Effects of a fall prevention exercise regimen on physical and psychosocial outcomes in elderly community dwellers: a randomized comparative study.

BACKGROUND: There is a need for comprehensive programs that address both the physical and psychosocial aspects of fall prevention for the elderly. OBJECTIVE: This study assessed the efficacy of the exercise regimen on various health metrics for elderly community dwellers. METHODS: Forty-four participants were divided into experimental and control groups. The experimental group adhered to a 9-step core exercise regimen for fall prevention, practicing three times a week for 30 minutes across 10 weeks, while the control group maintained their regular daily activities without any specific exercise program. Before and after the intervention, participants underwent the timed up-and-go t est to evaluate the physical function, the berg balance scale (BBS) and one-legged stance test (OLST) for balance assessment, the activity-specific balance confidence scale for fall-related self-efficacy, and measures for health-related quality of life. RESULTS: Participants in the experimental group showed significant improvements in physical function (p = .04, Cohen's effect size (d) = 0.2). and balance ability on BBS (p < .01, d = 0.2) and OLST (p < .01, d = 1.3) compared to the control group. Furthermore, there was a notable enhancement in the quality of life indicators for this group, especially in areas such as physical function (p = .04, d = 0.2), physical-role limitation (p = .04, d = 0.2), mental health (p = .01, d = 0.3), vitality (p = .02, d = 0.4), body pain (p = .04, d = 0.5), and general health (p = .04, d = 0.4). CONCLUSION: These findings highlight the potential of the fall prevention exercise program in improving physical health aspects, but its influence on specific psychosocial elements remains to be determined.

Prognostic Impacts of Increases in Amino Transaminases Following Coronary Artery Bypass Grafting on Mortality.

OBJECTIVE: To evaluate the prognostic impacts of postoperative increases in serum amino transaminases on 1-year mortality in patients who underwent coronary artery bypass graft. DESIGN: A retrospective analysis. SETTING: A tertiary care university hospital. PARTICIPANTS: A total of 1,950 patients who underwent coronary artery bypass graft. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Aspartate amino transaminase and alanine amino transaminase ratios were calculated as the ratio between the peak aspartate amino transaminase and alanine amino transaminase within the first 5 post-operative days and their respective upper limit of normal values. A ratio of 2.0 was seen to be the minimum for which a difference in 1-year mortality could be detected in univariate analysis, when considering simultaneously both aspartate amino transaminase and alanine amino transaminase ratios. Multivariable analysis showed an association between an aspartate amino transaminase ratio > 2.0 and increased 1-year mortality (hazard ratio [HR] 2.68, 95% confidence interval [CI] 1.42-5.05, P = 0.002), and also between both an aspartate amino transaminase and alanine amino transaminase ratio > 2.0 and increased 1-year mortality (HR 3.90, 95% CI 1.87-8.14, P < 0.001). However, increases in alanine amino transaminase only above the upper limit of normal were not associated with increased 1-year mortality. CONCLUSIONS: Postoperative increases in aspartate amino transaminase only and increases in both aspartate amino transaminase and alanine amino transaminase greater than twice the upper limit of normal were associated with increased 1-year mortality in patients undergoing coronary artery bypass graft.

Long-term clinical outcomes of Remote Ischemic Preconditioning and Postconditioning Outcome (RISPO) trial in patients undergoing cardiac surgery.

BACKGROUND: Remote ischemic conditioning has been shown to confer myocardial protection. However, there is still no sufficient data on its long-term clinical outcomes. We analyzed the long-term results of the Remote Ischemic Preconditioning and Postconditioning Outcome (RISPO) trial in cardiac surgery patients. METHODS: In the RISPO trial, 1280 patients were randomized to receive remote ischemic preconditioning (RIPC) with postconditioning (RIPostC, upper arm ischemia by four cycles of 5-min inflation followed by 5-min deflation of a pneumatic cuff, N=644) or sham (N=636) during cardiac surgery. Patient follow-up data were collected by review of medical records, telephone interviews, and from the National Statistical Office. The primary endpoint was major adverse cardiac and cerebrovascular events (MACCE; a composite of all-cause mortality, myocardial infarction (MI), stroke, and revascularization), and the secondary endpoints were the individual components of the primary endpoint. RESULTS: At completion of follow-up (mean 44months), there was no difference in MACCE between the groups (90 [14.0%] versus 101 [15.9%] in the RIPC with RIPostC versus control groups; hazard ratio [HR], 0.893; 95% confidence interval [CI], 0.672-1.187; P=0.435). However, MI was reduced to half in the RIPC with RIPostC group (10 [1.6%] versus 23 [3.6%]; HR, 0.468; 95% CI, 0.222-0.984; P=0.045). CONCLUSIONS: Remote ischemic preconditioning with RIPostC did not improve long-term MACCE after cardiac surgery. However, MI was reduced in the RIPC with RIPostC group compared with the control group during the follow-up period. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT00997217.

Effect of Exogenous Albumin on the Incidence of Postoperative Acute Kidney Injury in Patients Undergoing Off-pump Coronary Artery Bypass Surgery with a Preoperative Albumin Level of Less Than 4.0 g/dl.

BACKGROUND: Hypoalbuminemia may increase the risk of acute kidney injury (AKI). The authors investigated whether the immediate preoperative administration of 20% albumin solution affects the incidence of AKI after off-pump coronary artery bypass surgery. METHODS: In this prospective, single-center, randomized, parallel-arm double-blind trial, 220 patients with preoperative serum albumin levels less than 4.0 g/dl were administered 100, 200, or 300 ml of 20% human albumin according to the preoperative serum albumin level (3.5 to 3.9, 3.0 to 3.4, or less than 3.0 g/dl, respectively) or with an equal volume of saline before surgery. The primary outcome measure was AKI incidence after surgery. Postoperative AKI was defined by maximal AKI Network criteria based on creatinine changes. RESULTS: Patient characteristics and perioperative data except urine output during surgery were similar between the two groups studied, the albumin group and the control group. Urine output (median [interquartile range]) during surgery was higher in the albumin group (550 ml [315 to 980]) than in the control group (370 ml [230 to 670]; P = 0.006). The incidence of postoperative AKI in the albumin group was lower than that in the control group (14 [13.7%] vs. 26 [25.7%]; P = 0.048). There were no significant between-group differences in severe AKI, including renal replacement therapy, 30-day mortality, and other clinical outcomes. There were no significant adverse events. CONCLUSION: Administration of 20% exogenous albumin immediately before surgery increases urine output during surgery and reduces the risk of AKI after off-pump coronary artery bypass surgery in patients with a preoperative serum albumin level of less than 4.0 g/dl.

Monitored anesthesia care with dexmedetomidine in transfemoral percutaneous trans-catheter aortic valve implantation: two cases report.

Percutaneous trans-catheter aortic valve implantation (TAVI) is recommended for inoperable patients with severe aortic stenosis at high risk for conventional aortic valve replacement. Originally, TAVI was mostly performed under general anesthesia. Here we describe two cases of transfemoral TAVI performed under monitored anesthesia care (MAC) with dexmedetomidine. Dexmedetomidine provides sedation, analgesia with minimal respiratory depression. Although MAC during transfemoral TAVI has limitations, such as unexpected patient movement and difficulty in intra-procedural use of transesophageal echocardiography, MAC with dexmedetomidine is feasible with close monitoring, fluoroscopic guidance and the participation of experienced anesthesiologists.

The analgesic efficacy and safety of nefopam in patient-controlled analgesia after cardiac surgery: A randomized, double-blind, prospective study.

OBJECTIVE: The efficacy and side-effects of nefopam were prospectively compared with those of fentanyl for patient-controlled analgesia (PCA) following cardiac surgery. METHODS: Patients scheduled to undergo cardiac surgery were randomly assigned between three PCA groups (nefopam, fentanyl or nefopam + fentanyl). Pain was assessed at rest and during movement at 12, 24, 36, 48 and 72 h after surgery using a visual analogue scale (VAS). Total infused PCA volume, number of rescue drug injections, duration of intubation and length of stay in the intensive care unit were recorded. The incidence of adverse effects was noted at 48 h postoperatively. RESULTS: There were no significant between-group differences in VAS score, total PCA infusion volume or number of rescue injections (n = 92 per group). Nausea was significantly more common in the fentanyl group compared with both other groups. CONCLUSIONS: PCA with nefopam alone provides suitable postoperative analgesia after cardiac surgery.

Does remote ischaemic preconditioning with postconditioning improve clinical outcomes of patients undergoing cardiac surgery? Remote Ischaemic Preconditioning with Postconditioning Outcome Trial.

AIMS: The aim of this study was to evaluate whether remote ischaemic preconditioning (RIPC) combined with remote ischaemic postconditioning (RIPostC) improves the clinical outcomes of patients undergoing cardiac surgery. METHODS AND RESULTS: From June 2009 to November 2010, 1280 patients who underwent elective cardiac surgery were randomized into the RIPC with RIPostC group or the control group in the morning of the surgery. In the RIPC with RIPostC group, four cycles of 5-min ischaemia and 5-min reperfusion were administered twice to the upper limb-before cardiopulmonary bypass (CPB) or coronary anastomoses for RIPC and after CPB or coronary anastomoses for RIPostC. The primary endpoint was the composite of major adverse outcomes, including death, myocardial infarction, arrhythmia, stroke, coma, renal failure or dysfunction, respiratory failure, cardiogenic shock, gastrointestinal complication, and multiorgan failure. Remote ischaemic preconditioning with RIPostC did not reduce the composite outcome compared with the control group (38.0 vs. 38.1%, respectively; P = 0.998) and there was no difference in each major adverse outcome. The intensive care unit and hospital stays were not different between the two groups. However, in the off-pump coronary artery bypass surgery subgroup, multivariate logistic regression analysis revealed that RIPC with RIPostC was related to increased composite outcome (odds ratio: 1.54; 95% confidence interval: 1.02-2.30; P = 0.038). CONCLUSION: Remote ischaemic preconditioning with RIPostC by transient upper limb ischaemia did not improve clinical outcome in patients who underwent cardiac surgery.

Effect of remote ischemic preconditioning on cognitive function after off-pump coronary artery bypass graft: a pilot study.

BACKGROUND: Several studies have shown in animal models that remote ischemic preconditioning (rIPC) has a neuroprotective effect. However, a randomized controlled trial in human subjects to investigate the neuroprotective effect of rIPC after cardiac surgery has not yet been reported. Therefore, we performed this pilot study to determine whether rIPC reduced the occurrence of postoperative cognitive dysfunction in patients who underwent off-pump coronary artery bypass graft (OPCAB) surgery. METHODS: Seventy patients who underwent OPCAB surgery were assigned to either the control or the rIPC group using a computer-generated randomization table. The application of rIPC consisted of four cycles of 5 min ischemia and 5 min reperfusion on an upper limb using a blood pressure cuff inflating 200 mmHg before coronary artery anastomosis. The cognitive function tests were performed one day before surgery and again on postoperative day 7. We defined postoperative cognitive dysfunction as decreased postoperative test values more than 20% of the baseline values in more than two of the six cognitive function tests that were performed. RESULTS: In the cognitive function tests, there were no significant differences in the results obtained during the preoperative and postoperative periods for all tests and there were no mean differences observed in the preoperative and postoperative scores. The incidences of postoperative cognitive dysfunction in the control and rIPC groups were 28.6% (10 patients) and 31.4% (11 patients), respectively. CONCLUSIONS: rIPC did not reduce the incidence of postoperative cognitive dysfunction after OPCAB surgery during the immediate postoperative period.

Impact of the time of coronary angiography on acute kidney injury after elective off-pump coronary artery bypass surgery.

BACKGROUND: Previous studies have suggested that early surgery after coronary angiography may be associated with the risk of acute kidney injury (AKI) in cardiac surgery with cardiopulmonary bypass. However, the effect of coronary angiography on the risk of AKI after off-pump coronary artery bypass graft surgery (OPCABG) remains uncertain. METHODS: We assessed preoperative and perioperative data in 1,364 consecutive adult patients who underwent elective OPCABG surgery after coronary angiography. Acute kidney injury was defined by Acute Kidney Injury Network criteria based on changes in serum creatinine within the first 48 hours after OPCABG. Multivariable logistic regression was performed to evaluate the association of the time interval between coronary angiography and OPCABG with postoperative AKI. RESULTS: Acute kidney injury occurred in 391 patients (28.7%). The unadjusted and adjusted rates of AKI according to the length of time between coronary angiogram and OPCABG did not show any increasing or decreasing trend (p = 0.86 and p = 0.33 for trends of unadjusted and adjusted AKI rates, respectively), and early OPCABG after coronary angiography was not related to postoperative AKI. Results were the same in high-risk patients with preoperative renal insufficiency, low ejection fraction, or who received an ionic contrast agent or a high dose of contrast agent. CONCLUSIONS: The risk of postoperative AKI was not related to the time between coronary angiography and OPCABG. These findings suggest that delaying elective OPCABG after coronary angiography owing to the sole concern for renal function may be unnecessary.

Transcatheter aortic valve implantation: early experience in Korea.

BACKGROUND AND OBJECTIVES: Transcatheter aortic valve implantation (TAVI) was recently introduced in Korea. The present report describes the experience of early TAVI cases. SUBJECTS AND METHODS: Between March, 2010 and October, 2011, 48 patients with severe symptomatic aortic stenosis (AS) were screened at the Asan Medical Center to determine their suitability for surgical intervention. Of these, 23 were considered unsuitable and underwent TAVI. Procedural success rates, procedure-related complications, and clinical outcomes were evaluated in the TAVI patients. RESULTS: Transfemoral (n=20) or transapical (n=3) TAVI was performed. The mean age of patients was 75.9±5.4 years and 57% were females. The mean logistic European System for Cardiac Operative Risk Evaluation was 25.6±5.1%. Implantation was successful in 22 patients (19 transfemoral, three transapical). After successful implantation, the mean aortic valve area increased from 0.68±0.14 cm(2) to 1.45±0.33 cm(2). There were no procedure-related complications or mortality. The patients showed no paravalvular aortic regurgitation with ≥ moderate degree and remained stable without progression during follow-up. During follow-up (interquartile range, 1.1-12.9), all patients were alive without any occurrence of valve failure. CONCLUSION: TAVI procedure is feasible in patients with inoperative symptomatic AS leading to hemodynamic and clinical improvement. With accumulation of experience, proper patient selection and development of device technologies, TAVI should decrease adverse events and expand the indications in the near future.

Preoperative hypoalbuminemia is a major risk factor for acute kidney injury following off-pump coronary artery bypass surgery.

PURPOSE: To investigate the association between preoperative low serum albumin level and acute kidney injury (AKI) after off-pump coronary artery bypass surgery (OPCAB) METHOD: We assessed preoperative and perioperative risk factors, and preoperative serum albumin concentration in 1,182 consecutive adult patients with preoperative normal renal function who underwent OPCAB surgery. Each patient was categorized by maximal Acute Kidney Injury Network (AKIN) criteria based on creatinine changes within the first 48 h after OPCAB. Logistic regression and propensity analyses were performed to evaluate the association between preoperative low serum albumin level and postoperative AKI. RESULTS: Of the 1,182 patients, 334 (28.3%) developed AKI. Risk factors for AKI were old age, diabetes mellitus, maximal cardiovascular component of the sequential organ failure assessment score, perioperative transfusion, and postoperative C-reactive protein concentration. The risk of AKI was negatively correlated with the volume of crystalloid infused during surgery. A preoperative serum albumin level of <4.0 g/dl was independently associated Ith postoperative AKI [multivariable logistic analysis: odds ratio (OR) 1.83, 95 % confidence interval (CI) 1.27-2.64; P = 0.001; propensity analysis: OR 1.62, 95 % CI 1.12-2.35; P = 0.011). AKI was associated with prolonged stay in the intensive care unit and hospital and a high mortality rate. CONCLUSIONS: Preoperative low serum albumin level is an independent risk factor for AKI, and postoperative AKI is associated with poor outcomes after OPCAB in patients with preoperative normal renal function.

Prognostic implications of preoperative E/e' ratio in patients with off-pump coronary artery surgery.

BACKGROUND: The ratio of early transmitral flow velocity to early diastolic velocity of the mitral annulus (E/e') correlates with left ventricular (LV) filling pressure. In particular, an E/e' ratio more than 15 is an excellent predictor of increased LV filling pressure. The authors evaluated the prognostic implications of preoperative estimated LV filling pressure, assessed by E/e' ratio, in patients undergoing off-pump coronary artery bypass graft surgery. METHODS: This observational study investigated 1,048 consecutive adults undergoing elective off-pump coronary artery bypass graft surgery. The primary outcome was occurrence of major adverse cardiac events (MACE), defined as a composite of death, myocardial infarction, malignant ventricular arrhythmia, cardiac dysfunction, or need for new revascularization. Logistic regression and survival analyses were performed. RESULTS: An E/e' ratio more than 15 was independently associated with 30-day MACE (odds ratio 2.4, 95% CI 1.4-3.9, P = 0.001) and 1-yr MACE (hazard ratio 2.1, 95% CI 1.4-3.1, P = 0.001), irrespective of underlying LV ejection fraction. MACE free 1-yr survival rate was significantly decreased in patients with E/e' >15, irrespective of underlying LV ejection fraction. CONCLUSIONS: Increased LV filling pressure, assessed by E/e' ratio, is an independent predictor of 30-day and 1-yr MACE in patients who undergo elective off-pump coronary artery bypass graft surgery. These findings indicate that measurements of E/e' may assist in preoperative risk stratification of these patients.

Preoperative treatment with an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker has no beneficial effect on the development of new-onset atrial fibrillation after off-pump coronary artery bypass graft surgery.

BACKGROUND: The present study investigated whether preoperative angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) use affected the incidence of postoperative atrial fibrillation (POAF) in patients undergoing off-pump coronary artery bypass graft (OPCAB). HYPOTHESIS: Preoperative use of ACEI or ARB was related to POAF in patients undergoing OPCAB. METHODS: This retrospective, observational, cohort study involved 1050 patients who underwent OPCAB from January 2006 to December 2009. RESULTS: ACEI or ARB, ACEI alone, and ARB alone did not exert beneficial effect on the occurrence of POAF, and ACEI or ARB use was rather associated with an increased incidence of POAF (ACEI or ARB: odds ratio [OR]: 1.66, 95% confidence interval [CI]: 1.04-2.62, P = 0.03; ACEI alone: OR: 1.30, 95% CI: 0.57-2.97, P = 0.53; ARB alone: OR: 1.57, 95% CI: 0.93-2.64, P = 0.09). CONCLUSIONS: ACEI or ARB, ACEI alone, and ARB alone did not favorably influence the occurrence of POAF in patients undergoing OPCAB.

The prophylactic use of recombinant factor VIIa in a patient with DeBakey type III aortic dissection -A case report-.

Little is known about the prophylactic use of recombinant factor VIIa (rFVIIa) in patients undergoing surgery for a bleeding aorta employing cardiopulmonary bypass. We report the successful use of rFVIIa in a patient undergoing hypothermic circulatory arrest and prolonged cardiopulmonary bypass for repair of a DeBakey type III aortic dissection.

Temporary bilateral sensorineural hearing loss following cardiopulmonary bypass -A case report-.

Sudden sensorineural hearing loss has been reported to occur following anesthesia and various non-otologic surgeries, mostly after procedures involving cardiopulmonary bypass. Unilateral sensorineural hearing loss resulting from microembolism is an infrequent complication of cardiopulmonary bypass surgery that has long been acknowledged. Moreover, there are few reports on the occurrence of bilateral sensorineural hearing loss without other neurologic deficits and its etiology has also not been determined. We describe here a rare case of bilateral hearing loss without other neurologic deficits in an otherwise healthy 27-year-old woman who underwent cardiopulmonary bypass surgery for repair of severe mitral valve stenosis. The patient suffered from profound sensorineural hearing loss in both ears that was recognized immediately upon extubation, and audiometry tests confirmed the diagnosis. Without any treatment, her hearing recovered almost completely by the time of her discharge one week after surgery.

Anesthetic considerations of percutaneous transcatheter aortic valve implantation: first attempt in Korea -A report of 2 cases-.

Conventional aortic valve replacement for severe aortic stenosis is associated with a high operative mortality in the elderly patients with significant comorbidities, including severe respiratory dysfunction, renal insufficiency, and compromised cardiac function. Human transcatheter aortic valve implantation was first reported in 2002 and has become a valid alternative in selected high-risk patients in Europe and North America. This article describes the first attempt of transfemoral transcatheter aortic valve implantation in Korea. The procedure was applied in two consecutive patients with severe aortic stenosis. Despite several intra-operative complications during procedure, the post-operative outcomes were good for both patients. At post-operative 30 days there was satisfactory prosthetic valve function and hemodynamic stability.

The effects of gabapentin pretreatment on brain injury induced by focal cerebral ischemia/reperfusion in the rat.

BACKGROUND: Experimental studies have shown that gabapentin can reduce neuronal injury in the setting of cerebral ischemia, but the mechanisms have not yet been clearly determined. This study was conducted to determine whether gabapentin pretreatment altered expression levels of heat shock protein 70 and reduced acute phase neuronal injury in rats subjected to transient focal cerebral ischemia/reperfusion. METHODS: Forty male Sprague-Dawley rats (260-300 g) were randomly assigned to one of four groups (saline-treated, or 0.1, 0.5, or 5 mg/kg gabapentin group). In all animals, focal cerebral ischemia was induced by intraluminal middle cerebral artery occlusion for 1 hour. The animals of the gabapentin groups were pretreated with a single intravenous administration of gabapentin 20 minutes before ischemic insults. The infarct volume, brain edema and motor behavior deficits were analyzed 24 hours after ischemic insult. Caspase-3-reactive cells and cells showing Hsp70 activity were counted in the caudoputamen and fronto-parietal cortex. RESULTS: The infarction ratio was significantly decreased in the 5 mg/kg gabapentin group (P < 0.05) and brain edema ratios were significantly reduced in the 0.1 mg/kg, 0.5 mg/kg, and 5 mg/kg gabapentin groups 24 hours after ischemia/reperfusion injury (P < 0.05). There were more Hsp70-reactive cells in the 5 mg/kg gabapentin group than in the saline group in both the caudoputamen and fronto-parietal cortex (P < 0.05). CONCLUSIONS: These results indicate that gabapentin may have a neuroprotective effect and can reduce early neuronal injury caused by focal cerebral ischemia/reperfusion; this may be mediated by expression of Hsp70. However, gabapentin pretreatment did not prevent caspase-dependent apoptosis.

Nitric oxide and pulmonary hypertension.

Pulmonary hypertension is a serious complication of a number of lung and heart diseases that is characterized by peripheral vascular structural remodeling and loss of vascular tone. Nitric oxide can modulate vascular injury and interrupt elevation of pulmonary vascular resistance selectively; however, it can also produce cytotoxic oxygen radicals and exert cytotoxic and antiplatelet effects. The balance between the protective and adverse effects of nitric oxide is determined by the relative amount of nitric oxide and reactive radicals. Nitric oxide has been shown to be clinically effective in the treatment of congenital heart disease, mitrial valvular disease combined with pulmonary hypertension and in orthotropic cardiac transplantation patients. Additionally, new therapeutic modalities for the treatment of pulmonary hypertension, phosphodiesterase inhibitors, natriuretic peptides and aqueous nitric oxide are also effective for treatment of elevated pulmonary vascular resistance.

Growth suppression of four cancer cells by hyperbaric nitrous oxide and methotrexate.

BACKGROUND: Nitrous oxide concentration is easily controlled by respiratory ventilation. It suppresses bone marrow via the inhibition of thymidylate synthesis. The aim of this work was to determine the optimal pressure and exposure duration of nitrous oxide, as well as methotrexate concentration that maximizes the suppression of 4 cancer cells: CCRF-CEM, K562, A549 and MDA-MB-231. METHODS: Each cancer cell was cultured in a hyperbaric chamber at 1, 2 and 3 atmosphere of 74% nitrous oxide for 24, 48, and 72 hours at 0, 0.3, 0.7, 1, 2, 5 and 10 microM methotrexate (MTX), respectively. The results were expressed in the ratio of the number of cancer cells cultured under specific conditions (S cells) to that under normal conditions (N cells). RESULTS: The S/N ratio of CCRF-CEM cells was 87.4% in 24-hour culture, 95.0% in 48-hour culture and 115.9% in 72-hour culture (P < 0.05). The S/N ratio of K562 cells was 103.6% at 1 atm, 102.4% at 2 atm and 115.6% at 3 atm (P < 0.05). The S/N ratio of A549 cells was 94.3% at 1 atm, 94.1% at 2 atm, 99.3% at 3 atm, 96.2% in 24-hour culture, 99.2% in 48-hour culture and 99.3% in 72-hour culture (P > 0.05). However, the S/N ratio of MDA-MB 231 cells was 66.9% in 24-hour culture, 83.1% in 48 hour culture and 87.8% in 72-hour culture (P < 0.05). CONCLUSIONS: Only the growth of the MDA-MB-231 cells was significantly reduced after a longer exposure time to nitrous oxide, but those of the other cells were not.