Cooling the throat to protect the brain
Researchers at Okayama University, in collaboration with several medical centers in Japan, have demonstrated the safety and efficacy of a hypothermal treatment—pharyngeal cooling—for cardiac arrest patients. This research has been published in the journal Resuscitation.
Cooling the brain is known to prevent neurological problems in patients recovering from cardiac arrest. Current approaches to achieving therapeutic low temperatures include intravenous infusion of cold fluid, which can increase re-arrest rates, and nasal cooling which is prone to cause extreme nosebleeds (epistaxis) and accumulation of air in soft tissues (peri-orbital emphysema).
In the present study, researchers at Okayama University investigated an alternative method for cooling the brain. They targeted the area at the top of the throat—the pharynx—because the arteries that supply the head with oxygenated blood run nearby. Cooling this area should is a promising approach to cooling the brain but so far there have been no complete studies to determine whether pharyngeal cooling could be administered effectively or whether it may lead to other adverse side effects.
In partnership with doctors working in emergency and critical care clinics, the researchers set up a trial for 108 cardiac arrest patients. The medical staff administered treatments with or without pharyngeal cooling to patients at random and subsequently recorded success rates of resuscitation and physiological conditions, including temperature both at the body core and in the head near the ear (tympanic temperature), mechanical or temperature damage to the pharynx, inflammation and blood platelet levels.
Saline solution was supplied through a cuff at 5°C to avoid freezing and the treatment duration was also limited to two hours to avoid damage from the cold. The pressure was chosen to be below 60 cm H2O to avoid nerve damage which has been reported with the use of similar equipment.
The results of the trial indicated effective cooling of tympanic temperatures with no observed adverse side effects. In addition, incidences of inflammation and blood-clotting disorders were reduced in patients receiving pharyngeal cooling.
Systemic Inflammatory Response Syndrome (SIRS) has been highlighted as an important factor linked to illnesses following cardiac arrest that include brain and heart injury and restricted blood supplies to tissue. Poor blood clotting is observed with whole body cooling and severe brain damage and low levels of platelets can impair blood clotting.
Incidences of all three diseases were diminished in patients treated with pharyngeal cooling: SIRS incidences in the pharyngeal cooling group amounted to 31 percent of patients compared with 57 percent in the control, coagulopathy incidences were lower in the first three days and thrombocytopaenia incidences dropped to zero compared with 17 percent of the control group
As the researchers report, “In conclusion, it appears that the initiation of pharyngeal cooling is safe and feasible before and shortly after recovery of spontaneous circulation in the emergency room.”
The article can be found at: Takeda et al. (2014) Feasibility Study of Immediate Pharyngeal Cooling Initiation in Cardiac Arrest Patients After Arrival at the Emergency Room.
Category: Features, Technology & Devices
