title: Effect of laparotomy on respiratory muscle activation pattern.
abstract: Muscular tone of the abdominal wall is important in maintaining transdiaphragmatic pressures and its loss can lead to decreased lung volumes. Patients who are status postlaparotomy are at risk of developing atelectasis. The compensatory role of respiratory muscle activity in postlaparotomy is not well studied. Normally, inspiratory muscles are active during inspiration and passive during expiration to allow for lung recoil. However, electrical activities of the inspiratory muscles continue during early expiratory phase to prevent rapid loss of lung volume. This activity is known as post-inspiratory inspiratory activity (PIIA). In this study, we hypothesized that laparotomy will elicit an increase in PIIA, which is enhanced by respiratory chemical loading. Experiments were conducted in cats under three different conditions: intact abdomen (n = 3), open abdomen (n = 10), and post abdominal closure (n = 10) during eupnea and hypercapnia (10% CO2). Electromyography (EMG) activities of the diaphragm and parasternal muscles were recorded and peak EMG amplitude, PIIA time, and area under the curve were measured. Intraesophageal pressure was also obtained. PIIA was significantly higher under open abdominal conditions in comparison to intact abdomen during eupnea. Our data indicates that PIIA is increased during open abdomen and may be an important compensatory mechanism for altered respiratory mechanics induced by laparotomy. Also, PIIA remained elevated after abdominal closure. However, under hypercapnia, PIIA was significantly higher during intact abdomen in comparison to open abdomen, which is thought to be due to respiratory muscle compensation under chemical loading.
authors.affiliation: Department of Pediatrics, College of Medicine, Pennsylvania State University, Pennsylvania.
authors.forename: Pritish
authors.initials: P
authors.lastname: Mondal
authors.affiliation: Department of Pediatrics, University of Florida, Gainesville, Florida.
authors.forename: Mutasim
authors.initials: M
authors.lastname: Abu-Hasan
authors.affiliation: Department of Statistics, University of Florida, Gainesville, Florida.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Saha
authors.affiliation: Department of Neurological Surgery and Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky.
authors.forename: Teresa
authors.initials: T
authors.lastname: Pitts
authors.affiliation: Department of Physiological Sciences, University of Florida, Gainesville, Florida.
authors.forename: Melanie
authors.initials: M
authors.lastname: Rose
authors.affiliation: Department of Physiological Sciences, University of Florida, Gainesville, Florida.
authors.forename: Donald C
authors.initials: DC
authors.lastname: Bolser
authors.affiliation: Department of Physiological Sciences, University of Florida, Gainesville, Florida pdavenpo@ufl.edu.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Davenport
mesh_terms: D000818:Animals; D002415:Cats; D003964:Diaphragm / Q000502:physiology; D007366:Intercostal Muscles / Q000502:physiology; D007813:Laparotomy / Q000009:adverse effects* / Q000639:trends; D008297:Male; D011183:Postoperative Complications / Q000209:etiology / Q000503:physiopathology; D015656:Respiratory Mechanics / Q000502:physiology*; D012132:Respiratory Muscles / Q000502:physiology*
keywords: Diaphragm; hypercapnia; parasternal intercostal muscles; post‐inspiratory inspiratory activity PIIA; respiratory compensation