Sedation plays a vital role in equine practice, helping ensure the safety of the veterinarian and other handlers, the compassionate care of the horse, and the precise and efficient completion of procedures.
As practiced today, equine sedation for standing procedures typically involves administering a combination of any of several sedatives, tranquilizers or opioid analgesics. Alpha-2 agonists are widely used in these combination protocols because they provide rapid and reversible, dose-dependent sedation; are non-narcotic (non-scheduled); and produce clinically significant analgesia as well as profound sedation.
Although their manufacturers do not promote combination use of alpha-2 agonists with other agents, the practice of multi-drug sedation remains the norm in equine medicine. This is partly due to the limitations of xylazine, the original veterinary alpha-2 agonist. Xylazine is very short-acting and delivers comparatively poor analgesia compared to its successor detomidine, a more potent and selective alpha-2 agonist.
This has given rise to the use of various off-label drug combinations for equine sedation, an approach intended to provide a synergistic or supplementary effects to compensate for the limitations of xylazine. Examples include use of detomidine and xylazine (two alpha-2 agonists), and detomidine or xylazine and butorphanol (an opioid agonist/antagonist). When combination protocols are used, each drug is usually given at lower than recommended dosages, often for purposes of reducing drug costs. A disadvantage of this deliberate under-dosing is sub-optimal depth and duration of sedation. When that occurs, the horse resumes vigilance, lifts its head, moves about and needs to be re-sedated or “topped up.” This interrupts and prolongs the procedure and adds to drug costs for both the client and the veterinarian.
Increased drug costs resulting from re-sedation are sometimes passed along to the horse owner. However, some veterinarians absorb the additional drug costs rather than charge the client extra. In such cases, re-sedation not only takes additional time but imposes excess drug costs on the veterinarian, making the procedure even less profitable than if re-sedation had not been required. By using a better sedation protocol, veterinarians can save themselves and their clients time and money.
The study described below examined the frequency of re-sedation reported by 10 equine veterinarians who used their standard protocols for the identical standing sedation procedure. Re-sedation rates for individual veterinarians were then evaluated with respect to procedure duration, quality of sedation and economic return to the veterinarian. Power floating using a motorized grinding tool was the test procedure in all cases. For purposes of evaluating outcomes, this provided a relatively uniform procedure, billable on a cost-plus-fee basis, with minimal variation in time and technique. A large number of cases (363) gave statistical validity to the study.
Study Design
Ten equine practitioners were selected for the study. A diary study format was used whereby participants provided on-site data in response to a standard set of questions for each case. Each veterinarian documented up to 40 power dentistry cases requiring standing sedation. For each equine patient, the veterinarian recorded the sedation protocol used, whether re-sedation was required, overall duration of the procedure and quality of sedation achieved as scored on a 1 to 5 scale from lowest to highest quality. If multi-drug protocols were used, each drug was identified and the dosage volume and time of administration were indicated.
Participating veterinarians also noted the fee charged for each case, itemized by sedation and non-sedation charges. An average effective hourly billing rate (HBR) was calculated for non-sedation fees—the component of the total fee not affected by additional drug costs that can be passed on to the client.
Results
Sedation Regimens
The 10 participating veterinarians used various sedation protocols as shown in Table 1. The agents used were generally given as partial doses in multi-drug combinations. Nine of the 10 veterinarians used detomidine and four used xylazine alone or in combination with other sedative or analgesic agents as a primary sedation regimen. For re-sedation, five veterinarians used regimens that differed from their primary regimen. The remaining five veterinarians used their primary regimens for re-sedation. Detomidine was the most widely used sedative, given in 92.1% of the cases either for primary or secondary sedation or both. Detomidine, xylazine and butorphanol were all used at less than their approved dosages in the majority of cases. For example, in 243 cases (66.9%), the attending veterinarian used detomidine at a dosage less than the lowest approved dose of 20 µg/kg. There were no adverse, drug-associated safety events in any treated horse.
Re-sedation rates, procedure completion times, fees and billing rates
The re-sedation rate for the 10 participating veterinarians ranged from 2.5% to 73.5%. The mean overall re-sedation rate was 27.8% (101 of 363 cases). Average time to complete the equine dentistry procedure was 5.54 mins (28%) longer for horses requiring re-sedation compared to those that did not (25.27 vs. 19.73 mins). The average time to completion for all cases was 20.98 minutes.
As expected, cases requiring re-sedation had a higher average fee for sedation ($57.18 vs. $39.15), a difference of $18.03 (46.1%) compared to cases requiring primary sedation only. The cases requiring re-sedation also had a somewhat higher average non-sedation fee ($103.94 vs. $94.46) and a higher total fee ($160.06 vs. $133.31). The average non-sedation fee—the charge for the non-drug, procedural component of the procedure—was a proportionally larger component of the total average fee for cases not requiring re-sedation compared to those that did (ratio of 0.71 vs. 0.65), indicating greater time efficiency for the cases not requiring re-sedation. Overall, fees for sedation represented 31% of the average total fee. The average HBR for the non-sedation fee was $246.79 for cases requiring re-sedation versus $287.26 for those that did not, a difference of $40.47 per hour (14.1%). The average HBR for all cases was $277.46.
Outcomes for high- and low-efficiency veterinarians
Re-sedation rates, length of procedure and HBR for non-sedation charges were calculated for the three veterinarians with the highest re-sedation rates (representing 113 cases) and the three with the lowest re-sedation rates (representing 96 cases). In effect, data for these two groups compared outcomes for high-efficiency versus low-efficiency practitioners. There was a 6.3-fold difference between the three lowest and the three highest average re-sedation rates (8.8% vs. 55.5%) and a three-fold difference between the average of the three lowest rates and the group average (8.8% vs. 27.8%).
There was a linear relationship between the re-sedation rate and quality of sedation and length of procedure when the high- and low-efficiency veterinarians were compared. The veterinarians with the three lowest re-sedation rates had a mean quality-of-sedation score of 4.22 vs. a mean score of 3.15 for the veterinarians with the three highest re-sedation rates. The mean score for the group overall was 3.89. The average procedure duration was 21.4 minutes for the veterinarians with the three highest re-sedation rates vs 18.6 minutes for those with the three lowest re-sedation rates, a 15% difference. The group mean was 20.98 minutes.
The veterinarians with the three highest re-sedation rates had a mean HBR for non-sedation charges of $290.08 compared to $330.32 for the veterinarians with the three lowest re-sedation rates, a $40.24 (13.8%) difference. The mean non-sedation HBR for the three high-efficiency practitioners with an average 8.8% re-sedation rate exceeded the overall group mean HBR by $52.84 ($330.32 vs. $277.46).
Discussion
Re-sedation is a consequence of inadequate initial sedation, an outcome that occurred in more than one fourth of the cases followed in this study. This remarkable rate of re-sedation with its clear-cut adverse effect on procedure time, quality, cost and income reflects poorly on sedation protocols used in equine veterinary practice where sub-optimal dosages of individual drugs are given. A comparable rate of initial sedation failures in human medicine would be clearly unacceptable. For example, a retrospective study of outpatient oral surgery at a major U. S. hospital reported an IV sedation failure rate of 1.6% (9 of 539 cases), more than 17 times lower than the rate reported in the equine dental study described here.
Six of the 10 study participants preferred multi-drug primary combinations (Table 1). Combination regimens, where veterinarians generally administered partial doses of two or more agents, explain the low dosages of detomidine and xylazine used in most cases. Detomidine, the most commonly used sedative, was given at doses well below the minimum-approved level in the great majority of horses, in some cases at a fraction of the lowest approved dose. This approach, explained by the desire to save costs, runs the risk of shallow, short-lived sedation and the need for re-treatment in order to complete the procedure.
Diary notations revealed that higher re-sedation rates in some cases were due to inadequate time between administration of the sedative agent and initiating the dentistry procedure. For example, one veterinarian started the power floating procedure immediately after administering a sedative. In the case of alpha-2 agonists, 3 to 5 minutes must elapse before the full sedative effect occurs.
The study results provide a real-world perspective since all veterinarians experience some percentage of sedation failures. Results for the three high-efficiency veterinarians indicate that a re-sedation rate of ≤10% is both an achievable goal and an important benchmark associated with superior case outcomes as determined by time, quality and compensation. The three high-efficiency veterinarians scored a whole quintile (>20%) better on the five-point quality-of-sedation scale than their low-efficiency peers. Additionally, the three high-efficiency veterinarians completed the procedure nearly 3 minutes (>15%) faster and had a >$40 (13.8%) better HBR for non-sedation charges versus the three low-efficiency veterinarians.
The study revealed five consequences of re-sedation compared to cases where re-sedation is not required: longer time to procedure completion, lower quality of sedation, higher sedation fees to the client, higher sedation costs to the veterinarian and a lower HBR for non-sedation charges. Although not evaluated in this study, intra-operative re-sedation may also cause a drop-off in quality of technique and procedural efficacy.
One of the lessons of the study is that a consistently effective protocol has a major impact on sedation quality, procedural efficiency and economic return. Practitioners can establish an effective sedation protocol by using an equine-approved sedative at a dose sufficiently large to consistently provide an adequate response, then tracking the incidence of re-sedation and adjusting the protocol accordingly. This can result in safe and reliable sedation of the equine patient that minimizes the disruptive and costly effects of intra-operative re-sedation. The goal should be an initial sedation failure rate of 10%, the standard achieved by the three high-efficiency veterinarians in this study. This approach can be applied not only to power floating but to any repetitive procedure in equine practice.
This study was conducted by Edward L. Blach, DVM, MS, MBA of Edjje, Inc., Monument, Colorado, and John M. Donecker, VMD, MS, Dipl ABVP (equine), Outcomes Research, Pfizer Animal Health, Madison, New Jersey. The authors acknowledge the contribution of Mark Dana of Scientific Communications Services in the writing and editing of this report.
SIDEBAR
The Importance of Minimizing Re-sedation
Re-sedation is the result of inadequate initial sedation, an outcome that occurred in one-fourth of the cases in the study.
Sedation failure or re-sedation reduced the hourly billing rate by $40.47 (14.1%) and increased completion time by 5.5 minutes (28%) compared to cases that did not require re-sedation.
High re-sedation rates were associated with sub-optimal sedative dosages, highly variable sedation regimens and not allowing adequate time between administering the sedative and initiating the procedure.
Veterinarians should adopt a sedation protocol that focuses on achieving consistently successful initial sedation rather than minimizing drug costs. A re-sedation rate of ≤10% is an achievable goal and a benchmark associated with superior case outcomes as determined by time to completion of procedure, quality of sedation and compensation.
Table 1–Sedation Regimens Used by Veterinarians for Equine Dentistry Cases
SIDEBAR
Table 2–Average Re-sedation Rate, Quality of Sedation, Duration of Procedure and Effective Hourly Billing Rate for Equine Dentistry Procedures Performed by Veterinarians with the Three Highest and Three Lowest Re-sedation Rates
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Mean re- Mean quality Ave. non- Ave. non-
sedation of sedation Mean duration sedation sedation
Group rate (range) score* of procedure fee fee HBR
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(1) Veterinarians with three lowest 8.8% (2.5-12.5%) 4.22 18.6 mins $102.40 $330.32
re-sedation rates
(2) Veterinarians with three highest 55.5% (27.5-71.4%) 3.15 21.4 mins $104.43 $290.08
re-sedation rates
(3) Total group (n=10) 27.8% (2.5-73.5%) 3.89 20.98 mins $97.02 $277.46
____________________________________________________________________________________________
*1=lowest, 5=highest
HBR=hourly billing rate: The HBR was prorated by the average time to completion of the procedure, using the following formula: HBR = Fp ÷ (Tp mins ÷ 60 mins), where HBR is the hourly billing rate in dollars, Fp is the non-sedation fee for the procedure and Tp is the time for completion of the procedure.
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This study was conducted by Edward L. Blach, DVM, MS, MBA of Edjje, Inc., Monument, Colorado, and John M. Donecker, VMD, MS, Dipl ABVP (equine), Outcomes Research, Pfizer Animal Health, Madison, New Jersey. The authors acknowledge the contribution of Mark Dana of Scientific Communications Services in the writing and editing of this report.
