Table 1.

Characteristics of the included studies.

Author (Year)	Design	Setting; Country	Patients	Event and cause	Intervention	Results
Al Harbi et al. (2020) [12]	Case report	Operating room (Posterior spinal fusion with laminectomy); Saudi Arabia	80 years old male patient at intermediate cardiac risk	Two episodes of PEA at about 6 h from anesthesia induction. The latter in supine position. Cause: massive pulmonary embolism	First episode: CPR in prone position Second episode: CPR in supine position	First episode: ROSC, supination and second episode of cardiac arrest; Second episode: ROSC and ICU admission
Mishra et al. (2019) [13]	Case report	Operating room (Laminectomy and excision of a C2–C3 intradural extra-medullary meningioma); India	35 years old female patient	Intraoperative cardiac arrest, due to cardiac tamponade	1 min prone position CPR, followed by supination and standard CPR	ROSC, ICU admission with pericardial catheterism and negative suction; extubation at day 3
Mayorga-Buiza et al. (2018) [14]	Case report	Operating room (Excision of a large tumour in the posterior fossa); Spain	10 years old patient	Pulseless VT, then VF during mobilization and resection of the tumour	CPR in prone position	ROSC followed by spinal hematoma, then surgically drained. Survived without sequelae at 24 months
Burki et al. (2017) [15]	Case report	Operating room (Fourth ventricle tumour excision); Pakistan	6 years old female patient	Intraoperative cardiac arrest, due to massive bleeding (estimated blood loss 2 l)	CPR in prone position	ROSC and ICU admission. Death at day 5 after surgery
Kaloria et al. (2017) [16]	Case report	Operating room (Tethered cord release and removal of bony spur); India	1 year old girl	Electromechanical dissociation, possibly due to venous air embolism	CPR in prone position	ROSC, surgery completion, discharge at day 6
Lee-Archer and Chaseling (2017) [17]	Case report	Operating room (Posterior spinal fusion C5 to L4, for severe kyphoscoliosis); Australia	10 years old girl	Cardiac arrest during attempts to locate the epidural space with a loss of resistance air technique, possibly due to air embolism	Supination and standard CPR	ROSC, completion of surgery at day 4, right-sided brain infarction and left upper limb weakness, recovered after two weeks
Pinheiro et al. (2017) [18]	Case report	Operating room (Esthetic lipoplasty)	25 years old female patient	Asystole	Supination and standard CPR	ROSC, surgery cancelled, ICU admission, discharge
Taylor et al. (2013) [19]	Case report	Operating room (Craniotomy for metastatic melanoma); New Zeland	69 years old male patient with hypertrophic cardiomyopathy and impaired (34%) ejection fraction	Pulseless VT, then VF.	CPR in prone position	ROSC. Discharged home in stable neurological condition
De Souza Gomez et al. (2012) [20]	Case report	Operating room (Excision of highly vascularized parietal-occipital meningioma on the right side); Brazil	77 years old female patient	Cardiac arrest, due to rupture of sagittal sinus and subsequent hemorrhagic shock	CPR in prone position	ROSC, ICU admission, discharge at day 3
Pan et al. (2012) [22]	Case report	Endoscopic room (ERCP)	61 years old female patient	Intraprocedural cardiac arrest, due to venous air embolism	Supination and standard CPR	Death
Dooney (2010) [21]	Case report	Operating room (L4-L5 microscopic discectomy); South Australia	43 years old male patient	Asystole	CPR in prone position	ROSC
Dumont et al. (2010) [23]	Case report	Operating room (Arthrodesis for atlantoaxial instability)	38 years old male patient	Asystole, due to air embolism	Supination and standard CPR	ROSC, surgery completion, ICU admission and discharge without sequelae
Haffner et al. (2010) [24]	Case report	Operating room (Emergency craniotomy for cerebellar hemorrhage)	81 years old	Intraoperative cardiac arrest, possibly due to right heart failure	Prone CPR	ROSC; ICU admission; death at day 28
Almazan et al. (2009) (personal communication reported by Brock-Utne in “Case Studies of Near Misses in Clinical Anesthesia”) [25]	Case report	Operating room (Open reduction internal fixation for multiple pelvic fractures); NA	28 years old male patient	PEA due to pulmonary embolism	CPR in prone position	ROSC, ICU admission; surgery completion three days later; discharged from the hospital with intact neurological status
Beltran and Mashour (2007) [26]	Case report	Operating room (Skullbase craniotomy for tumour debulking); USA	21 years old female patient with neurofibromatosis type 2	PEA due to sigmoid sinus disruption, leading to significant blood loss	Supination and standard CPR	Intraoperative death
Wei et al. (2006) [9]	Single-centre nonrandomized study	ICU/healthy volunteers; Taiwan	a. 11 patients who had died in ICU b. 10 alive and healthy volunteers	a. Death b. None	a. One minute precordial cardiac massage followed by one minute thoracic massage in prone position; b. Back thoracic compressions with spontaneous breathing held and nose clipped	a. Mean blood pressure (invasively monitored) achieved with standard precordial compressions was 55 ± 20 / 13 ± 7 vs. 79 ± 20 / 17 ± 10 in prone position compression. b. Mean tidal volume with back thoracic compression was 399 ± 110 ml
Smelt (2005) [27]	Case report	Operating room (Scoliosis correction); The Netherlands	16 years old male patient with Duchenne muscular dystrophy and cardiomyopathy with EF 25%	VT, then pulseless VF	Supination and standard CPR	ROSC, ICU admission, discharge at day 10
Mazer et al. (2003) [10]	Single-centre nonrandomized study	ICU; USA	6 patients with cardiac arrest, enrolled after failed standard CPR	4 PEA; 1 pulseless VF; 1 pulseless VT	30 min of prone position CPR after standard CPR failure declared	Systolic blood pressure mean improvement 23 ± 14 mmHg from standard to reverse CPR; calculated MAP mean improvement of 14 ± 11 mmHg from standard to reverse CPR; diastolic blood pressure mean improvement of 10 ± 12 mmHg from standard to reverse CPR
Chen et al. (2002) [28]	Case report	Operating room (L2 and L4 percutaneous vertebroplasty); Taiwan	75 years old female patient with minor diastolic dysfunction and pulmonary hypertension	PEA, possibly due to pulmonary embolism	Supination and standard CPR	Intraoperative death
Miranda and Newton (2001) [29]	Case report	Operating room (Palliative debulking of metastatic tumour at T3 and internal fixation of the thoracic spine); UK	39 years old female patient	Intraoperative pulseless VF, possibly due to altered potassium levels	Sharp thump in prone position, followed by CPR	ROSC, completion of surgery and discharge home at 1 week from the event
Brown et al. (2001) [30]	Case report	Operating room (Thoracic spine decompression surgery for an invasive tumour between T11 and L1 vertebral levels); UK	60 years old female patient	Broad complex tachycardia followed by VT. Suspected cause: venous air embolism	Defibrillation in prone position	ROSC, completion of surgery, extubation on the following day, full recovery without sequelae
Atkinson (2000) [11]	Single-centre nonrandomized study	Mannequin based simulation	36 nurses trained in performing advanced life support	Simulation with prone positioned mannequin on standard examination coach, with gel-pad under the sternum	100 midline compressions	3376 registered by the skillmeter (91.8% of the total possible). 1168 (34.6%) effective, 1370 (40.6%) partially effective and 838 (24.6%) ineffective
Reid and Appleton (1999) [31]	Case report	Operating room (Spinal surgery to correct progressive scoliosis)	15 years old boy with Duchenne muscular dystrophy	Pulseless VF	Left posterior thoracotomy and direct cardiac massage, then defibrillation	ROSC, full recovery after ICU stay
Sutherland and Winter (1997) [32]	Case report	Operating room (a. T1-sacrum posterior spinal fusion with sublaminar wiring for a progressive scoliosis; b. T2-sacrum posterior spinal fusion with sublaminar wiring for a progressive scoliosis); UK	a.8 years old girl with limb girdle muscular dystrophy b.12 years old girl with athetoid cerebral palsy	a.Asystole due to massive venous air embolism b.Two episodes of asystole, possibly due to venous air embolism	CPR begun in prone position and continued in supine position	Intraoperative death
Dequin et al. (1996) [33]	Case report	ICU; France	48 years old male patient with CAP	Asystole, occurred few minutes after prone positioning	CPR in prone position	ROSC, recovery at day 7 from the event
Gueugniaud et al. (1995) [34]	Case report	Operating room (Surgical correction of a right dorsal and left lumbar scoliosis); France	15 years old boy	Intraoperative pulseless electromechanical dissociation followed by asystole, probably due to myocardial ischaemia	CPR in prone position, then supination	ROSC, surgery postponed, full recovery without neurological sequelae
Kelleher and Mackersie (1995) [35]	Case report	Operating room (Elective foramen magnum decompression); UK	6 months old achondroplastic baby with small patent foramen ovale and a left to right shunt	Multifocal ventricular ectopics, bradycardia and asystole (two episodes). Suspected cause: venous air embolism and estimated total blood loss of 1.1 l	CPR with fingers of one hand in prone position (two episodes)	ROSC, ICU admission, discharge at day 7
Tobias et al. (1994) [36]	Case report	Operating room (Spinal fusion for progressive scoliosis); USA	12 years old boy with severe spastic quadriplegia	Asystole, possibly due to large amount of blood loss	CPR in prone position	ROSC, ICU admission, uneventful postoperative course
Loewenthal et al. (1993) [37]	Case report	Operating room (Excision of a meningioma of the posterior fossa); France	53 years old female patient	Asystole, possibly due to large amount of blood loss	CPR in prone position	ROSC, ICU admission, recovery and completion of surgery during the day of the event
Sun et al. (1992) [38]	Case report	Operating room (a. posterior fossa craniotomy for intracerebral hematoma; b. emergency decompression laminectomy); Taiwan	a.14 years old girl b.34 years old male patient	a.Intraoperative pulseless idioventricular rhythm, possibly due to brain stem compression b.Pulseless VF, possibly due to tracheal tube obstruction and hypoxia	CPR in prone position	ROSC, surgery completion and uneventful recovery
Albin et al. (1991) [39]	Case report	Operating room (a. Lumbar laminectomy with fusion L3–4; b. lumbar laminectomy with fusion L5-S1); USA	a.40 years old male patient b.40 years old male patient	a.Asystole, possibly due to venous air embolism b.Cardiac arrest due to massive venous air embolism	Supination and standard CPR	Intraoperative death
Ewah and Calder (1991) [40]	Case report	Operating room (Surgical treatment of prolapsed lumbar intervertebral disc at L4–5); UK	26 years old female patient	Cardiac arrest, due to laceration of the aorta and subsequent retroperitoneal and peritoneal hemorrhage	Supination and standard CPR	Intraoperative death
Lang et al. (1989) [42]	Case report	Operating room (Posterior spinal fusion for progressive scoliosis); Canada	16 years old male patient with Duchenne muscular dystrophy	Cardiac arrest, due to venous air embolism	Supination and standard CPR	Intraoperative death
Kalenda and Greuter (1982) [41]	Case report	Operating room (excision of a cerebellar and fourth ventricle ependymoma); The Netherlands	1-year old boy	Circulatory arrest	CPR in prone position	ROSC, surgery completion and recovery

The table shows the characteristics of the included studies, as reported by the authors.

Data are reported as percentages, fractions, mean ± standard deviation or median (IQR), as appropriate.

CPR, cardiopulmonary resuscitation; EF, ejection fraction; ICU, intensive care unit; NA, not available; PEA, pulseless electric activity; ROSC, return of spontaneous circulation; UK, United Kingdom; USA, United States of America; VF, ventricular fibrillation; VT, ventricular tachycardia.