--- ----- ------- --------- ----------- -------------- ---------------- ------------------ -------------------- ---------------------- ------------------------------------------------------------------------- Can you identify this arthropod vector and the problem it causes ?
Ans: Female Aedes Aegyptii mosquito aka Yellow fever mosquito the transmitter for the causative agents of Dengue, Yellow Fever and Chikungunya how do i know that it's a female Aedes ? Ans Only the female Aedes, Anopheles etc. has a blood meal for the development of the eggs Aedes albopictus is also know to spread Dengue Discussion - the aim of presenting this case was to discuss the fluid Mx of Dengue shock syndrome and hemorrhagic fever. Harrison, Davidson, Oxford textbook of med. washington manual amd Nelson have not touched on the specifics and hav only given, what can b termed 'cover ur backside' advisories. But WHO has issued guidelines which clearly caters to plasma loss, but stays clear of coagulopathy / DIC Mx. So i will keep my tried and tested method and provide the link to WHO MX. WHO clinical Mx guidelines for Dengue Firstly we have to be alert to other possibilities, which can mimic Dengue on initial presentation when antibody titres may still be low. So it's clues on clinical exam that can point to the likely cause... the degree of fever, muscle ache, joint ache, vomiting are non specific and can often confound the diagnosis. clue 1 - above mentioned symptoms + severe retro-orbital pain (- just ask the patient to follow ur finger,without moving his head while u draw out a H. Some patients may have severe photophobia and may not be able to open their eyes, in which case u can ask them to move their eyes around with their eyelids shut or gently press on the eyeball) +/- severe back pain ( this feature has given rise to the colloquial designation "break-bone fever." . clue 2 - severe joint pain is the predominant complaint in Chikangunya and if the patient walks in without assisstance, he will have a classical crouched and very slow gait ( sec to the severe arthalgia / arthritis ). clue 3 - very high fever +/- delirium + relative bradycardia --> typhoid clue 4 - the periodic pattern of fever points to malaria and if the patient is severly obtunded +/- meningeal signs - think of 'Falciparum Malaria' Now to the Mx of Dengue Hemmorhagic fever and Shock syndrome - Early on ( critical period is usually on the day of defervescence, typically after the third day of illness)the patient loses fluid to the third space ( extracellular space ) and the hematocrit rises. Now this situation looks clinically like diarrhea or vomiting but is physiologically different, becos in diarrhea & vomiting the fluid is lost to the outside and needs to be entirely replaced. In some cases of 3rd space loss like dengue shock syndrome and septicemia ( but not cirrhosis or CHF - these are fluid overload scenarios and need diuretics ), the fluid will eventually return to the vascular space and then we can have an exceedingly high venous return and secondary lung congestion. Additionally if we infuse fluids too rapidly, then the fluid will just leak out of the capillaries and venules, further crowding the 3rd space and spill over into pleural and peritoneal and pericardial cavities( the 3rd spce reservoirs ). We rarely would venture into thinking that the patient's dialysis (sec. to abdominal compartment syndrome) or ventilator requirements ( sec. to pleural effusion and pulmonary edema ) are the direct result of our over enthusiastic fluid replacement. and why do we hav this - first leakage and then return of fluid into the vascular space ? becos unlike in meningococcemia and viper bite, no iinflammatory or destructive vascular changes are observed and the leak is due to release of short acting mediators from the monocyte / macrophages and platelets....that's the good news. The evidence that supports the existence of plasma leakage includes findings of pleural effusion and ascites by examination or radiography,haemoconcentration, hypoproteinaemia and serous effusion (at post mortem). Now let's get into the meat of the matter Remember anticipation is the key and b prepared for the worst case scenario. settle ur patient into a bed with mosquito net or apply mosquito repellent to exposed areas ( barring the area/s u plan to stick the iv ) - v imp. to prevent spread. take his vitals and capillary refill time When u suspect dengue or any other hemorrhagic fever - first collect blood for grouping and cross matching ( becos collecting blood after fluid resuscitation can interfere with grouping and cross matching esp. after colloid resuscitation ) secondly ask for baseline platelets, hemoglobin and hematocrit values weigh the patient - this will help calculate fluid loss in the course of the illness while the patient is still stable - ask for a chest X ray....even a mild pleural effusion shud b an indicator of things to come ( as this effusion is due to capillary leak since fluid resuscitation has not started ) ask for both IgG and IgM ( remember if this is a second attack, then IgM levels cud be lo and IgG cud b high and anticipate bith shock and hemorrhage syndromes when IgG titers r high ). Well this is counterintutive and the reasons r given in the Xtra edge section also order widal test and look at blood smear for N meningitidis and malarial parasite If vitals are stable give only oral fluids and feed. If it's a child who is vomitting, then give WHO ORS or any other fruit juice @ 1 spoon every 2 - 3 minutes. Adults can also take WHO - ORS and u may hav to feed some of them ( they will act like real kids, when sick ). Fever Mx - No ibuprofen ( bleeding risk ) and No aspirin ( bleeding risk and Reye's syndrome ) - Paractamol is the way to go Paracetamol Dosage Paracetamol is preferable to reduce fever but should be used with caution, in the following doses: < 1 year 60mg/dose 1–3 years 60–120mg/dose 3–6 years 120mg/dose 6–12 years 240mg/dose. A dose should be administered when body temperature is greater than 39 °C, but no more than 6 doses should be administered in a 24-hour period. courtesy WHO guidelines - Cold sponging should never be with ice water - remember shivering increases core body temp. and according to some sources can cause vasodilation and increase the risk of bleeding. So water at room temp ( 25 - 30 degree celcius ) is all that is required. Don't stick ice into the axilla or groin and agitate the patient. - if the patient wishes to be covered then provide a thin bedsheet; a thick blanket or bedsheet will cook him up. Pain control - again it's paracetamol and for very severe pain give opioids. Now let's look at iv fluid Mx ( what to give and when ) first let's understand the crux of the problem - giving the wrong type of fluid ( ex. Dextrose ) can cause further leakage of fluid into the extracellular space and notoriously, brain edema. - giving very little fluid can lead to stagnation which can cause hypoxia, acidosis and sets the stage for DIC. - giving too much fluid can compound the leak into the extravascular space and cause pleural effusion, increased intra-abdominal pressure ( i cud hav just said ascites, but then that will not hav the same impact as saying abdominal compartment syndrome ), periardial effusion and brain edema. So intensive monitoring is required esp. when iv fluids are running. Employing the shock position / trendelenburg position ( i.e legs at higher level than heart ) can reduce the fluid requirements. Monitoring is very simple Helps decide in minutes - capillary refill time ( shud b less than 2 seconds ),BP, pulse, mental status changes ( gives the earliest clue ) Helps decide over a longer period - hematocrit and urine o/p For mild cases - typified by a person who inspite of adequate oral intake is showing some mild distress, tachycardia, but BP still normal. ( Acc to WHO, this is called - 5 % fluid deficit ) Mx - ask for blood glucose ( or do a finger prick test ), hematocrit, platelets and start N.s or 5% dextrose + 1/2 N.S at 5-7 ml kg / hour and slow down ( 2 - 3 ml/kg/hr ) as the heart rate and capillary refill returns to normal....continue at this rate for about 1/2 an hour with close monitoring and titrate up if required or completely clamp down, if the patient is stable. Indications for bolus fluid ( Dengue Shock Syndrome according to WHO ) may be necessary where signficant dehydration (> 10% of normal body weight) has occurred and rapid volume expansion is needed. Signs of significant dehydration include: • Tachychardia • Increased capillary refill time (> 2s) • Cool, mottled or pale skin • Diminished peripheral pulses • Changes in mental status • Oliguria • Sudden rise in haematocrit or continuously elevated haematocrit despite administration of fluids • Narrowing of pulse pressure (< 20 mmHg ) • Hypotension (a late ?nding representing uncorrected shock). Now we can have 2 distinct scenarios here 1) capillary leak - typified by rising hematocrit + unstable vitals 2) internal bleeding - typified by falling hematocrit + unstable vitals. This condition can be further complicatd by DIC Initial Mx is the same and in the midst of rapid resuscitation it is often difficult to send the blood for hematocrit and platelet count, D-dimer, PT, appt etc. and torniquet test is often useless. So common sense coupled with capllary refill time, BP and pulse witha bedside coagulation screening test demonstrated below is all that may be practically possible. So start with 10 - 20 ml/kg with 2 - 18 bore canullas and send it down in 20 minutes. If patient doesn't improve then i alert the blood bank and send another bolus of crystaloid at 10 ml/kg. No improvement then pass an NG tube to see for GI bleed and use only syringe for suction ( the suction machine can damage the gastric mucosa and potentially begin or worsen a gi bleed ). If blood returns then, give cold saline wash and start proton pump inhibitor while asking somebody to giv another bolus, but this time a coloid at 10 ml/kg in 15 - 20 minutes. No recovery - give blood ( 10 ml/kg ) after first bringing ot down to room temp. GIve 1/2 as bolus and the other half at a slower rate 5 ml/kg/hr. when to stop iv fluids? The administration of intravenous fluids should be discontinued when the haematocrit level drops to approximately 40%, with stable vital signs. In the mean time if the labs hav not returned then u can do a simple beside test for clotting abnormality ( courtesy - pathfinder international ) - Draw venous blood into a dry, clean, plain or red topped glass tube. If the room temp is below 32 degree celcius, then hold the tube in ur closed fist to keep it warm. After 4 minutes, tip the tube slowly to see if a clot is forming...repeat every min until the blood clots. If no clot forms in 7 minutes, this suggests coagulopathy. consider FFP if prothrombin time is > 1.5 times control value and the bleeding is unabated inspite of the above measures or after6 units of blood have been tranfused. ( hct is expected to rise by approx 1.5 after each unit of whole blood and by 3 % after each unit of packed cell provided bleeding has stopped ). How much FFP to give ? ...i will keep it simple only 15 - 35 % of the normal levels of factors are required to maintain homeostasis. So if a patient is bleeding due to coagulopathy, he has definitely lost close to 70%.Each unit of FFP raises factor levels by 3 - 5 % in adults and more in children depending on the age. So 1 to 2 units are definitely insufficient in adults. So initially give atleast 4 units of FFP or 10 - 15 ml/ kg in adults and 2 units in children and then reassess. Does FFP have to be used immediately after thawing? After thawing, the level of factor VIII falls rapidly.Factor V also falls, but levels of fibrinogen and the other haemostatic proteins are maintained. NewUK guidelines permit the use of plasma that hasbeen stored in the bloodbank for up to 24 h after thawing. This has the advantage that plasma can be released quickly when required for urgent management of massive bleeding. ref - Practical transfusion medicine, 3rd edition How rapidly to transfuse FFP ? Each unit can be transfused in 20 - 30 minutes, but after thawing. Otherwise.... What about platelets...in an actively bleeding patient with a platelat count < 50 k - do a bed side bleeding time with lancet...if high, then give platelets The usual quantity transfused to adults is a pool of five or six units, containing a total of 250 to 300 mL of plasma. Individual platelet concentrate units, which contain 40 to 50 mL of plasma, may be used for infants or small children. Apheresis platelets are collected from a single donor and contain a minimum of 3 x 10[SUP]11[/SUP] platelets (approximately equivalent to five or six platelet concentrate units) suspended in 200 to 300 mL of plasma. In adults, a pool of five or six platelet concentrates, or a single apheresis unit should achieve a clinically meaningful increase in circulating, functioning platelets. A corrected count increment (CCI) of >7,500 or a platelet count increase of approximately 5,000 to 10,000/µL per platelet concentrate unit administered is considered an acceptable response. If the increment observed is significantly lower than expected, in the absence of infection, splenomegaly, active bleeding, autoimmune thrombocytopenia, or other circumstances associated with platelet destruction, the patient may be alloimmunized to human leukocyte antigen (HLA) or platelet antigens. Patients who are refractory to platelet transfusions because of alloimmunization may benefit from HLA-matched or crossmatch-compatible platelets. Transfused platelets have been found to survive four to five days when returned to healthy subjects. However, because 7,000 to 10,000 platelets/µL are consumed daily in plugging endothelial gaps, platelet survival in thrombocytopenic patients is reduced. ref - http://www.wadsworth.org/labcert/blood_tissue/pdf/plts0607final.pdf Now some comments about the fluid reabsorptive phase It is typified by a falling hematocrit and improving or stable vitals. This is good news time and it means that the patient has weathered the cytokine storm and the fluid / plasma is returning home to the vascular space...but this joyous moments can b short lived if the returning fluid overwhelms the vascular space. Watch for the development of a wide pulse pressure, pleural effusion and ascites. Don't shy away from using diuretics or digitalising the patient if the need be. In summary - courtesy WHO This happens only on Faculty Of Medicine !!!
gr8photos of the deadly mosquito- wow,did ya click them? ----the evil spirit u jus strted believing in!P:
dear joey, also give a case discussion on snake bite,i have never evr seen a case of even treated in ER for that matter but i am always intrigued as to what to do 1st as in A,B,Cs... would be grateful. tx! p.s-pls dont post pics of snakes,i am dead scared,wont b able to sleep for days and nights!
