Multilevel Surgery Research Articles

A PhD completed. Issues related to indication, surgery, and outcome of maxillomandibular advancement in obstructive sleep apnea

Obstructive sleep apnea is a common sleep-related breathing disorder. Although maxillomandibular advancement is widely recognized for its proven effectiveness, there are still uncertainties surrounding this procedure. This research therefore focused on the indication, surgical techniques, and outcomes of maxillomandibular advancement in patients with obstructive sleep apnea. A systematic review and meta-analysis showed that maxillomandibular advancement is more effective than multilevel surgery for the treatment of obstructive sleep apnea. Both maxillomandibular advancement and hypoglossal nerve stimulation were identified as effective and safe treatment methods for obstructive sleep apnea. Various retrospective studies also indicated that patients with hypopnea-dominant obstructive sleep apnea are better candidates for maxillomandibular advancement, in contrast to patients with cardiovascular diseases or a higher central apnea index. Furthermore, it was demonstrated that maxillomandibular advancement is effective in patients with a high percentage of central and mixed apneas, despite the potential surgical inaccuracies of maxillomandibular advancement, highlighting the broad applicability of this treatment method.

Effects of multilevel OSA surgery on patients with poor cardiopulmonary performance: A prospective pilot study

ObjectiveMultilevel airway surgery for obstructive sleep apnea/hypopnea syndrome (OSA) has benefits in improving sleep quality, but its effect on polysomnography (PSG) and 6-minute walk test (6MWT) parameters, including walking distance and cardiopulmonary performance, in patients with poor pre-operative cardiopulmonary performance remains understudied, which should be further investigated. MethodsThis prospective pilot study enrolled 27 consecutive OSA patients with poor pre-operative 6MWT results. All patients received multilevel OSA surgery, and the alterations of sleep parameters and 6MWT profiles were studied. The pre- and post-operative values of polysomnographic data and 6MWT profiles were analyzed using the Wilcoxon signed-rank tests. The relationships among changes of the indices of PSG and 6MWT were further investigated with the Spearman's correlations. ResultsAfter surgery, the sleep parameters and certain cardiopulmonary indices improved. When analyzing the correlations among changes of the indices of PSG and 6MWT, the improvement of daytime sleepiness (with ESS) was found related to farther walking distance (ρ=-0.414, p = 0.032) and higher percentage of “distance/target distance” (ρ=-0.435, p = 0.023). Moreover, the change of maximal expiratory pressure was the only index associated with the changes of AHI (apnea/hypopnea index, /hr.; ρ=-0.407, p = 0.035) and AHI in REM (ρ=-0.502, p = 0.009) among the cardiopulmonary performance parameters. ConclusionThis pilot study showed that OSA patients with poor pre-operative cardiopulmonary status undergoing multilevel sleep surgery could experience improvement in the sleep study and 6MWT to some extent. The relatively better walking distance and cardiopulmonary performance after the operation might potentially result from the improvement of daytime sleepiness and better respiration.

Physical Therapy Dose After Orthopedic Multilevel Surgery Varies by Ambulatory Status in Children With Cerebral Palsy: A Pilot Study.

To characterize physical therapy (PT) dose for children with cerebral palsy (CP) after multi-level surgery (MLS) and examine variation by ambulatory status and surgical burden. PT dose (Frequency, Intensity, Time, Type) data were extracted from electronic records of children with CP who received outpatient PT the year after MLS. Seventeen children, mean 9 years, female (n=10), ambulatory (n=10), and high surgical burden (n=12) were included. In the year after surgery, 345 visits occurred. Intensity across visits was above average. Time was greatest for pre-functional activities, gait, and transitions/transfers. Types most often delivered were neuromuscular, musculoskeletal, and education/training. Ambulatory children received significantly more visits, higher intensity, and time in pre-functional activities and gait than non-ambulatory children. No differences in type by ambulatory status and PT dose by surgical burden were found. PT dose varied the first year after MLS indicating the need for guidelines by ambulatory status. Supplemental Digital Content available at: http://links.lww.com/PPT/A516.

Impact of International Classification of Functioning, Disability and Health personal factors on outcomes following lower limb orthopaedic surgery in children with cerebral palsy: a systematic review

Purpose To investigate impact of International Classification of Functioning, Disability and Health (ICF) personal factors on pain, function, or quality of life following lower limb orthopaedic surgery in children with cerebral palsy (CP). Materials and methods Systematic review of prospective studies of lower limb orthopaedic surgery in children with CP reporting relationships between ICF personal factors, and pain, function, or quality of life. Results Eight prospective studies reporting various orthopaedic procedures (median follow-up 2.1 years) were eligible, but not sufficiently homogenous for meta-analysis. Functional outcomes most reported (n = 6), then pain (n = 3) and quality of life (n = 1). Personal factors were age (n = 3), sex (n = 4), child education (n = 1), and co-morbidities (n = 1). Older children had lower function (p < 0.01), and children in “special education” greater improvement in function compared to those in “regular” education (p = 0.001) post-single-event multi-level surgery (SEMLS). Age and sex not associated with function, pain, or quality of life post-single-joint procedures (p > 0.05), except females with higher pain intensity (p = 0.019) and lower function (p = 0.018) post-Schanz procedure. No association between sex and function post-SEMLS (p > 0.05). Conclusions Further prospective cohort studies are needed to understand the influence of personal factors identified in this review and investigate the effect of other personal factors on pain, quality of life, and function.

Dysphagia After Cervical Spinal Surgery: An Assessment of Incidence and Predisposing Factors

Background: Dysphagia is common following cervical spinal surgery (CSS) yet reported incidence and risk factors are highly heterogeneous. This case-control study aimed to determine the incidence of dysphagia after CSS and identify its predisposing factors. Methods: Records of 1199 patients who underwent CSS over a 2-year period at our center were reviewed. Patients with postoperative dysphagia and an equal number of randomly selected patients without dysphagia were included for analysis. Demographic, clinical, intraoperative, and perioperative factors were compared using univariate followed by multivariable logistic regression analysis. Results: The study population consisted of 94 (7.8%) patients with dysphagia and 94 controls. Patients with postoperative dysphagia were older [mean (SD) 60.7(12) vs 54.7(12), P = .002] and more likely to have preoperative dysphagia (16% vs 0%, P &lt; .001). No other demographic or clinical factors were significant. Mid-level (C3-4, C4-5) (66% vs 48%, P = .018) and multilevel surgeries (67% vs 50%, P = .026) were associated with dysphagia. No other intraoperative factors were significant. The presence of any (abscess, dehiscence, hematoma, CSF leak, prevertebral edema, esophageal, or vocal cord injury) perioperative complication (20% vs 3.2%, P &lt; .001) was associated with dysphagia, with dehiscence (6.5% vs 0%, P = .029) and hematoma (6.5% vs 0%, P = .029) showing the strongest association. Multivariable analysis identified age ≥70 [OR (95% CI): 2.8 (1-7), P = .031] and any perioperative complication [OR (95% CI): 6.7 (2-25), P = .004] as independent predictors of dysphagia. Conclusion: The incidence of dysphagia after cervical spine surgery is 7.8%. The risk of postoperative dysphagia is 6.7-times higher in those with perioperative complications and 2.8-times higher in patients over 70.

OTHR-12 INCIDENCE, CLINICAL PRESENTATION, MANAGEMENT AND ONE- AND TWO-YEAR SURVIVAL OF PATIENTS WITH MEDULLOBLASTOMA AT INKOSI ALBERT LUTHULI CENTRAL HOSPITAL, KWAZULU NATAL PROVINCE: A TEN YEAR REVIEW

Abstract OBJECTIVE Epidemiology, clinical presentation, stage and multidisciplinary treatment modalities for Medulloblastoma (Mb) at Inkosi Albert Luthuli Central Hospital (IALCH) for the 10 year period from 2003 to 2012. It also evaluated the 1 and 2 year survival rate. Methodology: Single center- retrospective study of Mb patients below the age of 18 years in a low and middle income country (LMIC) setting. RESULTS The 30 patients included in the study, median age was 9 years. Male to female ratio of 1.3:1. 70% were black race. Average incidence was 14 per 1000 children years. Headache was most common symptom in 70% of the patients. Majority presented with advanced non metastatic disease (T3b). All patients had shunt insertion prior to debulking surgery and 60% had gross total resection. More than half of the cases had reduced dose irradiation (30.6Gy) to the cranial and spinal compared to 36% who had 36Gy. 96% received concurrent vincristine with radiotherapy. 89.7% received adjuvant chemotherapy and 82.8% completed 6 cycles. There was not enough data to determine any trends in the different modalities of treatment offered over the period of 10 years. One year survival rate was 83.33% [95% CI 64.55; 93.70%] and probability of surviving two years was 80.00% [95% CI 60.87%; 91.60%]. CONCLUSION Children present with advanced stages requiring multi-level surgeries. Dedicated multi-disciplinary approach to treatment conferred decent survival outcomes despite the advanced stages at presentation. Similar successes were reflected in the only other study on the subject in Cape Town in a 3 decade retrospective study between the years 1985-2005. These studies highlight the importance of implementing multidisciplinary team management in parallel with modern radiotherapy techniques to improve survival for children with medulloblastoma. Current training programs like Access to Care Capetown could further improve the outcome in countries establishing or transitioning to new radiotherapy techniques.

Long-term Outcomes of Multilevel Surgery in Adults with Cerebral Palsy: A Prospective Study

Long-term Outcomes of Multilevel Surgery in Adults with Cerebral Palsy: A Prospective Study

Psoas attenuation is associated with early postoperative complications in geriatric patients undergoing multilevel lumbar fusion surgery for degenerative lumbar spinal stenosis

BackgroundMorphometric analysis of the psoas major muscle has shown utility in predicting postoperative morbidity in various surgical fields, but its usefulness in predicting complications in elderly patients undergoing multilevel lumbar fusion surgery has not been studied. The study aimed to investigate if psoas major parameters are independent risk factors of early postoperative complication among elderly patients.MethodsPatients who underwent multilevel lumbar fusion for degenerative lumbar spinal stenosis (DLSS) were included. The psoas major was measured at the lumbar 3/4 intervertebral disc level in three ways on computed tomography image: psoas muscle mass index, mean muscle attenuation, and morphologic change of the psoas major. Early complications were graded using the Clavien-Dindo classification system and the Comprehensive complication index (CCI). A CCI ≥ 26.2 indicated severe complications. Logistic regression was performed to identify independent risk factors.ResultsThis retrospective study reviewed 108 patients (mean age 70.9 years, female to male ratio 1.8:1). Complications were observed in 72.2% of patients, with allogeneic blood transfusion being the most frequent (66.7%), followed by wound infection, acute heart failure (2.8% each). Severe complications occurred in 13.9% of patients. After multivariable regression analysis, those in the lowest psoas muscle attenuation tertile had higher odds of experiencing early postoperative complications (OR: 3.327, 95% CI 1.134–9.763, p = 0.029) and severe complications (OR: 6.964, 95% CI 1.928–25.160, p = 0.003).ConclusionThe psoas muscle attenuation can be used as a predictor of early postoperative complications in elderly patients undergoing multilevel lumbar fusion surgery for DLSS.

P182. Age as a criterion in multilevel posterior cervical fusion surgery: a propensity scored analysis

P182. Age as a criterion in multilevel posterior cervical fusion surgery: a propensity scored analysis

Lingual Tonsillectomy as Part of a DISE-Directed Multilevel Upper Airway Surgery to Treat Complex Pediatric OSA: A Safe and Appropriate Procedure.

To study the efficiency of lingual tonsillectomy (LT) as part of multilevel surgery in children with complex obstructive sleep apnea (OSA). To evaluate the safety and the outcomes of LT. Retrospective case series. Pediatric tertiary care academic center. We included all children operated for LT to treat complex OSA, from January 2018 to June 2022. All patients underwent a protocolized drug-induced sleep endoscopy (DISE) followed by a coblation LT, associated with the treatment of all other obstructive sites. Patient demographics, medical history, surgery, and outcomes were reviewed. The efficiency of LT was analyzed exclusively in patients with a preoperative and postoperative sleep study. One hundred twenty-three patients were included. Median age was 8 years (interquartile range, IQR [3-12]). Sixty-five (53%) patients had Down syndrome, 22 (18%) had a craniofacial malformation, and 8 (7%) were obese. LT was associated with adenoidectomy (n = 78, 63%), partial tonsillectomy (n = 70, 57%), inferior turbinoplasty/turbinectomy (n = 59, 48%), epiglottoplasty (n = 92, 75%), and/or expansion pharyngoplasty (n = 2, 2%). Eighty-nine patients underwent a sleep study before and after surgery. The median apnea-hypopnea index (AHI) decreased from 18 events/h (IQR [9-36]) before surgery to 3 events/h (IQR [1-5]) after surgery (P < .001) (patients with a postoperative AHI <1.5 events/h, n = 31, 35%, and an AHI <5 events/h, n = 32, 36%). Seventeen out of 30 (57%) patients could be weaned from continuous positive airway pressure after surgery. Two patients had a postoperative hemorrhage and 2 patients required a transient postoperative reintubation. In children with complex OSA, LT as part of a DISE-directed multilevel upper airway surgery, was a very efficient and safe procedure.

Impact of Predictive Hemodynamic Monitoring on Intra-operative Hypotension and Postoperative Complications in Multi-level Spinal Fusion Surgery

Impact of Predictive Hemodynamic Monitoring on Intra-operative Hypotension and Postoperative Complications in Multi-level Spinal Fusion Surgery

Biomechanical Effects on the Prostheses and Vertebrae of Three-Level Hybrid Surgery: A Finite Element Study.

Three-level hybrid surgery (HS) consisting of cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF) has been partly used for the treatment of multi-level cervical degenerative disc disease (CDDD). The complications related to the implants and the collapse of the surgical vertebral bodies had been reported in multi-level anterior cervical spine surgery. Thus, this study aimed to explore the biomechanical effects on the prostheses and vertebrae in three-level HS. A FE model of cervical spine (C0-T1) was constructed. Five surgical models were developed. They were FAF model (ACDF-CDA-ACDF), AFA model (CDA-ACDF-CDA), FFF model (three-level ACDF), SF model (single-level ACDF), and SA model (single-level CDA). A 75-N follower load and 1.0-N·m moment was applied to produce flexion, extension, lateral bending, and axial rotation. Compared with the intact model, the range of motion (ROM) of total cervical spine in FAF model decreased by 34.54%, 54.48%, 31.76%, and 27.14%, respectively, in flexion, extension, lateral bending, and axial rotation, which were lower than those in FFF model and higher than those in AFA model. The ROMs of CDA segments in FAF and AFA models were similar to the intact model and SA model. Compared with the intact model, the ROMs at C3/4 segment in FFF model increased from 5.71% to 7.85%, and increased from 5.31% to 6.81% at C7/T1 segment, following by FAF model, then the FAF model. The maximum interface pressures of the Prestige-LP in FAF model were similar to SA model, however the corresponding values were increased in AFA model. The maximum interface pressures of the Zero-P were increased in FAF and AFA model compared with those in SF and FFF models. The stress was mainly distributed on the screws. In AFA model, the maximum pressures of the ball and trough articulation in superior and inferior Prestige-LP were all increased compared with those in SA and FAF model. In FFF model, the maximum pressures of the vertebrae were higher than those in other models. The stress was mainly distributed on the anterior area of the vertebral bodies. HS seemed to be more suitable than ACDF for the surgical treatment of three-level CDDD in consideration of the biomechanical effects, especially for the two-level CDA and one-level ACDF construct. But a more appropriate CDA prosthesis should be explored in the future.

Outcomes and Predictors of Success Following Multilevel Surgery in Positional and Nonpositional Obstructive Sleep Apnea.

To assess the surgical outcomes and identify predictors of surgical success in patients with positional and non-positional obstructive sleep apnea following multilevel airway surgery. Retrospective cohort study. Singe-tertiary medical center. This study included 158 patients with obstructive sleep apnea who underwent multilevel airway surgery. Patients were divided into 2 groups according to position dependency: "positional patients" group (n = 100), and "nonpositional patients" group (n = 58). The characteristics and surgical outcomes of the 2 groups were compared. The nonpositional group included younger and more obese patients in comparison to the positional group. Moreover, the nonpositional group had more severe disease than the positional group. Both groups showed overall improvement after surgery, and the surgical success rate did not differ significantly between the 2 groups (nonpositional, 41.4% vs positional, 48.0%; P = .424). Notably, 69.0% of patients belonging to the non-positional group converted to positional group postoperatively. Logistic regression analysis revealed that larger tonsil size, female sex, and higher mean O2 saturation were associated with higher success rate in the positional group, whereas larger tonsil size was associated with surgical success in the nonpositional group. Both nonpositional and positional groups showed improvements following multilevel airway surgery, and surgery induced a transition from nonpositional to positional group. Given that the factors related to surgical success differed between the two groups, surgeons should consider position dependency and these distinct factors during decision-making.

General Rehabilitation Principles for Patients with Cerebral Palsy After Single-Event Multilevel Surgery (SEMLS)

Single-Event Multilevel Surgery (SEMLS) is the standard for surgical correction of secondary orthopedic deformities in cerebral palsy (CP). SEMLS include simultaneous correction of soft tissue contractures, bone deformities, incomplete and complete joint dislocation to improve the gait and functional activity of patients with CP. The surgery volume determines the need for planned and long-term postoperative rehabilitation, however, there are no confirmed guidelines, neither Russian, nor foreign, on the patient’s management during postoperative period. This review provides an analysis of rehabilitation approaches after SEMLS at CP, offers recommendations on preparation and step-by-step postoperative restoration of motor function, and prevention of any associated complications.

Opioid-Obviating Analgesia for Adolescent Multilevel Spinal Fusion Surgery: A Problem-Based Learning Discussion.

A female teenager with a history of polysubstance use, including a recent overdose, is scheduled for multilevel posterior spinal fusion surgery due to idiopathic scoliosis and has asked to avoid the use of opioids in the context of her upcoming surgery. This problem-based learning discussion (PBLD) focuses on the examination of the care of a spinal fusion patient that allowed for the successful provision of opioid-obviating care.

Retrospective evaluation of radiofrequency volumetric tissue reduction for hypertrophic turbinates in dogs with brachycephalic obstructive airway syndrome.

The objective of this study was to retrospectively assess the effect of Radiofrequency Volumetric Tissue Reduction (RFVTR) on hypertrophic turbinates and clinical outcome in brachycephalic dogs when included in multi-level surgery (MLS). Clinical retrospective multicenter study. 132 client-owned brachycephalic dogs. 132 brachycephalic dogs with high-grade Brachycephalic Obstructive Airway Ayndrome (BOAS) and hypertrophic turbinates were treated with RFVTR as part of MLS of the upper airways. Intranasal obstruction was evaluated by computer tomography (CT) and antero-/retrograde rhinoscopy before and 6 months after RFVTR. The clinical records, the CT images and the rhinoscopy videos were reviewed and clinical evolution was evaluated using a standardized questionnaire. The data was scored semi-quantitatively. In this study, 132 patients were included for a follow-up period of 120 weeks. RFVTR resulted in minor complications, including serous nasal discharge within the first postoperative week in all dogs, and intermittent nasal congestion between 3-8 weeks after treatment in 24.3% of the patients. Rhinoscopy and CT follow-ups were available for 33 patients. Six months after treatment intranasal airspace was increased (p = 0.002) and the presence and overall amount of mucosal contact points was reduced (p = 0.039). MLS with RFVTR led to a significant reduction in turbinate volume at the 6-month follow-up examination and significant clinical improvement over a long-term period of 120 weeks. This suggests the viability of RFVTR as a turbinate-preserving treatment for intranasal obstruction in dogs with BOAS. RFVTR is a minimally invasive turbinoplasty technique for intranasal obstruction in dogs with BOAS and can be included in MLS without increasing complication rates.

Does Screw Number of Zero-profile Implants in Fusion Segment Influence Intervertebral Stability?

The unclear clinical outcomes of two different zero-profile implants with different number of screws in hybrid surgery restricts the choice of patient-specific implants. This study aims to compare two different implants on its postoperative subsidence, motion stabilization and clinical outcomes. It also provides references to the most reasonable implant choice in fusion surgery. This was a retrospective study. From February 2014 to March 2022, 173 patients who underwent hybrid surgery were included. Among them, 122 received surgery with a four screw implant, while 51 received a two screw implant. We analyzed the significance of patient-specific factors, radiographic factors and clinical outcomes. The Wilcoxon rank sum test, t tests/analysis of variance (ANOVA) test and stepwise multivariate logistic regression were adopted for statistical analysis. No statistically significant difference was observed between the two screw and four screw groups in terms of immediate, middle, and long-term stability and fusion rate (p > 0.05). However, the two screws group had higher FSU height subsidence at 3, 6, and 12 months postoperatively and higher rates of significant subsidence at three and 6 months postoperatively (p < 0.05). Both groups showed significant clinical improvements at the final follow-up. Two screw and four screw implants provide comparable stability, fusion rates and clinical outcomes. However, the two screw implant was inferior to the four screw implant in subsidence prevention. Therefore, the two-screw implant is non-inferior to the four-screw implant in most patients. It can be used as the priority choice in the fusion segment by its easy manageability. However, the patients with a high risk of subsidence such as multilevel surgery, the elderly, lower BMD, bad cervical alignment should receive a four screw implant rather than a two screw implant.

Adult Obstructive Sleep Apnea: A Practical Guide for the Allergist

Obstructive sleep apnea (OSA) is a common sleep disorder, affecting 15-30% of males and 10-15% of females in North America. OSA is characterized by the recurrent obstruction of the upper airway during sleep resulting in apneas and hypopneas. OSA can be diagnosed using a home sleep apnea test (i.e., a level 3 sleep study) or a polysomnogram (PSG) (i.e., a level 1 study or PSG) in a supervised sleep laboratory which quantifies the number of apneas and hypopneas per hour using the apnea-hypopnea index (AHI). In broad terms, the diagnosis is made when an individual with symptoms or cardiac risk factors has an AHI of ≥5, or an asymptomatic individual has an AHI of ≥15. Continuous Positive Airway Pressure (CPAP) is considered the first-line treatment of OSA. Other treatment options include an oral appliance called a mandibular advancement device, or multilevel surgery of the upper airway, especially uvulopalatopharyngoplasty (UPPP). Herein we review OSA in the context of conditions commonly observed in the allergy clinic, namely asthma, chronic rhinosinusitis, rhinitis, and contact dermatitis.

Opioid-free versus opioid-based anesthesia in major spine surgery: a prospective, randomized, controlled clinical trial.

Major spine surgery is associated with severe postoperative pain and increased opioid consumption. Opioid-free anesthesia (OFA) is thought to provide adequate intraoperative analgesia with reduced postoperative opioid consumption. The aim of this study is to compare the impact of intraoperative OFA approach to the conventional opioid-based anesthesia (OBA) on postoperative pain, opioid consumption, and related side effects in patients undergoing multilevel spinal fusion surgery. Forty-eight patients undergoing elective major spine surgery were randomly allocated to either receive intraoperative dexmedetomidine and lidocaine (OFA group) or fentanyl during induction and intraoperative remifentanil (OBA group). All patients received intraoperative sevoflurane, propofol, rocuronium, ketamine, dexamethasone, ondansetron and postoperative paracetamol and patient-controlled analgesia device set to deliver intravenous morphine for 48 hours after surgery. Postoperative pain was measured using numerical rating scale. Opioid side effects were documented, when present. OFA group required less morphine in the first 24 hours post-surgery (17.28±12.25 mg versus 27.96±19.75 mg, P<0.05). The incidence of postoperative nausea and vomiting (PONV) was significantly lower in the OFA group. More patients in the OFA group required antihypertensive medications compared to patients in the OBA group (P<0.05). In the post anesthesia care unit, OFA patients had a significantly longer stay than OBA patients (114.1±49.33 min versus 89.96±30.71 min, P<0.05). OFA can be an alternative to OBA in patients undergoing multilevel spine fusion surgery. OFA reduces opioids consumption in the first 24 hours and PONV.

Intra-Operative Hypotension is an Important Modifiable Risk Factor for Major Complications in Spinal Fusion Surgery.

Retrospective observational cohort. This study explores the impact of Intraoperative hypotension (IOH)on post-op complications for major thoracolumbar spine fusion procedures. IOH with mean arterial pressure (MAP) < 65mmHg is associated with post-op acute kidney injury (AKI) in general surgery. In spinal deformity surgery, IOH is a contributing factor to MEP changes and spinal cord dysfunction with deformity correction. 539 thoracolumbar fusion cases, > 6 surgical levels and > 3 hours duration were identified. Anesthetic/surgical data included OR time, fluid volume, blood loss, blood product replacement and use of vasopressors. Arterial-line based MAP data was collected at 1 min intervals. Cummulative duration of MAP < 65mmHg was recorded. IOH within the first hour of surgery vs. the entire case was determined. Post-op course and complications including SSI, GI complications, pulmonary complications, MI, DVT, PE, AKI and encephalopathy were noted. Cumulative complications were grouped as none, 1-2 complications, or >3 complications. There was a significant association between occurrence of complications and duration of IOH within the first hour of surgery (8.2 vs. 5.6 min, P<0.001) and across the entire procedure (28.1 vs. 19.3 min, P=0.008). This association persisted for individual major complications including SSI, acute respiratory failure, PE, ileus requiring NGT and post-operative cognitive dysfunction. Comparison of patients with 0 vs. 1-2 vs. 3 or more complications demonstrated that patients with 3 or more complications had a longer duration of IOH in the first hour of the surgery and that patients who had no complications received less vasopressor than patients who had 1-2 or 3 or more complications. This study identifies duration of IOH during the first hour of surgery as a previously unrecognized modifiable risk associated with major complications for multi-level lumbar fusion surgery.