OU-MRU Vol.2 Oct 2014
Okayama University Medical Research Updates （OU-MRU）
Source: Okayama University (JAPAN), Center for Public Information For immediate
release: 29 October 2014
Okayama University research: Ensuring a cool recovery from cardiac arrest(Okayama, 29 October 2014) Researchers at Okayama University in collaboration
with several medical centres in Japan have demonstrated the safety and efficacy ofa hypothermal treatment – pharyngeal cooling – for cardiac arrest patients.
Cooling the brain is known to prevent neurological problems in patients recoveringfrom cardiac arrest. However the most of current methods for therapeutic
hypothermia may not be initiated before return of spontaneous circulation.
Researchers at Okayama University investigated a method for cooling the area at the
top of the throat – the pharynx - because the arteries that supply the head withoxygenated blood run nearby. Cooling this area should be a good approach tocooling the brain but so far there have been no complete studies to determine
whether pharyngeal cooling could be administered effectively or whether it may leadto other adverse side effects.
The researchers alongside people working in emergency and critical care clinics set
up a trial for 108 cardiac arrest patients. The medical staff administered treatmentswith 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 (tympanictemperature), mechanical or temperature damage to the pharynx, inflammation andblood platelet levels.
The results of the trial indicated effective cooling of tympanic temperatures, with noobserved adverse side effects. In addition, incidences of inflammation and bloodclotting disorders were reduced in patients receiving pharyngeal cooling. As theresearchers 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.”
BackgroundHypothermia treatments and limitations
Previous clinical data has indicated that quickly achieving therapeutic hypothermia is
one of the most important factors for improving neurological outcomes for cardiac
arrest patients. Approaches to achieving therapeutic hypothermia includeintravenous infusion of cold fluid, which can increase re-arrest rates, and nasal
cooling which is prone to cause extreme nosebleeds (epistaxis) and accumulation ofair in soft tissues (peri-orbital emphysema).
OKAYAMA UNIVERSITY
1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 JAPAN© 2014 OKAYAMA UNIV.

OU-MRU Vol.2 Oct 2014
Pharyngeal cooling method
Pharyngeal cooling was begun during chest compression as soon as patients entered
the emergency room or on return of spontaneous circulation (ROSC) if ROSC
returned before entering the emergency room.
In the current study pharyngeal cooling was administered using a pharyngeal cuff, avinyl chloride tubular structure fitted into the upper oesophagus and pharynx. Salinesolution at a temperature of 5 °C was perfused into the cuff at a rate of 500 ml
min−1 and pressure of 50 cm H 2 O.
The temperature was chosen to be above freezing so that ice did not form, andtreatment duration was also limited to 2 hours to avoid damage from the cold. The
pressure was chosen to be below 60 cm H 2 O to avoid neuropathy – nerve damage –which has been reported with the use of equipment similar to the cuff.
Low mechanical damage to the pharynx was thought to be largely due to similarities
between the cuff and other medical instruments, as clinicians administering thetreatment were familiar with using similar equipment.
Choice of patients
Patients aged 14-89 years old were considered eligible for the study within 15
minutes of collapse if they had suffered cardiogenic cardiac arrest or had been
resuscitated from non-cardiogenic arrest by medical personnel. A shortage ofhuman resources meant that not all eligible patients were used in the study. Of the818 patients that met the criteria, 113 were enrolled on the study. The researchers
believe that the relatively small size of the fraction of eligible patients that wereenrolled does not affect the quality of the study data because the random selection
for treatment with or without pharyngeal cooling was undertaken after enrolment,and exclusion from the study after enrolment was very low.
Inflammation and blood clotting disorders post cardiac arrest
Systemic Inflammatory Response Syndrome (SIRS) has been highlighted as animportant factor linked to illnesses following cardiac arrest that include brain andheart injury and restricted blood supplies to tissue. Poor blood clotting(coagulopathy) is observed with whole body cooling and severe brain damage andlow levels of platelets (thrombocytopaenia) 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% of
patients compared with 57% in the control, coagulopathy incidences were lower inthe first three days and thrombocytopaenia incidences dropped to zero comparedwith 17% of the control group

OKAYAMA UNIVERSITY
1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 JAPAN© 2014 OKAYAMA UNIV.

OU-MRU Vol.2 Oct 2014
Reference
Yoshimasa Takeda,∗, Takahisa Kawashima, Kazuya Kiyota, Shigeto Oda,NaokiMorimoto, Hitoshi Kobata, Hisashi Isobe, Mitsuru Honda, Satoshi Fujimi, Jun Onda,
Seishi I, Tetsuya Sakamoto, Masami Ishikawa, Hiroshi Nakano, Daikai Sadamitsu,
Masanobu Kishikawa, Kosaku Kinoshita, Tomoharu Yokoyama, Masahiro Harada,Michio Kitaura, Kiyoshi Ichihara, Hiroshi Hashimoto Beng, Hidekazu Tsuji Beng,Takashi Yorifuji, Osamu Nagano, Hiroshi Katayama,Yoshihito Ujike and Kiyoshi
Morita, “Feasibility study of immediate pharyngeal cooling initiation in cardiacarrest
patients after arrival at the emergency room” , Resuscitation, x, (x), pp.xx­xx, (2014)
DOI: 10. 0.1016/j.resuscitation.2014.09.014.
Figure 1

Pharyngeal cooling cuff (left) and circulator (right). Physiological saline (5 °C) is
initially supplied to the oesophageal cuff through the inflow tube, where thetemperature is continuously monitored, and subsequently fills the pharyngeal cuff
before being discharged through bilateral outlets. The bilateral outlets areconnected to an outflow tube, where pressure is continuously monitored. According
to a pilot study, intra-cuff pressures at the oesophageal and pharyngeal cuffs were 8cm H 2 O and 6 cm H 2 O higher than the pressure monitored at the outlet tube,respectively. The intra-cuff pressure at the pharyngeal cuff was controlled at 50 cm
H 2 O. The cuff is made from vinyl chloride, has passed biological safety tests, andtolerates up to 200 cm H 2 O of intra-cuff pressure
Correspondence toAssociate Professor Yoshimasa Takeda, M.D., Ph.D.
Department of Anesthesiology , Okayama University
Graduate School of Medicine, Dentistry andPharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku,
Okayama 700-8558, Japan
E-mail: yoshit@cc.okayama-u.ac.jp
OKAYAMA UNIVERSITY
1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 JAPAN© 2014 OKAYAMA UNIV.

OU-MRU Vol.2 Oct 2014

Further information
Okayama University
1-1-1 Tsushima-naka , Kita-ku , Okayama 700-8530, Japan
Planning and Public Information Division, Okayama University
E-mail: www-adm@adm.okayama-u.ac.jp
Website: http://www.okayama-u.ac.jp/index_e.html

Okayama University Medical Research Updates （OU-MRU）
Vol.1：Innovative non-invasive ‘liquid biopsy’ method to capture circulating tumor
cells from blood samples for genetic testing

About Okayama University
Okayama University is one of the largest
comprehensive universities in Japan withroots going back to the Medical Training
Place sponsored by the Lord of Okayamaand established in 1870. Now with 1,300
faculty and 14,000 students, the Universityoffers courses in specialties ranging frommedicine and pharmacy to humanities
and physical sciences. Okayama
University is located in the heart of Japan
approximately 3 hours west of Tokyo byShinkansen.

Website: http://www.okayama-u.ac.jp

OKAYAMA UNIVERSITY
1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 JAPAN© 2014 OKAYAMA UNIV.