Table 2:
Summary of findings for adverse anesthesia or clinical events in iMRI suites.
| Study (author and year) | Description Magnetic Field Strength in Tesla (T) | Incidence of outcome | N (included cases) | Data quality GRADING (reason) | Critique/comments |
|---|---|---|---|---|---|
| Ahmadi 2016 | Retrospective chart review that identified anesthesia complications for patients undergoing intracranial surgery with iMRI compared to procedures without iMRI. (1.5 T) |
No adverse anesthesia event reported in either group | 1126 (516 in IMRI group, 610 controls) | VERY LOW (observational, nonrandomized, no control of confounders between cohorts) | Adverse anesthesia event not defined. Patients in this study were transferred between the OR and adjacent scan room. The authors did not report about transport problems. |
| Birkholz 2004 | Observational study of impact of electrical interference and ECG analysis. This study did not explicitly report on adverse events. (1.5 T) |
3 Arrhythmias 3 Arrhythmia-type artifacts |
19 | LOW (observational) | We considered the reported true and artifactual arrhythmias relevant clinical events: supraventricular tachycardia (n=1), supraventricular extra beats (n=2), and artifactual ventricular arrhythmia (n=1), artifactual ventricular fibrillation (n=1), artifactual atrial flutter (n=1). |
| Choudhri 2014 | Retrospective study that assessed primarily surgical difficulties for pediatric neurosurgical patients undergoing iMRI procedures. (3 T) | No adverse anesthesia event | 168 | VERY LOW (observational, no control group) | Adverse anesthesia event not defined. |
| Cox 2011 | Retrospective study that described clinical challenges and anesthesia outcomes in 98 pediatric patients undergoing 105 iMRI procedures over 10 years. These patients were transferred to a pediatric hospital close-by for postoperative care. (1.5 T) |
No adverse anesthesia event 4 clinical complications 1 safety breach not resulting in harm |
105 | VERY LOW (observational, no control group) | Adverse anesthesia event not defined. Authors reported no anesthesia event, 4 clinical events (2 postoperative seizures, 1 swollen lip, 1 inflamed ear) and 1 safety event resulting in no harm (ferromagnetic clamp left in the field during MRI scan). |
| Fomekong 2014 | Analysis of pituitary microsurgery with iMRI, primarily focused on surgical considerations. (3 T) |
4 anesthesia events: - 3 patient monitor dysfunctions, - 1 unplugged IV line, |
73 | VERY LOW (observational, no control group) | Anesthesia events were among 17 reported “technical problems” (see also later in Table 4). It is unclear if the 17 described problems occurred during 17 separate procedures, or whether one patient experienced >1 problem. |
| Fried 1998 | Case series that detailed the first endoscopic sinus surgery procedures in the iMRI suite at the author’s institution. (0.5 T) |
No adverse anesthesia event | 12 | VERY LOW (observational, no control group) | Adverse anesthesia event not defined. |
| Iturri-Clavero 2016 | Review of anesthetic considerations for intracranial iMRI procedures. Prospective study of incidents and time requirements during cases using low-field iMRI compared to controls without iMRI. (0.15 T) |
Anesthetic incidents occurred during all iMRI cases (n=109). Brachial plexus compression in all lateral and prone cases (no n provided), but no postoperative neurologic damage. |
159 (109 for iMRI, 50 control) | VERY LOW (observational, no control of confounders between cohorts, possibly incomplete reporting) | Anesthetic incident was very broadly defined and included change from routine practice (including avoidance of intubating stylet or metal-reinforced endotracheal tubes), interruption of monitoring, and interference with monitoring. The rate of incidents for the control group was not reported. |
| Kamata 2016 | Case series about critical events during awake craniotomy cases using iMRI, specifically during scan sequences in patients with an unsecured airway. (field strength not specified) |
21 critical events 90 scans with cardiovascular changes Monitoring disruptions for: - blood pressure - heart rate - pulse oximetry - respiratory rate |
580 scans (in 365 patients) | VERY LOW (observational, no control group) | Published in abstract form only. 21 critical events were observed: general convulsive seizure (n=6), respiratory arrest (n=2), nausea and vomiting (n=7), and emotional incontinence (n=9). No cardiac arrest or accidental death occurred. Cardiovascular changes of >20% deviation from pre-scan baseline occurred during 90 scans: hypertension (n=32), tachycardia (n=58), hypotension (n=26), bradycardia (n=15). Monitoring disruptions occurred for BP and HR monitoring (n=2 each), and for SpO2 monitoring (n=25). Respiratory rate monitoring was used during only 175 scans. |
| Panigrahi 2008 | Case series about anesthetic challenges and operative advantages of intracranial iMRI procedures. (1.5 T) |
2 difficult intubations 4 delayed extubations ECG artifacts “quite often” |
112 | VERY LOW (observational, no control group) | Published in abstract form only. Adverse anesthesia event was defined as difficult intubation or delayed extubation. Delayed extubation was attributed to “prolonged anesthesia and hypothermia”. |
| Panigrahi 2012 | Retrospective analysis of anesthesia implications of intracranial iMRI cases. (1.5 T) |
4 difficult intubations 4 cases of delayed emergence |
388 | VERY LOW (observational, no control group) | Published in abstract form only. Anesthesia complication was defined as difficult intubation, delayed emergence, and hypothermia. May include the 112 cases from prior abstract, but did not provide date range for the newer study. |
| Rahmatulla 2012 | Overview of safety considerations for iMRI environment and retrospective assessment of the first intracranial iMRI cases over 29 months at the author’s institution. (1.5 T) |
No adverse event | 120 | VERY LOW (observational, no control group) | Adverse event was not defined. The authors mentioned that potential safety events discovered by check lists and safety protocols were not tracked, so their incidence was unknown. |
| Schmitz 2003 | Case series about anesthesia for initial neurosurgical iMRI cases at the author’s institution. (1.5 T) |
1 case of hypothermia leading to delayed extubation | 80 | VERY LOW (observational, no control group) | Adverse anesthesia event not defined. Authors stated “no adverse event” but do report 1 case of hypothermia. |
Abbreviations: iMRI: intraoperative magnet-resonance imaging; OR: operating room; ECG: electrocardiogram; BP: blood pressure; HR: heart rate; SpO2: pulse oximetry.