Association between intraoperative hypotension and postoperative nausea and vomiting: a retrospective cohort study

Figures & data

Table 1. Patients’ characteristics.

	All	H0	H50	H60	H70
N	18,674	5,249	1,132	4,585	7,708
Age [Y]	55 (38/69)	55 (39/69)	65 (52/74)	55 (39/69)	53 (36/67)
BMI	25.0 (22.2/28.4)	26.0 (23.2/29.4)	24.5 (21.6/27.8)	24,4 (21.6/27.8)	24.8 (22.1/28.1)
ASA III/IV [%/n]	40/7536	38/1997	65/741	44,2/2028	36/2770
Female [%/n]	52/9815	45/2354	49.3/559	57.7/2650	55/4252

Data are given as numbers (median (Q1/Q3)) and/or proportion. All: All groups; H0: group without hypotension period; H: group with any hypotension period, H50, H60, H70: groups with hypotension periods following the given definitions; N: number of patients in this specific group; Age is given in years; BMI: Body-Mass-Index given in kg/m²; ASA: American Society of Anesthesiology Classification Score; Female: proportion of female patients.

Table 2. Statistical results in the different study groups after propensity score matching.

	Group
	H50 versus H0		H60 versus H0		H70 versus H0
	H50	H0	H60	H0	H70	H0
[n]	1132	1511	4585	3840	7708	4766
PONV [n]	197	167	619	399	860	451
No PONV [n]	935	1344	3966	3441	6848	4315
PONV [%]	17.4	11.0	13.5	10.4	11.2	9.4
Risk Ratio PONV detected [hypotension versus no hypotension]	1.285		1.1852		1.1236
99% CI Risk Ratio	1.102–1.498		1.0665–1.3172		1.013–1.2454
PONV detected [hypotension versus no hypotension]	p < 0.001		p < 0.001		p = 0.0027

PONV: postoperative nausea and vomiting. Data are presented as numbers [n] or percentages; H0: group without hypotension period; H50-H70: groups with a hypotension period according to the given definitions. CI: Confidence-Interval.

Table 3. Influence of PONV prophylaxis on incidence of PONV in the different groups of hypotension.

		Not-adjusted data									Adjusted data
		1–3 antiemetic drugs			One antiemetic drug			Two antiemetic drugs			1–3 antiemetic drugs
		%	n	p	%	n	p	%	n	p	%	n	p
H50 group	Prophylaxis given	7.6	a	0.380	6.1	55	0.860	3.6	29	0.128	8,1	87	0.417
	Prophylaxis not given	9.7	110		12.1	110		13.6	110		9,1	97
H60 group	Prophylaxis given	7.3	336	0.914	5.7	207	0.953	4.9	123	0.812	7.2	301	0.421
	Prophylaxis not given	6.1	283		7.8	283		9.4	283		6.7	283
H70 group	Prophylaxis given	5.7	441	0.762	4.9	331	0.216	2.5	108	0.040	5.6	416	0.912
	Prophylaxis not given	5.4	419		6.7	419		8.1	419		5.6	419

PONV: postoperative nausea and vomiting. Data are presented as numbers [n] or percentages; H0: group without hypotension period; H50-H70: groups with a hypotension period according to the given definitions.

Figure 1. Process of patient inclusion.

*Central venous catheter installation, dialysis catheter installation, vascular embolization, etc.

ENT: ear, nose and throat surgery.

Table A1/1. Summary of balance for all data before and after matching.

Summary of balance for all data:
Variable	Means treated	Means control	Std. mean diff	Var. ratio	eCDF mean	eCDF max
Distance	0.4340	0.1221	0.9973	5.7081	0.3392	0.5238
Gender	0.4938	0.4485	0.0907	.	0.0453	0.0453
Age	61.6060	54.1892	0.4398	0.8958	0.0927	0.2106
PONV-History	0.0548	0.0640	−0.0406	.	0.0092	0.0092
TIVA	0.3860	0.6239	−0.4886	.	0.2379	0.2379
Anesthesia-Time	201.9655	97.6729	0.9152	3.9353	0.2291	0.4738
PONV-Prophylaxis	0.4700	0.4302	0.0797	.	0.0398	0.0398
Opioid-Dose	142.7037	67.9124	0.4112	7.5671	0.1626	0.2193
Smoker y/n	0.1555	0.1351	0.0563	.	0.0204	0.0204
Fluid-Balance	1769.3825	881.8926	0.6730	2.3979	0.1723	0.3704
Summary of balance for matched data:
Variable	Means treated	Means control	Std. mean diff	Var. ratio	eCDF mean	eCDF max	Std. pair dist
Distance	0.4340	0.4334	0.0019	1.0033	0.0006	0.0345	0.0088
Gender	0.4938	0.5188	−0.0501	.	0.0250	0.0250	0.9842
Age	61.6060	59.4476	0.1280	1.0056	0.0320	0.0922	1.0988
PONV-History	0.0548	0.0509	0.0168	.	0.0038	0.0038	0.4543
TIVA	0.3860	0.3731	0.0266	.	0.0130	0.0130	0.8964
Anesthesia-Time	201.9655	205.4906	−0.0309	0.8375	0.0145	0.0406	0.4700
PONV-Prophylaxis	0.4700	0.5174	−0.0950	.	0.0474	0.0474	1.0012
Opioid-Dose	142.7037	157.2677	−0.0801	0.8735	0.0214	0.0610	0.7277
Smoker y/n	0.1555	0.1428	0.0349	.	0.0127	0.0127	0.7062
Fluid-Balance	1769.3825	1627.9470	0.1072	1.4768	0.0242	0.0922	0.6623

SD: standard deviation for all variables, where applicable. Std. Mean Difference: standardized mean difference for all variables. Var. Ratio: variance ratio. eCDF: empirical cumulative distribution function. Std. Pair. Dist.: standardized pair distance. Opioid-Dose as mg morphine equivalent.

Table A1/2. Summary of balance for all data before and after matching.

Summary of balance for all data
Variable	Means treated	Means control	Std. mean diff	Var. ratio	eCDF mean	eCDF max	′
Distance	0.5670	0.3782	0.8744	1.5507	0.2505	0.3672
Gender	0.5780	0.4485	0.2622	.	0.1295	0.1295
Age	53.9252	54.1892	−0.0141	1.1005	0.0101	0.0303
PONV-History	0.0735	0.0640	0.0364	.	0.0095	0.0095
TIVA	0.4844	0.6239	−0.2792	.	0.1395	0.1395
Anesthesia-Time	158.0951	97.6729	0.6357	2.7379	0.1274	0.2989
PONV-Prophylaxis	0.5448	0.4302	0.2302	.	0.1146	0.1146
Opioid-Dose	107.4553	67.9124	0.3102	3.7178	0.0961	0.1432
Smoker y/n	0.1583	0.1351	0.0637	.	0.0233	0.0233
Fluid-Balance	1389.7760	881.8926	0.4895	1.4844	0.1015	0.2169
Summary of balance for matched data:
Variable	Means treated	Means control	Std. mean diff	Var. ratio	eCDF mean	eCDF max	Std. pair dist
Distance	0.5670	0.5669	0.0003	1.0005	0.0003	0.0100	0.0027
Gender	0.5780	0.5863	−0.0168	.	0.0083	0.0083	0.9038
Age	53.9252	53.1371	0.0422	1.1168	0.0175	0.0505	1.1098
PONV-History	0.0735	0.0726	0.0036	.	0.0009	0.0009	0.5118
TIVA	0.4844	0.4843	0.0001	.	0.0001	0.0001	0.8963
Anesthesia-Time	158.0951	159.5117	−0.0149	0.9520	0.0082	0.0279	0.4676
PONV-Prophylaxis	0.5448	0.5785	−0.0676	.	0.0337	0.0337	0.9257
Opioid-Dose	107.4553	111.1537	−0.0290	0.9334	0.0132	0.0565	0.7119
Smoker y/n	0.1583	0.1553	0.0084	.	0.0031	0.0031	0.7193
Fluid-Balance	1389.7760	1289.1151	0.0970	1.5427	0.0205	0.0635	0.6723

SD: standard deviation for all variables, where applicable. Std. Mean Difference: standardized mean difference for all variables. Var. Ratio: variance ratio. eCDF: empirical cumulative distribution function. Std. Pair. Dist.: standardized pair distance. Opioid-Dose as mg morphine equivalent.

Table A1/3. Summary of balance for all data before and after matching.

Summary of balance for all data:
Variable	Means treated	Means control	Std. mean diff	Var. ratio	eCDF mean	eCDF max
Distance	0.6274	0.5472	0.5915	1.1375	0.1662	0.2432
Gender	0.5516	0.4485	0.2074	.	0.1032	0.1032
Age	51.9751	54.1892	−0.1186	1.0972	0.0279	0.0576
PONV-History	0.0685	0.0640	0.0178	.	0.0045	0.0045
TIVA	0.5624	0.6239	−0.1240	.	0.0615	0.0615
Anesthesia-Time	130.9528	97.6729	0.4188	1.9135	0.0754	0.1871
PONV-Prophylaxis	0.5176	0.4302	0.1750	.	0.0875	0.0875
Opioid-Dose	90.0845	67.9124	0.2123	2.4942	0.0584	0.0972
Smoker y/n	0.1526	0.1351	0.0487	.	0.0175	0.0175
Fluid-Balance	1130.5627	881.8926	0.2891	1.0200	0.0507	0.1064
Summary of balance for matched data:
Variable	Means treated	Means control	Std. mean diff	Var. ratio	eCDF mean	eCDF max	Std. pair dist
Distance	0.6274	0.6273	0.0003	1.0013	0.0002	0.0030	0.0021
Gender	0.5516	0.5545	−0.0058	.	0.0029	0.0029	0.8489
Age	51.9751	51.5749	0.0214	1.1101	0.0136	0.0349	1.0814
PONV-History	0.0685	0.0661	0.0096	.	0.0024	0.0024	0.4876
TIVA	0.5624	0.5483	0.0283	.	0.0141	0.0141	0.9478
Anesthesia-Time	130.9528	130.5449	0.0051	0.9990	0.0037	0.0110	0.5064
PONV-Prophylaxis	0.5176	0.5333	−0.0314	.	0.0157	0.0157	0.8918
Opioid-Dose	90.0845	90.7828	−0.0067	1.0242	0.0055	0.0331	0.6636
Smoker y/n	0.1526	0.1542	−0.0046	.	0.0016	0.0016	0.7105
Fluid-Balance	1130.5627	1081.8883	0.0566	1.4449	0.0112	0.0322	0.7403

SD: standard deviation for all variables, where applicable. Std. Mean Difference: standardized mean difference for all variables. Var. Ratio: variance ratio. eCDF: empirical cumulative distribution function. Std. Pair. Dist.: standardized pair distance. Opioid-Dose as mg morphine equivalent.

Table A2/1. Summary of balance for all data before and after matching.

Summary of balance for all data:
	Means treated	Means control	Std.mean diff.	Var. ratio	eCDF mean	eCDF max
Distance	0.5549	0.3946	0.8648	1.0541	0.2326	0.3462
Gender	0.6485	0.3567	0.6112	n.a.	0.2918	0.2918
Age	58.7124	64.1717	−0.3080	1.2848	0.0699	0.1456
Ponv-History	0.0883	0.0250	0.2232	n.a.	0.0633	0.0633
TIVA	0.3064	0.4567	−0.3260	n.a.	0.1503	0.1503
Anaesthesia-TIme	200.1617	203.5650	−0.0309	0.8844	0.0119	0.0465
Opioid-Dose	123.5649	159.6735	−0.2389	0.5494	0.0475	0.0890
Smoker Y/n	0.1504	0.1600	−0.0269	n.a.	0.0096	0.0096
Fluid-Balance	1705.4474	1826.0717	−0.1027	0.6708	0.0330	0.0739
Summary of balance for matched data:
	Means treated	Means control	Std. mean diff.	Var. ratio	eCDF mean	eCDF max	Std. pair dist.
Distance	0.5549	0.4260	0.6957	1.2265	0.1886	0.3064	0.6958
Gender	0.6485	0.4023	0.5158	n.a.	0.2462	0.2462	0.6417
Age	58.7124	63.1353	−0.2495	1.2264	0.0566	0.1165	1.0691
Ponv-History	0.0883	0.0282	0.2119	n.a.	0.0602	0.0602	0.3179
TIVA	0.3064	0.3910	−0.1835	n.a.	0.0846	0.0846	0.9256
Anaesthesia-TIme	200.1617	204.0677	−0.0354	0.8740	0.0134	0.0489	1.1200
Opioid-Dose	123.5649	148.0072	−0.1617	0.6411	0.0330	0.0658	0.8880
Smoker Y/n	0.1504	0.1654	−0.0421	n.a.	0.0150	0.0150	0.7362
Fluid-Balance	1705.4474	1795.3571	−0.0766	0.6507	0.0295	0.0639	1.1851
Sample sizes:	Control	Treated
All	600	532
Matched	532	532
Unmatched	68	0
Discarded	0	0

Table A2/2. Summary of balance for all data before and after matching.

Summary of balance for all data:
	Means treated	Means control	Std. mean diff.	Var. ratio	eCDF mean	eCDF max
Distance	0.6095	0.4674	0.8369	0.9216	0.2181	0.3379
Gender	0.7106	0.4193	0.6424	.	0.2913	0.2913
Age	51.1829	57.2075	−0.3232	1.0458	0.0744	0.1609
Ponv-History	0.1141	0.0249	0.2805	.	0.0892	0.0892
TIVA	0.4460	0.5304	−0.1699	.	0.0845	0.0845
Anaesthesia-TIme	155.9303	160.6862	−0.0504	0.9672	0.0126	0.0469
Opioid-Dose	103.4040	112.3045	−0.0739	0.7901	0.0142	0.0313
Smoker Y/n	0.1437	0.1759	−0.0916	.	0.0321	0.0321
Fluid-Balance	1375.1181	1407.3206	−0.0330	0.7751	0.0182	0.0376
Summary of balance for matched data:
	Means treated	Means control	Std. mean diff.	Var. ratio	eCDF mean	eCDF max	Std. pair dist.
Distance	0.6637	0.4674	1.1564	0.5079	0.3024	0.4763	1.1564
Gender	0.8495	0.4193	0.9488	.	0.4303	0.4303	1.0037
Age	48.8275	57.2075	−0.4496	0.9979	0.1035	0.2199	1.1094
Ponv-History	0.1366	0.0249	0.3512	.	0.1116	0.1116	0.3662
TIVA	0.4552	0.5304	−0.1513	.	0.0752	0.0752	1.0266
Anaesthesia-TIme	153.8620	160.6862	−0.0724	0.9874	0.0160	0.0517	1.0699
Opioid-Dose	100.2848	112.3045	−0.0999	0.7440	0.0193	0.0364	0.8805
Smoker Y/n	0.1275	0.1759	−0.1380	.	0.0484	0.0484	0.7253
Fluid-Balance	1349.6603	1407.3206	−0.0591	0.7126	0.0246	0.0508	1.0209
Sample sizes:	Control	Treated
All	2087	2498
Matched	2087	2087
Unmatched	0	411
Discarded	0	0

Table A2/3. Summary of balance for all data before and after matching.

Summary of balance for all data:
	Means treated	Means control	Std.mean diff.	Var. ratio	eCDF mean	eCDF max
Distance	0.5964	0.4331	0.8767	1.0447	0.2323	0.3496
Gender	0.7033	0.3889	0.6881	.	0.3143	0.3143
Age	49.2479	54.9018	−0.3087	0.9704	0.0698	0.1478
Ponv-History	0.1170	0.0164	0.3130	.	0.1006	0.1006
TIVA	0.5278	0.5995	−0.1436	.	0.0717	0.0717
Anaesthesia-TIme	133.5995	128.1124	0.0673	1.1178	0.0123	0.0374
Opioid-Dose	91.6674	88.3858	0.0316	0.9717	0.0125	0.0652
Smoker Y/n	0.1406	0.1654	−0.0714	.	0.0248	0.0248
Fluid-Balance	1154.3737	1105.0097	0.0604	0.8190	0.0106	0.0423
Summary of balance for matched data:
	Means treated	Means control	Std. mean diff.	Var. ratio	eCDF mean	eCDF max	Std. pair dist.
Distance	0.6226	0.4331	1.0174	0.8144	0.2699	0.4029	1.0174
Gender	0.7547	0.3889	0.8007	.	0.3658	0.3658	0.8737
Age	47.9508	54.9018	−0.3795	0.9382	0.0858	0.1813	1.1257
Ponv-History	0.1256	0.0164	0.3397	.	0.1092	0.1092	0.3464
TIVA	0.5137	0.5995	−0.1719	.	0.0858	0.0858	1.1179
Anaesthesia-TIme	134.7265	128.1124	0.0811	1.1643	0.0148	0.0436	1.0322
Opioid-Dose	92.1050	88.3858	0.0359	1.0161	0.0114	0.0586	0.7880
Smoker Y/n	0.1374	0.1654	−0.0805	.	0.0280	0.0280	0.7614
Fluid-Balance	1163.2765	1105.0097	0.0713	0.7498	0.0108	0.0414	0.9663
Sample sizes:	Control	Treated
All	3718	3990
Matched	3718	3718
Unmatched	0	272
Discarded	0	0