Veterinary Anesthesia and Nerve Blocks Study

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Questions and Answers

What are the proposed cut-off values for detecting nerve block failure in dogs undergoing arthrotomy?

The proposed cut-off values are b p values of 6 mmHg, DSAP greater than 10 mmHg, and DDAP greater than 8 mmHg.

Explain the range of agreement levels used for assessing nerve block outcomes.

The agreement levels are categorized as: no (0), slight (0.01e0.20), fair (0.21e0.40), moderate (0.41e0.60), substantial (0.61e0.80), and perfect (0.81e1.00).

What is the minimum alveolar concentration (MAC) of isoflurane in dogs according to the study?

1.28%

What physiological variables did nurse anaesthetists speculate have overlapping effects on intraoperative assessment?

Nurse anaesthetists speculated that there is overlap in physiological variables such as cardiovascular metrics (HR and BP) during intraoperative assessment. Signup and view all the answers

What MAC multiple was observed to inhibit movement in 95% of anesthetized humans?

1.2 to 1.4 times MAC Signup and view all the answers

How did cardiovascular and ventilatory variables relate to surgical stimulation responses, according to the study?

Cardiovascular variables (HR and BP) and ventilatory variables (fR and VT) had better associations with responses to surgical stimulation compared to anaesthetic depth. Signup and view all the answers

Which cardiovascular variable had the best discriminating ability in the ROC analysis?

Mean Arterial Pressure (MAP) Signup and view all the answers

What was the average anaesthetic time for premedication before the arthrotomy?

The average anaesthetic time for premedication to arthrotomy was 116.5 ± 37.4 minutes. Signup and view all the answers

What challenges does an inadequate plane of anaesthesia pose according to the study?

An inadequate plane of anaesthesia can complicate the distinction between nociception and arousal. Signup and view all the answers

What was the clinically relevant fraction of expired isoflurane (FE0 Iso) used in the study?

1.6 ± 0.06% Signup and view all the answers

What is the significance of the 50% and 80% ranges proposed by the ACVIM for oscillometric measurements?

The ACVIM suggests that 50% of oscillometric measurements should be within 10 mmHg and 80% within 20 mmHg of invasive pressure readings. Signup and view all the answers

Did the study find that 1.5 times MAC of isoflurane was sufficient to prevent a hemodynamic response in humans?

No, it did not prevent the response. Signup and view all the answers

Why did none of the dogs require rescue analgesic intervention during the study?

None of the responses to surgical stimulus were severe enough to warrant rescue analgesic intervention. Signup and view all the answers

What two types of blocks were analyzed in the study for their effectiveness in detecting responses to surgical stimulus?

Guided saline block (GSB) and guided bupivacaine block (GBB) Signup and view all the answers

What were the premedications used in this study for dogs undergoing anesthesia?

Medetomidine and morphine Signup and view all the answers

What conclusion can be made about the respiratory variables in comparison to cardiovascular variables in the study's ROC analysis?

Respiratory variables had poor discriminating ability. Signup and view all the answers

What was the age and body weight range of male dogs included in the study?

Male dogs were 4.4 ± 2.6 years old with an average body weight of 40.8 ± 12 kg. Signup and view all the answers

What role do isoflurane and medetomidine play in the cardiovascular effects observed in dogs under anesthesia?

Isoflurane and medetomidine likely affect cardiovascular function and may unquantifiably influence the associated criterion values during surgical procedures. Signup and view all the answers

What were the anticipated outcomes regarding block failure in the BBB group compared to the GBB group?

The authors anticipated that the BBB group would exhibit a larger proportion of block failure compared to the GBB group. Signup and view all the answers

Why should the absolute values of cardiovascular variables be approached with caution in surgical patients?

The absolute values may not be directly translatable to every dog undergoing surgery, as individual responses can vary significantly. Signup and view all the answers

What criteria were used for the objective assessment of nerve block outcomes in the study?

The criteria for objective assessment of nerve block outcomes are indicated in Table 2 of the study. Signup and view all the answers

What concern is raised regarding the use of oscillometric devices in detecting surgical stimulus responses?

The study hesitates to recommend oscillometric devices for this purpose due to their inadequacy in accurately reflecting the cardiovascular status during surgery. Signup and view all the answers

What effect can different anesthetic drug combinations have on the cardiovascular system of a dog?

Different anesthetic drug combinations can significantly influence the cardiovascular system's function and the dog's overall physiological response. Signup and view all the answers

How might the antinociceptive effects of medetomidine and morphine interfere with monitoring during anesthesia?

The antinociceptive effects of medetomidine and morphine may provide an unquantiﬁable influence on the readings, complicating the monitoring process. Signup and view all the answers

What are the prevalence rates of nerve injury and systemic toxicity as reported by Barrington et al. (2009)?

The prevalence rates are 0.0004% for nerve injury and 0.0001% for systemic toxicity. Signup and view all the answers

What does the SHAM score proposed by McGuirk et al. (2011) signify in the study context?

The SHAM score of 3 signifies a moderate risk associated with the use of a placebo and blind group. Signup and view all the answers

How did the BBB group compare to other groups regarding the risk of nerve injury?

The BBB group had a higher degree of risk associated with nerve injury and block failure. Signup and view all the answers

What role do placebo groups play in peripheral nerve block studies according to Papadopoulos et al. (2022)?

Placebo groups play an important role in peripheral nerve block studies to evaluate treatment effects. Signup and view all the answers

What practice was maintained across all three groups to reduce serious complications?

A good standard of practice was maintained to reduce the incidence of serious complications. Signup and view all the answers

What precautions were taken regarding needle positioning in the study?

Excessive tissue probing was avoided and aspirations were performed prior to needle positioning. Signup and view all the answers

Who provided financial support for the study mentioned in the acknowledgements?

Valley Farm Animal Hospital provided financial support for the study. Signup and view all the answers

Which organizations were acknowledged for supplying equipment for the study?

Lomaen Medical provided the ultrasound machine, and DIAG supplied the nerve stimulator needles. Signup and view all the answers

What is the purpose of the surgical Pleth Index in assessing anaesthesia?

The surgical Pleth Index assesses nociception-anti nociception balance during general anaesthesia. Signup and view all the answers

How does remifentanil administration affect propofol consumption and recovery times in outpatient anaesthesia?

Remifentanil administration reduces propofol consumption and shortens recovery times. Signup and view all the answers

What was one of the outcomes measured in the comparison of femoral and sciatic nerve blockade for surgeries in dogs?

The effectiveness and safety of the nerve blocks for surgical procedures were compared. Signup and view all the answers

Why is heart rate variability significant in monitoring anaesthesia depth in dogs?

Heart rate variability provides insights into the autonomic nervous system's response to anaesthesia. Signup and view all the answers

What are the challenges associated with identifying nerve block failure during procedures?

Challenges include accurately assessing sensory responses and variations in individual patient physiology. Signup and view all the answers

What was the focus of the evaluation conducted by Bergfeld et al. regarding local anaesthetic interventions?

The focus was on the use of invasive placebos in research surrounding local anaesthetic efficacy. Signup and view all the answers

How does pupillometry serve in veterinary anaesthesia monitoring according to Mills et al.?

Pupillometry is used to develop reference intervals for assessing anaesthesia depth in healthy dogs. Signup and view all the answers

What role does K€ astner SB's research play in the context of veterinary anaesthesia?

K€ astner SB's research focuses on comparisons of nerve block techniques to improve anaesthetic practices in dogs. Signup and view all the answers

Study Notes

Introduction

Authors investigated the use of blood pressure (BP) variables to detect nerve block failure in dogs undergoing arthrotomy.
This was a prospective study involving 30 dogs.
They evaluated the association between nerve block confidence scores & subjective and objective scores for the outcome of the block.
A comparison was made between guided saline block (GSB) and guided bupivacaine block (GBB).

Methods

Dogs were premedicated with medetomidine & morphine before induction with propofol.
Anesthesia was maintained with isoflurane.
Nerve block outcome was evaluated subjectively and objectively.
Objective assessment of nerve block failure was based on changes in HR, DHR, fR, DfR, SAP, DSAP, MAP, DMAP, DAP, and DDAP.

Results

There was a poor association between nerve block confidence scoring and the outcome of the block based on subjective and objective scores .
ROC analysis revealed that cardiovascular variables had good discriminative ability in distinguishing a response to surgical stimulus while respiratory variables showed poor discriminating ability.
HR, DHR, fR, and DfR did not meet the criteria for diagnostic purposes.
MAP and DAP were the most effective variables for detecting a response to surgical stimulus.

Discussion

The results suggest that DBP variables can be considered as an objective score to detect a response to surgical stimulation and nerve block failure.
The authors warn against direct translation of these findings to all dogs due to factors like anaesthetic drug combinations and individual cardiovascular system function.
They emphasize the importance of considering the effects of different anaesthesia drug combinations and individual cardiovascular system function in determining criterion values.
The use of invasive arterial BP and veterinary-specific oscillometric devices is discussed, with emphasis on the limitations of oscillometric devices in detecting a response to surgical stimulus.
Although the study acknowledges the risk associated with blind bupivacaine block, it highlights the importance of placebo groups in nerve block studies.
The need for good standard of practice in all groups to reduce the incidence of serious complications is stressed.

Conclusion

Use of DBP variables can potentially be a valuable tool for objectively detecting a response to surgical stimulation and identifying nerve block failure.
Determination of these criterion values for different canine populations can enhance evaluation of nerve block techniques and improve ERAS (Enhanced Recovery After Surgery).

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Description

This quiz focuses on a study investigating the use of blood pressure variables to detect nerve block failure in dogs during arthrotomy. It evaluates the relationship between nerve block confidence scores and the actual outcomes based on both subjective and objective measurements. Participants will learn about the methods used, including anesthesia and nerve block techniques.