JADA Continuing Education
The effect of external nasal dilators on blood oxygen levels in dental patients
ALLEN J. MOSES, D.D.S. and
MARCUS LIEBERMAN, Ph.D.
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ABSTRACT
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Background. The authors conducted a study to examine the use of external nasal dilators, or ENDs, on dental patients and to determine whether the subjective improvement in comfort level noted in dental patients using ENDs is accompanied by a rise in the level of oxygen saturation as measured by pulse oximetry, or SpO2.
Methods. The authors used a hand-held pulse oximeter to monitor 45 patients’ SpO2 levels during routine dental procedures.
Results. The data suggest that dental procedures in general result in a lowering of the SpO2 level and that patients using an END do experience a rise in the SpO2 level.
Conclusions. The data do not clearly establish that the increase in patient comfort with use of an END is due to a rise in the SpO2 level.
Clinical Implications. The results of this study demonstrate that the use of an END facilitates nasal breathing in dental patients.
The use of external nasal dilators, or ENDs (also called nasal breathing strips), can make dental appointments easier, more pleasant experiences for dentists and particularly for patients who predominantly use their mouths to breathe.1 The article pointed out that patients with obstructed nasal breathing need to keep their oral airways open to breathe, so they are constantly swallowing, choking or gagging during most dental procedures. Also, the patient’s oral breathing fogs the dentist’s mirror, hiding the dentist’s visualization of the working field.
An END is made of flat spring-action strips placed under a contoured piece of adhesive tape. When the tape is adhered transversely across the nose, the device lifts the skin and opens the nasal passages. The subjective impression of people who breathe through their mouths is improved nasal breathing.1
The results of this study demonstrate that the use of an external nasal dilator facilitates nasal breathing in dental patients.
Three changes have been quantified objectively in clinical studies as a result of using ENDs:
- – increase in cross-sectional area at the nares2–9;
- – increase in transnasal airflow2,6,9;
- – decrease in nasal airflow resistance.3,6,7,10,11
If ENDs do all that, it might be logical that using an END would result in a rise in blood oxygen levels. Our current study focuses on determining whether use of an END, as a result of making nasal breathing seem easier for dental patients who are identified primarily as mouth breathers, results in an increased level of oxygen saturation as measured by pulse oximetry, or SpO2.
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METHODS AND MATERIALS
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A group of 45 ambulatory dental patients in an urban practice comprised the study group. The multiracial group consisted of 33 men and 12 women. Their ages ranged from 26 to 82 years. We performed each dental procedure with the patient in a supine position. A rubber dam was not used for any of these procedures.
At the beginning of the dental appointment, we placed the Nonin 8500M hand-held pulse oximeter (Nonin Medical, Plymouth, Minn.) over the patient’s index fingernail using a finger clip to determine the patients’ levels of arterial SpO2. We left it in place for the entire time the patient was in the dental chair.
Shelledy and colleagues12 conducted a study in which they compared the performance of a pulse oximeter (Nonin 9500 [with circuitry identical to that of the Nonin 8500], Nonin Medical) to a device using co-oximetry (the actual measure of blood gases) and the results correlated significantly. The results using the Nonin 8500M Pulse Oximeter were both accurate and consistent for the purposes of our study.
The Nonin 8500M pulse oximeter records data every four seconds. It shines hemoglobin red and infrared light through the tissue and detects the fluctuating signals caused by the arterial blood pressure pulses. Well-oxygenated blood is bright red, and poorly oxygenated blood is dark red. The pulse oximeter determines the level of oxygen saturation from the color differences in the blood by measuring the ratio of absorbed hemoglobin red and infrared light. Steady conditions such as venous blood flow, skin thickness and the presence of bone and fingernails do not cause fluctuations and, therefore, do not affect the saturation reading. Dark fingernail polish, which can affect the light intensity, could produce an inaccurate reading. Therefore, we excluded patients who were wearing red fingernail polish from the study, which may have resulted in the low percentage of women in this study.
The etiology of the aspirating and choking in mouth-breathing dental patients may be elevated carbon dioxide levels in the blood and not low oxygen levels.
We used Moyers’13 clinical technique to differentiate patients who predominantly breathed through their mouths from those who predominantly breathed through their noses. We instructed patients to seal their lips and inhale through their nose as rapidly and deeply as they could. In patients who habitually breathed through their noses, their nares flared; however, in patients who breathed predominately through their mouths, their nares constricted.
We then placed an END (Breathe Right Nasal Strips, CNS, Minneapolis) according to the manufacturer’s instructions on any patient who had an initial arterial SpO2 level at or below 95 percent. We left the END in place for the entire dental procedure.
We used Profox Oximetry Software (Version PFW OAT 08/99, PROFOX Associates, Escondido, Calif.) to transfer the oximetry data from the Nonin 8500M to a personal computer for graphic display and data analysis. We used SPSS data software (SPSS, Version 11.5, SPSS, Chicago) to perform statistical analyses of the data.
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RESULTS
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Initially we classified the study population into four groups:
- – group 1: mouth breathers with an initial arterial SpO2 level at or below 95 percent (we placed ENDS on these patients);
- – group 2: mouth breathers with an initial arterial SpO2 level above 95 percent (we did not place ENDs on these patients);
- – group 3: nose breathers with an initial arterial SpO2 level at or 95 percent (we placed ENDs on these patients);
- – group 4: nose breathers with an initial arterial SpO2 level above 95 percent (we did not place ENDs on these patients).
The computer program in the pulse oximeter displayed a graph of the arterial SpO2 level for each patient during the time he or she was being monitored. We noted periodic fluctuations in blood oxygen levels in all of the patients. In the group of mouth breathers who used ENDs, seven of 10 patients had one or more desaturation events (Table 1
). A desaturation event is a decrease in the arterial SpO2 level of 4 percent or more within a three-minute period. In the group of mouth breathers who were not wearing ENDs, two of six patients had desaturation events. In the group of nose breathers who were wearing ENDs, one of five patients had a single desaturation event. In the group of nose breathers who were not using ENDs, 10 of 24 patients had desaturation events. There appeared to be no relationship between the occurrence of desaturation events and the use of ENDs.
The mean arterial SpO2 level was above 95 percent in eight of 15 people with initial SpO2 levels at or below 95 percent (Table 1
). The initial reading of 95 percent, however, does not represent an average over a specific period, but merely a momentary initial reading. The trend over the entire period the patient was monitored is more reflective of what happened to his or her arterial SpO2 level during the time the END was used.
Using the raw data, we calculated the slope for each of the 45 patients. We used a sequence number for the independent variable and the arterial SpO2 level reading as the dependent variable. We ran a simple linear regression to calculate the value of the coefficient (slope). In many cases, the slope varied from a visual conclusion. We categorized the slopes into three groups. Slopes greater than .001 were "positive," slopes less than –.001 were "negative," and level lines showing no trend were termed "zero."
Table 2 shows the independent variables mouth breathers (1) or nose breathers (2). We found no relationship between type of breather and slope group.
Table 3 looks at the relationship between using and not using the END. We found that there was a significant relationship between using or not using the END and the slope group. Using the END resulted in a positive slope in the SpO2 level, and not using it resulted in a negative slope, irrespective of whether the patient was a mouth breather or nose breather.
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DISCUSSION
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A trend for the arterial SpO2 level rising with the use of an END on patients (mouth breathers and nose breathers) with an initial arterial SpO2 level reading of at or below 95 percent from the beginning to the end of the dental appointment was demonstrated in this study. We noted a lowering of the arterial SpO2 level in a statistically significant number of patients who did not use ENDs during their dental procedures. We also noted a rising trend in arterial SpO2 level in just the mouth-breathing group of patients, but it was not a statistically significant number. This is consistent with the fact that nasal breathing is predictably obstructed in the mouth-breathing group. The data also seem to substantiate Moyers’ criteria for differentiating nose breathers and mouth breathers.
The data did not validate the premise that the increased comfort level mouth breathers have from using ENDs during dental appointments is based on a rise in the arterial SpO2 level.
While demonstrating that using an END did increase blood oxygen levels in dental patients (both mouth breathers and nose breathers) with an initial SpO2 level at or below 95 percent, the results of this study do not establish the exact physiological mechanism by which the END increases patient comfort.
According to West,14 the most important factor in the control of ventilation is the partial pressure of carbon dioxide, or PCO2, of the arterial blood. This is reportedly a very sensitive mechanism. The etiology of the aspirating and choking in mouth-breathing dental patients may be elevated carbon dioxide, or CO2, levels in the blood and not low oxygen levels. Further research is warranted to examine whether it is really the high level of CO2 in the blood that is the initiating factor in the brain that forces aspiration and the subsequent choking and gagging during dental procedures on mouth breathers.
This study relates to the use of END for dental patients, and the results do not necessarily extrapolate to use of ENDs while sleeping.
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CONCLUSION
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This study indicates that dental procedures in general result in a lower arterial SpO2 level at the end of the appointment than was noted at the beginning in a statistically significant number of patients. Use of an END during a dental appointment, however, resulted in an increase in the arterial SpO2 level in a statistically significant number of dental patients. The increase in the arterial SpO2 level noted in the group of both mouth breathers and nose breathers with an initial arterial SpO2 level at or below 95 percent who wore ENDs during their dental procedures demonstrates that ENDs facilitate nasal breathing. Any facilitation of nasal breathing would tend toward idealization of both oxygen and CO2 levels.
The exact relationship between the arterial SpO2 level and PCO2 relative to choking, gagging and constant swallowing to clear the oral airway of mouth-breathing patients in the supine position in the dental chair was not elicited by this study.
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Dr. Moses is in private practice, 233 S. Wacker Drive, Chicago, Ill. 60606, e-mail "ajmoses{at}earthlink.net". Address reprint requests to Dr. Moses.
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REFERENCES
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- Moses AJ. External nasal dilators: a clinical aid for dentists, patients. JADA 2001;132:1555–6.[Free Full Text]
- Roithmann R, Cole P, Chapnik J, Shpirer I, Hoffstein V, Zamel N. Acoustic rhinometry in the evaluation of nasal obstruction. Laryngoscope 1995;105:275–81.[Medline]
- Roithmann R, Chapnik J, Zamel N, Barreto SM, Cole P. Acoustic rhinometric assessment of the nasal valve. Am J Rhinol 1997;11: 379–85.[Medline]
- Amis TC, Kirkness JP, Di Somma E, Wheatley JR. Nasal vestibule wall elasticity: interactions with a nasal dilator strip. J Appl Physiol 1999;86:1638–43.[Abstract/Free Full Text]
- Griffin JW, Hunter G, Ferguson D, Sillers MJ. Physiologic effects of an external nasal dilator. Laryngoscope 1997;107:1235–8.[Medline]
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- Roithmann R, Chapnik J, Cole P, Szalai J, Zamel N. Role of the external nasal dilator in the management of nasal obstruction. Laryngoscope 1998;108:712–5.[Medline]
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- Gosepath J, Mann WJ, Amedee RG. Effects of the Breathe Right nasal strips on nasal ventilation. Am J Rhinol 1997;11:399–402.[Medline]
- Kirkness JP, Wheatley JR, Amis TC. Nasal airflow dynamics: mechanisms and responses associated with an external nasal dilator strip. Eur Respir J 2000;15:929–36.[Abstract]
- Gehring JM, Garlick SR, Wheatley JR, Amis TC. Nasal resistance and flow resistive work of nasal breathing during exercise: effects of a nasal dilator strip. J Appl Physiology 2000;89:1114–22.[Abstract/Free Full Text]
- Schelledy DC, Smith PK, Downing RA, Accuracy of the Nonin Onyx 9500 pulse oximeter for the measurement of arterial oxygen saturation (abstract). Respir Care 1999;44(10):1226.
- Moyers RE, ed. Handbook of orthodontics for the student and general practitioner. 3rd ed. Chicago: Year-Book; 1972:331.
- West JB. Respiratory physiology: The essentials. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 1999:110–14.
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ABSTRACT
METHODS AND MATERIALS
