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ORIGINAL ARTICLE
Year : 2017  |  Volume : 35  |  Issue : 4  |  Page : 338-345
 

Assessment of hypoxia, sedation level, and adverse events occurring during inhalation sedation using preadjusted mix of 30% nitrous oxide + 70%oxygen


1 Department of Pedodontics and Preventive Dentistry, Kalinga Institute of Dental Sciences, Bhubaneswar, Odisha, India
2 Department of Pedodontics and Preventive Dentistry, Sri Sai College of Dental Surgery, Vikarabad, Telangana, India

Date of Web Publication15-Sep-2017

Correspondence Address:
Srinivas Namineni
Department of Pedodontics and Preventive Dentistry, Sri Sai College of Dental Surgery, Kothrepally, Vikarabad - 501 101, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JISPPD.JISPPD_15_17

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   Abstract 


Purpose: To assess the efficacy of nitrous oxide (N2O)-oxygen (O2) inhalation sedation by rapid induction technique using preadjusted mix of 30% N2O and 70% O2 in children. Materials and Methods: Sixty children with a treatment plan which included pulp therapy were recruited for the study. Children categorized 3 and 4 of Frankl behavior rating scale and American Society of Anesthesiologists health status I and II were included for the study. Children were distributed into study group (Group-I) and control group (Group-II) by fishbowl randomization. Children in Group-I were induced inhalation sedation using a preadjusted mix of 30% N2O and 70% O2 through rapid induction technique, and children in Group-II were exposed to inhalation sedation by conventional slow induction technique. Parameters such as least oxygen saturation, sedation levels by Richmond Agitation–Sedation Scale, time taken to achieve ideal sedation, maximum N2O concentrations used, and adverse events were recorded and evaluated for each procedure. Data were analyzed using independent sample t-test and Chi-square tests. Results: Analysis of data showed statistically significant difference between both groups in time taken to achieve ideal sedation (P < 0.001). No significant difference was seen in incidence of hypoxia (P < 0.512), maximum N2O concentrations used (P < 0.118), and occurrence of any adverse events. Conclusion: None of the children from both groups exhibited hypoxia. Sense of detachment was seen in one child each from both groups. Rapid induction by preadjusted mix resulted in ideal sedation in 57% children of the Group-I; rest had achieved these levels at 40% N2O. There was a significant difference in the time taken to achieve ideal sedation by rapid induction which was almost half the time taken with slow induction.


Keywords: Adverse events, hypoxia, minimal sedation, optimal sedation, rapid induction, slow induction


How to cite this article:
Samir P V, Namineni S, Sarada P. Assessment of hypoxia, sedation level, and adverse events occurring during inhalation sedation using preadjusted mix of 30% nitrous oxide + 70%oxygen. J Indian Soc Pedod Prev Dent 2017;35:338-45

How to cite this URL:
Samir P V, Namineni S, Sarada P. Assessment of hypoxia, sedation level, and adverse events occurring during inhalation sedation using preadjusted mix of 30% nitrous oxide + 70%oxygen. J Indian Soc Pedod Prev Dent [serial online] 2017 [cited 2019 Jul 15];35:338-45. Available from: http://www.jisppd.com/text.asp?2017/35/4/338/214915





   Introduction Top


Nitrous oxide (N2O) was introduced into dentistry by Horace Wells in 1844 using it for a dental extraction, which marked a major historical event in medicine. N2O-O2 inhalation sedation was adopted into mainstream dentistry ever since. It has gained a reputation as the most popular mode of sedation over others. Benefits of N2O include anxiolysis, mild analgesia, and amnesia properties. Analgesia produced by 20% N2O is almost equivalent to 15 mg of morphine intravenously.[1] Since N2O can raise the pain threshold to a greater level, it has proved to be a better anxiolytic drug.[2] Hallmark features of N2O are due to its rapid onset of action and equally rapid postoperative recovery, which can be achieved through titration.

It can be administered by two different techniques:

  1. Conventional slow induction
  2. Rapid induction.


In conventional slow induction, - initially, 100% O2 is administered to about 4–5 L/min in children to determine the minute volume followed by increments in the N2O concentration of 5%–10% for every 1–3 min. Generally, between 15% and 20% N2O, first cortical signs of sedation are observed that is referred to as baseline sedation. Adequate sedation and analgesia obtained for carrying out the dental procedure are usually achieved by administering around 30%–40% N2O.[3]

Incremental increase of N2O by 10% for every 3 min till a desired level of consciousness is generally considered safe, thus preventing unintended over sedation. However, the amount of the time taken and gases consumed during induction are liability and can contribute to occupational hazards.

During rapid induction, concentrations of ≥50% N2O are administered directly as an STAT dose in an uncooperative child till he/she gains his/her composure. After the child settles down, N2O concentrations are appropriately adjusted either upward or downward.[2]

However, use of higher concentrations is not usually recommended in anticipation of certain adverse effects such as inability to recognize baseline levels of sedation, nausea, vomiting, dizziness, and sense of detachment. Incidence of adverse events with N2O-O2 sedation with conventional method of administration is around 4%–10% much less compared to other drugs. Nausea and vomiting may occur due to prolonged exposure of N2O-O2 for more than 2 h or higher concentrations of >50% N2O, with 0.7% chances of occurrence of hypoxia.[4]

Literature supports the use of 20%–30% N2O for minimal levels of sedation without many adverse effects, but its use for rapid induction in pediatric dental population lacks any evidence.

Therefore, the objective of this study was to assess the efficacy of rapid induction technique using preadjusted mix of 30% N2O + 70% O2 for sedation in children while monitoring the procedure for adverse effects such as hypoxia, nausea, and vomiting.


   Materials and Methods Top


A randomized clinical study was conducted in the Department of Pedodontics and Preventive Dentistry, Sri Sai College of Dental Surgery, Vikarabad. Sixty children of 5–12 years of age with a treatment plan of pulp therapy and root canal therapy were selected for the study. Children categorized under American Society of Anesthesiologists (ASA) Physical Status I and II and Frankl behavior rating scale of 3 and 4 were included in the study. The behavior rating of the child was done by a single observer. Children with active upper respiratory tract infections, obstructive mouth breathing, and predisposing factors causing airway obstruction such as adenoid hyperplasia, nasal septum problems, nasal polyps, and enlarged turbinates were excluded from the study. Clinical and radiographic examination of all the children followed by a thorough recording of medical and dental history was performed before the dental procedure to assess their fitness to undergo N2O-O2 inhalation sedation.

Children were distributed into the following groups by fishbowl randomization:

  • Control group (Group-I): Children were induced with inhalation sedation by conventional slow induction
  • Study group (Group-II): Children were induced with inhalation sedation using a preadjusted mix of 30% N2O and 70% O2 through rapid induction.


The parents/guardians of the children were given a complete verbal explanation about the procedure, need, safety, and side effects of N2O-O2 inhalation sedation including other options before the procedure. Along with consent for the treatment, separate written consent for inhalation sedation and for the participation of their child in the study was obtained from each child. AAPD fasting guidelines were given to guardians in both written and verbal formats.

Armamentarium

  1. Inhalation sedation unit - Matrx Quantiflex MDM ANALOGUE relative analgesia machine (Matrx Medical Inc., Orchard Park, New York, USA) was used for the study
  2. Pulse oximeter - It was used to continuously assess the oxygen saturation (SPO2) and pulse rate throughout the procedure
  3. Emergency kit - It comprised O2 delivering system, suction and suction tips, syringes for drug administration, orotracheal tube, nasopharyngeal tube, laryngoscope, and Ambu bag
  4. Emergency drugs - They comprised epinephrine, antihistamines, vasodilators, bronchodilators, glucose, and aspirin as an antithrombotic
  5. Appropriate pulp therapy and endodontic armamentarium.


All the children were demonstrated about the placement of the nasal hood and pulse oximeter and how to respond to the commands during the procedure by tell-show-do. Preoperative SPO2 and pulse rate were recorded using a pulse oximeter.

Each child was first administered 100% O2 for 2–3 min, followed by determination of their flow rate. Baseline levels of SPO2 were recorded. A titrated dose of N2O was then administered to the child according to the group, following fishbowl method of randomization.

Children in Group-I were administered N2O through slow induction. Sedation levels were assessed using Richmond Agitation–Sedation Scale (RASS) at each increment, and baseline level of sedation was identified at around 15%–20%. N2O was further increased to achieve appropriate anxiolysis and reduced pain perception for local anaestesia injection. After administering LA, the N2O was reduced back to the minimal level and maintained in the same level throughout the treatment.

Children of Group-II were administered N2O-O2 through rapid induction by direct preadjusted mix of 30% N2O and 70% O2. Sedation levels were assessed by RASS. Levels of sedation achieved by 30% N2O were recorded. The N2O concentration was further adjusted slowly with the increments of 10% to achieve the optimal sedation if the child had not achieved appropriate levels of sedation at 30%. If the child was hypersedated, the N2O concentration was adjusted by decrements of 10% called reverse titration.

SPO2 levels, sedation levels, and occurrences of any adverse events such as nausea and vomiting were monitored for and recorded appropriately on the sedation event chart of all the children. The lowest level of SPO2 throughout the procedure was also recorded. SPO2 <95% were considered as the occurrence of hypoxia. Sedation level scores of 2 and 3 in RASS were considered representing minimal and moderate levels of sedation, respectively.

The data consisting of least SPO2 levels, levels of sedation, time taken to achieve minimal sedation, and maximum N2O concentrations administered in both the groups were subjected to independent sample t-test, and incidence of adverse events was subjected to Chi-square test for statistical analysis using SPSS version 14 software.


   Results Top


The present study was used to evaluate and compare between Group-I and Group-II; the recorded values are presented as mean ± standard deviation, range, and percentage changes. The values were statistically analyzed using SPSS version 14. A P < 0.05 is set to be statistically significant. Mean comparisons between the parameters were performed using independent sample t-test. Categorical variables were compared with Chi-square test. The results were tabulated and presented in graphs.

In this study, 17 children of Group-II (57%) had minimal sedation at 30% N2O during rapid induction using a preadjusted mix of 30% N2O + 70% O2, while remaining 13 (43%) achieved minimal sedation at 40% N2O after raising the N2O concentration by 10%. During slow induction in Group-I, minimal sedation at 30% N2O was seen in 22 children (71%), while remaining 8 (29%) had minimal sedation at 40% N2O [Table 1] and [Graph 1].
Table 1: Comparison of the mean, standard deviation and significance (P-value) of levels of sedation according to Richmond Agitation–Sedation Scale during sedation in Group-I and Group-II

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Comparison of least SPO2 values in both groups had no statistically significant difference in O2 desaturation (P - 0.512) [Table 2] and [Graph 2].
Table 2: Comparison of the mean, standard deviation, and significance (P-value) of difference in the least intraoperative oxygen saturation during sedation in Group-I and Group-II

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Comparison between the time taken to achieve minimal sedation in Group-I and Group-II had statistically significant difference (P < 0.001). Minimal sedation by rapid induction of a preadjusted mix of 30% N2O + 70% O2 was achieved in (4.30 min) almost half the time taken to achieve minimal sedation by slow induction (9.30 min) [Table 3] and [Graph 3].
Table 3: Comparison of the mean, standard deviation, and significance (P-value) of difference in time taken to achieve minimal sedation according to the Richmond Agitation–Sedation Scale during sedation in Group-I and Group-II

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In Group-I, maximum concentrations of 30% N2O were administered in five children (16.7%), 40% N2O in 18 (60%), and 50% N2O in 7 (23.3%). In Group-II, maximum concentration of 30% N2O was administered in three children (10%), 40% N2O in 14 (46.7%), and 50% N2O in 13 (43.3%) [Graph 4].



There was no statistically significant difference between the maximum N2O concentrations used in both groups (P < 0.118). However, there was a notable difference in the range of maximum N2O concentrations used within Group-II. We could not find any appropriate reasoning for this variability. The difference in the means of the maximum N2O percentage used was not significant between Group-I (40.67%) and Group-II (43.3%) [Table 4].
Table 4: Comparison of the mean, standard deviation, and significance (P-value) of difference in maximum nitrous oxide levels administered during sedation in Group-I and Group-II

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Comparison of incidence of adverse events in both the groups had no statistically significant difference. One child each from both Group-I and Group-II had incidence of adverse event at the rate of 3.3% [Table 5] and [Graph 5].
Table 5: Comparison of the mean, standard deviation, and significance (P-value) of difference in incidence of adverse events during sedation in Group-I and Group-II

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   Discussion Top


N2O-O2 inhalation sedation is considered as one of the most efficient, pharmacological behavior management techniques due to its unique properties such as rapid onset, faster recovery, and minimal adverse effects. Optimal level of sedation for dental treatment is achieved using N2O within the range of 30% and 40%.[3],[5],[6],[7]

N2O-O2 inhalation sedation can be induced in two different techniques; conventional slow induction and rapid induction. Incremental titration of N2O concentrations during slow induction is considered as the safest way of induction and known for its reduced chances of over sedation and adverse events due to continuous assessment of the sedation levels at each increment. Although it is considered safe, slow induction takes more time to achieve adequate levels of sedation. Added to this, concentration up to 25% N2O is not known to produce an adequate sedation. Guedel in 1937 explained depths of anesthesia when under the influence of inhalational anesthetic agents exclusively such as N2O. The clinical signs are classified into IV stage. Each stage is further subclassified into planes. Joseph Artusio in 1954 attempted further classification of Stage I into three planes. The effects and clinical signs of N2O in the concentrations are further subdivided into three planes based on the amount of N2O: Plane 1 (0%–25%), Plane 2 (25%–50%), and Plane 3 (50%–70%). The Stage I is marked by beginning of induction of sedative effects to loss of consciousness, which is N2O dose dependent. During Plane1 of Stage I, the patients undergo only anxiolysis. Progressing further into Plane 2 of Stage I patient experiences mild analgesia and amnesia. However, Plane 3 of Stage III is marked by moderate analgesia and amnesia. The concentrations at 30%–40% of N2O have been documented in the literature to produce an optimal sedation. With evidence of optimal sedation levels at 30% N2O in children, we intended to assess its efficacy by rapid induction when advocated as a preadjusted mix of 30% N2O + 70% O2 in producing optimal levels of sedation, time taken for achieving the same, and recording incidence of diffusion hypoxia or any adverse events.

Fixed N2O dosage using higher concentrations as ≥50% is routinely used by nonanesthesiologists in medicine, without any risk of hypoxia or ill effects during administration. Entonox ® and Nitronox ® with a premix of 50% N2O-50% O2 are used in prehospital care, relieving cancer pain in emergency rooms and obstetrics.[8],[9],[10]

During sedation using N2O-O2, three important physiological parameters must be monitored. They are consciousness, respiration, and saturation. All three parameters can be effectively monitored clinically without any advanced equipment. Use of pulse oximeter will add additional benefit of prompt and almost immediate identification eminent hypoxia.

Hypoxia is defined as a pathological condition, in which a body as a whole (generalized) or a region of the body (tissue localized) is deprived of adequate O2 supply. Reduced O2 supply to brain may lead to cerebral hypoxia resulting in its immediate dysfunction, unconsciousness within 15 s, which may be reversible. Prolonged hypoxic effect beyond 4 min may result in progressive irreversible damage to the brain.

SPO2 therefore should be constantly monitored to detect early signs of hypoxia and avoid more lethal side effects such as respiratory depression, which is the primary sequela of hypoxia. Clinically, hypoxia can be monitored by measurement of heart rate, respiratory rate, and blood pressure along with visual observation of mucosa and nail beds for pallor and cyanosis. Clinical observation of these parameters is valuable but may not reflect hypoxia until the SPO2 reaches the moderate or severe levels. Pulse oximeter is more sensitive to even mild forms of hypoxia. Our aim to determine earliest signs of hypoxia during the sedation makes the use of a pulse oximeter a compulsion for monitoring hypoxia in our study.[4],[11]

None of the children from both Group-I and Group-II had SPO2 <95% or an episode of hypoxia during the procedure. Literature of rare incidence of hypoxia even at higher concentrations by rapid induction is well documented.

However, Kaviani and Birang observed hypoxia in 1 of 32 adults subjected to periodontal treatment under 50% N2O-50%O2 inhalation sedation.[4]

Incidence of hypoxia must be differentiated between a momentary, a prolonged occurrence, or a progressively worsening one. The latter two are a representative of a serious consequence. Clinically, only one incident of extremely low SPO2 of 72%, which lasted only for few seconds, was recorded during the procedure in Group-II, but the SPO2 came back to normal levels immediately without any intervention determining it as an error in pulse oximeter reading. Apart from true hypoxia, there is also a possibility of errors due to reasons such as the movement of pulse oximeter probe clipped to the patient's finger, due to the tingling sensation in his/her hand or due to the sense of discomfort experienced by a child during the procedure.[12] The other factors that may cause errors in pulse oximeter readings are nail polish, bright light, reduced blood flow to the peripheries, hypovolemic shock, and carbon monoxide poisoning.[4]

Quarnstrom et al. with their clinical experience in over 10,000 administrations of N2O sedation without postoperative O2 could not detect any clinical problems such as hypoxia.[8] Notini-Gudmarsson et al. revealed that hypoxia or adverse events such as headache were not seen in 38 patients treated with 50% N2O.[9] Saunders et al. found no hypoxia or headache but drowsiness and hypotension in 3% and 7% of the 47 individuals treated with 50% N2O, respectively.[10] Brodsky et al. and Frumin and Edelist found that hypoxia is not clinically significant even in very high levels of N2O in healthy patients maintaining normal ventilation.[13],[14]

Fail proof safety mechanisms built into a dental sedation unit prevent any possibility of hypoxia occurring. This is primarily because of safety feature where N2O is always delivered in combination with O2 with minimum dosage being 30% of O2. Additional safety features add to safety such as O2 flush button which delivers 100% O2 immediately, bypassing flow of N2O on detecting earliest signs of hypoxia. Furthermore, the presence of an emergency air inlet, as a standard fitment in dental sedation units, allows the patient to breathe atmospheric O2 from room air at the sudden emptying of the O2 cylinders. Removal of nasal hood and asking the patient to breathe atmospheric air that consists of 21% O2 itself can improve patient from hypoxia quickly.[15]

Diffusion hypoxia is defined as an abrupt transient decrease in alveolar O2 tension when room air is inhaled at the conclusion of N2O-O2 anesthesia. N2O can cause diffusion hypoxia in two ways: first, by displacing O2 directly affecting oxygenation, and second, by diluting with alveolar carbon dioxide and decreasing the respiratory drive and ventilation. Fink observed diffusion hypoxia in eight healthy gynecological patients undergoing endotracheal anesthesia using 75% N2O in O2 at 4 L/min supplemented with intravenous thiopental. Literature also reports of an average 8% drop in SPO2 when the patients were switched to room air.[16] Dunn-Russell et al. assessed 24 children who were allowed to breathe room air after N2O inhalation sedation. None of the children exhibited any abnormal levels of SPO2 or any other side effects.[17]

None of the children in this study from both groups had an incidence of diffusion hypoxia after termination of N2O and postoperative administration of 100% O2 for 5 min.

From this study, margin of safety in terms of hypoxia when using N2O rendered by rapid induction with a preadjusted mix of 30% N2O + 70% O2 is similar to that of slow induction.

The effects of anesthesia are best explained as a continuum which is dose dependent. ASA classified sedation/anesthesia continuum into four levels, according to the state of central nervous system depression: minimal sedation, moderate sedation, deep sedation, and general anesthesia.[18] Minimal and moderate levels of sedation are considered to be the ideal forms of sedation for carrying out dental treatment in an anxious child. During these first two stages, the respiration remains spontaneous, and heart rate remains unaffected. During minimal sedation, the consciousness remains unaffected, but anxiety levels are reduced. However, during moderate sedation stage, the consciousness is depressed and anxiety and pain are reduced.[19] The minimum alveolar concentration (MAC) of an inhalation agent determines its potency in causing sedation. N2O has got the weakest MAC value of 104 as compared to other inhalational agents such as halothane (0.75), isoflurane (1.17), and sevoflurane (1.8). When used alone, N2O may produce anesthesia in 50% people only under hyperbaric conditions or high volume percentages, which is not possible in dental sedation as a dedicated dental sedation unit can deliver a maximum of 70% N2O. Thus, N2O has large and integral margin of safety even at higher concentrations for dental treatment.[15] At concentrations between 30% and 50%, N2O will produce a relaxed, somnolent patient who may appear dissociated and easily susceptible to suggestions.

The physiologic, physical, and psychological signs of the child should be under constant monitoring to recognize the levels of sedation during the procedure.

A child is said to be minimally sedated when he/she is comfortable and relaxed; mood can be categorized as happy, pleasant, satisfied, or ambivalent, acknowledges reduced fear and anxiety, aware of surroundings, responds to verbal commands, protective cough and gag reflex are intact, glazed and less active eyes; resonated voice or hypernasal tone, may experience tingling or heaviness in extremities, light feeling, body warmth, vasodilation in face and neck.

A child is said to be oversedated when he/she experiences a sense of detachment from the environment, in a state of dreaming, hallucination, or a fantasy, has out of the body experiences, floating or flying experience, inability to move, open his/her mouth or communicate, worsening of humming or vibrating sounds, may experience nausea, vomiting, dizziness, drowsiness, light-headedness, uncomfortable body warmth, fixed eyes, no verbal response and slurred speech, sluggish or delayed responses, may become unconscious.

Monitoring the activity of the patient's eyes can be used as a good tool to assess the levels of sedation.[20] Therefore, we used the RASS to assess the levels of sedation based on the eye contact and opening of the child.

Children expressed a relaxed mood, reduced anxiety at the concentrations of 30%–40% N2O with a tingling sensation in extremities, and reduced blink rate of eyes <10 s as per RASS used in our study. No child exhibited a sign of over sedation at the concentrations of 30% N2O.

An anxious and restless child during the start of the slow induction procedure may become more restless of wearing the nasal hood for longer time to achieve optimal sedation and may cause tantrums to remove it. As the 30% N2O proved to be efficient enough to cause optimal sedation, it can be administered by rapid induction instead of increments of 5%–10% N2O for every 3 min to minimize the time taken to achieve optimal sedation.

From the results of our study, rapid induction of preadjusted mix of 30% N2O + 70% O2 has a better time efficacy and can be used as an alternative to slow induction to achieve minimal sedation in an anxious restless child.

After determining the minimal level of sedation in both the groups, N2O concentration was raised by 10% to have a mild analgesic effect for an LA shot. Concentrations were brought back to the minimal level after administering LA. Levels of sedation at 30% N2O by rapid induction of preadjusted mix of 30% N2O + 70% O2 were recorded and N2O concentration was further adjusted slowly with the increments or decrements of 10% to achieve the appropriate levels of sedation. In three children showing signs of moderate sedation at 30% N2O, the N2O concentration was reduced by 10% to achieve optimal sedation. N2O concentration was again raised to 30% N2O for a local anesthetic shot and then reduced back by 10% to the concentration of ideal sedation in these children.

Children in both Group-I and Group-II experienced a plane of dissociation sedation or analgesia at the 30%–50% N2O concentrations. The children had a warm feeling with a floating sensation and exhibited both the psychosedation and somatic sedation.

Acute and chronic adverse events of N2O are rare when used with O2. Various adverse events that may be seen are nausea, vomiting, sense of detachment, headache, hiccups, and double vision. Nausea and vomiting are the most common adverse events occurring in 0.5% of patients.[21] Various factors responsible for causing adverse events during N2O-O2 inhalation sedation are length of the procedure, sharp increase or decrease in the concentrations of N2O, hypoxia, over sedation.[22]

Sense of detachment was the only adverse event to be seen in both the groups. This sense of detachment may be due to the difference in expression of subjective symptoms of psychosedation by children during the plane of dissociation sedation or analgesia.[23]

In this study, optimal sedation at concentrations of 30%–40% N2O was seen in both the groups. In 57% children, it was seen with rapid induction using preadjusted mix of 30% N2O + 70% O2, wherein the time taken for achieving optimal sedation was almost half of the time taken for slow induction. Rapid induction by preadjusted mix of 30% N2O + 70%O2 has the same efficacy and margin of safety as of slow induction in achieving optimal sedation but in lesser time.

Thus, rapid induction can be used as a definite alternative to slow induction in anxious kids restless during the start of the procedure as it is equally safe and efficacious but has a faster onset.

In this study, the only adverse effect seen was sense of detachment for one child in both groups. None of the patients experienced hypoxia. All the observations were made by a single observer. Validity and reliability of these observations can be increased by inter-examiner observations in the future studies.


   Conclusion Top


Based on this study results, the following conclusions can be drawn:

  1. There was no significant difference between the least SPO2 recorded in both groups. None of the children from both the groups exhibited hypoxia
  2. Rapid induction by preadjusted mix of 30% N2O + 70% O2 was seen to cause optimal sedation in 57% children of the group
  3. There was no significant difference in N2O concentrations to achieve optimal sedation in both the groups around 30%–40% N2O
  4. There was a significant difference in the time taken to achieve optimal sedation by rapid induction with a preadjusted mix of 30% N2O + 70%O2 which was almost half the time taken with slow induction
  5. There was no significant difference in the maximum concentrations of N2O administered in both the groups
  6. There was no significant difference in the incidence of adverse events in both the groups.


Rapid induction by preadjusted mix of 30% N2O + 70%O2 has the same efficacy as of slow induction in achieving optimal sedation but in lesser time. Thus, it can be used as an alternative to slow induction for induction of N2O-O2 inhalation sedation in restless anxious patient.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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Clark M, Brunick A, editors. Signs and symptoms of N2O/O2 sedation. In: Handbook of Nitrous Oxide and Oxygen Sedation. 2nd ed., Ch. 12. St. Louis, MO: CV Mosby Co.; 2003. p. 111-7.  Back to cited text no. 20
    
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Malamed SF, editor. Inhalation sedation: Complications. In: Sedation: A Guide to Patient Management. 4th ed., Ch. 16. St. Louis, MO: CV Mosby Co.; 2003. p. 257-61.  Back to cited text no. 21
    
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Clark M, Brunick A, editors. Anatomy and physiology of respiration and airway management. In: Handbook of Nitrous Oxide and Oxygen Sedation. 2nd ed., Ch. 8. St. Louis, MO: CV Mosby Co.; 2003. p. 77-88.  Back to cited text no. 22
    
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Houpt MI, Limb R, Livingston RL. Clinical effects of nitrous oxide conscious sedation in children. Pediatr Dent 2004;26:29-36.  Back to cited text no. 23
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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  2005 - Journal of Indian Society of Pedodontics and Preventive Dentistry | Published by Wolters Kluwer - Medknow 
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