Could anaesthesia be a key factor for the good outcome of bone ablation procedures? A retrospective analysis of a musculoskeletal interventional centre

Abstract

Objective:

To choose the best anaesthetic approach through the retrospective review of different bone ablation procedures.

Methods and materials:

We retrospectively evaluated 118 ablation procedures carried out in our institute over the last 30 months. Three different anaesthetic approaches were used: general anaesthesia, i.v. sedation/analgesia and loco-regional anaesthesia (brachial plexus block, spinal anaesthesia). The outcomes were evaluated based on three parameters: technical success, patient comfort (Scale 1–5) and operator comfort (Scale 1–5).

Results:

The 118 interventional procedures were carried out on 62 benign and 56 malignant bone lesions. The overall procedural success rate was 100%. Three cases were treated under general anaesthesia: patient comfort was 5/5 in all cases; operator comfort was 5/5 in one case, and 4/5 in two cases. Twenty-one patients underwent sedation/analgesia: in three patients with benign bone lesions, patient comfort was 1/5 and operator comfort 3/5; in two patients with malignant bone lesions, patient comfort was 3/5 and operator comfort 4/5. Ninety-four patients underwent loco-regional anaesthesia: patient and operator comfort was 5/5 in all cases.

Conclusion:

Based on our experience, loco-regional anaesthesia is probably the best anaesthetic approach during bone ablation procedures. Benign bone lesions ablation are the more painful procedures.

Advances in knowledge:

This is the first paper that systematically investigates about the best anaesthesiological support for IR procedures.

Introduction

Interventional radiology (IR) has known an impressive expansion in the last few decades, particularly in the oncological field. The procedures are usually painful and require anaesthesiological support both for patient comfort and for safety. In parallel, non-operative-room anaesthesia (NORA) procedures have widely developed and are currently estimated to account for 30–40% of all hospital procedures in the USA. ¹ IR represents one of the most interesting and challenging fields of application.

Even if minimally invasive, IR procedures can provoke pain and anxiety in patients, ² who may be unable to follow the operator’s instructions. In addition, feeling pain and apprehension, the patient can be exposed to the risk of procedural complications also of cardiovascular nature. ³

The number and complexity of IR procedures ⁴ have increased the demand for a safe anaesthetic management of patients. ⁵ Comfort has become a crucial issue not only for patients, but also for operators, since it ensures better conditions of safety and efficacy. The most common procedures performed for oncological treatments, ablations, require adequate pain killer protocols that have to be adopted also during the post-procedural period. Collaboration between interventional radiologist and anaesthetist becomes, therefore, unavoidable necessity.

The aim of our study was to evaluate how anaesthesia can influence the good outcome of IR procedures and what is the best anaesthesiological approach. To this scope, we retrospectively reviewed the bone ablation procedures performed in our institute over the last 30 months.

Methods and materials

In the period between June 2018 and January 2020, we have systematically recorded details regarding 118 bone ablation procedures performed in the radiological department of our hospital. For each procedure, the following data were recorded: characteristics of the lesion treated, type of IR procedure and type of anaesthesia performed, patient and operator comfort, and technical success.

Two interventional radiologists performed all the procedures (LZ and FA, with respectively more than 15 and 5 years of experience in musculoskeletal intervention). The procedures included radiofrequency ablation (RFA), microwave ablation (MWA), cryoablation and magnetic resonance guided ultrasound surgery (MRgFUS). The kind of procedure performed depended both on the lesion and on the availability of the system in the hospital in the required period.

The anaesthesiological approach was chosen based on:

• Lesion type and localization;

• Patient characteristics;

• Experience of the anaesthetists. The anaesthesiological team in our department is made up of two anaesthetists, each with different skills and experiences. Although this criterion could be considered a bias, however we have applied it because it reflects routine clinical practice in most hospitals.

Three different anaesthesiological approaches were used:

• General anaesthesia (GA)

  Medication protocol: Sedative (Propofol and/or Sevoflurane) + Opioid (Remifentyanil or Sufentyanil + Morphine) +Rocuronium Bromide.

• Sedation/ IntraVenous ANALGESIA (IVA)

  Medication protocol: Sedative (Midazolam or Diazepam or Propofol) + Opioids (Remifentanil or Sufentyanil + Morphine) always performed in combination with a local anesthesia (Lidocaine derivates) on the site of treatment.

• Loco-regional Anaesthesia (LA)

  • Medication protocol: Lidocaine derivates (Bupi- or Ropivacaine) + Morphine.

  • Administered with two different techniques:

The dose of drug was calculated on the weight of the patient.

Apart from the technical success (yes/no) defined as the completion of the procedure as planned, the other outcomes (patient and operator comfort) were evaluated using a 1–5 point scale (1 = poor; 5 = excellent).

In particular, we asked both patients and operators to evaluate globally their comfort level during the procedure, taking into consideration the following aspects, each group for their competence: for patients: pain, difficulty to keep an adequate position and level of anxiety; operator: difficulty to keep adequate concentration and to perform the procedure due to patient movements. Complications were recorded.

The study was approved by the local Institutional Review Board.

Statistical analysis

Data were collected, organized, and analyzed through XLSTAT 2017: Data Analysis and Statistical Solution for Microsoft Excel (Addinsoft, Paris, France 2017). Descriptive statistics were calculated for all variables. Separate Mann-Whitney U-tests were conducted to determine group differences between variables p values of < 0.05 were considered as statistically significant. All numerical data were expressed as mean ± standard error of the mean.

Results

The patients treated included 62 males and 56 females (mean age, 44.8 y.o.; range 8–83 y.o.).

Treatments were performed on 62 benign and 56 malignant lesions, localized as follows: lower extremities (41), spine (30), pelvis (23), upper extremities (16) and ribs (8) (Figure 1). The ablation techniques used were: RFA in 53 cases, Cryoablation in 30 cases, MRgFUS in 25 cases and MWA in 10 cases (Figure 2). Technical success rate was 100% in all cases.

Figure 1.

Lesion Localization.

Figure 2.

Ablation Techniques used. MRgFUS, Magnetic resonance guided ultrasound surgery; MWA, Microware ablation; RFA, Radiofrequency ablation; Cryoablation.

GA was used in three cases, which were all benign lesions. Patient comfort was 5/5 in all cases. Operator comfort was 5/5 in one case and 4/5 in two cases with a mean value of 4.3.

Twenty-one patients underwent IVA approach: of them, six presented benign lesions and 15 malignant ones. Total patient comfort mean value was 4.2 and operator comfort 4.6. In the benign bone lesions, patient and operator comfort mean values were 3 and 4, respectively. In the malignant bone lesions, patient and operator comfort were 4.7 and 4.8, respectively. A statistically significant difference (p.01) was found in patient comfort between benign and malignant lesions (mean value 3 vs 4.7).

Ninety-four patients underwent LA. They included 53 benign and 41 malignant bone lesions. In all cases, patient and operator comfort was 5/5.

All data are summarized on Table 1. No intra- and post-procedural complications were observed.

Table 1.

Results based on anaesthetic approaches

Anaesthetic Approaches	Number of Patients	Benign/Malignant Lesions	Ablation Techniques	Technical Success (%)	Patient Comfort (mean value)	Operator Comfort (mean value)
General Anaesthesia (GA)	3	3 (B)	1 RFA 2 HIFU	100 %	5	4.3
		0 (M)			–	–
Sedation/ Analgesia (IVA)	21	6 (B)	2 HIFU 4 RFA	100 %	3	4
		15 (M)	2 CRIO 4 MWA 9 RFA		4.7	4.8
Loco-regional Anaesthesia (LA)	94	53 (B)	3 CRIO 21 HIFU 29 RFA	100 %	5	5
		41 (M)	25 CRIO 6 MWA 10 RFA		5	5

B, Benign lesion; CRIO, Crioablation; HIFU, High-intensity-focused-ultrasound; M, Malignant lesion; MWA, Microwave ablation; RFA, Radiofrequency ablation.

Scores of Patient Comfort and Operator Comfort are based on a 1–5 (min-max) scale.

Discussion

Due to the increase in the number and complexity of the IR procedures, a safe and effective anaesthetic management of patients is necessary not only to ensure adequate pain and anxiety control, but also to prevent procedural problems caused by operator discomfort.

The anaesthesiological approach can be of three different types: sedation, analgesia and local anaesthesia. Sedation is the administration of drugs that calm the nervous system. Anxiety potentiates the perception of pain. Sedated patients are more likely to remain immobile, thus allowing a faster and safer procedure. Four levels of sedation can be identified: minimal, moderate, deep sedation and general anaesthesia. ⁶ The most commonly used sedatives are benzodiazepines (Midazolam or Diazepam) ⁷ and Propofol. ⁸ Analgesia is the symptomatic relief of pain with use of pharmacological agents. Pain signals are received, but medication prevents their perception. The most used drugs are opioids such as Morphine, Fentanyl, Sufentanil and Remifentanil. Finally, local anaesthetics reversibly depress impulse transmission in nerves with subsequent anaesthesia and motor block of a specific area. Sufficient infiltration with local anaesthesia may markedly reduce sedation and analgesic requirements but does not entirely obviate these medications in most situations. ^9,10 The infiltration can last from 1 to 2 to several hours, depending on type and doses. Sedation, analgesia and local anaesthesia can be used alone or in concert, depending on the clinical conditions of the patient.

Moreover, depending from the type of procedures, not all the three aspects are required to be obtained simultaneously or are always necessarily useful: for istance, the skin sensibility of the limbs is very useful during ablation procedure of vertebral bone to avoid damages of the spine. On the other hand, in the patient submitted to spinal anesthesia (usually effective for pain due to procedure in the inferior limbs), because anxious, a mild sedation could be useful to better finalize the procedure.

The type of anaesthesiological approach used is chosen on the basis of various radiological as well as anaesthesiological parameters.

Lesion localization. For lesions localized in the low spine (below D12), pelvis and upper or lower extremities, we prefer loco-regional anaesthesia (through spinal anaesthesia or brachial plexus block). Lesions localized in the cervical and thoracic spine or in the chest wall require sedation/analgesia. General anaesthesia is limited to particular cases, like paediatric patients, who do not collaborate during treatment.

Clinical conditions of the patient. Patients with chronic obstructive pulmonary disease are at substantial risk of respiratory adverse events resulting from the administration of sedation and analgesia. These patients already have a blunted ventilatory response to CO₂, and excessive sedatives and opioids will further compromise this response, predisposing them to severe respiratory depression. In patients with coronary artery disease, inadequate sedation can increase the risk of acute cardiac events as a result of increased cardiac demand. Similarly, excessive sedation or respiratory suppression can also precipitate cardiac complications. Sedated obese patients are at increased risk of gastroesophageal reflux, upper airway obstruction and over sedation. ^11,12 Obese patients are more susceptible to respiratory depressant effects of sedative agents, and drug doses should be computed on an estimated mean body mass not total body mass. In elderly patients, sedatives and analgesics elicit a longer lasting and more pronounced effect because of changes in bioavailability and reduction in drug metabolism. ¹³ Other factors to be considered are paediatric population, ¹⁴ chronic renal failure, drug-dependency, allergies to drugs, etc.

In our experience, general anaesthesia, even although rarely used, ensures adequate intra procedural pain control and optimal patient comfort (5/5). However, it is associated to low operator comfort (mean value, 4.3) owing to the increase in procedural times, and to the presence, in the interventional suite, of dedicated anaesthesiological equipment. The latter has to be MRI compatible if the procedure is performed within the MRI suite. Another limitation is represented by the positioning of the patient on the operative table (usually supine). Moreover, IR procedures are performed outside the operating room (NORA procedure), which is different from being in a surgical room equipped for the management of possible complications. In agreement with the anaesthesiologists, therefore, the use of GA is limited to paediatric patients alone, due to their inability to collaborate.

Loco-regional anaesthesia ensures optimal intra procedural pain control (patient comfort 5/5 in all treated cases). Absence of pain reduces patient anxiety and help them maintain the right position throughout the procedure. Moreover, the dedicated anaesthesiological equipment present in the IR suite is limited to a few devices. All these aspects result in optimal operator comfort (5/5 in all cases) with reduced procedural time and good outcome. In addition, loco-regional anaesthesia is associated to low rates of intra procedural complication risks.

Sedation/analgesia, even when associated with a local anaesthesia, is less effective in ensuring adequate pain management than general anaesthesia and loco-regional anaesthesia [mean values, 4.2 (SD = 0.98) vs 5 (SD = 0); p.01] and this causes reduced patient comfort, which is more evident during treatment of benign bone lesions that require stronger pain control than malignant ones [mean values, 3 (SD = 0.84) vs 4.7 (SD = 0.48); p.01]. Lower operator comfort, due to patient movements, may determine the loss of reference points with an increase in procedural times and problems to the operator's discomfort. Moreover, due to the possible onset of respiratory complications, the position of the CT or MRI tables is fixed. However, when operating in the cervical or dorsal spine, sedation/analgesia remains the best anaesthetical approach due to the good risk/benefit ratio. An additional local anaesthesia around the target lesion may be of help and should be performed especially in the treatment of benign lesions.

Significant differences in operator and patient comfort between the treatment of benign and malignant lesions were observed. They are probably due to the nature of the lesions themselves: owing to the inflammatory content, in fact, benign lesions like osteoid osteoma or osteoblastoma provoke intra-procedural pain thus demanding the use of more effective analgesic drugs. Conversely, in malignant lesions, the pathological tissue almost completely disrupts the sensitive nervous terminations, and the doses of necessary analgesic drugs are minor. However, a significant statistically difference in comfort operator was not found between benign and malignant lesions [IVA: 4 (benign lesions, SD = 1.26) vs 4.8 (malignant lesions, SD = 0.41); p.196; LA not differences: 5 vs 5].

There are, nevertheless, some limitations in this study. The overall number of procedures analized is limited, but in particular, there is an inhomogeneity in the ratio among the three types of anaesthesiological approach (3 GA, 21 sedations and 94 LA). This disproportion may affect the analytical process, but it reflects a real and everyday interventional setting and can be easily explained as follows: GA is rarely used for the reasons mentioned above, while LA, bringing low risks, is preferred by the anaesthesiologists over the other two techniques. Another limit is the lack of a specific analysis of the procedures performed with every single technique of ablation (RFA, MW, etc.). The authors consider this analysis too detailed, specific and beyond the aim of the study. Moreover, the authors believe that it is possible to overcome the differences among the techniques (cryoablation is considered less painful during the procedure than MWA or RFA) by choosing an appropriate and well performed anaesthesiological approach.

Conclusion

Despite the aboved-mentioned limitations, our experience shows that the loco-regional anaesthesia is probably the best approach for bone ablation procedures because it ensures optimal patient and operator comfort without significant contraindications: Figure 3 summarizes a possible algorithm in order to choose the more appropriate anaesthesiological approach. It is however good to keep in mind that in the treatment of benign lesions, stronger anaesthesiological approach is required than in malignant ones, because the first are more painful owing to the presence of inflammation. In conclusion, we believe that a close collaboration between interventional radiologists and anaesthesiologists is the key factor for the success of ablation procedures.

Figure 3.

Proposal of an algorithm for choosing of the most appropriate anesthesiological approach in bone ablation procedures