Risk Factors For Intraocular Pressure Research Articles

Intraocular Pressure Spike Following Stand-Alone Phacoemulsification in the IRIS® Registry (Intelligent Research in Sight)

ObjectiveTo evaluate risk factors for intraocular pressure (IOP) spike following cataract surgery using the IRIS® Registry (Intelligent Research in Sight). DesignRetrospective clinical cohort study. SubjectsAdults with IRIS® Registry data who underwent stand-alone phacoemulsification from January 1, 2013 to September 30, 2019. MethodsIOP spike was defined as a postoperative IOP >30 mmHg and >10 mmHg from baseline within the first postoperative week. Odds ratios (OR) for demographic and clinical characteristics were calculated with univariate and multivariate logistic regression analyses. Main Outcome MeasuresIncidence and OR of IOP spike. ResultsWe analyzed data from 1,191,034 eyes (mean age 71.3 years, 61.2% female sex and 24.8% with glaucoma). An IOP spike occurred in 3.7% of all eyes, 5.2% of eyes with glaucoma and 3.2% of eyes without glaucoma (P<0.0001). Multivariable analyses of all eyes indicated a greater risk of IOP spike with higher baseline IOP (OR 1.57 per 3 mmHg), male sex (OR 1.79), glaucoma (OR 1.19), Black race (OR 1.39 compared to Asian and OR 1.21 compared to Hispanic), older age (OR 1.07 per 10 years), and complex surgery coding (OR 1.22, all P<0.0001). Diabetes (OR 0.90) and aphakia after surgery (OR 0.60) appeared to be protective against IOP spike (both P<0.0001). Compared to glaucoma suspects, there was a greater risk of IOP spike with ocular hypertension (OR 1.55), pigmentary glaucoma (OR 1.56), and pseudoexfoliative glaucoma (OR 1.52), and less risk for normal tension glaucoma (OR 0.55), primary angle closure (PAC) suspect (OR 0.67), and PAC glaucoma (OR 0.81, all P<0.0001). More baseline glaucoma medications was associated with IOP spike (OR 1.18 per medicine) while topical beta-blocker use (OR 0.68) was protective (both P<0.0001). ConclusionsHigher baseline IOP, male sex, glaucoma, Black race, older age, and complex cataract coding were associated with an early postoperative IOP spike whereas diabetes and postoperative aphakia were protective against a spike following stand-alone phacoemulsification. Glaucomatous eyes demonstrated different risk profiles dependent on subtype of glaucoma. The findings may help surgeons stratify and mitigate the risk of IOP spike after cataract surgery.

Risk factors for intraocular pressure elevation in a six-month period after ab interno trabeculotomy using a Kahook Dual Blade

BackgroundTo examine the risk factors for an early postoperative intraocular pressure (IOP) increase after ab interno trabeculotomy using a Kahook Dual Blade (KDB trabeculotomy).MethodsA retrospective study was performed in 76 exfoliation glaucoma (EXG) eyes and 56 primary open angle glaucoma (POAG) eyes that underwent KDB trabeculotomy, with or without cataract surgery at Kumamoto University Hospital. Postoperative high IOP was classified as IOP≥20 mmHg (within three months after surgery, whether persistent or temporary), transient IOP≥20 mmHg (IOP≥20 mmHg after surgery, then dropped below 20 mmHg), and the presence of IOP spikes (≥ 10 mmHg from baseline). Risk factors were examined using logistic regression analysis.ResultsThe preoperative mean IOP (SD) was 24.98 (7.23) mmHg in patients with EXG and 21.28 (6.58) mmHg in patients with POAG. IOP was reduced by 32.1% in patients with EXG and by 17.7% in patients with POAG at 6 months after surgery. Postoperative IOP≥20 mmHg was observed in 56.6% of EXG patients and in 51.8% of POAG patients. IOP spikes occurred in 15.8% of EXG patients and in 14.3% of POAG patients. Logistic regression analysis showed that factors with significant odds ratios (ORs) were age (OR = 0.866, 95% CI = 0.793–0.945), preoperative medication use (OR = 2.02, 95% CI = 1.17–3.49), trabeculotomy in combination with cataract surgery (OR = 0.0674, 95% CI = 0.015–0.303), and IOP at day 1 (OR = 1.41, 95% CI = 1.18–1.68) for postoperative IOP≥20 mmHg, the IOP at day 1 (OR = 1.1, 95% CI = 1.03–1.17) for transient IOP≥20 mmHg, and age (OR = 0.948, 95% CI = 0.901–0.997) and preoperative IOP (OR = 0.83, 95% CI = 0.736–0.936) for IOP spikes.ConclusionAlthough KDB trabeculotomy is an effective treatment for patients with EXG and POAG, patients who take multiple preoperative medications and have a high IOP on day 1 require careful follow-up to prevent postoperative IOP elevation.

Risk factors for intraocular pressure elevation during the early period post cataract surgery.

To assess the risk factors for intraocular pressure (IOP) elevation during the early period post cataract surgery. Retrospective study. This study involved 1587 eyes that underwent cataract surgery at the Baptist Eye Institute, Kyoto, Japan between April 2020 and May 2021. In all subjects, risk factors for early postoperative IOP elevation (i.e., an increase of IOP of 10 mmHg or more at 1-day postoperative compared with that at baseline, or a postoperative IOP of 28 mmHg or more) were analyzed by multivariate logistic regression analysis. Of the 1587 treated eyes in this study, 100 (6.3%) experienced early-postoperative IOP elevation. Of those 100 eyes, 78.0% were men, 27.0% had an axial length (AL) of ≥ 26.5mm, 23.0% had a history of glaucoma treatment, 11.0% had poor mydriasis and 10.0% had intraoperative floppy iris syndrome (IFIS). Multivariate analysis findings revealed that male [odds ratio (OR) 4.36; 95% confidence interval (CI) 2.63-7.23; P < 0.001], AL of ≥ 26.5mm (3.11; 1.83-5.30; P < 0.001), a history of glaucoma treatment (2.83; 1.63-4.91; P < 0.001), poorly mydriasis (2.63; 1.16-6.01; P = 0.02), IFIS (4.37; 1.78-10.74; P = 0.001) and baseline high IOP (1.09; 1.01-1.18; P = 0.03) were associated with increased IOP during the early period post cataract surgery. The findings in this study reveal that male sex, high myopia, a history of glaucoma treatment, poor mydriasis, IFIS and baseline high IOP are risk factors for IOP elevation during the early period post cataract surgery.

Incidence and Risk Factors for Intraocular Pressure Rise after the Scleral Buckle Surgery for Retinal Detachment.

Purpose:To determine the incidence and risk factors for intraocular pressure (IOP) rise after the scleral buckle (SB) procedure for retinal detachment (RD).Methods:A retrospective chart review of the medical records of patients, who underwent RD repair by SB performed by a single surgeon and had a minimum follow-up of 6 months was carried out. The outcome measures were the incidence of IOP rise in the operated eyes and the associated risk factors.Results:Fifty-two eyes of 52 patients with a median postsurgical follow-up of 18 months (interquartile range: 6, 36, range: 6–60 months) were included. Seven eyes had encircling buckle, 23 eyes had encircling buckle and 1 quadrant segmental buckle, and 22 eyes had encircling buckle and 2 quadrant segmental buckle. IOP rise was seen in 15/52 eyes (28.85%), within 1 month of the SB surgery. Nine out of 15 eyes (60%) of patients <40 years of age had a rise in IOP as compared to 6/37 eyes (16.2%) of patients >40 years of age (P = 0.002). Patients <40 years had a significant increased risk of developing IOP rise, compared to those above 40 years of age (adjusted odds ratio: 7.246 with 95% confidence interval of 1.641–31.986, P = 0.009). None of the fellow eyes had a rise in IOP during the follow-up period. None of the operated eyes with raised IOP progressed to glaucoma.Conclusions:Elevated IOP is a common complication after the SB procedure, and age <40 years is associated with a greater risk of development of increase in the IOP. Hence, IOP monitoring after the SB surgery is of paramount importance to detect early rise during follow-up.

Changes in Intraocular Pressure and Anterior Chamber Angle After Congenital Cataract Extraction.

Anterior chamber angle (ACA) narrowing continues to occur for at least 2 years after congenital cataract surgery. Risk factors for intraocular pressure (IOP) elevation after congenital cataract surgery were higher central corneal thickness (CCT) and surgery at <2 months. The purpose of this study was to study the changes in IOP and in the ACA during the first 2 years after pediatric cataract surgery and to determine risk factors for such changes. A retrospective observational study was done on infants who underwent pediatric cataract surgery in Cairo University Hospitals and completed a 1-year follow-up. Demographic and clinical characteristics were recorded including age at surgery, sex, corneal diameter, CCT pupil diameter, IOP, gonioscopic findings, presence of persistent hyperplastic primary vitreous, surgical approach, primary intraocular lens implantation, and perioperative subconjunctival steroid injection. Changes in IOP and in the ACA were recorded, and the risk factors for such changes were analyzed. Postoperative IOP elevation >18 mm Hg occurred in 23 eyes of 206 eyes (11%), who completed Year 1 and in 9 (13%) of 86 eyes who completed Year 2. Risk factors for IOP elevation were larger preoperative CCT (P=0.01) in Year 1, and younger age at surgery (P=0.01), and aphakia (P=0.05) in Year 2. In multivariate analysis only younger age at surgery was a risk factor for IOP elevation in Year 2. ACA narrowing occurred in 49% and in 21% of the examined eyes in Years 1 and 2, respectively. Aphakia was not a significant risk factor of angle narrowing in Years 1 and 2 (P=0.17 and 0.42, respectively). Higher preoperative CCT was a risk factor for early-onset IOP elevation. Surgery at >2 months was associated with lower susceptibility to late-onset IOP elevation.

Intraocular Pressure in General and Diabetic Populations From Southern China: the Dongguan Eye Study.

To investigate the distribution and risk factors for intraocular pressure (IOP) among general and diabetic populations in Southern China. The study participants aged 40 years or older were enrolled from the Dongguan Eye Study, a population-based cross-sectional study from September 2011 to February 2012. Systemic and ophthalmic examinations were performed, and diabetes status was screened based on the American Diabetes Association diagnostic criteria (2010). IOP was measured by a noncontact tonometer per standardized protocol. Regression analyses were used to assess the association between potential risk factors and IOP. A total of 2112 subjects were included with a median age of 55 years. IOP for general population showed a near normal distribution with an average of 15.58 ± 3.27 mm Hg. Multiple regression analyses revealed that higher IOP was significantly correlated with younger age, higher body mass index (BMI), shorter height, higher blood pressure (BP), higher fasting blood glucose (FBG), higher low-density lipoprotein cholesterol (LDL-C), lower high-density lipoprotein cholesterol (HDL-C), and thicker central corneal thickness (CCT). There was no association between diabetes status and IOP after adjusting for possible confounders. IOP for diabetic participants showed a right-skewed distribution. Risk factors for IOP elevation in diabetes included female, younger age, higher BP, higher LDL-C, lower HDL-C, and thicker CCT. The present study identifies risk factors for elevated IOP in general and diabetic populations. Younger age and lower HDL-C, as well as higher BP, LDL-C, and CCT were significant factors contributing to higher IOP, especially in the female diabetic population.

Raised Intraocular Pressure in Nonjuvenile Idiopathic Arthritis-Uveitis Children: Risk Factors and Effect on Retinal Nerve Fiber Layer.

To determine risk factors for intraocular pressure (IOP) elevation and glaucoma in children with nonjuvenile idiopathic arthritis-related uveitis and any IOP-related changes in the retinal nerve fiber layer (RNFL) thickness. Clinical data were collected from children attending a tertiary referral uveitis clinic between May 2010 and October 2012. We assigned 206 eyes of 103 children into 32 normal eyes, 108 normotensive uveitics (NU), 41 hypertensive uveitics (HU: raised IOP without glaucomatous disc), and 25 glaucomatous uveitics (GU: raised IOP with glaucomatous disc). Risk factors for raised IOP, glaucoma and steroid response (SR) were evaluated and RNFL thickness across groups was compared with determine changes related to raised IOP. IOP elevation occurred in 40 patients (38.8%) or 66/174 eyes with uveitis (37.9%); and SR occurred in 35.1% of all corticosteroid-treated eyes. Chronic uveitis was a significant risk factor for raised IOP [odds ratio (OR)=9.28, P=0.001], glaucoma, and SR (OR=8.4, P<0.001). Higher peak IOP was also a risk factor for glaucoma (OR=1.4, P=0.003). About 70% of SR eyes were high responders (IOP increase >15 mm Hg from baseline), associated with younger age and corticosteroid injections. Although no significant RNFL thinning was detected between HU and NU eyes, significant thinning was detected in the inferior quadrant of GU (121.3±28.9 μm) compared with NU eyes (142.1±32.0 μm, P=0.043). Children with chronic uveitis are at higher risk of raised IOP and glaucoma. Thinning of the inferior RNFL quadrant may suggest glaucomatous changes in uveitic children with raised IOP.

The Risk of Intraocular Pressure Elevation in Pediatric Noninfectious Uveitis

To characterize the risk and risk factors for intraocular pressure (IOP) elevation in pediatric noninfectious uveitis. Multicenter retrospective cohort study. Nine hundred sixteen children (1593 eyes) younger than 18 years at presentation with noninfectious uveitis followed up between January 1978 and December 2007 at 5 academic uveitis centers in the United States. Medical records review by trained, certified experts. Prevalence and incidence of IOP of 21 mmHg or more and 30 mmHg or more and incidence of a rise in IOP by 10 mmHg or more. To avoid underascertainment, outcomes were counted as present when IOP-lowering therapies were in use. Initially, 251 (15.8%) and 46 eyes (2.9%) had IOP ≥21 mmHg and ≥30 mmHg, respectively. Factors significantly associated with presenting IOP elevation included age of 6 to 12 years (versus other pediatric ages), prior cataract surgery, pars plana vitrectomy, duration of uveitis ≥6 months, contralateral IOP elevation, presenting visual acuity worse than 20/40, and topical corticosteroid use (in a dose-response relationship). The median follow-up was 1.25 years (interquartile range, 0.4-3.66). The estimated incidence of any observed IOP elevation to ≥21 mmHg, to ≥30 mmHg, and increase in IOP by ≥10 mmHg was 33.4%, 14.8%, and 24.4%, respectively, within 2 years. Factors associated with IOP elevation included pars plana vitrectomy, contralateral IOP elevation (adjusted hazard ratio [aHR], up to 9.54; P < 0.001), and the use of topical (aHR, up to 8.77 that followed a dose-response relationship; P < 0.001), periocular (aHR, up to 7.96; P < 0.001), and intraocular (aHR, up to 19.7; P < 0.001) corticosteroids. Intraocular pressure elevation affects a large minority of children with noninfectious uveitis. Statistically significant risk factors include IOP elevation or use of IOP-lowering treatment in the contralateral eye and local corticosteroid use that demonstrated a dose-and route of administration-dependent relationship. In contrast, use of immunosuppressive drug therapy did not increase such risk. Pediatric eyes with noninfectious uveitis should be followed up closely for IOP elevation, especially when strong risk factors such as the use of local corticosteroids and contralateral IOP elevation are present.

Intraocular Pressure Elevation after Vitrectomy for various Vitreoretinal Disorders

To determine the incidence of and risk factors for intraocular pressure (IOP) elevation in the immediate postoperative period after vitrectomy for various vitreoretinal disorders. A prospective study was performed in 228 consecutive patients with various vitreoretinal disorders. The IOP was measured before surgery, at the end of surgery, and at 5 hours and 1 day after surgery using Tono-Pen XL. The IOP at the end of surgery was adjusted to 15.0 ± 2.0 mm Hg. Intraocular pressure elevation (>25 mm Hg) was found in 55 (24.1%) and 52 (22.8%) patients at 5 hours and 1 day postoperatively, respectively. The IOP at 5 hours was significantly lower in patients with macular hole (MH) than in those with diabetic macular edema, proliferative diabetic retinopathy (PDR), proliferative vitreoretinopathy, or rhegmatogenous retinal detachment (RD). The IOP at 1 day was significantly higher in patients with PDR and RD than in those with MH and epiretinal membrane. Multiple regression analysis revealed that IOP at 5 hours postoperatively had a significant correlation with the number of laser photocoagulation, preoperative IOP, combined cataract surgery, and 20-gauge vitrectomy. The IOP at 1 day postoperatively was significantly associated with these 4 parameters as well as the severity of postoperative vitreous hemorrhage and use of expanding gas tamponade. Intraocular pressure elevation was found in approximately one-quarter of cases within 1 day following vitrectomy. The risk factors for IOP elevation included number of laser photocoagulation, combined cataract surgery, severity of postoperative vitreous hemorrhage, and use of expanding gas tamponade.

Complications of intravitreal triamcinolone acetonide for macular edema and predictive factors for intraocular pressure elevation.

To investigate the complications of intravitreal triamcinolone acetonide (IVTA) for the treatment of macular edema, and to determine the risk factors for intraocular pressure (IOP) elevation. Charts of patients with macular edema secondary to branch retinal vein occlusion (BRVO), diabetic retinopathy and uveitis who had received IVTA injections were reviewed to document its complications. IOP elevation was defined as a pressure of ≥24mmHg at some point during follow-up. Multivariate logistic regression analysis was performed to characterize baseline risk factors for this elevation. The study included 111 eyes of 65 female and 46 male patients with a mean follow-up of (11.6±5.1) months. Of the 111 eyes, 52 (46.8%) had macular edema secondary to BRVO, 44 (39.6%) had clinically significant diabetic macular edema (CSDME) and 15 (13.5%) had non-infectious uveitis with macular edema. IOP was recorded ≥ 24mmHg in 38 eyes (34.2%) during the follow-up. Higher baseline IOP (P=0.022), younger age (P=0.003), and male gender (P=0.014) were significant risk factors for IOP elevation after IVTA injection. Eyes with prior vitrectomy were less likely to have IOP elevation (P=0.054). Two eyes (5.2% of eyes with increased IOP) underwent trabeculectomy, and 9 eyes (16.3% of the phakic eyes) necessitated cataract surgery. Other complications included branch vein occlusion (1.8%), sterile endophthalmitis (0.9%) and pseudohypopyon (0.9%). IVTA has side effects with IOP elevation and cataract formation being the two most common. A subset of patients is more prone to developing increased IOP following IVTA, namely, younger male patients with higher baseline IOP.

Intraocular pressure elevation in the early postoperative period after vitrectomy for rhegmatogenous retinal detachment

The purpose of this study was to determine the incidence of and risk factors for intraocular pressure (IOP) elevation within 24 h following vitrectomy for rhegmatogenous retinal detachment (RD). We assessed 34 eyes of 34 consecutive patients with RD undergoing vitrectomy and 12 eyes of 12 patients with macular hole as controls. IOP was measured using Tonopen XL before surgery, at the end of surgery, and at 5 h and 1 day postoperatively. IOP at the end of surgery was adjusted to 15.0 ± 2.0 mmHg. IOP elevation was found in five RD eyes at 5 h and in 13 1 day postoperatively. IOP in patients with RD at both 5 h and 1 day postoperatively was significantly higher than that of controls. Circumferential dimension of retinal tears and disease duration were significantly associated with IOP elevation at both 5 h and 1 day postoperatively. IOP elevation in the early postoperative period following vitrectomy for RD is common. The risk factors for IOP elevation include the extent of retinal tears and duration of detachment. Prophylactic treatment may be useful in eyes with higher risks of IOP elevation.

Risk Factors for Intraocular Pressure Elevation After Descemet Stripping Automated Endothelial Keratoplasty

To identify the incidence of and risk factors for intraocular pressure (IOP) elevation after Descemet stripping automated endothelial keratoplasty (DSAEK). Retrospective review was conducted of 68 consecutive DSAEK procedures alone, or in combination with phacoemulsification with intraocular lens implantation or exchange, performed by two surgeons at the University of Texas Southwestern Medical Center between 2005 and 2009. Eyes that developed IOP elevation above 21 mm Hg after DSAEK and requiring initiation or escalation of glaucoma therapy were evaluated. Thirty-seven (54%) eyes showed IOP elevation responsive to medical treatment by a mean follow-up of 11.38 +/- 7.81 months. Six (8.8%) eyes required glaucoma surgery. In the eyes, which developed elevated IOP, gonioscopy did not reveal any new peripheral anterior synechiae formation. Prolonged topical steroid usage, rebubbling, combined DSAEK/cataract surgery, or repeat DSAEK were not significant factors (P>0.05) for development of elevated IOP, but history of previous glaucoma or ocular hypertension (OHTN) was significant (P=0.007). Intraocular pressure elevation is not uncommon in eyes after DSAEK, but most cases can be controlled with conservative management. Intraocular pressure elevation post-DSAEK occurred by mechanisms other than peripheral anterior synechial angle closure. The only significant risk factor for development of elevated IOP in our series was a previous history of glaucoma or OHTN.

Intraocular Pressure Elevation after Injection of Triamcinolone Acetonide: A Multicenter Retrospective Case-Control Study

To determine the risk factors for intraocular pressure (IOP) elevation after the injection of triamcinolone acetonide (TA). Retrospective interventional case-control study. Multicenter. Four hundred and twenty-seven patients. Intraocular pressure levels after TA treatment by the sub-Tenon capsule injection (STI; 12 mg, 20 mg, or 40 mg), intravitreal injection (IVI; 4 mg or 8 mg), or the combination of STI (20 mg) and IVI (4 mg), and IOP levels after two TA treatments. Risk factors for IOP levels of 24 mm Hg or higher. Younger age (hazards ratio [HR], 0.96/year; P < .0001), IVI (HR, 1.89/year; P < .0001), and higher baseline IOP (HR, 1.15/mm Hg; P = .003) were identified as risk factors. Dose dependency was shown in STI-treated eyes (HR, 1.07/mg; P = .0006), as well as after IVI (HR, 1.64/mg; P = .013). The combination of STI and IVI was a significant risk factor (HR, 2.27; P = .003) compared with STI alone. In eyes receiving two TA treatments, IVI (HR, 2.60; P = .010), higher IOP elevation after the first injection (HR, 1.18/mm Hg; P = .011), and increased dosage of STI (HR, 1.07/mm Hg; P = .033) were risk factors. Younger age, higher baseline IOP, IVI, and increased TA dosage were associated with TA-induced IOP elevation. IOP elevation after repeated TA injection was frequently associated with eyes treated with IVI, high IOP elevation after the first injection, and high doses of STI.

Risk factors for a postoperative intraocular pressure spike after phacoemulsification

Background: The aim of our study was to examine several potential risk factors for intraocular pressure (IOP) spikes 2 to 3 hours after phacoemulsification.Methods: 50 eyes of 50 consecutive patients undergoing uncomplicated phacoemulsification under topical anesthesia were included in this prospective study. The following variables were recorded:preoperative IOP, nuclear colour,cortical lens opacity,posterior subcapsular lens opacity,patient age;and presence or absence of preexisting glaucoma.Results: The mean IOP at each time interval was as follows: preoperatively, 14.5 (SD 3.4) mm Hg; 2–3 hours postoperatively, 23.1 (7.0) mm Hg; and 24 hours postoperatively, 17.0 (6.0) mm Hg. The postoperative IOP was significantly higher than baseline at 2–3 hours (p < 0.001) and at 24 hours (p = 0.002). Overall there were 10 cases (20%) of IOP spikes 2–3 hours postoperatively. Higher mean baseline IOP was significantly associated with postoperative IOP spikes (p = 0.013). Patient age, sex, operating surgeon, absolute phacoemulsification time, lens nuclear colour, cortical opacity, and posterior opacity were not significantly different between groups with or without an IOP spike (p > 0.05).Interpretation: Patients with high IOP at the preoperative assessment are more likely to have IOP spikes after surgery and should be scheduled at the start of the operating list. In a day-case setting with restricted opening hours, postoperative checks in those patients at risk of IOP spikes can then coincide with the time IOP reaches its peak.

Increases in Intraocular Pressure During Hemodialysis in Eyes During Early Postvitrectomy Period

To identify risk factors for intraocular pressure (IOP) increases during hemodialysis (HD) in the early postoperative period following pars plana vitrectomy (PPV). Comparisons of 36 vitrectomized eyes of 22 diabetics undergoing maintenance HD with those of 138 eyes of 69 nonoperated patients. Serial IOPs were measured before PPV, after PPV/before dialysis, and during dialysis. Serum osmolarity and blood pressure were also recorded. In 20 of 36 operated eyes (55.6%) and 18 of 138 nonoperated eyes (13.0%) IOP was increased (> or =4 mm Hg) during HD. In the operated group, marked increases (> or =7 mm Hg) were noted in 9 eyes and ocular pain in 5 eyes. Eyes with pre-existing outflow obstruction and/or acute postoperative outflow compromise carried high risks. No correlation with changes in serum osmolarity or blood pressure was found. Monitoring of IOP during HD seems warranted when diabetics with pre-existing outflow obstruction and/or postoperative outflow compromise, undergo HD following PPV.