Subpectoral implantation of a cardioverter defibrillator under local anaesthesia

Issues and challenges associated with nurse-administered procedural sedation and analgesia in the cardiac catheterisation laboratory: a qualitative study

AIMS AND OBJECTIVES

To explore issues and challenges associated with nurse-administered procedural sedation and analgesia in the cardiac catheterisation laboratory from the perspectives of senior nurses.

BACKGROUND

Nurses play an important part in managing sedation because the prescription is usually given verbally directly from the cardiologist who is performing the procedure and typically, an anaesthetist is not present.

DESIGN

A qualitative exploratory design was employed.

METHODS

Semi-structured interviews with 23 nurses from 16 cardiac catheterisation laboratories across four states in Australia and also New Zealand were conducted. Data analysis followed the guide developed by Braun and Clark to identify the main themes.

RESULTS

Major themes emerged from analysis regarding the lack of access to anaesthetists, the limitations of sedative medications, the barriers to effective patient monitoring and the impact that the increasing complexity of procedures has on patients' sedation requirements.

CONCLUSIONS

The most critical issue identified in this study is that current guidelines, which are meant to apply regardless of the clinical setting, are not practical for the cardiac catheterisation laboratory due to a lack of access to anaesthetists. Furthermore, this study has demonstrated that nurses hold concerns about the legitimacy of their practice in situations when they are required to perform tasks outside of clinical practice guidelines. To address nurses' concerns, it is proposed that new guidelines could be developed, which address the unique circumstances in which sedation is used in the cardiac catheterisation laboratory.

RELEVANCE TO CLINICAL PRACTICE

Nurses need to possess advanced knowledge and skills in monitoring for the adverse effects of sedation. Several challenges impact on nurses' ability to monitor patients during procedural sedation and analgesia. Preprocedural patient education about what to expect from sedation is essential.

Nurse-administered procedural sedation and analgesia in the cardiac catheter laboratory: an integrative review

OBJECTIVES

To identify and appraise the literature concerning nurse-administered procedural sedation and analgesia in the cardiac catheter laboratory.

DESIGN AND DATA SOURCES

An integrative review method was chosen for this study. MEDLINE and CINAHL databases as well as The Cochrane Database of Systematic Reviews and the Joanna Briggs Institute were searched. Nineteen research articles and three clinical guidelines were identified.

RESULTS

The authors of each study reported nurse-administered sedation in the CCL is safe due to the low incidence of complications. However, a higher percentage of deeply sedated patients were reported to experience complications than moderately sedated patients. To confound this issue, one clinical guideline permits deep sedation without an anaesthetist present, while others recommend against it. All clinical guidelines recommend nurses are educated about sedation concepts. Other findings focus on pain and discomfort and the cost-savings of nurse-administered sedation, which are associated with forgoing anaesthetic services.

CONCLUSIONS

Practice is varied due to limitations in the evidence and inconsistent clinical practice guidelines. Therefore, recommendations for research and practice have been made. Research topics include determining how and in which circumstances capnography can be used in the CCL, discerning the economic impact of sedation-related complications and developing a set of objectives for nursing education about sedation. For practice, if deep sedation is administered without an anaesthetist present, it is essential nurses are adequately trained and have access to vital equipment such as capnography to monitor ventilation because deeply sedated patients are more likely to experience complications related to sedation. These initiatives will go some way to ensuring patients receiving nurse-administered procedural sedation and analgesia for a procedure in the cardiac catheter laboratory are cared for using consistent, safe and evidence-based practices.

Safety and Acceptability of Implantation of Internal Cardioverter-Defibrillators Under Local Anesthetic and Conscious Sedation

BACKGROUND

Implantation and testing of implantable defibrillators (ICDs) using local anesthetic and conscious sedation is widely practiced; however, some centers still use general anesthesia. We assessed safety and patient acceptability for implantation of defibrillators using local anesthetic and conscious sedation.

METHODS

The records of 500 consecutive device implants from two UK cardiac centers implanted under local anesthetic and conscious sedation from January 1996 to December 2004 were reviewed. Procedure time, left ventricular ejection fraction (LVEF) sedative dosage (midazolam), analgesic dosage (fentanyl or diamorphine), requirement for drug reversal, and respiratory support were recorded. Patient acceptability of the procedure was also assessed.

RESULTS

Of 500 implants examined, 387 were ICDs, 88 were biventricular ICDs, and 25 were generator changes. Patients with biventricular-ICDs had significantly longer (mean +/- SD) procedure times 129.7 +/- 7.6 minutes versus 63.3 +/- 32.3 minutes; P < 0.0001 and lower LVEF 24.4 +/- 8.4% versus 35.7 +/- 15.4%; P < 0.0001. There were no differences in the doses (mean +/- SD) of midazolam 8.9 +/- 3.5 mg versus 8.0 +/- 3.1 mg; P = NS, diamorphine 4.3 +/- 2.0 mg versus 3.8 +/- 1.7 mg; P = NS or fentanyl 94.4 +/- 53.7 mcg versus 92.2 +/- 48.6 mcg; P = NS, between the two groups. There were no deaths or tracheal intubations in either group. Acceptability was available for 373 of 500 (75%) patients, 41 of 373 (11%) described "discomfort," but from these 41 patients only 14 of 373 (3.8%) declined a second procedure under the same conditions.

CONCLUSIONS

Implantation of defibrillators under local anesthetic and sedation is safe and acceptable to patients. General anesthesia is no longer routinely required for implantation of defibrillators.

The dilemma of ICD implant testing

Ventricular fibrillation (VF) has been induced at implantable cardioverter defibrillator (ICD) implant to ensure reliable sensing, detection, and defibrillation. Despite its risks, the value was self-evident for early ICDs: failure of defibrillation was common, recipients had a high risk of ventricular tachycardia (VT) or VF, and the only therapy for rapid VT or VF was a shock. Today, failure of defibrillation is rare, the risk of VT/VF is lower in some recipients, antitachycardia pacing is applied for fast VT, and vulnerability testing permits assessment of defibrillation efficacy without inducing VF in most patients. This review reappraises ICD implant testing. At implant, defibrillation success is influenced by both predictable and unpredictable factors, including those related to the patient, ICD system, drugs, and complications. For left pectoral implants of high-output ICDs, the probability of passing a 10 J safety margin is approximately 95%, the probability that a maximum output shock will defibrillate is approximately 99%, and the incidence of system revision based on testing is < or = 5%. Bayes' Theorem predicts that implant testing identifies < or = 50% of patients at high risk for unsuccessful defibrillation. Most patients who fail implant criteria have false negative tests and may undergo unnecessary revision of their ICD systems. The first-shock success rate for spontaneous VT/VF ranges from 83% to 93%, lower than that for induced VF. Thus, shocks for spontaneous VT/VF fail for reasons that are not evaluated at implant. Whether system revision based on implant testing improves this success rate is unknown. The risks of implant testing include those related to VF and those related to shocks alone. The former may be due to circulatory arrest alone or the combination of circulatory arrest and shocks. Vulnerability testing reduces risks related to VF, but not those related to shocks. Mortality from implant testing probably is 0.1-0.2%. Overall, VF should be induced to assess sensing in approximately 5% of ICD recipients. Defibrillation or vulnerability testing is indicated in 20-40% of recipients who can be identified as having a higher-than-usual probability of an inadequate defibrillation safety margin based on patient-specific factors. However, implant testing is too risky in approximately 5% of recipients and may not be worth the risks in 10-30%. In 25-50% of ICD recipients, testing cannot be identified as either critical or contraindicated.

Can we implant cardioverter defibrillator under minimal sedation?

Aim In a prospective study, we tested the feasibility of implantable cardioverter-defibrillator (ICD) implantation under local anaesthesia (LA) with minimal sedation (MS) vs. short general anaesthesia (SGA) for defibrillation test (DT).

METHODS AND RESULTS

We implanted ICDs in 118 patients between October 2002 and November 2003. Surgery was performed under LA with MS. Depending on the day of admission, patients had DT without SGA with a shock delivered when patient is unconscious (MS group, n = 73) or with short general anaesthesia (SGA group, n = 45). The patients were asked to rate the intensity of pain on a 10-point visual analogue scale (VAS) at the end of the implantation procedure and for the patient of MS group just after DT (VAS-DT). Visual analogue scale was not influenced by the type of anaesthesia (MS vs. SGA). Univariate analysis showed that NYHA >III, 3 leads implanted and an incomplete understanding of the explanation on the procedure were risk factors of VAS >4. Only understanding of the explanation on the procedure has an influence on pain in multivariate analysis.

CONCLUSION

ICD implantation under MS even for DT is feasible and acceptable for the patient.

Nitrous Oxide Sedation Reduces Discomfort Caused by Atrial Defibrillation Shocks

An implantable cardioverter defibrillator with atrial therapies (ICD-ATs) is an effective therapy to manage atrial tacharrhythmias. Acceptance of this therapy is limited by atrial shock related anxiety and discomfort. Inhaled nitrous oxide (N2O) is a potent sedative-analgesic-anxiolytic agent that may mitigate shock discomfort and anxiety and improve patient ICD-AT acceptance. ICD-AT patients with more than one ambulatory atrial shock within 12 months were enrolled and grouped by ICD-AT shock method; awake (n = 9) or asleep (n = 4) when ambulatory ICD-AT shock is delivered. A baseline questionnaire assessed the most recent ambulatory ICD-AT shock (3 +/- 3 months). A 65% N2O/35% O2 mixture was inhaled for 4 minutes followed by an ICD-AT test shock (18 +/- 8 J). The test shock mimicked the awake shock method. The test shock experience during N2O was evaluated via questionnaire immediately following and 24 hours after the shock. Shock related anxiety, intensity, pain, and discomfort were assessed using a ten-point rank scale. Baseline test shock scores were similar between the shock method groups. In the awake shock method group, N2O greatly reduced preshock anxiety by 48% (6.4 +/- 2.4 to 3.3 +/- 2.0, or), and shock related intensity (5.9 +/- 3.1 to 3.3 +/- 2.5), pain (5.0 +/- 2.6 to 2.0 +/- 2.1), and discomfort (5.6 +/- 2.4 to 1.3 +/- 1.4) from baseline values by 45%, 60%, and 78% (P < 0.05), respectively. The asleep shock method group reported no changes in shock related anxiety, intensity, pain, or discomfort. Atrial shock concern, assessed via a five-point rank scale (5 = extreme concern) was improved by N2O but only in the awake group (3.1 +/- 1.0 baseline to 1.6 +/- 0.5 N2O, P = 0.008). There were no adverse events with N2O and patients fully recovered within 5 minutes after N2O. In conclusion, 65% N2O greatly reduced shock related pain and discomfort, and significantly reduced atrial shock concern but only in the awake shock method group. The benefits of N2O therapy may expand the use and acceptability of ICD-AT therapy into a larger atrial fibrillation cohort.

Halothane, isoflurane, and fentanyl increase the minimally effective defibrillation threshold of an implantable cardioverter defibrillator: first report in humans

Placing an implantable cardioverter defibrillator (ICD) involves the induction of ventricular fibrillation, whereupon the minimally effective defibrillation energy threshold (DFT) is determined. We evaluated the effects of 0.7% halothane, 1% isoflurane, or 1.5 micro g/kg of IV fentanyl during N(2)O/oxygen-based general anesthesia (GA) or those of subcutaneous 1.5% lidocaine plus IV 0.35 mg/kg of propofol on the DFT during ICD implantation in humans (n = 20 per group). Thirty minutes after the first set of DFT measurements under such conditions, the inhaled anesthetics were withdrawn, and all three GA groups received fentanyl 1 microg/kg IV (second set). A third set was taken 30 min later, before the GA patients awakened and when only N(2)O/oxygen was delivered for GA. The lidocaine plus propofol patients were given the same IV propofol bolus 1 min before each fibrillation/defibrillation trial and at the same time points as the three GA groups. The first DFTs were 16.1 +/- 2.2 J (halothane), 17.7 +/- 2.7 J (isoflurane), 16.4 +/- 2.9 J (fentanyl), and 12.9 +/- 3.8 J (lidocaine plus propofol) (P = 0.01). The second set of DFTs were significantly lower than the first sets for the halothane (P = 0.01) and isoflurane (P = 0.02), but not the fentanyl or lidocaine plus propofol, regimens. The third DFTs were significantly (P < 0.01) lower than the first ones for the three GA groups, but not for the lidocaine plus propofol patients. Thus, halothane, isoflurane, and fentanyl increased DFT values during ICD implantation in humans, whereas lidocaine plus intermittent small-dose IV propofol minimized these thresholds.

IMPLICATIONS

Halothane, isoflurane, and IV fentanyl added to N(2)O/oxygen-based general anesthesia similarly increase minimal defibrillation threshold energy requirements (DFT) during cardioverter defibrillator implantation in humans. Subcutaneous lidocaine plus intermittent small-dose IV propofol minimizes DFT compared with these general anesthetics while providing equal patient satisfaction.

Effect of general anesthesia on the defibrillation energy requirement in patients undergoing defibrillator implantation

BACKGROUND

The effect of general anesthesia on defibrillation efficacy in humans is not known. The purpose of this study was to determine the effect of general anesthesia on the defibrillation energy requirements in patients undergoing implantation of a pectoral defibrillator.

METHODS AND RESULTS

Nineteen consecutive patients who underwent defibrillator implantation under general anesthesia were prospectively compared to 16 consecutive patients who underwent defibrillator implantation by the same physicians, using similar devices, at another hospital under conscious sedation. Pre-discharge testing was performed 1.4 +/- 1.0 days after implant using sedation in both groups. The defibrillation energy requirement was determined using the same predefined step-down protocol (15, 10, 8, 5, 3, 1 J) at the time of implantation and during pre-discharge testing. The clinical characteristics of the patients were similar between groups. There was no significant difference in the mean implant defibrillation energy requirement compared to the mean pre-discharge defibrillation energy requirement in either the general anesthesia group (8.5 +/- 4.7 vs. 8.4 +/- 3.4 J; p = 0.9) or in the conscious sedation group (9.4 +/- 3.9 vs. 9.0 +/- 3.8 J; p = 0.7).

CONCLUSIONS

When compared to conscious sedation, general anesthesia with mechanical ventilation has no significant effect on defibrillation efficacy in patients undergoing defibrillator implantation.

Who needs an implantable defibrillator?

Ventricular arrhythmias account for 80% of sudden cardiac deaths. The implantable defibrillator (ICD) is an effective means of preventing these deaths. This article discusses which patients may benefit from ICD implantation and addresses the cost-effectiveness of their use.