UNDER THE MICROSCOPE
Dengue is once again hugging the headlines. There were over 136,000 cases from Jan. 1 to Aug. 3 2024, 33 percent higher than last year. There were 396 deaths attributed to this mosquito-borne viral disease, far too many by any standard.
There isn’t any progress in reducing the country’s dengue burden, what with the Dengvaxia controversy sidelining what could have been an effective solution to the problem. The 4S program hasn’t done anything yet health authorities keep pushing it. You know what they say about doing the same thing over and over and expecting a different result.
But what caught my eye was a news item asking the public for more blood donations due to high demand for blood during dengue outbreaks. Based on my experience as a blood banker of 36 years, clinicians often request platelet concentrates for dengue patients. That runs counter to WHO recommendations that state that hydration or increasing fluid intake, either by mouth or intravenously, is the mainstay of dengue treatment due to the increased concentration of blood (high hematocrit).
Apparently, what many doctors are treating is the occurrence of low platelet counts (thrombocytopenia) which may go as low as 10,000/ml or lower. It is a phenomenon that occurs in many dengue cases but usually, the platelet count recovers as the majority of patients improve. In medical circles, we call this as treating the laboratory result, but not the patient.
Per WHO recommendations, the only indication for blood use is if the patient experiences severe bleeding. There are parameters to watch out for when this happens, and transfusion of red cell concentrates is done for these cases, not platelet concentrates. In fact, many studies show that transfusing platelet concentrates in these cases does not show any improvement of the platelet counts, and may do more harm than good. Our dictum in the practice of medicine is Primum non nocere, Latin for “First, do no harm.”
Most cases of dengue are self-limiting. In fact, 75 percent of cases are asymptomatic. Only a fraction of infections, 0.5-5 percent, develop into severe dengue, which if untreated can be fatal in up to 20 percent of the severe cases.
Severe cases manifest usually after the fever lyses, which is when the patient’s hematocrit, or red cell concentration in the bloodstream, increases and can lead to shock and if untreated, death. The manifestations are severe abdominal pain, persistent vomiting, rapid breathing, bleeding gums or nose, fatigue, restlessness, blood in vomit or stool, feeling thirsty, pale, cold skin and weakness.
It is often at this point that physicians may panic and order platelet transfusions. As previously stated, this reflex action doesn’t result in the amelioration of the disease process, and in fact, may exacerbate it.
Treatment of severe cases is with careful hydration to prevent hypovolemic shock, the so-called dengue shock syndrome (DSS). The patient’s hematocrit should be carefully monitored, meaning blood is drawn every few hours to do a complete blood count. The object of giving intravenous fluids is to reduce hematocrit to normal levels but overhydration can also be dangerous and lead to fluid overload and acute heart failure. So, don’t get mad at the doctors and nurses for pricking your patient every now and then.
If the patient starts having gum bleeding or has skin rashes, he/she should be advised to limit physical activity to prevent further bleeding. Intramuscular injections should be avoided and if nasogastric tubes are to be inserted, it must be done with utmost care to prevent bleeding.
If massive bleeding occurs, which manifests as a sudden drop in the increased hematocrit, then red cell transfusions are given carefully. Only if the patient is not responding to the red cell transfusions that platelet concentrates and fresh frozen plasma may be given. There is a risk of fluid overload though.
With all these WHO recommendations in mind, it is hard to believe we will need more blood just because there are dengue outbreaks. Not that we don’t need more blood donations. We do, since there are a lot more indications for giving blood products other than dengue. In fact, I just donated blood on my last birthday to celebrate life and extend it for others. All able-bodied persons should donate blood every three months so we can save more lives.
But we also need more rational use of blood and blood products, and base it on medical science. Dengue outbreaks are bad and can cause some deaths. But it is not a reason to prescribe platelet transfusions simply because a patient’s platelet count is dropping. We should be more concerned with a rising hematocrit and correct it with hydration, oral if disease is mild, and intravenous in severe cases while monitoring the signs and symptoms of the patient.
Blood is life. Let’s use it rationally.