Effects Of Postural Chances On Tidal Volumes Of Obese And Non-Obese Healthy Adults While Breathing On BiPAP

Faculty Advisor / Facilitator

Kelly Buzbee AAS, RRT-NPS, RCP

Research Members

Courtney Coffman RCS Taiwo Roberts B.ED, CCNA, CPhT, RCS Cynde Heaton RCS Dianna Herrington LRA, RCS Bahaa Mahrous RCS Jackie Hauser RCS

Hypothesis:

The tidal volume of obese and non-obese healthy adults will be affected while breathing in various positions on BiPAP.

Biological Question:

Will the tidal volume of obese and non-obese healthy adults be affected while breathing in various positions on BiPAP?

Background:

      Newest form of non-invasive ventilation.

Consist of two phases: inspiratory phase and expiratory phase.

IPAP provides assistance in the form of pressure support during the inspiratory phase (IPAP).

EPAP prevents closure of airways during the expiratory phase.

The BiPAP ventilator alternates between IPAP and EPAP levels at respiratory frequencies that synchronize with patient’s breathing pattern.

As the patient inspires, the ventilator delivers IPAP which stop as the patient expires, but pressure within airways remains positive because of EPAP.

Background cont.

IPAP

    Provides assistance during inspiratory phase by generating a positive pressure (greater than the atmospheric pressure) at a level pre-set by clinician.

Increases patient’s tidal volume thus minute ventilation Decreases carbon dioxide levels in arterial blood.

IPAP (pressure support) ends at the start of expiratory phase

   

Background cont.

EPAP

On the BiPAP machine , PEEP/CPAP is termed expiratory positive airway pressure (EPAP). EPAP increases functional residual capacity of the lungs which results in the increase in arterial oxygen levels, compliance and decreased airway closure.

Areas of atelectasis can re-expand and fluid accumulation due to pulmonary edema can be prevented or reduced.

Supplemental oxygen can be given

         

Background cont.

Obesity

Accumulation of excess body fat Most common nutritional disorder in humans Airway narrowing can result from additional fat deposits Health problems increases with neck circumferences of 17 or more.

Abdominal fat accumulation tend to be accompanied by a decrease in vital capacity and FEV1 among adults Expiratory reserve volume is decreased in obesse patients.

Airway resistances increases significantly with levels of obesity People with lean mass are positively associated with respiratory functions, Fat mass in severely obese persons has a negative association.

The effects of position changes during each breath might change the compliance and tidal volume as measured by the BiPAP.

Indications:

   Sleep apnea Exacerbation of COPD when intubation is not recommended.

Short term management of cardiogenic pulmonary edema when intubation is not recommended.

Contraindications:

Pneumothorax: The result of a tear in the pleura allowing air to leave the lung and enter the plural space.

Pathologically low B/P: Low blood pressure causing a decreased preload could be a contraindication.

Severe cardiac arrhythmias: History of cardiac arrhythmias may become affected if sever alkalosis occurs as a result of deep and fast breathing.

Coronary artery disease: Impaired coronary circulation due to positive pressure breathing resulting in an increased intrathoracic pressure decreasing venous return.5

Seizures: Results in inability to protect the airway.

Bullous lung disease: Weakened lung parenchyma at increased risk for pneumothorax.

Methodology:

Individuals wishing to participate in the study were be asked to complete a health questionnaire. Selected individuals received a detailed explanation for the procedure and encouraged to ask questions before a consent form was signed by all participants. Individuals with potential health problems (existing orthopedic problems which could be exacerbated by positioning) were excluded from the study. A total of twelve participants were tested in this study. The subjects will remain anonymous by assignment of numbers. Participants will be allowed access to final results on the internet at www.

        

Methodology cont:

Heart rate, blood pressure, and respiratory rate was be taken and documented in the ICU classroom of Kingwood College in private. Skin color, auscultation, and accessory muscles use, was noted to observe the subject for any signs and symptoms of illness.

Height and weight was be taken and documented (Scale used and calibrated as per instruction manual).

Individual BMI (body mass index) was be calculated.

Subjects were be fitted with the Respironics BiPaP S/T-D breathing mask, and mask adjusted with each subsequent position. Subjects were placed on Hill-Rom Contra multi positional standard Hospital bed in four positions; supine, prone, left side and right side. Subjects were then will be placed on Respironics BiPAP S/T-D ventilatory support system for a minimum of 3 minutes at the rate of IPAP 10 cm H2O and EPAP of 5 cm H2O and titrated to patient’s comfort.

Tidal volume, minute ventilation, percent leak, heart rate, respiratory rate, oxygen saturation, and tolerance to the procedure was documented in each position by the digital read out from the Respironics machine, pulse oximeter and observation.

After the allotted time was reached in each position individual’s post tidal volume, heart rate, blood pressure and respiratory rate was be recorded while in each position.

Data: patientall12.xls

Data Analysis:

Average Min. Volume Differences

140 120

Supine Prone Left Right

100

100 88.96

85.04

80.98

80

Normal BMI differences in Min. Volumes Supine Prone Left Right

60 40

100 71.03

79.11

78.85

Obese BMI differences in Min volumes Supine 100 Prone 124.83

Left 80.75

Right 89.88

20 0 Average Normal BMI Obese BMI Supine Prone Left Right

Recommendations:

     Broader and diverse test group must be considered.

A larger group is required.

Active search for people that might have a mild cold or flu, but otherwise healthy.

Starting the IPAP at eight and the EPAP at three cmH2O and titrating from there for comfort to get a baseline for each subject.

Including sitting down as one of the positions.

 Changing the environment somewhat to make the subject more comfortable.

Limitations:

The first and foremost limitation of our experiment was the number of test subjects. In order to conduct an experiment of this caliber and for the experiment to be truly meaningful a much broader and larger test pool must be considered. From the twelve subjects, eight had a normal BMI status and four were of obese stature. A more acceptable test pool for an experiment this small would have considered perhaps, six normal, six obese, and six overweight subjects. Another major limitation that we placed on ourselves because of time, legal, and ethical questions is that we only evaluated healthy individuals. Where as a person with significant changes in tidal volume and minute ventilation due to postural changes would in fact, probably be ill. The limitations of our experiment included:

     The IPAP and EPAP were set at 10 and 5 cmH2O respectively, for all of the twelve subjects; this should have been titrated individually for the comfort of each subject.

The test group of twelve people should have been more diverse in the sense of body types.

Four out of twelve of the test subjects complained that the machine did not feel spontaneous and this probably affected their volumes.

Two of the twelve test subjects complained that they were unable to stop inspiration when they wanted to, again affecting the volume.

The Hawthorne effect, because of the setting itself; the subject knows they were being watched so this may have affected volumes.

Conclusion:

After analysis of all the data, the experiment was inconclusive at best and actually may indicate that obese people in the prone position had larger tidal volumes and minute ventilations. Respiration rates varied from 12 to 20 breaths per minute with a standard deviation of 3.27 and an average of 16.75. Tidal volumes averaged from 891 mls in the supine position, 727 mls in the prone position, 673 mls lying on the left-hand side to 666 mls lying on the right hand side, with a standard deviation of 334, 296, 214, and 225 mls, respectively. Results indicated that the supine position had the highest tidal volumes for both groups. Significant decreases in the tidal volumes for all other positions with the exception of the prone position in 3 out of 4 of the obese subjects occurred. However, because of the limited number of subjects in the obese category it would be irresponsible to determine that obese subjects in the prone position with BiPAP had larger tidal volumes and minute ventilations.

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References:

Preston R (2001) Introducing non-invasive positive pressure ventilation. Standard. 15,26,42-45. Date of acceptance: October 24, 2000.

Nursing M. Ohayon, C. Guileminault, R. Priest, M. Caulet (1997) Snoring and breathing pauses during sleep: telephone interview survey of a United Kingdom population sample. BMJ, March 22, 1997; 314:860.

A. DeLorenzo, C. Maiolo, E. Mohamed, A. Andreoli, P. Petrone-De Luca, P. Rossi (2001) Body Composition Analysis and Changes in Airways Function in Obese Adults Hypocaloric Diet. from outlines_Part1.pdf

Chest.

119:1409-1415. Date of acceptance: December 18, 2000.Retrieved September 16, 2005, http://www.ems.doh.ms.gov/pdf/selfstudy/mod_iii_objectives_and R. Wilkins, J. Stoller, C. Scanlan (2003) Egan’s Fundamentals of Respiratory Care, Eighth Edition. Mosby. St. Louis (2003).

R. Schwab (2003) Pro: Sleep Apnea Is an Anatomic Disorder. Respiratory and Critical Care Medicine October 27, 2005.

Syndrome. Vol 168. pp. 270-271. Date of acceptance: Dr. Woodson (2005) Evaluation of Upper Airway in Obstructive Sleep Apnea Medical College of Wisconsin. American Journal of Date of acceptance: October 24, 2005.

G. Gibson (2005) Obstructive sleep apnea syndrome: underestimated and Under treated. 2005.

British Medical Bulletin. 72 (1):49-65 Date of acceptance: October 24,