BACKGROUND AND PURPOSE: Cerebrovascular reactivity (CVR) can be estimated by measuring the change of cerebral blood flow that occurs during vasostimulation. To estimate the cerebrovascular reactivity, we investigated the change of flow velocity of the internal carotid artery (ICA) and the middle cerebral artery (MCA) during hyperventilation and hypoventilation with the transcranial doppler. So we studied whether the CVR measured by this method could show a significant difference between the normal and the atherosclerotic subjects and whether the CVR may decrease with age in normal gubjects. METHODS: Using transcranial doppler, we measured the mean velocity (Vm), the pulsatility index (P.I.) at the resting state, the end of breath-holding and the end of hyperventilation in 30 normal and 10 atherosclerotic subjects, so we calculated the percentile change of mean velocity (% Vm) and P.I. (% P.I.) after the vasostimulation. We estimated the change of Vm, P.I., % Vm and % P.I. By the age group and compared those parameters between the age-matched normal control and atherosclerotic subjects. RESULTS: The Vm in ICA and MI significantly decreased with age (p<0.01), but there was no significant difference in Vm and P. I. Between normal and atherosclerotic subjects. The % Vm and % P.I. In response to hyperventilation significantly decreased with age in ICA, M1, M2 and there was significant difference in % Vm of ICA and M1 after breath-holding and % Vm of ICA after hyperventilation between the normal and atherosclerotic subjects. CONCLUSION: The breath-holding and hyperventilation tests could be non-invasive and useful methods in estimation of the cerebrovascular reactivity and could be applied in the basal and follow-up evaluation of the cerebrovascular reserve of the ischemic stroke patients.
Carotid Artery, Internal ; Humans ; Hyperventilation ; Hypoventilation ; Middle Cerebral Artery ; Stroke

BACKGROUND: Bag and mask devices are used frequently to provide patients with positive-pressure-assisted ventilation. One of the disadvantages is the fact that they do not deliver high concentrations of oxygen without special adaptors or attention to technique. In order to investigate the variables affecting oxygen delivery, we designed a study to determine the fractions of delivered oxygen (FDO2) under varying ventilating techniques and conditions. METHODS: We designed special wooden box, in which the Laerdal resuscitator bag had been. We measured the fractions of delivered oxygen with or without reservoir bag in various tidal volumes, respiration rates and oxygen flows. RESULTS: Without reservoir bag, the fractions of delivered oxygen were increased up to only 73% in spite of 15 l/min oxygen flow. With reservoir bag, the fractions of delivered oxygen were increased up to nearly 96% in 5-7.5 l/min oxygen flow. CONCLUSIONS: While using the Laerdal resuscitator bag, it is desirable to adapt reservoir bag and supply 5 l/min oxygen in conventional ventilation and 7.5 l/min in hyperventilation minimally for higher fraction of delivered oxygen.
Humans ; Hyperventilation ; Masks ; Oxygen* ; Respiratory Rate ; Tidal Volume ; Ventilation

BACKGROUND: QT interval dispersion (QTD) reflects the regional inhomogeneity of ventricular repolarization, and heart rate variability reflects the autonomic tone of the heart. The relation between QTD and heart rate is not clarified yet. The object of this study was to examine the influence of heart rate on QTD using exercise treadmill test in healthy subjects. METHODS: The influence of heart rate on QTD was studied in 42 young healthy pilots by evaluating the changes in QTD induced by hyperventilation and exercise. QTpeak interval dis-persion (QTp D) was defined as the difference between maximum and minimum QTpeak interval measured on 12 lead ECG at single cardiac beat. Paired t test was used between QTp D at rest, QTp D after hyperventilation and QTp D after exercise to determine the effect of heart rate on QTp D. RESULTS: The QTp D after hyperventilation (37+/-11 msec) was greater compared to QTp D at rest (35 +/-14 msec), but there was no difference (P>0.05). The QTp D after exercise was 31 +/-11 msec at stage 1, 28 +/-13 msec at statge 2 and 31 +/-12 msec at stage 3. and there was the significant difference in QTp D at statge 2 compared to QTp D at rest (P<0.05). CONCLUSION: The QTp D significantly decreased at stage 2 after graded exercise in healthy men. This finding suggests that anti-arrhythmogenic effect associated with decreased QTp D during physiologic exercise is present in apparently healthy men.
Electrocardiography ; Exercise Test ; Heart Rate* ; Heart* ; Humans ; Hyperventilation ; Male

Pneumocephalus is common after brain surgeries, but usually is not substantial enough to cause serious complications. We recently encountered a case of post-operative tachypnea after an endoscopic 3rd ventriculostomy. At first, we thought that the hyperventilation was the result of residual paralysis after emergence from anesthesia, but during further evaluation we found a massive pneumocephalus. In such unusual post-operative situations, physicians should consider surgery-related complications as the possible cause as well, along with the anesthetic factors.
Anesthesia ; Brain ; Hyperventilation* ; Paralysis ; Pneumocephalus* ; Postoperative Care ; Tachypnea ; Ventriculostomy*

A hyperventilation attack is common in people with overanxiety and nervous prostration. However, persistent hyperventilation can cause many severe complications. Although there have been many case reports and studies on the hyperventilation attack, there has been no case report that occured during the recovery from general anesthesia. We experienced a unique case of hyperventilation attack during recovery from general anesthesia. The patient was a previously healthy 18 years old female who did not have any other history of hyperventilation or psychogenic problems. During general anesthesia recovery, she suddenly hyperventilated (respiratory rates>50/min). This hyperventilation waxed and waned in proportion to the sedation by the target- controlled infusion with propofol. The respiratory rates were stabilized to below 20/minute in 5 hours later.
Adolescent ; Anesthesia, General* ; Anxiety ; Female ; Humans ; Hyperventilation* ; Propofol ; Respiratory Rate

The causes of a transient loss of consciousness (TLOC) are divided into syncope, epileptic seizures, cerebrovascular diseases and functional disorders such as hyperventilation (HV) syndrome, psychogenic pseudosyncope. The differential diagnosis of TLOC is may be difficult due to lack of history, misleading features, or confusion over the definition of syncope. We have experienced a rare case of HV syncope that TLOC developed after HV from mental stress, and differentiated by head-up tilt table test with transcranial doppler.
Diagnosis, Differential ; Epilepsy ; Humans ; Hyperventilation* ; Syncope* ; Tilt-Table Test* ; Unconsciousness

The routine management of head injury includes hyperventilation to produce hypocapnis with arterial CO2 tension 25~30 torr. But a decrease in cerebral blood flow with hypocapnia may result in cerebral ischemia. Our study was to evaluate the change of cerebral blood flow during hyperventilation in halthane anesthesia. The jugular venous oxygen saturation(SjvO2), arterio-venous oxygen content difference(CaO2-CjvO2), and oxygen extraction ratio(O2ER) were used as criteria of cerebral ischemia with reduced cerebral blood flow. The results are as follows: 1) SjvO2 was lower in group 2(PaCO2=22.8torr) than group 1(PaCO2=30.3 torr). 2) CaO2-CjvO2 and O2ER were higher in Group 2 than group 1. 3) No more increased possibility of cerebral ischemia with reduced cerebral blood flow was observed Group 2 than group 1.
Anesthesia ; Brain Ischemia ; Craniocerebral Trauma ; Hyperventilation ; Hypocapnia ; Oxygen*

OBJECTIVE: To investigate and demonstrate persistent increase of peak cough flow after mechanical in-exsufflator application, in patients with neuromuscular diseases and pneumonia. METHODS: A mechanical in-exsufflator was applied with patients in an upright or semi-upright sitting position (pressure setting, +40 and −40 cmH2O; in-exsufflation times, 2–3 and 1–2 seconds, respectively). Patients underwent five cycles, with 20–30 second intervals to prevent hyperventilation. Peak cough flow without and with assistive maneuvers, was evaluated before, and 15 and 45 minutes after mechanical in-exsufflator application. RESULTS: Peak cough flow was 92.6 L/min at baseline, and 100.4 and 100.7 L/min at 15 and 45 minutes after mechanical in-exsufflator application, respectively. Assisted peak cough flow at baseline, 15 minutes, and 45 minutes after mechanical in-exsufflator application was 170.7, 179.3, and 184.1 L/min, respectively. While peak cough flow and assisted peak cough flow increased significantly at 15 minutes after mechanical in-exsufflator application compared with baseline (p=0.030 and p=0.016), no statistical difference was observed between 15 and 45 minutes. CONCLUSION: Increased peak cough flow after mechanical in-exsufflator application persists for at least 45 minutes.
Cough* ; Humans ; Hyperventilation ; Neuromuscular Diseases* ; Pilot Projects* ; Pneumonia*

Respiration protocols have been developed to manipulate mental states, including their use for therapeutic purposes. In this systematic review, we discuss evidence that respiration may play a fundamental role in coordinating neural activity, behavior, and emotion. The main findings are: (1) respiration affects the neural activity of a wide variety of regions in the brain; (2) respiration modulates different frequency ranges in the brain's dynamics; (3) different respiration protocols (spontaneous, hyperventilation, slow or resonance respiration) yield different neural and mental effects; and (4) the effects of respiration on the brain are related to concurrent modulation of biochemical (oxygen delivery, pH) and physiological (cerebral blood flow, heart rate variability) variables. We conclude that respiration may be an integral rhythm of the brain's neural activity. This provides an intimate connection of respiration with neuro-mental features like emotion. A respiratory-neuro-mental connection holds the promise for a brain-based therapeutic usage of respiration in mental disorders.
Humans ; Respiration ; Brain ; Hyperventilation ; Heart Rate/physiology* ; Lung

OBJECTIVEMedically unexplained dyspnea is common in adult and accounts for 14% patients complaining of dyspnea. Its occurrence in children is seldom recognized. In the present paper, 34 children with medically unexplained dyspnea (age 10 to 18 years) seen in Peking Union Medical College Hospital from 1996 to 2002 are reported.

METHODSThe diagnosis of medically unexplained dyspnea was clinical: it was based on the presence of dyspnea and other complaints which cannot be explained by an organic disease. The patients answered Nijmegen questionnaire and state and trait anxiety (STAI), and performed hyperventilation provocation test. Twenty sessions of breathing therapy were applied and 13 out of 34 children were followed up after the therapy.

RESULTSAmong the children, 75% started to have symptoms at the age of 13 to 16 years, though the age of first episode could be as early as 8 years. In most of the cases, the course was chronic clinically. In addition to marked dyspnea, their clinical profile included symptoms of hyperventilation i.e. blurred vision, dizziness, tingling, stiff fingers or arm. The symptoms of anxiety were less frequent in children and accordingly the level of anxiety evaluated by means of STAI was lower in children compared to adult patients. The precipitating psychological factors appeared to be related to middle school competition. Pressure from exams, reprimand from stern and unsympathetic teachers coupled with high parental expectation could be emotionally damaging to psychologically susceptible children. Thirteen patients were followed up after 2-3 months of breathing therapy with emphasis on abdominal breathing and slowing down of expiration. After therapy, the sum score of the Nijmegen Questionnaire was markedly decreased. Dyspnea and symptoms of hyperventilation were improved. The level of anxiety was minimally modified.

CONCLUSIONThe cases illustrated the need for careful diagnostic evaluation and treatment because of the high rate of chronicity of the disorder.

Adolescent ; Child ; Dyspnea ; etiology ; pathology ; therapy ; Female ; Humans ; Hyperventilation ; Male ; Prognosis ; Treatment Outcome