Table 2.

Main results of pain outcomes from included trials of cryoanalgesia for postoperative pain.

Author, year	Procedure	Comparator	Pain outcome measures	Pain measured at rest, with movement, or not specified?	Follow-up time	Pain outcomes (s)
Brichon [33], 1994	Thoracotomy	TE, OA, NOA (Group B)	VAS	Not specified	Days 1–12	Patients in the epidural group had better pain relief than the cryoanalgesia group on POD 1 and 2.
Ju [36], 2008	Thoracotomy	TE, OA	NRS, chronic pain incidence	Rest and movement	Days 1–3, Months 1, 3, 6, 12	No significant difference for acute pain. Fewer patients in the epidural group reported moderate or severe chronic pain on POM 6.
Yang [41], 2004	Thoracotomy	TE, OA, NOA	VAS, NRS, chronic pain incidence	Rest and movement	Days 1–7, Months 1, 3, 6	Patients who received cryoanalgesia with epidural had less pain on movement than epidural alone on POD 7. Incidence and severity of post-thoracotomy chronic pain at POM3 was worse at rest in the cryoanalgesia and epidural group than in the epidural alone group.
			Frequency of morphine consumption	N/A	Days 1–7	Patients who received cryoanalgesia with epidural used less analgesic than epidural alone on POD 7.
Mustola [42], 2011	Thoracotomy	TE, OA, NOA	VAS, VPS	Rest and movement	Days 1–7, Months 1, 2, 6	Patients who received cryoanalgesia with epidural had more pain at rest than epidural alone at 12 h, POD 2, and POM 2.
			Frequency of epidural bolus; Oxycodone requirements	N/A	Days 1–3	No significant difference
Momenzadeh [25], 2011	Thoracotomy	OA	VAS	Not specified	Days 1–7	Patients who received cryoanalgesia had significantly less pain than the control group on POD 1–7.
			Pethidine consumption	N/A	Days 1–7	Mean pethidine consumption was significantly higher in the control group than the cryoanalgesia group on POD 1. Patients in the control group used pethidine until POD 7, whereas patients in the cryoanalgesia group stopped on POD 4.
Ma [29], 2009	Thoracotomy	OA	VAS	Not specified	Days 1, 3, 5, 9, Months 1–3, 6	Compared with the control group, pain scores in the cryoanalgesia group were significantly lower at days 1, 3, 5, 9, and 30.
			Pethidine consumption	N/A	Days 1, 3, 5, 9	Patients in the cryoanalgesia use used significantly less pethidine at all time points.
Katz [37], 1980	Thoracotomy	INB, OA	NRS	Not specified	Days 1, 3, 5	At all points in follow up, the cryoanalgesia group had significantly less pain than the comparator group.
			Morphine consumption	N/A	Day 1	Compared with cryoanalgesia, comparator patients required significantly more morphine on POD 1
Keenan [32], 1983	Thoracotomy	OA (Group 4)	VAS	Rest and movement	Days 1, 2	Cryoanalgesia reduced pain significantly, compared with comparator at rest and on movement. Combining cryoanalgesia with indomethacin appeared to have an additive effect.
			Papaveretum consumption	N/A	Day 1	The combination of indomethacin and cryoanalgesia significantly reduced the need for opioid analgesia compared with comparator.
Muller [30], 1989	Thoracotomy	OA,/NOA	Non-standard pain scale (0–4)	Not specified	Days 1–3, 5, 7	No significant difference.
			Methadone consumption	N/A	Days 1–3, 5, 7	No significant difference.
Miguel [35], 1993	Thoracotomy	OA (Group 4)	VAS, chronic pain incidence	Not specified	Days 1, 2, 5, Month 12	Patients receiving epidural morphine had significantly lower pain scores than patients receiving cryoanalgesia on POD 0. Patients receiving cryoanalgesia had significantly less incidence of post-thoracotomy pain syndrome at POM 3.
			Morphine consumption	N/A	Days 1, 2, 5	No significant difference.
Moorjani [27], 2001	Thoracotomy	OA	VAS	Not specified	Days 1–7, 10, 20, Month 1	Patients receiving cryoanalgesia had significantly less pain on POD 1–7.
			Pethidine consumption	N/A	Days 1–7	Patients receiving cryoanalgesia used significantly less pethidine on POD 1–6 than patients receiving conventional analgesia.
Joucken [38], 1987	Thoracotomy	INB, OA (Group 2)	Frequency of piritramide consumption	N/A	Hours 1-36	Patients in the cryoanalgesia group used significantly fewer narcotic injections compared to control and intercostal block groups.
Ba [23], 2014	Thoracotomy	NOA	VAS	Not specified	Days 1–3, 7 Months 1, 6	Patients receiving cryoanalgesia had significantly less pain than patients receiving parecoxib on POD 1–3, 7 and POM 1.
Pastor [31], 1996	Thoracotomy	OA, NOA	Non-standard pain scale (0–5)	Not specified	Days 1–7	Patients receiving cryoanalgesia had significantly less pain on POD 1–7.
			Frequency of aminopyrine consumption	N/A	Days 1–7	Patients receiving cryoanalgesia used significantly less major analgesia on POD 1–7 than comparator.
Roberts [39], 1988	Thoracotomy	INB, OA	VAS (0–12)	Not specified	Days 1–3	Patients receiving cryoanalgesia had significantly less pain on POD 1–3 than patients receiving bupivacaine block.
			Pethidine consumption	N/A	Days 1–3	Patients receiving cryoanalgesia used significantly less pethidine on POD 1–3 than patients receiving bupivacaine block.
Roxburgh [34], 1987	Thoracotomy	LE, OA, NOA	VPS	Not specified	Days 1–14	No significant difference.
			OA/NOA consumption	N/A	Days 1–14	No significant difference.
Gwak [26], 2004	Thoracotomy	OA	VAS, chronic pain incidence	Rest and movement	Days 1–7	No significant difference.
			Fentanyl consumption	N/A	Days 1–7	No significant difference.
Sepsas [28], 2013	Thoracotomy	OA, NOA	VPS	Rest and coughing	Days 1–7, Week 2, Months 1, 2	Patients receiving cryoanalgesia had significantly less pain at rest at all timepoints, compared to comparator. . .
			Morphine consumption; OA/NOA frequency of consumption	N/A	Days 1–7, Week 2, Months 1, 2	Patients receiving cryoanalgesia used significantly less morphine at all timepoints, compared to comparator (Data reported in 6-h intervals).
Lu [24], 2013	Esophagectomy with thoracotomy	NDMIF, OA, NOA	VAS	Not specified	Days 1–7, Months 1, 3, 6, 9, 12	Patients receiving cryoanalgesia had significantly more pain at POM 6, 9, 12 than patients receiving NDIMF. .
			Incidence of OA/NOA consumption	N/A	Days 1–7, Months 1, 3, 6, 9, 12	Patients receiving cryoanalgesia used significantly more likely to be using oral pain medication at POM 6, 9, 12 than patients receiving NDIMF. .
Callesen [19], 1998	Herniorrhaphy	OA, NOA	Non-standard pain scale (0–3)	Rest and movement	Days 1–7, Months 1, 2	No significant difference.
			Acetaminophen consumption	N/A	Days 1–7	No significant difference.
Khiroya [20], 1986	Herniorrhaphy	OA, NOA	VAS	Rest	Days 1, 2, Month 3	No significant difference.
			Pethidine consumption; Distalgesic consumption	N/A	–	No significant difference.
Ahmadnia [21], 2010	Nephrectomy	OA	Morphine consumption	N/A	Days 1, 2	No significant difference.
Robinson [22], 2000	Tonsillectomy	OA, NOA	VAS	Not specified	Days 1–10	Over the duration of follow up, patients receiving cryoanalgesia had significantly less pain than comparator group. .
			OA/NOA consumption	N/A	Month 1	No significant difference.
Graves [40], 2019	Nuss Procedure	TE, OA, NOA	VAS	Not specified	Days 1, 3, 5, Week 2, Months 1, 3, 12	No significant difference.
			OA consumption (oral morphine equivalents)	N/A	Days 1–3	Patients who received cryoanalgesia used significantly less opioids throughout the postoperative stay than patients receiving epidural.

VAS: Visual analog scale; NRS: Numeric rating scale; VPS: Verbal pain scale; NDIMF: Non-divided intercostal muscle flap; POD: Post-operative day; POM: Post-operative month; IC: Intercostal; OA: Opioid analgesia; NOA: Non-Opioid analgesia; TE: Thoracic epidural; INB: Intercostal nerve block; LE: Lumbar Epidural; NDIMF: Non-divided intercostal muscle flap.