An Outbreak of Airborne Nosocomial Varicella

PEDIATRICS ◽  
1982 ◽  
Vol 70 (4) ◽  
pp. 550-556 ◽  
Author(s):  
Tracy L. Gustafson ◽  
Gail B. Lavely ◽  
Earl R. Brawner ◽  
Robert H. Hutcheson ◽  
Peter F. Wright ◽  
...  
Keyword(s):  
Hospital Stay ◽  
Negative Pressure ◽  
Sulfur Hexafluoride ◽  
Index Patient ◽  
Nosocomial Transmission ◽  
Positive Pressure ◽  
Tracer Gas ◽  
Common Mode ◽  
Immunocompromised Child ◽  
Mode Of Transmission

An outbreak of nosocomial varicella was traced to airborne spread from an immunocompromised child hospitalized from Nov 11-19, 1980. Seventy potentially susceptible children were hospitalized on the ward during that period. Although the index patient remained in strict room isolation throughout his hospital stay, eight of these patients contracted varicella. The afternoon of November 12 was the period of highest risk for acquiring varicella. Eight of 36 patients (22%) present that afternoon, compared to none of 34 patients not present that afternoon, acquired the infection. A patient's risk of contracting varicella was significantly related to how near he/she came to the index patient's room that afternoon. Airflow studies, using the tracer gas, sulfur hexafluoride (SF6), demonstrated that patient rooms on this ward were at positive pressure with respect to the corridor. Despite isolation procedures, SF6 released in the index patient's room achieved concentrations in the corridor as high as 10% of those inside the room. Airborne spread of varicella has rarely been reported, but it may be a common mode of transmission in hospitals. We suggest that patients hospitalized with varicella be placed in strict isolation in negative-pressure rooms to reduce the risk of nosocomial transmission.

Study of Toynbee Phenomenon by Combined Intranasopharyngeal and Tympanometric Measurements

1988 ◽  
Vol 97 (2) ◽  
pp. 199-206 ◽  
Author(s):  
Yehuda Finkelstein ◽  
Yuval Zohar ◽  
Yoav P. Talmi ◽  
Nelu Laurian
Keyword(s):  
Middle Ear ◽  
Negative Pressure ◽  
Pressure Change ◽  
Positive Pressure ◽  
New Information ◽  
Pressure Changes ◽  
Rapid Pressure

The Toynbee maneuver, swallowing when the nose is obstructed, leads in most cases to pressure changes in one or both middle ears, resulting in a sensation of fullness. Since first described, many varying and contradictory comments have been reported in the literature concerning the type and amount of pressure changes both in the nasopharynx and in the middle ear. In our study, the pressure changes were determined by catheters placed into the nasopharynx and repeated tympanometric measurements. New information concerning the rapid pressure variations in the nasopharynx and middle ear during deglutition with an obstructed nose was obtained. Typical individual nasopharyngeal pressure change patterns were recorded, ranging from a maximal positive pressure of + 450 to a negative pressure as low as −320 mm H2O.

Effect of airway wall flexibility on clearance by simulated cough

1987 ◽  
Vol 63 (2) ◽  
pp. 707-712 ◽  
Author(s):  
V. Soland ◽  
G. Brock ◽  
M. King
Keyword(s):  
Negative Pressure ◽  
Rectangular Cross Section ◽  
Dynamic Compression ◽  
Wave Formation ◽  
Bottom Surface ◽  
Positive Pressure ◽  
Airway Wall ◽  
Wall Flexibility ◽  
Mucus Rheology ◽  
The Relationship

In our previous study, we investigated the relationship between mucus rheology, depth of mucus layer, and clearance by simulated cough. The purpose of the present study was to examine the effect of airway wall flexibility on the clearance of mucuslike gels. Transient airflows similar to cough were generated by both positive and negative pressure, the latter to mimic the dynamic compression that occurs during real cough. As in the previous study, the trachea was modeled as a trough of rectangular cross section with only the bottom lined with the mucus simulant. Clearance was followed by observing the displacement of marker particles. Since cough clearance is intimately related to wave formation in the mucus blanket, we hypothesized that clearance might be impeded if the wave formation occurred simultaneously in the wall and its lining layer. Thus, in one set of experiments the bottom rigid surface of the model trachea was replaced with a frame over which a flexible membrane could be drawn, whereas in the other set the rigid top was replaced by the frame. We also examined the effect of negative-pressure cough in excised canine tracheae, comparing the case where the tracheal membrane was free to deform vs. the case where it was secured. For the rigid-walled model, clearance by positive or negative pressure, with matched flow pattern, was the same. With the mucus simulant lining the flexible bottom surface, clearance increased with increasing membrane flexibility for negative-pressure cough and decreased for positive-pressure cough.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of intrathoracic pressure on pressure-volume characteristics of the lung in man

1975 ◽  
Vol 38 (3) ◽  
pp. 411-417 ◽  
Author(s):  
H. S. Goldberg ◽  
W. Mitzner ◽  
K. Adams ◽  
H. Menkes ◽  
S. Lichtenstein ◽  
...  
Keyword(s):  
Negative Pressure ◽  
Total Lung Capacity ◽  
Human Subjects ◽  
Ambient Pressure ◽  
Intrathoracic Pressure ◽  
Dynamic Compliance ◽  
Positive Pressure ◽  
Lung Capacity ◽  
Airway Opening ◽  
Volume Characteristics

Quasi-static pressure-volume (P-V) curves in normal seated human subjects were determined with pressure at the airway opening (Pa0) set below (negative pressure), above (positive pressure), or equal to ambient pressure. Dynamic compliance (Cdyn) during controlled continuous negative pressure breathing (CNPB) was also studied. Quasi-static P-V curves at negative pressure were decreased in slope, reflected a decrease in total lung capacity, and intersected the P-V curve obtained at ambient Pa0. At positive pressure the P-V curves showed an increase in slope and an increase in total lung capacity. During CNPB a fall in Cdyn was found. The fall in Cdyn was rapid and persisted for the duration of CNPB. Cdyn promptly returned to control levels when Pa0 was adjusted to ambient pressure.

A LEAK QUANTIFICATION METHOD USING SULFUR HEXAFLUORIDE AS TRACER GAS

2004 ◽  
Vol 86 (6) ◽  
pp. 613-618 ◽  
Author(s):  
V. Vishnu Karthik ◽  
Andrew R. McFarland
Keyword(s):  
Sulfur Hexafluoride ◽  
Tracer Gas ◽  
Quantification Method

Simple Device for Producing Continuous Negative Pressure in Infants With IRDS

PEDIATRICS ◽  
1973 ◽  
Vol 52 (1) ◽  
pp. 128-131
Author(s):  
Eduardo Bancalari ◽  
Tilo Gerhardt ◽  
Ellen Monkus
Keyword(s):  
Intensive Care Unit ◽  
Negative Pressure ◽  
Positive Pressure Ventilation ◽  
Newborn Infants ◽  
Transpulmonary Pressure ◽  
Intermittent Positive Pressure Ventilation ◽  
Positive Pressure ◽  
School Of Medicine ◽  
Newborn Intensive Care Unit ◽  
Newborn Intensive Care

Increasing experience with the use of continuous transpulmonary pressure, either positive or negative, during the last years has clearly demonstrated the success of this mode of therapy in IRDS.1-3 Forty newborn infants with this disease have been treated with continuous negative pressure (CNP) in the Newborn Intensive Care Unit, Department of Pediatrics, University of Miami School of Medicine, using a modified incubator-respirator.* Twenty-one required only CNP, three of whom died (14%). Among the 19 who needed CNP plus intermittent positive pressure ventilation, nine died (47%). All required more than 70% oxygen to maintain a Pao2 over 50 mm Hg before using CNP.

Esophageal and Gastric Disorders

2016 ◽  
pp. 241-250
Author(s):  
Amy S. Oxentenko
Keyword(s):  
Pressure Gradient ◽  
Lower Esophageal Sphincter ◽  
Negative Pressure ◽  
Positive Pressure ◽  
Gastric Contents ◽  
Esophageal Sphincter

The main functions of the esophagus are to transport food and prevent reflux. To transport food from the mouth to the stomach, the esophagus must work against a pressure gradient, with negative pressure in the chest and positive pressure in the abdomen. The lower esophageal sphincter helps to prevent reflux of gastric contents back into the esophagus.

scholarly journals A comparative study of the efficacy of topical negative pressure moist dressings and conventional moist dressings in chronic wounds

2007 ◽  
Vol 40 (02) ◽  
pp. 133-140
Author(s):  
Surajit Bhattacharya ◽  
J Ravikrishnan ◽  
B S Satish Rao ◽  
H. Divakar Shenoy ◽  
S R Shetty ◽  
...  
Keyword(s):  
Hospital Stay ◽  
Surface Area ◽  
Negative Pressure ◽  
Chronic Wounds ◽  
Tissue Formation ◽  
Granulation Tissue Formation ◽  
Topical Negative Pressure ◽  
Graft Take ◽  
The Mean ◽  
Negative Pressure Dressings

ABSTRACT Aim: To assess the efficacy of topical negative pressure moist wound dressing as compared to conventional moist wound dressings in improving the healing process in chronic wounds and to prove that negative pressure dressings can be used as a much better treatment option in the management of chronic wounds. Materials and Methods: This is a prospective comparative study of data from 112 patients with chronic wounds, of which 56 patients underwent topical negative pressure dressings (17 diabetic, 10 pressure sores, nine ischemic, two varicose, 10 post-infective raw areas and eight traumatic - six had bone exposed, two orthopaedic prosthesis exposed). The remaining 56 patients underwent conventional moist dressings (20 diabetic, two ischemic, 15 pressure sores, three varicose, eight post-infective raw areas and eight traumatic - five had bone exposed, three orthopaedic prosthesis exposed). The results were compared after 10 days. The variables compared were, rate of granulation tissue formation as a percentage of ulcer area covered, skin graft take up as the percentage of ulcer surface area and duration of hospital stay. The variables were compared using Unpaired Student′s t test. A " P" value < 0.05 was considered significant. Results: Out of 56 patients who underwent topical negative pressure dressings, six (10.71%) were failures, due to failure in maintaining topical negative pressure due to defective sealing technique; these were included into the study group. After 10 days, the mean rate of granulation tissue formation was 71.43% of ulcer surface area. All these 56 cases underwent split-thickness skin grafting. The mean graft take-up was 79.29%. The mean hospital stay was 32.64 days. In the remaining 56 patients, the mean rate of granulation tissue formation was 52.85% of ulcer surface area. The mean graft take-up was only 60.45% of the total ulcer surface area. The mean hospital stay was 60.45 days. Conclusion: To conclude, topical negative pressure dressings help in faster healing of chronic wounds and better graft take-up and reduce hospital stay of these patients.

Effect of continuous pressure breathing on right ventricular volumes

1967 ◽  
Vol 22 (6) ◽  
pp. 1053-1060 ◽  
Author(s):  
Maylene Wong ◽  
Edgardo E. Escobar ◽  
Gilberto Martinez ◽  
John Butler ◽  
Elliot Rapaport
Keyword(s):  
Right Ventricular ◽  
Negative Pressure ◽  
Atmospheric Pressure ◽  
Diastolic Pressure ◽  
Venous Pressure ◽  
Intrathoracic Pressure ◽  
Transmural Pressure ◽  
Positive Pressure ◽  
End Diastolic Volume ◽  
Negative Pressure Breathing

We measured the end-diastolic volume (EDV) and stroke volume (SV) in the right ventricle of anesthetized dogs during continuous pressure breathing and compared them to measurements taken during breathing at atmospheric pressure. During intratracheal positive-pressure breathing, EDV, and SV decreased and end-diastolic pressure became more positive relative to atmospheric pressure. During intratracheal negative-pressure breathing, EDV enlarged and SV tended to increase; end-diastolic pressure became more negative. During extrathoracic negative-pressure breathing SV decreased, EDV fell, though not significantly, and end-diastolic pressure rose, but insignificantly. Changes in EDV observed during intratracheal positive-pressure breathing and intratracheal negative-pressure breathing were associated with minor shifts in transmural pressure (end-diastolic pressure minus intrapleural pressure) in the expected directions, but during extrathoracic negative-pressure breathing a large increase in transmural pressure took place with the nonsignificant reduction in EDV. We believe that intrathoracic pressure influences right ventricular filling by changing the peripheral-to-central venous pressure gradient. The cause of the alteration in diastolic ventricular distensibility demonstrated during extra-thoracic negative-pressure breathing remains unexplained. positive-pressure breathing; negative-pressure breathing; extrathoracic negative-pressure breathing Submitted on August 16, 1966

Cardiopulmonary effects of continuous pressure breathing in hypothermic dogs

1965 ◽  
Vol 20 (4) ◽  
pp. 669-674 ◽  
Author(s):  
J. Salzano ◽  
F. G. Hall
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Stroke Volume ◽  
Negative Pressure ◽  
Alveolar Ventilation ◽  
Positive Pressure ◽  
Negative Pressure Breathing ◽  
Continuous Positive Pressure ◽  
Respiratory Dead Space

Continuous pressure breathing was studied in hypothermic anesthetized dogs. Alveolar ventilation decreased during continuous positive-pressure breathing and increased during continuous negative-pressure breathing. The changes in alveolar ventilation were due to changes in respiratory rate as well as in respiratory dead space. Cardiac output fell significantly during continuous positive-pressure breathing due to a reduction in heart rate and stroke volume. During continuous negative-pressure breathing cardiac output was only slightly greater than during control as a result of a fall in heart rate and an increase in stroke volume. Oxygen consumption was reduced to 60% of control during continuous positive-pressure breathing of 16 cm H2O but was 25% greater than control during continuous negative-pressure breathing. Qualitatively, CO2 production changed as did O2 consumption but was different quantitatively during continuous negative-pressure breathing indicating hyperventilation due to increased respiratory rate. Mean pulmonary artery pressures and pulmonary resistance varied directly with the applied intratracheal pressure. The results indicate that the hypothermic animal can tolerate an imposed stress such as continuous pressure breathing and can increase its oxygen consumption during continuous negative-pressure breathing as does the normothermic animal. hypothermia; respiratory dead space; metabolic rate; cardiac output Submitted on December 8, 1964

scholarly journals Negative pressure rooms and COVID-19

2020 ◽  
Vol 31 (1-2) ◽  
pp. 18-23
Author(s):  
Sammy Al-Benna
Keyword(s):  
Negative Pressure ◽  
Health Care Professionals ◽  
Healthcare Professionals ◽  
Clinical Care ◽  
Public Health Emergency ◽  
Positive Pressure ◽  
Global Pandemic ◽  
Operating Theatres ◽  
Novel Coronavirus ◽  
Surrounding Areas

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes 2019 novel coronavirus disease (COVID-19), has rapidly developed into a global pandemic and public health emergency. The transmission and virulence of this new pathogen have raised concern for how best to protect healthcare professionals while effectively providing care to the infected patient requiring surgery. Although negative pressure rooms are ideal for aerosol-generating procedures, such as intubation and extubation, most operating theatres are generally maintained at a positive pressure when compared with the surrounding areas. This article compares negative and positive pressure rooms and the advantages of a negative pressure environment in optimising clinical care and minimising the exposure of patients and health care professionals to SARS-CoV-2.

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