Yukihiko Ogihara

Brain injury following cardiac arrest: pathophysiology for neurocritical care

AbstractCardiac arrest induces the cessation of cerebral blood flow, which can result in brain damage. The primary intervention to salvage the brain under such a pathological condition is to restore the cerebral blood flow to the ischemic region. Ischemia is defined as a reduction in blood flow to a level that is sufficient to alter normal cellular function. Brain tissue is highly sensitive to ischemia, such that even brief ischemic periods in neurons can initiate a complex sequence of events that may ultimately culminate in cell death. However, paradoxically, restoration of blood flow can cause additional damage and exacerbate the neurocognitive deficits in patients who suffered a brain ischemic event, which is a phenomenon referred to as “reperfusion injury.” Transient brain ischemia following cardiac arrest results from the complex interplay of multiple pathways including excitotoxicity, acidotoxicity, ionic imbalance, peri-infarct depolarization, oxidative and nitrative stress, inflammation, and apoptosis. The pathophysiology of post-cardiac arrest brain injury involves a complex cascade of molecular events, most of which remain unknown. Many lines of evidence have shown that mitochondria suffer severe damage in response to ischemic injury. Mitochondrial dysfunction based on the mitochondrial permeability transition after reperfusion, particularly involving the calcineurin/immunophilin signal transduction pathway, appears to play a pivotal role in the induction of neuronal cell death. The aim of this article is to discuss the underlying pathophysiology of brain damage, which is a devastating pathological condition, and highlight the central signal transduction pathway involved in brain damage, which reveals potential targets for therapeutic intervention.

The Effectiveness of the Fukuhara Laryngeal Mask Airway Holding Forceps (F Forceps)

The laryngeal mask airway (LMA) was introduced more than two decades ago cl), and a comprehensive review article on the LMA has been published (2). The LMA has many advantages over the endotracheal tube (3), including increased speed in establishing an airway, reduced anesthetic requirements for airway tolerance, and lower frequency of coughing during emergence. Insertion of the LMA is performed blindly so that the LMA cuff is placed to cover the laryngeal inlet. The technique of LMA insertion described by Brain (4,5) has been widely accepted and used. Fukuhara (6) had designed and developed the J-shaped LMA holding forceps, named the Fukuhara (F) forceps, for easy and accurate placement of the LMA. The current study was undertaken to evaluate the effectiveness of the F forceps, which have been approved by the Food and Drug Administration.

Are the incidences of cardiac events during noncardiac surgery in Japan the same as in the United States and Europe

In Japan, an ever-present problem in the preoperative evaluation of patients with ischemic heart disease is that although such evaluations are based on Western data, these data serve as the basis for determining perioperative risk in Japanese patients. To remedy this problem, the Cardiac Ischemia and Anesthesia Research Committee was formed in 1997 and has conducted studies of perioperative complications in noncardiac surgery in Japan. In two retrospective studies in 1997, the proportions of patients with ischemic heart disease were 3.9% and 3.1%, approximately one tenth the rates reported in Europe and the United States. The incidences of perioperative cardiac complications in patients with ischemic heart disease were 16.4% and 13.2%, not widely divergent from rates reported in Europe and the United States. To investigate the baseline characteristics involved in perioperative complications, we conducted a prospective study of 237 patients classified as having intermediate risk for perioperative cardiac complications according to the American College of Cardiology/American Heart Association Guidelines for Perioperative Cardiovascular Evaluation for Noncardiac Surgery. We found that the prominent factor in intraoperative cardiac complications was the presence of hypertension (odds ratio = 2.911). Factors contributing to postoperative cardiac complications included those reflecting coronary lesion severity and cardiac dysfunction (history of heart failure; odds ratio = 6.884, coronary risk index grade; odds ratio = 2.884, and a history of intervention; odds ratio = 4.774).

Retraction Note: Brain injury following cardiac arrest: pathophysiology for neurocritical care

[This retracts the article DOI: 10.1186/s40560-016-0140-9.].

Effects of temperature gradient reduction in three different carbon dioxide absorbents.

Background and objective Temperature gradients in CO2 absorbents may locally increase the water content by condensation. We hypothesized that temperature gradient reduction (TGR) would prevent increased water content, thus preserving the reactivity of the CO2 absorbent and thereby increasing its time to exhaustion (longevity). The purpose of this study was to compare the effects of TGR on the longevity of CO2 absorbent with three different types of CO2 absorbents. Methods We constructed a novel TGR canister. Experiments were conducted using three different types of CO2 absorbents: Drägersorb 800 Plus (D800), Drägersorb Free and Amsorb Plus. One kilogram of fresh CO2 absorbent of each type was placed into two types of canister: the conventional control canister (n = 6) and the TGR canister (n = 6). Results In the case of Drägersorb Free, the TGR canister most effectively and specifically prevented local increase in water content of the CO2 absorbent and markedly increased the longevity (30% increase) compared with the control canister. In the case of Amsorb Plus, the TGR canister also prevented local excessive water content, but the increase in longevity was smaller (17% increase). In the case of D800, the TGR canister markedly increased the longevity (27% increase), but its prevention of local excessive water content was smaller. Conclusions TGR is a useful method to prevent local increase in water content and improve the longevity of CO2 absorbent. The effectiveness of TGR on longevity and water content changes varied in the different types of CO2 absorbent.

Molecular Mechanisms of Brain Ischemia and Its Protection

Ischemia is defined as a reduction in blood flow to a level that is sufficient to alter normal cellular function. Brain tissue is highly sensitive to ischemia, such that even brief ischemic periods in neurons can initiate a complex sequence of events that may ultimately culminate in cell death. Stroke and cardiac arrest induce the cessation of cerebral blood flow, which can result in brain damage. The primary intervention to salvage the brain under such a pathological condition is to restore the cerebral blood flow to the ischemic region. However, paradoxically, restoration of blood flow can cause additional damage and exacerbate the neurocognitive deficits in patients who suffered a brain ischemic event, which is a phenomenon referred to as “reperfusion injury.” Transient brain ischemia following a stroke, cardiac arrest, hypoxia, head trauma, cerebral tumor, cerebrovascular disorder, and intracranial infection results from the complex interplay of multiple pathways including excitotoxicity, acidotoxicity, ionic imbalance, peri-infarct depolarization, oxidative and nitrative stress, inflammation, and apoptosis. Many lines of evidence have shown that mitochondria suffer severe damage in response to ischemic injury. Mitochondrial dysfunction based on the mitochondrial permeability transition (MPT) after reperfusion, particularly involving the calcineurin/immunophilin signal transduction pathway, appears to play a pivotal role in the induction of neuronal cell death. Here, we discuss the underlying pathophysiology of brain damage, which is a devastating pathological condition, and highlight the central signal transduction pathway involved in brain damage, which reveals potential targets for therapeutic intervention.

Inadequate gas supply to patients with an adjustable pressure-limiting valve in the fully opened position

With spontaneous ventilation, sufficient exhaust resistance at the adjustable pressure-limiting (APL) valve when fully opened ensures that the reservoir bag fills and adequately supplies gas to patients. A lack of exhaust resistance with the APL valve fully open caused inadequate gas supply to patients with four types of anesthesia machines: SA2 (Dräger), Excel-210 SE (GE), Fabius (Dräger), and Cato (Dräger). Mechanically, the SA2 and Excel-210 SE APL valve systems, which are of the spring-loaded disc type positioned horizontally, cannot maintain sufficient exhaust resistance with the APL valve fully open. As for the Fabius and Cato, an exhaust valve independent of the APL valve should maintain sufficient exhaust resistance continuously. However, accumulated viscous substances on the thin diaphragm of the exhaust valve contributed to hindrance of diaphragm closure.

Anesthesia for Intracranial Vascular Surgery

Subarachnoid hemorrhage (SAH) secondary to ruptured cerebral aneurysm carries a poor outcome and high mortality. There are various types of cerebral aneurysm and several risk factors for aneurysm development or rupture.