A Survey of Dentist Anesthesiologists on Preoperative Intramuscular Sedation

Abstract

Objective:

The induction of general anesthesia for children and patients with special needs frequently requires preinduction sedation, especially when anxiety and agitation lead to violent or combative behavior. In these situations, preoperative intramuscular (IM) sedation may facilitate patient transfer, intravenous cannulation, and/or mask induction. This survey aimed to capture data regarding the current preoperative IM sedation practices of dentist anesthesiologists.

Methods:

An electronic survey was distributed in 2020 to all members of the American Society of Dentist Anesthesiologists regarding the administration of preoperative IM sedation. It included questions about the demographics of respondents and their patients who require IM sedation, the most common drug regimens used, decision-making criteria regarding ketamine dosing, the intended level of sedation, sequence of anesthetic management following IM sedation, and observed outcomes.

Results:

A total of 193 responses (43%) were received; of those, 162 reported using preoperative IM sedation. Ketamine was included in 98.7% of reported IM drug regimens. The most common IM sedation regimen was combined ketamine and midazolam (median 2.5 mg/kg and 0.1 mg/kg, respectively). Of the respondents who use preoperative IM sedation, 87% reported using the same drug regimen in at least 80% of cases.

Conclusion:

The most frequently reported drug regimen used by dentist anesthesiologists in North America for preoperative IM sedation was a combination of ketamine and midazolam.

General anesthesia induction for children and patients with special needs can be very challenging, as patient anxiety and agitation can cause preoperative disturbances and disrupt clinic schedules. In extreme circumstances, violent or combative behavior poses a physical risk to the patient, their caregivers, and health care personnel. In these situations, preoperative intramuscular (IM) sedation is often used to facilitate safe transfer to the operating room (OR) and intravenous (IV) cannulation, with the primary goal being behavior modification.

There are neither clear guidelines for preoperative IM sedation nor data about the practice patterns of dentist anesthesiologists who use this technique. Specifically, it is not known what drug regimens are typically used, how frequently preoperative sedatives are administered by the IM route, what factors influence clinical decisions regarding the use of preoperative IM sedation, or what the perceived success of preoperative IM sedation is. We conducted a survey of dentist anesthesiologists in North America to characterize their current use of preoperative IM sedation in clinical practice.

METHODS AND MATERIALS

We conducted an institutional review board–approved survey of dentist anesthesiologists regarding their current use of preoperative IM sedation prior to the induction of general anesthesia. The survey was administered electronically through Qualtrics in April 2020, and email invitations were sent to all members (447) of the American Society of Dentist Anesthesiologists (ASDA). Follow-up emails were sent 2 weeks later. Responses were accepted from April 24, 2020, through May 26, 2020. Participation was voluntary with no offered incentive for completion. The survey included 13 items assessing respondent and patient demographics, frequency of preoperative IM sedation use, practice location, drugs and dosages used, the intended level of sedation using the Richmond Agitation and Sedation Scale (RASS), success at achieving the intended level of sedation, use of anticholinergics, factors influencing ketamine dosing, and occurrence of select adverse events (Appendix 1).

Statistical Analysis

All surveys were evaluated for completeness and quality. Surveys were excluded if respondents failed to identify as a dentist anesthesiologist or failed to answer any questions beyond demographics. Any inappropriate responses to individual questions were also excluded from analysis for that question only (e.g., providing non–weight-based dosages for preoperative IM sedation drugs or listing percentages not summing to 100%). When respondents provided a dose range rather than a single dose, the calculated midpoint was used for analysis.

Where noted in the tables, a weighting factor was applied to specific responses, and a weighted average was calculated to better characterize the data. For example, survey question 13 allowed respondents to select 1 of the following options regarding the number of adverse events observed over the last year after preoperative IM sedation: 0, 1 to 2, 3 to 5, or >5. A weighting factor of 0, 1.5, 4, and 8 was applied to each choice, respectively. This weighting factor was multiplied by the number of respondents who selected each option, and the total results were averaged.

Descriptive data analysis was performed using Microsoft Excel version 16.35 (Microsoft). Distribution of the reported ketamine dosing regimen was examined for normality using the Shapiro-Wilk test and found to be not normally distributed. Therefore, Wilcoxon rank-sum tests were performed to examine the differences in reported ketamine dosing by several practice-related variables. Analyses were performed using SAS version 9.4. Where applicable, P < .05 was considered statistically significant.

RESULTS

Overall, 447 surveys were distributed to the ASDA membership, 193 responses were received (43% overall response rate), and a total of 180 responses were included for analysis. Of the 13 excluded surveys, 6 were due to failed identification as a dentist anesthesiologist and 7 were due to respondents not answering any questions regarding IM drug regimens. A high percentage of responses to question 6 were deemed inappropriate; therefore, all responses to question 6 were excluded from the analysis. Most respondents (91%) reported using preoperative IM sedation at least once annually, and of those, 42% reported more than 100 cases involving preoperative IM sedation (Table 1).

Table 1.

Respondent and Patient Demographics*†

	Total respondents (N = 180)	Responses by venue
		Hospital OR	Hospital NORA/ASC/dental school	Office
Use of preoperative IM sedation, n (%)	164 (91)	12 (7)	36 (20)	116 (64)
Years in practice,‡ n (%)
0-5	51 (28)	5 (3)	11 (6)	35 (19)
6-10	44 (24)	2 (1)	7 (4)	31 (17)
11-20	32 (18)	2 (1)	6 (3)	21 (12)
21-30	19 (11)	0 (0)	8 (4)	11 (6)
>30	27 (15)	3 (2)	4 (2)	16 (9)
Teaches residents or fellows, n (%)	67 (37)	12 (7)	22 (12)	33 (18)
Annual number of cases using preoperative IM sedation,§ n (%)
<6	24 (15)	2 (1)	7 (4)	15 (9)
6-25	35 (22)	4 (2)	8 (5)	23 (14)
26-50	15 (9)	1 (1)	8 (5)	6 (4)
51-100	20 (12)	1 (1)	5 (3)	14 (9)
101-500	45 (28)	4 (2)	7 (4)	34 (21)
>500	23 (14)	0 (0)	1 (1)	22 (14)
Percentage of annual patients treated with preoperative IM sedation‡§
Typical children ages 2-12 y	45	31	29	51
Special needs children ages 2-12 y	20	24	17	21
Specials needs ages 13 y and older	35	45	54	27

^*Abbreviations: ASC, ambulatory surgical center; NORA, non–operating room anesthesia; OR, operating room.

^†Descriptive data provided by respondents to questions regarding demographics, with columns segregating data based on the most common venue in which respondents administer preoperative IM sedation. In some cases, the total numbers may be different than the sum of each respective column; this is due to respondents leaving selected questions unanswered.

^‡Inaccurate sum totals reflect missing respondent data, and percentages may not total 100 due to rounding.

^§Denotes n = 162.

Of the 151 respondents who provided their most common drug regimen for preoperative IM sedation, 149 (98%) use a ketamine-based drug regimen (Tables 2 and 3). The most frequently reported drug regimen was ketamine with midazolam (52%; median 2.5 mg/kg and 0.1 mg/kg, respectively), followed by ketamine alone (32%; median 3 mg/kg). Less commonly reported adjunctive IM sedatives were dexmedetomidine, fentanyl, meperidine, and clonidine (reported in 16, 4, 3, and 1 IM regimens, respectively).

Table 2.

Most Common Preoperative IM Sedation Drug Regimens*

IM drug regimen	Value, n (%), N = 151
Ketamine alone	48 (32)
Ketamine and midazolam	79 (52)
Ketamine and dexmedetomidine	3 (2)
Ketamine, midazolam, and dexmedetomidine	11 (7)
Ketamine plus other drugs	8 (5)
Non–ketamine-based drug regimen	2 (1)

^*IM, intramuscular.

Table 3.

Most Common Preoperative IM Sedation Drug Dosages by Venue*

IM drug dosing	Median (IQR)	By venue, median
		Hospital OR	Hospital NORA/ASC/dental school	Office
Ketamine alone, mg/kg	3 (2-3)	3	2.5	3
Ketamine and midazolam
Ketamine, mg/kg	2.5 (2-3)	5	2.5	2.5
Midazolam, mg/kg	0.1 (0.07-0.1)	0.05	0.1	0.1
Ketamine and dexmedetomidine
Ketamine, mg/kg	3 (n/a)	3	n/a	2.75
Dexmedetomidine, mcg/kg	0.5 (n/a)	1	n/a	0.4
Ketamine, midazolam, and dexmedetomidine
Ketamine, mg/kg	2.3 (2-3)	3.5	2	2
Midazolam, mg/kg	0.1 (0.09-0.1)	0.3	0.1	0.1
Dexmedetomidine, mcg/kg	1 (0.4-1.6)	2	0.3	1

^*ASC, ambulatory surgical center; IM, intramuscular; IQR, interquartile range; n/a, not applicable; NORA, non–operating room anesthesia; OR, operating room.

Table 4 displays the respondents' clinical practice patterns regarding preoperative IM sedation. A large majority of respondents (87%) indicated that they administer the same drug regimen in ≥80% of cases requiring preoperative IM sedation. Most respondents (96%) target a RASS score of −3, −4, or −5 after administering preoperative IM sedation. Similarly, 96% of respondents report achieving their anticipated level of sedation in >80% of cases. A small majority of respondents (51%) routinely administer anticholinergics with IM ketamine. When an anticholinergic is administered, IV glycopyrrolate is the most common drug and route of administration (24%). After administering preoperative IM sedation, most providers (74%) establish IV access next in their anesthetic management sequence.

Table 4.

Practice Patterns*†

	Total (N = 156)	By venue
		Hospital OR	Hospital NORA/ASC/dental school	Office
Frequency of using most common IM drug regimen, n (%)
100%	40 (26)	6 (4)	8 (5)	26 (17)
90-99%	74 (47)	1 (1)	13 (8)	59 (38)
80-89%	21 (13)	3 (2)	3 (2)	15 (10)
60-79%	16 (10)	2 (1)	7 (4)	7 (4)
<60%	5 (3)	0 (0)	2 (1)	3 (2)
Routine anticholinergic administration with ketamine, n (%)
N/A	1 (1)	0 (0)	0 (0)	1 (1)
No	75 (48)	7 (4)	11 (7)	57 (37)
IV glycopyrrolate	37 (24)	3 (2)	10 (6)	24 (15)
IV atropine	15 (10)	0 (0)	4 (3)	10 (6)
IM glycopyrrolate	24 (15)	2 (1)	8 (5)	14 (9)
IM atropine	4 (3)	0 (0)	0 (0)	4 (3)
Typical intervention after IM sedation, n (%)
Start IV	116 (74)	7 (4)	31 (20)	77 (49)
Mask induction	33 (21)	3 (2)	1 (1)	29 (19)
Other	7 (4)	2 (1)	1 (1)	4 (3)
Expected RASS level of sedation, n (%)
RASS −5	20 (13)	3 (2)	0 (0)	17 (11)
RASS −4	92 (59)	5 (3)	21 (13)	66 (42)
RASS −3	37 (24)	4 (3)	10 (6)	23 (15)
RASS −2	5 (3)	0 (0)	1 (1)	4 (3)
RASS −1	2 (1)	0 (0)	1 (1)	1 (1)
Frequency of attaining expected RASS level of sedation, n (%)
100%	9 (6)	1 (1)	1 (1)	7 (4)
90-99%	101 (65)	9 (6)	18 (12)	74 (47)
80-89%	39 (25)	2 (1)	11 (7)	26 (17)
60-79%	6 (4)	0 (0)	3 (2)	3 (2)
<60%	1 (1)	0 (0)	0 (0)	1 (1)

^*Abbreviations: ASC, ambulatory surgery center; IM, intramuscular; IV, intravenous; NORA, non–operating room anesthesia; OR, operating room; RASS, Richmond Agitation Sedation Scale.

^†Inaccurate sum totals reflect missing respondent data, and percentages may not total 100 due to rounding.

Select side effects were reported to be infrequent among all providers (Table 5). The most common unwanted side effect was dysphoria, either immediately postinjection or on emergence from general anesthesia.

Table 5.

Unwanted Side Effects and Adverse Events*

Event	Number†
Dysphoria (emergence)	2.05
Dysphoria (postinjection)	1.90
Vomiting	0.93
Laryngospasm	0.63
Desaturation (SpO2 <90%)	0.58

^*The average reported number of events that occurred in the previous year for each provider.

^†Survey question 13 (“In last year, in how many patients did you observe the following adverse events after using preoperative IM sedation?”) allowed respondents to select 0, 1 to 2, 3 to 5, and >5 to which a corresponding weighting factor of 0, 1.5, 4, or 8 was applied.

Providers also identified the importance of multiple factors when determining their dose of IM ketamine (Table 6). The highest scoring responses were “pre-injection patient behavior/agitation” and “certainty of IM effect.”

Table 6.

Ketamine Dose Decision*†

Factor	Importance‡
Certainty of IM effect	3.1
Preinjection patient behavior/agitation	2.9
Use the lowest dose possible	2.5
Rate of onset of sedation	2.4
Duration of recovery	2.1
Patient appearance at parental separation	2.1
Duration of procedure	1.9
Incidence of psychomimetic reactions	1.7

^*Abbreviation: IM, intramuscular.

^†List of the average relative importance of factors that may affect ketamine dosing.

^‡Survey question 12 (“In determining your dose of IM ketamine for preoperative sedation, how important are the following considerations?”) allowed responses ranging from not, slightly, moderately, very, and extremely important, to which a corresponding weighting factor of 0, 1, 2, 3, or 4 was applied.

As seen in Table 7, further analysis was undertaken to understand whether there were any statistically significant differences in ketamine dosages when comparing selected subgroups of respondents. Anesthesiologists who typically start an IV after IM sedation reported a higher ketamine dose compared with those who typically start with an inhalational induction after IM sedation (median 3 vs 2 mg/kg; P = .0002). A significantly higher median dose of ketamine (3 vs 2 mg/kg; P = .007) was reported by anesthesiologists who expected a deeper level of sedation (RASS 4 or 5 vs RASS 1, 2, or 3). No other selected comparisons reached the threshold for statistical significance.

Table 7.

Ketamine Dose Comparison*†

Comparison	Ketamine dose, median (IQR)	P value
Inhalational induction	2 (2, 2.5)	.0002‡
IV induction	3 (2, 3)
Hospital OR	3 (2.5, 3)	.08
Office	2.5 (2, 3)
Ketamine alone	2.5 (2, 3)	.32
Ketamine with another sedative	3 (2, 3)
High-use providers (>100 IM cases/y)	2.5 (2, 3)	.63
Low-use providers (<26 IM cases/y)	3 (2, 3)
In practice 0-5 years	2.5 (2, 3)	.89
In practice >20 years	3 (2, 3)
Preoperative patient behavior very/extremely important	2.5 (2, 3)	.42
Preoperative patient behavior not/slightly/moderately important	3 (2, 3)
Certainty of IM effect very/extremely important	2.5 (2, 3)	.33
Certainty of IM effect not/slightly/moderately Important	3 (2, 3)
Expected RASS −1/−2/−3	2 (2, 3)	.007‡
Expected RASS −4/−5	3 (2.2, 3)
50% or more of patients special needs 13 y and older	2.5 (2, 3)	.05
<50% of patients special needs 13 y and older	2.9 (2, 3)

^*Abbreviations: IQR, interquartile range; IM, intramuscular; IV, intravenous; OR, operating room; RASS, Richmond Agitation Sedation Scale.

^†For the purposes of these comparisons, no adjustments were made whether ketamine was administered alone or with other sedatives.

^‡Denotes P < .05.

DISCUSSION

Most dentist anesthesiologists provide general anesthesia in the dental office setting. When treating children or patients with special needs, the two most common routes of general anesthesia induction are inhalation or IM. Some dentist anesthesiologists travel with portable anesthesia machines. These providers are likely to induce general anesthesia by the inhalational route. However, when the patient is physically combative, or when an anesthesia machine is not available, providers are likely to induce general anesthesia by the IM route.

Preoperative IM sedation typically occurs in nontreatment areas of private offices or in the preoperative holding area of hospitals or ambulatory surgical centers prior to any formal patient monitoring. In rare instances, due to emotional distress, behavioral defiance, or physical limitations, preoperative IM sedation may even be administered in a vehicle parked at the hospital or treatment facility. It is critical that the sedative regimen achieves an adequate level of sedation predictably, rapidly, and safely. Once adequate sedation has been achieved, the patient can be separated from caregivers and transported to the desired location. The order of the subsequent sequence of events may vary depending on the preferences of the anesthesia providers and the available resources or the level of sedation achieved. In general, these events include transfer to the OR/dental operatory, placement of anesthesia monitors, IV cannulation, and induction (either IV or inhalation) of general anesthesia.

Although recommendations can be found in various anesthesia sources regarding ketamine-based drug regimens for preoperative IM sedation, there are no clear guidelines about the most effective drugs, drug combinations, or dosages. Furthermore, there are minimal data regarding dentist anesthesiologists' current practice habits regarding IM sedation and the safety of these techniques. The questions in this survey were designed to characterize current practices of individual dentist anesthesiologists including demographic data about providers, practice location, frequency of preoperative IM sedation, drug regimens (both drugs and dosages), next steps after IM sedation, the intended RASS level of sedation, the success of achieving this level of sedation, use of anticholinergics, factors that influence ketamine dosages, and adverse events. The highest reported drug regimen was a combination of ketamine and midazolam (median 2.5 mg/kg and 0.1 mg/kg, respectively), with the second most being ketamine alone (median 3.0 mg/kg). Dysphoria observed immediately after injection or upon emergence were the most reported side effects, with 67% of respondents reporting at least 1 case in the previous year.

Ketamine is widely used for IM sedation because it rapidly and predictably produces immobility, amnesia, analgesia, and a classic “dissociative” state in which airway reflexes and respiratory drive are largely preserved.¹ The US Food and Drug Administration (FDA) package insert for ketamine alternately references IM doses of 9 to 13 mg/kg and 6.5 to 13 mg/kg to produce 12 to 25 minutes of surgical anesthesia but makes no statement about the use of ketamine specifically for preoperative IM sedation.² The Emergency Medicine (EM) guidelines for procedural sedation recommend an IM ketamine dose of 4 to 5 mg/kg noting, “there is no apparent benefit . . . to using 3 mg/kg rather than 4 to 5 mg/kg IM, except perhaps a slightly faster recovery with the lower dose.”³ Emergency procedures (eg, fracture reduction) requiring IM sedation are often painful yet brief and rely in part on the analgesia produced by ketamine. In addition, these EM guidelines recommend against the routine use of a benzodiazepine or anticholinergic due to a lack of evidence demonstrating improved patient outcomes in that setting. Preoperative IM sedation is distinct from surgical anesthesia (as noted in the FDA label) or procedural sedation (as addressed by the EM guidelines) in that only behavior modification is required to facilitate separation from caregivers, transfer to the OR, establishment of IV access, and/or induction of general anesthesia. Unfortunately, the anesthesia literature is relatively silent on the issue of ideal drug regimens for preoperative IM sedation.

A comparison of some of the most popular anesthesia textbooks provides a wide range of recommendations regarding preoperative IM sedation. Jaffe recommends ketamine 2 mg/kg with midazolam 0.2 mg/kg and glycopyrrolate 0.1 mg/kg.⁴ Morgan & Mikhail's Clinical Anesthesiology suggests midazolam 0.1 to 0.15 or ketamine 2 to 3 mg/kg with atropine 0.02 mg/kg.⁵ Miller's Anesthesia suggests ketamine 4 to 5 mg/kg IM for reduction of anxiety and 5 to 10 mg/kg to induce general anesthesia.⁶ Furthermore, this text also suggests IM coadministration of a benzodiazepine to reduce hallucinations and an anticholinergic to reduce sialorrhea but specifies neither specific agents nor dosages. Basics of Anesthesia recommends ketamine 5 mg/kg and notes that IM atropine or glycopyrrolate can be used (but does not specify an anticholinergic dose).⁷

Cote's A Practice of Anesthesia for Infants and Children offers a more detailed discussion of ketamine and preoperative IM sedation, beginning with the observation that ketamine 2 mg/kg will calm most children enough to accept a mask without prolonging discharge times, while the addition of midazolam 0.1 to 0.2 mg/kg may prolong recovery and discharge times after very short procedures.⁸ Cote also notes that larger doses of ketamine (eg, 4-5 mg/kg) may be used for a more rapid onset of sedation or when maintenance of blood pressure is important, such as in the treatment of patients with congenital heart disease, and that ketamine 10 mg/kg will produce deep sedation for a period of 12 to 25 minutes. Cote recommends routine administration of an anticholinergic to reduce ketamine-induced sialorrhea but clarifies that IV administration is usually sufficient once IV access has been established as opposed to IM coadministration with ketamine. In addition, Cote also notes that glycopyrrolate is twice as effective as an antisialagogue when compared with atropine. In short, there is little agreement in the major anesthesia texts regarding the best approach to preoperative IM sedation.

In this survey, the single highest reported dosage of IM ketamine was 5 mg/kg (ketamine with midazolam 0.07 mg/kg). Of the 149 ketamine dosages reported (with or without adjunctive sedatives), 82% ranged from 2 to 3.5 mg/kg (8% were ≥4 mg/kg, and 10% were <2 mg/kg). In addition to using lower ketamine dosages than found in the FDA package insert or in the EM guidelines for procedural sedation, respondents frequently (67%) rely on adjunctive sedatives, such as midazolam or dexmedetomidine, for preoperative IM sedation. Interestingly, the reported ketamine dosages were minimally altered whether used alone or with adjunctive sedatives. In addition, despite published evidence showing that the combination of IM ketamine with midazolam can prolong recovery after very short procedures,⁹ data from this survey suggest prolonged recovery time does not appear to be a primary concern for most dentist anesthesiologists. This may be because most dental procedures requiring general anesthesia are at least 45 minutes in length. Individual dentist anesthesiologists are generally consistent with their preoperative IM sedation drug regimens. Although reported drug regimens varied widely, most providers also reported a high success rate with their chosen drug regimen, as determined by the percentage of cases in which providers reported achieving their desired RASS level of sedation.

This survey had several limitations. As a survey, respondents' answers are subject to several biases. These include recency bias (the tendency to give higher importance to recent events), recall bias (incomplete memories), response bias (incorrect or untruthful responses produced by survey design, perceived “right” answers, or other factors), reporting bias (selective event reporting), and participation bias (systematic differences between those who responded to the survey and those who did not).

The survey does not fully characterize the resources of each anesthesia provider. For example, some office-based providers may not have access to inhalational anesthetics, and this limitation may affect their preoperative IM sedation drug regimen. In addition, this survey did not specifically address why providers use their selected regimens or why providers may alter their selected drug regimens. For example, a provider may administer one drug regimen to a healthy child and an alternative drug regimen to a combative, nonverbal adult male with autism spectrum disorder. This survey was not designed to address causality between adverse events and preoperative IM drug regimens. There is also the possibility that unclear wording of questions may have led to unintentionally inappropriate responses.

CONCLUSION

In summary, this survey captures dentist anesthesiologists' current practice patterns regarding preoperative IM sedation. We report that ketamine-based drug regimens are the primary choice for preoperative IM sedation and that ketamine is frequently coadministered with midazolam or other sedatives. Prospective research is needed to identify the differences in effects produced by various preoperative IM sedation drug regimens in different patient populations.