is performed by marking a spot on the back, at the mid line, at the level of iliac crest. Then two points vertically 10 cm above and 5 cm below this point is marked while the patient is standing. The the patient is asked to bend as much as he can and the distance between the two marked point is measured. A reading less than 5 cm implies spinal stiffness. The reading of this particular patient was only 2 cm. The patient also had reduced chest expansion as a result of costochondral junction involvement (normal chest expansion should be at least 5 cm at the nipple level).

With all these findings, the patient is clinically diagnosed to have ankylosing spondylitis. Three out of four of following clinical criteria should be there to diagnose a patient as having ankylosing songilitis. These clinical features are,

1. Morning stiffness lasting more than 30 min. 
2. Improvement of back pain with movements but not with rest.
3. Awakening because of back pain during second half of the night only
4. Alternating buttock pain.

Ankylosing spondylitis, as the name implies, is a inflammatory disorder of the spine. This is mainly seen among young males who are in their late teen or early twenties. Even though both men and women (2.5: 1) can be affected but symptoms are more prominent in men. The disease has a strong association with HLA B27 gene. These patients are also more susceptible to develop iritis also.

Investigations are performed to confirm the diagnosis.

1. ESR - elevated
• The patient's ESR was 112 mm/1st hour
2. CRP (C reactive proteins) - elevated
• The patients CRP level was 24
3. HLA B 27 testing 
4. MRI - shows sacroilitis before it is seen on X rays
5. X rays 
• X ray lumbar spine
• The fusion of vertebra leads to a
  bamboo spine
• X ray sacroiliac joint
• The following radiograph is taken from our patient. There is sclerosis of either sides of the joint with irregular joint space suggestive of sacroilitis, but there is no ankylosis of the sacroiliac joint.

Ankylosing sondylitis - Sacroilitis

Treatment

• Exercising - Exercising plays a major role in preventing the progression of the disease and improving the symptoms.
• NSAIDs - Sometimes, the pain makes it impossible for the patient to carryout exercises. This is where NSAIDs come in to play. An evening dose of slow releasing NSAID, oral or as a suppository will reveal pain and help in carrying out an active lifestyle and improve sleep.
• Methrotexate is helpful if there is peripheral joint involvement, but will not improve spinal disease.
• Sustained and dramatic reduction of inflammation can be achieved by TNF alpha blocking drugs.
• Rituximab does not help in seronegative arthritis.

Prognosis

The prognosis is good with adequate exercises. Fifty percent of the HLA B27 positive patients have the risk of transmitting the gene to their offspring. Thirty percents of these offspring may get the disease eventually. 

Pneumothorax

Case History

A 30 year old, previously well male patient was admitted to the casualty ward with sudden onset of left side chest pain. The pain was severe in the beginning. On admission the patient was complaining of pleuritic type of chest pain. On examination, his respiratory rate was 18 breaths per minute, and saturation was 100% without oxygen. His vocal fremitus and air entry was reduced on left side of the chest. His heart sounds were difficult to auscultate too. The clinical diagnosis of pneumothorax was made and an emergency chest x ray was taken. The chest x ray showed a left sided pneumothorax. The patient was immediately referred to the chest physician who put an intercostal tube to the left side of the chest to take out the air.

Pneumothorax

Air in the pleural space is called pneumothorax. Air can accumulate within the pleural space as a result of injury to the chest wall or as a result of injury to the lungs.

Spontaneous pneumothorax

Spontaneous pneumothorax is commonly seen among young, tall and thin men. This is mainly due to a rupture of a pleural bleb. The male to female ratio of spontaneous pneumothorax is 6:1.

Pneumothorax in a diseased lung

Pneumothorax is common among people with an already diseased lung. Patients with COPD, asthma, carcinoma of the lung, bronchopulmonary fistula etc are at a higher risk of developing pneumothorax. Pneumothorax in such patients should be taken seriously regardless of the size.

The following x ray shows a right sided small pneumothorax in a COPD lung. This lung also shows a band of bronchiectasis in the right upper zone.

Right sided pneumothorax in a COPD lung

Tension Pneumothorax

Sometimes a valve mechanism develops which allows air to fill in the plueral space during inspiration and prevents air from getting out of pleural space during expiration. As a result, each time the patient breaths, the air accumulates within the pleural space and the pressure gradually increases causing the mediustinum to shift to the other side. The patient gradually becomes breathless and tachycardic and can even die unless the pressure is not relieved immediately. This is an emergency and requires immediate aspiration of the air.

Aspiration of pneumothorax

Aspiration of a pneumothorax is performed by first taking informed consent from the patient. Then 2% lidocaine is injected in to the pleural space. Then 3-4 cm of 16 french guage needle is inserted in to the pleural space in the second intercostal space midclavicular line. The cannula is connected to a three way tap and 50 cc syringe. Upto 2.5 liters of air can be aspirated through the syringe.