Biomedical subjects

J N Han

Publications and source records attributed to J N Han.

10 recordsLinked to original sources

PubMed2001

Hyperventilation beyond fight/flight: respiratory responses during emotional imagery.

Hyperventilation (HV) is often considered part of a defense response, implying an unpleasant emotion (negative valence) combined with a strong action tendency (high arousal). In this study, we investigated the importance of arousal and valence as triggers for HV responses. Forty women imagined eight different scripts varying along the arousal and valence dimensions. The scripts depicted relaxation, fear, depressive, action, and desire situations. After each trial, the imagery was rated for valence, arousal, and vividness. FetCO2, inspiratory and expiratory time, tidal volume, and pulse rate were measured in a nonintrusive way. FetCO2 drops and decreases in inspiratory and expiratory time occurred in all but the depressive and the relaxation scripts, suggesting that a defense conceptualization of hyperventilation is not always appropriate.

Adolescent↗

PubMed2001

Critical conditions for hyperventilation responses. The role of autonomic response propositions during emotional imagery.

Hyperventilation is often conceived of as part of a fight-or-flight response, triggered by situations with high arousal and negative valence. However, a previous study using emotional imagery found hyperventilation responses during imagery of high-arousal scenes regardless of their valence. Those imagery scripts contained suggestions of autonomic activity, which may have partly induced or enhanced the hyperventilatory responsivity. The present study used four emotional scripts--depicting relaxing, fearful, depressive, and pleasant situations--without suggestions of autonomic or respiratory responses. After each imagery trial, participants rated their imagery for valence, arousal, and vividness. Fractional end-tidal carbon dioxide (FetCO2), inspiratory and expiratory time, tidal volume, and pulse rate were measured in a non-intrusive way. Results showed significant FetCO2 drops during the fearful and pleasant scripts. However, this effect was much smaller compared to imagery scripts with autonomic response propositions. Participants imagining scripts without autonomic response information found it harder to imagine the scripts vividly and reported lower levels of subjective arousal.

Adolescent↗

PubMed2001

Effects of decreasing the frequency of ventilator circuit changes to every 7 days on the rate of ventilator-associated pneumonia in a Beijing hospital.

INTRODUCTION: We investigated whether decreasing ventilator circuit changes from every 2 days to every 7 days would impact ventilator-associated pneumonia rates at our institution. METHODS: All mechanically ventilated patients at Peking Union Medical College Hospital were studied over a 21 month period. From March 1998 to February 1999, ventilator circuits were changed every 2 days, and from June through December 1999, ventilator circuits were changed every 7 days. Nosocomial pneumonia was identified using the criteria of the Centers for Disease Control. RESULTS: In the 2-day-change group, there were 2,277 ventilator-patient days and 38 patients developed pneumonia, resulting in a pneumonia rate of 16.7 cases per 1,000 ventilator days. The 7-day-change group accumulated 972 ventilator days and 8 patients contracted pneumonia, resulting in a pneumonia rate of 8.2 cases per 1,000 ventilator days. The pneumonia rate was significantly lower in the 7-day-change group (p = 0.007). To standardize for seasonal variability, we compared results from the same seasonal time frames (June to December 1998 for the 2-day-change group, and June to December 1999 for the 7-day-change group), and obtained similar findings: during those periods, pneumonia rates were 24.2 cases per 1,000 ventilator days for the 2-day-change group and 8.9 cases per 1,000 ventilator days for the 7-day-change group (p = 0.001). CONCLUSIONS: A circuit change interval of 7 days had a lower risk of ventilator-associated pneumonia than a 2-day change interval. Therefore, ventilator circuits can be safely changed every 7 days in our setting.

Cross Infection↗

PubMed2000

Psychosomatic symptoms and breathing pattern.

OBJECTIVE: Study of the links between breathing pattern, negative affectivity, and psychosomatic complaints at rest and following hyperventilation. METHODS: In 819 patients with anxiety and somatoform disorders and 159 healthy subjects, self-reported symptoms, breathing pattern, and end-tidal CO(2) concentration (FetCO(2)) were recorded during rest and following a hyperventilation provocation test (HVPT). The relationship between disorder category, symptoms, age, and score of STAI-trait (as a measure of negative affectivity) on the one hand, and breathing pattern on the other was investigated, separately in men and women. RESULTS: Anxiety disorders, and to a lesser extent, somatoform disorders, were characterized by breathing instability (progressive decrease of FetCO(2) at rest during mouthpiece breathing, delayed recovery of FetCO(2) following HVPT), the mean values of respiratory frequency, and FetCO(2) being modulated by STAI-trait. After grouping the symptoms into independent factors, links were observed between symptoms and breathing pattern, independently from the presence of an anxiety or somatoform disorder. CONCLUSION: Some symptom factors appeared to be related to a lower FetCO(2) during hyperventilation, others likely directly influenced the breathing pattern. Among those, mainly respiratory symptoms were accompanied by a reduction of FetCO(2) at rest, with slower recovery of FetCO(2) following HVPT. The latter was observed also in the presence of marked anxiety. In contrast, subjects complaining of dizziness, fainting, and paresthesias in daily life presented higher values of FetCO(2) following HVPT, probably due to a voluntary braking of ventilation during HVPT.

Adult↗

PubMed1998

Subjective symptoms and breathing pattern at rest and following hyperventilation in anxiety and somatoform disorders.

The purpose of the present study was to investigate the diagnostic specificity of bodily symptoms and respiratory behavior at rest and after a hyperventilation provocation test (HVPT) in patients that were either grouped according to the DSM classification or diagnosed as suffering from hyperventilation syndrome. Nine hundred three anxiety and somatoform patients, showing symptoms supposedly caused by psychogenic hyperventilation, and 170 healthy subjects, were studied. Breathing pattern and end-tidal CO2 concentration were recorded during breathing at rest and following a HVPT. Subjective symptoms in daily life and after HVPT were measured. A principal-components analysis was performed on both the symptoms and breathing variables and their specificity levels were compared in the two classifications of patients. Some symptoms in daily life were grouped together with the same symptoms after the HVPT, other symptoms were not. This suggests that the HVPT elicited partly specific symptoms, and partly reproduced the symptoms experienced in daily life. Similar findings were observed with respect to the breathing variables. Patients with panic differed from other patients with anxiety disorders by an increased level of symptoms and a FETCO2 decline at rest. The HVPT may be informative for diagnosis because it provokes some of the typical somatic and psychological symptoms, and it identifies the breathing instability that is characteristic of both patients with HVS and with anxiety. The same symptoms and breathing variables characterized the patients, whatever their classification. Overall, the specificity of breathing variables is rather low.

Adult↗

PubMed1997

Influence of awareness of the recording of breathing on respiratory pattern in healthy humans.

This study was designed to test whether awareness of the measurement of breathing influences the breathing pattern in healthy subjects under routine laboratory conditions. Seventy four subjects (40 females and 34 males), aged 21-63 yrs, were studied under three different conditions whilst their breathing was being recorded for 5 min by means of inductance plethysmography (Respitrace): 1) subjects were misled into believing that their breathing was not being recorded but that they had to wait for 5 min whilst equipment was calibrated; 2) subjects were instructed that their breathing pattern was being recorded for 5 min; 3) the subject's breathing was recorded for 5 min with mouthpiece and pneumotachograph. The first two conditions were randomized. The Respitrace was calibrated by means of multiple linear regression carried out during the 5 min period of quiet breathing through a mouthpiece. Awareness of the recording of breathing caused prolongation of inspiratory (tI) and expiratory time (tE). Breathing through the mouthpiece resulted in an increase of tI, tE and tidal volume (VT). The breathing irregularities (sighs and end-expiratory pauses) decreased when subjects were aware of the recording of breathing and nearly disappeared when subjects breathed through the mouthpiece. The end-tidal carbon dioxide concentration was not significantly different between the three conditions. Mouthpiece breathing often induced some respiratory discomfort and even anxiety, particularly in females. Awareness by the subject that his or her breathing was being recorded altered the spontaneous breathing pattern, mainly the breathing frequency. In addition, use of a mouthpiece markedly increased tidal volume, particularly in females in whom mouthpiece breathing induced more complaints than in males.

Adult↗

PubMed1997

Unsteadiness of breathing in patients with hyperventilation syndrome and anxiety disorders.

The breathing pattern of 399 patients with hyperventilation syndrome (HVS) and/or with anxiety disorders and that of 347 normal controls was investigated during a 5 min period of quiet breathing and after a 3 min period of voluntary hyperventilation. The diagnosis of HVS was based on the presence of several suggestive complaints occurring in the context of stress, and reproduced by voluntary hyperventilation. Organic diseases as a cause of the symptoms were excluded. The anxiety disorders were diagnosed by means of an abbreviated version of the Anxiety Disorders Interview Schedule (ADIS). There was a large overlap between the two diagnoses. Simply breathing via a mouthpiece and pneumotachograph made end-tidal CO2 fractional concentration (FET,CO2) decrease progressively both in hyperventilators and in patients with anxiety disorders, but not in normals. At the start of the measurement the FET,CO2 was not different between patients and healthy subjects. In patients < or = 28 yrs, the decrease of FET,CO2 resulted from a higher tidal volume, and in patients > or = 29 years from an increase in frequency. After voluntary hyperventilation, the recovery of FET,CO2, was delayed in patients, due to a slower normalization of respiratory frequency in females and in older males, and of tidal volume in younger males, and also due to less frequent end-expiratory pauses. When breathing was recorded first by means of inductive plethysmography (Respitrace), the progressive decline of FET,CO2 seen in patients was not observed: from the onset of the recording, FET,CO2 was reduced in patients. It did not change further when, immediately afterwards, the subject switched to mouthpiece breathing. The finding that breathing through a mouthpiece induces hyperventilation in patients and that recovery of FET,CO2 is delayed after voluntary hyperventilation, suggests that the respiratory control system is less resistant to challenges (mouthpiece or voluntary hyperventilation) in those patients. On the other hand, the lower values of FET,CO2 measured during recording by means of a Respitrace probably result from a challenge, prior to the recordings, induced by the fitting of the measuring device to the patient. This unsteadiness of breathing characterizes patients with hyperventilation syndrome and those with anxiety disorders, but is not sufficiently sensitive to be used for individual diagnosis.

Adult↗

PubMed1996

Influence of breathing therapy on complaints, anxiety and breathing pattern in patients with hyperventilation syndrome and anxiety disorders.

The effect of breathing therapy was evaluated in patients with hyperventilation syndrome (HVS). The diagnosis of HVS was based on the presence of several suggestive complaints occurring in the context of stress, and reproduced by voluntary hyperventilation. Organic diseases as a cause of the symptoms were excluded. Most of these patients met the criteria for an anxiety disorder. The therapy was conducted in the following sequence: (1) brief, voluntary hyperventilation to reproduce the complaints in daily life: (2) reattribution of the cause of the symptoms to hyperventilation: (3) explaining the rationale of therapy-reduction of hyperventilation by acquiring an abdominal breathing pattern, with slowing down of expiration: and (4) breathing retraining for 2 to 3 months by a physiotherapist. After breathing therapy, the sum scores of the Nijmegen Questionnaire were markedly reduced. Improvements were registered in 10 of the 16 complaints of the questionnaire. The level of anxiety evaluated by means of the State-Trait Anxiety Inventory (STAI) decreased slightly. The breathing pattern was modified significantly after breathing retraining. Mean values of inspiration and expiration time and tidal volume increased, but end-tidal CO2 concentration (FETCO2) was not significantly modified except in the group of younger women (< or = 28 years). A canonical correlation analysis relating the changes of the various complaints to the modifications of breathing variables showed that the improvement of the complaints was correlated mainly with the slowing down of breathing frequency. The favorable influence of breathing retraining on complaints thus appeared to be a consequence of its influence primarily on breathing frequency, rather than on FETCO2.

Adolescent↗

PubMed1994

Contribution of the parasternal intercostals to inspiratory rib elevation in dogs.

To estimate the contribution of the parasternal intercostals to rib elevation during quiet breathing, parasternal intramuscular pressure, Pim, in the fourth interspace and displacement of the rib just below were measured in eight supine anesthetized dogs during: (1) bilateral stimulation of the parasternals, (2) quiet breathing before, after phrenicotomy, and subsequent vagotomy. During quiet breathing, the parasternal contribution averaged 66 +/- 12% of the rib elevation caused by inspiratory rib cage muscles. This contribution decreased in relative terms after phrenicotomy (37 +/- 14%) and subsequent vagotomy (26 +/- 14%) while it tended to increase in absolute terms (from 1.9 +/- 2.4 to 2.1 +/- 2.5 NS, and 2.4 +/- 2.4 mm P < 0.01, respectively). Rib elevation caused by inspiratory rib cage muscles increased after phrenicotomy (116 +/- 63%, P < 0.001) and subsequent vagotomy (279 +/- 60%, P < 0.001) as did Pim (19 +/- 10% NS and 41 +/- 36% P < 0.01, respectively). Moreover, the mechanical interaction of the parasternals among different interspaces measured in three other dogs, was likely to be limited during quiet breathing. We conclude that after diaphragm paralysis, the parasternals played a progressively smaller role while other rib cage muscles were increasingly recruited.

Animals↗

PubMed1993

Respiratory function of the rib cage muscles.

Elevation of the ribs and expansion of the rib cage result from the co-ordinated action of the rib cage muscles. We wished to review the action and interaction of the rib cage muscles during ventilation. The parasternal intercostal muscles appear to play a predominant role during quiet breathing, both in humans and in anaesthetized dogs. In humans, the parasternal intercostals act in concert with the scalene muscles to expand the upper rib cage, and/or to prevent it from being drawn inward by the action of the diaphragm. The external intercostal muscles are considered to be active mainly during inspiration, and the internal intercostal muscles during expiration. The respiratory activity of the external intercostals is minimal during quiet breathing both in man and in dogs, but increases with increasing ventilation. Inspiratory activity in the external intercostals can be enhanced in anaesthetized animals and humans by inspiratory mechanical loading and by CO2 stimulation, suggesting that the external intercostals may constitute a reserve system, that may be recruited when the desired expansion of the rib cage is increased. The triangularis sterni is an important expiratory muscle during quiet breathing in animals, but it is not active during quiet breathing in man. However, during expiration below functional residual capacity (FRC), and during speech, laughing and coughing, the triangularis sterni is recruited and plays an increasingly important role.

Biomechanical Phenomena↗