Neil G Parry

London Health Sciences Centre, London, Ontario, Canada

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Publications (18)38.06 Total impact

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    ABSTRACT: Abdominal compartment syndrome (ACS) is associated with an increased rate of multiple organ dysfunction and is an independent marker for mortality. Our objective was to develop an animal model to study the mechanisms of tissue and microvascular injury associated with ACS at the microscopic level. ACS was established in rats with CO2 insufflation at 20 mm Hg for 2 h, with an abdominal cast. Sinusoidal perfusion, inflammatory response, and cell death were quantified in exteriorized livers. Respiratory and renal dysfunction were assessed biochemically and morphologically. Myeloperoxidase levels, a marker of neutrophil activation, were measured in the liver, lung, and small intestine. Continuously perfused sinusoids were significantly lower in the ACS group (81.4 ± 2.2% versus 99.6% ± 0.50), with an increase in nonperfused and intermittently perfused sinusoids (P < 0.05). Hepatocellular death and the number of activated leukocytes in postsinusoidal venules showed 7- and 18-fold increases, respectively, in the ACS group (P < 0.05). A significant increase in blood urea nitrogen levels in experimental rats was also observed. Myeloperoxidase levels were found to be 8-fold higher in lungs of ACS rats relative to control (P < 0.05), as well as statistically significant increase in the pCO2 and decrease in pH of ACS rats. We have successfully developed a model of ACS with documented evidence of renal and respiratory dysfunction. In addition, we have microscopy-confirmed evidence of early inflammatory changes and perfusion deficits in the liver with a concomitant increase in cell death in the ACS group. Copyright © 2015 Elsevier Inc. All rights reserved.
    Journal of Surgical Research 04/2015; 197(2). DOI:10.1016/j.jss.2015.04.049
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    ABSTRACT: Loss to follow-up (LTFU) can be a major difficulty for any clinical research study. The objective of this systematic review was to assess the extent of LTFU and its potential effect in studies of adult trauma patients with blunt thoracic aortic injuries (BTAIs). Studies comparing management of BTAIs were systematically reviewed. Duplicate independent review was used for study selection, data abstraction, and critical appraisals. Thirty-six studies were included for synthesis, of which 94.1% applied a retrospective cohort design to prospective institutional databases. The mean LTFU at 1 year was 26.5% ± 31.6% for endovascular repair and 20.6% ± 34.2% for open repair groups. Not having a surgical/interventional specialist as a first or senior author was associated with a 39.7% higher LTFU at 1 year (P = .002). Studies with a higher risk of bias, later publication year, or North American origin were associated with a significantly higher risk for LTFU at 1 year (P ≤ .001). Nearly half of included studies assessed in-hospital outcomes exclusively. Only 38.2% explicitly reported LTFU data. Eight studies explicitly described the method of dealing with LTFU: eight used survival analysis and one used a national Social Security Death Index. Sensitivity analyses using plausible worst-case LTFU scenarios resulted in 14% to 17% of studies changing direction of effect. There is significant LTFU in trauma studies comparing operative methods for BTAIs. LTFU is generally handled and reported suboptimally, and sensitivity analyses suggest that study results are sensitive to differential LTFU. This has implications for the evidence-based choice of the operative method. Some protective factors that may aid in reducing LTFU were identified, one of which was involvement of a surgical or interventional specialist as a key author. Copyright © 2015 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
    Journal of Vascular Surgery 03/2015; 61(6). DOI:10.1016/j.jvs.2015.02.017
  • Journal of Vascular Surgery 11/2014; 60(5):1401. DOI:10.1016/j.jvs.2014.08.022
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    ABSTRACT: Delayed splenic rupture is the Achilles' heel of nonoperative management (NOM) for blunt splenic injury (BSI). Early computed tomographic (CT) scanning for features suggesting high risk of nonoperative failure, splenic pseudoaneurysms (SPAs), and arterial extravasation (AE), in concert with the appropriate use of splenic arterial embolization (SAE) is a viable method to reduce rates of failure of NOM. We report our 12-ear experience with a protocol for mandatory repeat CT evaluation at 48 hours and selective SAE.
    Journal of Trauma and Acute Care Surgery 06/2014; 76(6):1349-53. DOI:10.1097/TA.0000000000000228
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    ABSTRACT: Previous studies have identified missed injuries as a common and potentially preventable occurrence in trauma care. Several patient- and injury-related variables have been identified, which predict for missed injuries; however, differences in rate and severity of missed injuries between surgeon and nonsurgeon trauma team leaders (TTLs) have not previously been reported. A retrospective review was conducted on a random sample of 10% of all trauma patients (Injury Severity Score [ISS] > 12) from 1999 to 2009 at a Canadian Level I trauma center. Missed injuries were defined as those identified greater than 24 hours after presentation and were independently adjudicated by two reviewers. TTLs were identified as either surgeons or nonsurgeons. Of our total trauma population of 2,956 patients, 300 charts were randomly pulled for detailed review. Missed injuries occurred in 46 patients (15%). Most common missed injuries were fractures (n = 32, 70%) and thoracic injuries (n = 23, 50%). The majority of missed injuries resulted in minor morbidity with only 5 (11%) requiring operative intervention. On univariate analysis, higher ISS (p < 0.01), higher maximum Abbreviated Injury Scale (MAIS) score of the thorax (p < 0.01), and nonsurgeon TTL status were predictive of missed injuries (p = 0.02). Multivariable logistic regression revealed that, after adjustment for age, ISS, and severe head injuries, the presence of a nonsurgeon TTL was associated with an increased odds of missed injury (odds ratio, 2.15; 95% confidence interval, 1.10-4.20). Missed injuries occurred in 15% of patients. A unique finding was the increased odds of missed injury with nonsurgeon TTLs. Further research should be undertaken to explore this relationship, elucidate potential causes, and propose interventions to narrow this discrepancy between TTL provider types. Therapeutic study, level IV. Prognostic and epidemiologic study, level III.
    09/2013; 75(3):387-390. DOI:10.1097/TA.0b013e31829cfa32
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    ABSTRACT: Blunt thoracic aortic injury (BTAI) is associated with high mortality. Recent Society for Vascular Surgery (SVS) guidelines recommend repair of all but SVS grade I injuries. This study's objective was to retrospectively determine guideline adherence at the authors' trauma center, and its impact on mortality. A retrospective review of the trauma database at the authors' university-affiliated trauma center identified and graded all BTAIs between 1999 and 2011. Patient demographics, treatment, and outcomes were recorded. Imaging was available for 52 of 59 (85.2%) patients with BTAI. For these 52 patients, injury distribution was: 14 (27.0%) grade 1; 1 (1.9%) grade 2; 35 (67.3%) grade 3; and 2 (3.8%) grade 4. Nonoperative management was used for 92.8% (13), 100% (1), 34.3% (12), and 0% of grade 1, 2, 3, and 4 injuries, respectively. The operatively managed grade I injury was initially misclassified as grade 3. He was lost to follow-up after discharge. Of the 12 patients with nonoperatively managed grade 3 injuries, 7 (58.3%) died before consideration of endovascular repair and another died early secondary to brain injury. The remaining 4 (11.4%) with nonoperatively managed grade 3 injuries survived to discharge but were lost to follow-up. For grade 3 injuries, endovascular repair was significantly associated with decreased mortality (odds ratio [OR], 0.10; 0.02-0.53; P = 0.007). Exclusion of those with presentation-day mortality negated this significant association (OR, 0.84; 0.07-9.68; P = 1.00). Minor deviation (9.6%) from guidelines did not result in additional morbidity/mortality. However, a high rate of loss to follow-up limits conclusions. The mortality reduction seen with endovascular repair for grade 3 injury is inflated by patients who die before repair is considered in the nonoperative group. Larger prospective studies with appropriate inclusion and exclusion criteria and improved follow-up are needed to determine the consequences of selective nonoperative management of these injuries.
    Annals of Vascular Surgery 06/2013; 27(8). DOI:10.1016/j.avsg.2012.09.017
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    ABSTRACT: This study was undertaken to determine if, amongst civilian trauma patients requiring massive transfusion (MT), the use of a formal trauma transfusion pathway (TTP), in comparison with transfusion without a TTP, is associated with a reduction in mortality, or changes in indices of coagulation, blood product utilisation and complications. A systematic review of three bibliographic databases, reference lists and conference proceedings was conducted. Studies were included if comparisons were made between patients receiving transfusion with and without a TTP. Data were extracted by two independent reviewers on population characteristics, transfusion strategies, blood product utilisation, indices of coagulation, clinical outcomes and complications. Data were pooled using a random effects model and heterogeneity explored. Seven observational studies met all eligibility criteria. Amongst 1801 patients requiring MT, TTPs were associated with a significant reduction in mortality (RR 0·69, 95% CI 0·55, 0·87). No significant increase in the mean number of PRBC transfused between TTP and control patients was seen (MD -1·17 95% CI -2·70, 0·36). When studies assessing only trauma patients were considered, TTPs were associated with a reduction in the mean number of units of plasma transfused (MD -2·63, 95% CI -4·24, -1·01). In summary, the use of TTPs appears to be associated with a reduction in mortality amongst trauma patients requiring MT without a clinically significant increase in the number of PRBC transfused and a potential reduction in plasma transfusion. Effects of TTPs on platelet transfusion, indices of coagulation and complications remain unclear. A randomised controlled trial is warranted.
    Transfusion Medicine 04/2012; 22(3):156-66. DOI:10.1111/j.1365-3148.2012.01150.x
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    ABSTRACT: Pulmonary embolisms (PE) are an often preventable cause of late morbidity and mortality after trauma. Although there is evidence for the use of therapeutic inferior vena cava (IVC) filters (defined as IVC filters implanted in those with proven deep venous thrombosis [DVT] in order to prevent PE), there is not as much evidence to support the use of prophylactic IVC filters. Thus, we undertook a systematic review of the literature to assess the following in prophylactic IVC filters: efficacy in PE reduction, prevalence of filter-related complications and the indications for use. After screening 249 studies, 24 studies met inclusion criteria for qualitative synthesis. Overall, the literature is supportive of the use of prophylactic IVC filters in high-risk poly-trauma patients who may have contraindications to DVT prophylaxis. Filter-associated complications are uncommon and, when they do occur, tend to be of limited clinical significance. Limited data, mostly in the form of case series, supports a reduction in PE and PE-related mortality. There has been increasing use of retrievable filters as well as the ability to safely retrieve them at longer intervals. Despite the addition of a few matched-control studies, the literature is still plagued by a lack of high quality data, and therefore the true efficacy of prophylactic IVC filters for prevention of PE in trauma patients remains unclear. Further studies are required to determine the true role of prophylactic IVC filters in trauma patient.
    Injury 03/2012; 43(5):542-7. DOI:10.1016/j.injury.2012.01.020
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    ABSTRACT: There is a paucity of research on substance use in the pediatric trauma population. This study aims to describe trends in substance use and screening in the Canadian pediatric trauma population. A retrospective review of the London Health Sciences Centre trauma database from April 1999 to January 2009 identified patients less than 18 years old admitted after major trauma [injury severity score (ISS) > 12]. Data extracted included age, gender, ISS, blood alcohol concentration (BAC), and results of toxicology screens. BAC data were available for 799 patients and toxicology screens for 761 patients. BAC testing was completed in 30% (21% positive). Toxicology screens were completed in 7% (44% positive). Increasing age was associated with screening for alcohol (odds ratio = 1.4; 95% confidence interval 1.3-1.5). Screening for drug use had a bimodal distribution, with no children aged 4-10 years screened. Those screened for drugs and alcohol had a significantly higher ISS than those not tested (BAC 28 versus 23, P < 0.001, toxin screening 29 versus 24, P = 0.003). The most common ingestions were alcohol, benzodiazepines, cannabinoids, and opiates. Screening for drugs and alcohol is sporadic in the pediatric trauma population. Further study utilizing a universal approach to drug and alcohol screening is needed to further delineate the true prevalence of substance use in this population.
    Therapeutic drug monitoring 08/2011; 33(4):439-42. DOI:10.1097/FTD.0b013e318222d951
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    ABSTRACT: Acute compartment syndrome (CS) is a limb-threatening disease that results from increased intracompartmental pressure. The pathophysiologic mechanisms by which this occurs are poorly understood. This study was designed to measure the effects of increased intracompartmental pressure on skeletal muscle microcirculation, inflammation and cellular injury using intravital videomicroscopy (IVVM) in a clinically relevant small animal model. We induced CS in 10 male Wistar rats (175-250 g), using a saline infusion technique. Intracompartmental pressure was controlled between 30 and 40 mm Hg and maintained for 45 minutes. After fasciotomy, the extensor digitorum longus muscle was visualized using IVVM, and perfusion was quantified. We quantified leukocyte recruitment to measure the inflammatory response. We measured muscle cellular injury using a differential fluorescent staining technique. The number of nonperfused capillaries increased from 12.7 (standard error of the mean [SEM] 1.4 ) per mm in the control group to 30.0 (SEM 6.7) per mm following 45 minutes of elevated intracompartmental pressure (CS group; p = 0.031). The mean number of continuously perfused capillaries (and SEM) decreased from 78.4 (3.2) per mm in the control group to 41.4 (6.9) per mm in the CS group (p = 0.001). The proportion of injured cells increased from 5.0% (SEM 2.1%) in the control group to 16.3% (SEM 6.8%) in the CS group (p = 0.006). The mean number of activated leukocytes increased from 3.6 (SEM 0.7) per 100 μm(2) in the control group to 8.6 (SEM 1.8) per 100 μm(2) in the CS group (p = 0.033). Early CS-induced microvascular dysfunction resulted in a decrease in nutritive capillary perfusion and an increase in cellular injury and was associated with a severe acute inflammatory component.
    Canadian journal of surgery. Journal canadien de chirurgie 04/2011; 54(3):194-200. DOI:10.1503/cjs.048309
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    ABSTRACT: Indomethacin may preserve tissue viability in compartment syndrome. The mechanism of improved tissue viability is unclear, but the anti-inflammatory effects may alter the relative contribution of tissue necrosis versus apoptosis to cellular injury. Existing studies have only considered indomethacin administration before induction of elevated intracompartment pressure. The purpose of this study was to determine the effect of timing of indomethacin administration on muscle damage in elevated intracompartment pressure and to assess apoptosis as a cause of tissue demise. Twenty-four Wistar rats were randomized to elevated intracompartmental pressure (EICP) for either 45 or 90 minutes (30 mmHg). In the 45-minute cohort, indomethacin was withheld in Group 1 (CS45), given before induction of EICP in Group 2 (CS45Indo0), or given after 30 minutes of EICP/15 minutes before fasciotomy in Group 3 (CS45Indo30). In the 90-minute cohort, indomethacin was withheld in Group 4 (CS90) or given after 30 or 60 minutes of EICP in Groups 5 (CS90Indo30) and 6 (CS90Indo60). Intravital microscopy and fluorescent staining assessed capillary perfusion, cell damage, and inflammatory activation within extensor digitorum longus muscle. Apoptosis was assessed using spectrophotometric assessment of caspase levels. Groups 1 to 3 and 4 to 6 were compared using analysis of variance with P < 0.05 deemed significant. Perfusion and tissue viability improved in indomethacin-treated groups. Nonperfused capillaries decreased from Group 1 (CS45) (50.1 +/- 2.5) to Group 2 (CS45Indo0) (38.4 +/- 1.8) and Group 3 (CS45Indo30) (14.13 +/- 1.73) (P < 0.05). Similarly, Group 5 (CS90Indo30) and Group 6 (CS90Indo60) had 25% fewer nonperfused capillaries compared with Group 4 (CS90) (P < 0.0001). Group 2 (CS45Indo0) and Group 3 (CS45Indo30) showed fewer damaged cells (1% +/- 0.5% and 8.7% +/- 2%) compared with Group 1 (CS45) (20% +/- 14%) (P < 0.0001). Group 5 (CS90Indo30) showed decreased cell damage (13% +/- 1%) compared with Group 4 (CS90) (18% +/- 1%) (P < 0.01). Group 6 (CS90Indo60) also showed decreased cell damage (11% +/- 1%) compared with Group 4 (CS90) (18% +/- 1%); however, this difference was not significant (P > 0.05). Apoptotic activity was present with elevated intracompartment pressure. At 30 minutes, there were elevated caspase levels in Group 4 and Group 6 EICP groups (0.47 +/- 0.08) compared with control subjects (0.19 +/- 0.02) (P < 0.003). However, indomethacin-treated groups did not differ from control subjects with regard to caspase levels (P > 0.05). Indomethacin decreased cell damage and improved perfusion in elevated intracompartment pressure. The benefits of indomethacin were partially time-dependent; some improvement in tissue viability occurred regardless of timing of administration. Although apoptosis was common in elevated intracompartment pressure, the protective effect of indomethacin does not appear to be related to apoptosis. Adjuvant treatment with indomethacin may improve outcome in compartment syndrome.
    Journal of orthopaedic trauma 09/2010; 24(9):526-9. DOI:10.1097/BOT.0b013e3181f2247e
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    ABSTRACT: Gastric volvulus can occur along the organoaxial axis or the mesenteroaxial axis. We present a patient with a gastric bascule: a gastric volvulus due to two lead points. A 17-year-old boy with dextrogastria, asplenia, and left diaphragmatic eventration presented with acute onset of nonbilious emesis, jaundice, and diffuse abdominal tenderness. Surgical exploration demonstrated a gastric volvulus, with lead points of torsion at the gastroesophageal junction and the second part of the duodenum, causing biliary obstruction. After decompression, reduction, and gastropexy, the patient recovered well. Gastric bascule is a subtype of gastric volvulus, whereby two lead points cause gastric rotation and folding of the stomach upon itself.
    The Annals of thoracic surgery 03/2010; 89(3):e15-6. DOI:10.1016/j.athoracsur.2009.12.026
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    ABSTRACT: Heme oxygenase (HO) represents the rate-limiting enzyme in the degradation of heme into carbon monoxide (CO), iron, and biliverdin. Recent evidence suggests that several of the beneficial properties of HO, may be linked to CO. The objectives of this study were to determine if low-dose inhaled CO reduces remote intestinal leukocyte recruitment, proinflammatory cytokine expression, and oxidative stress elicited by hindlimb ischemia-reperfusion (I/R). Male mice underwent 1 h of hindlimb ischemia, followed by 3 h of reperfusion. Throughout reperfusion, mice were exposed to AIR or AIR + CO (250 ppm). Following reperfusion, the distal ileum was exteriorized to assess the intestinal inflammatory response by quantifying leukocyte rolling and adhesion in submucosal postcapillary venules with the use of intravital microscopy. Ileum samples were also analyzed for proinflammatory cytokine expression [tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta] and malondialdehyde (MDA) with the use of enzyme-linked immunosorbent assay and thiobarbituric acid reactive substances assays, respectively. I/R + AIR led to a significant decrease in leukocyte rolling velocity and a sevenfold increase in leukocyte adhesion. This was also accompanied by a significant 1.3-fold increase in ileum MDA and 2.3-fold increase in TNF-alpha expression. Treatment with AIR + CO led to a significant reduction in leukocyte recruitment and TNF-alpha expression elicited by I/R; however, MDA levels remained unchanged. Our data suggest that low-dose inhaled CO selectively attenuates the remote intestinal inflammatory response elicited by hindlimb I/R, yet does not provide protection against intestinal lipid peroxidation. CO may represent a novel anti-inflammatory therapeutic treatment to target remote organs following acute trauma and/or I/R injury.
    AJP Gastrointestinal and Liver Physiology 02/2009; 296(1):G9-G14. DOI:10.1152/ajpgi.90243.2008
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    ABSTRACT: Mucositis is one of the most debilitating side effects of head and neck cancer therapy and is currently believed to arise from an inflammatory cascade leading to cellular damage. However, no effective treatment has been identified despite extensive attempts with anti-inflammatory medications. To compare real-time microvascular inflammatory changes with oral mucositis levels in patients undergoing radiotherapy or chemoradiotherapy for head and neck tumours. Prospective, longitudinal, cohort, observational study. Regional cancer program. Twenty patients with head and neck tumours were assessed on a weekly basis throughout the course of radiotherapy. Levels of mucositis were graded objectively using the Oral Mucositis Assessment Scale and subjectively using a patient symptom questionnaire. Video imaging of the sublingual microcirculation was obtained using orthogonal polarized spectral imaging to quantify inflammatory markers such as microcirculatory velocity, white blood cell margination, and extravasation. Despite very high levels of objective and subjective mucositis, inflammatory changes were not present in the microcirculation. Typical microvascular inflammatory changes are not demonstrated in radiation-induced mucositis. These findings contradict the currently proposed mechanism of mucosal damage and may therefore have important implications in the development of novel therapeutic interventions.
    Journal of otolaryngology - head & neck surgery = Le Journal d'oto-rhino-laryngologie et de chirurgie cervico-faciale 11/2008; 37(5):730-7.
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    ABSTRACT: The distance beyond which helicopter transport is faster than ground for interfacility transfer of trauma patients has not been established. Our objective was to determine whether such a threshold exists. A retrospective cohort study was conducted involving 243 patients transported by land and 139 patients by air from 13 sites during a 3-year period. Time intervals between critical events were compared for the two modes of transport at each site. The time interval between the decision to transfer and the actual departure time was shorter for patients transferred by land from all sites studied (mean 41.3 versus 89.7 minutes, p < 0.001). The travel time was shorter by helicopter from all sites (mean 58.4 versus 78.9 minutes, p < 0.001). The time between the decision to transfer and the arrival at the trauma center was similar at most sites but faster by land overall (mean 120.3 versus 150.0 minutes, p = 0.014). No threshold was detected beyond which helicopter transport was superior. Several factors other than the distance to be traveled determine the time required for interfacility transfer of trauma patients. A fixed distance threshold beyond which helicopter transport should be used does not exist. The decision as to which mode of transport to use for emergent trauma patient transfers should be based upon multiple factors including the distance traveled and ambulance availability, and must be individualized for each site that transfers patients.
    The Journal of trauma 08/2006; 61(2):396-403. DOI:10.1097/01.ta.0000222974.31728.2a
  • Critical Care Medicine 12/2005; 33. DOI:10.1097/00003246-200512002-00446
  • The Journal of Trauma Injury Infection and Critical Care 01/2005; 59(2). DOI:10.1097/00005373-200508000-00144
  • Source
    Thomas L Forbes, Neil G Parry
    Canadian journal of surgery. Journal canadien de chirurgie 10/2004; 47(5):386-7.

Publication Stats

68 Citations
38.06 Total Impact Points


  • 2008–2015
    • London Health Sciences Centre
      • Division of General Surgery
      London, Ontario, Canada
  • 2004–2013
    • The University of Western Ontario
      • • Division of General Surgery
      • • Division of Orthopaedic Surgery
      • • Division of Vascular Surgery
      London, Ontario, Canada
  • 2009
    • Lawson Health Research Institute
      London, Ontario, Canada