Biomedical subjects

P J Offner

Publications and source records attributed to P J Offner.

At least 37 records · Page 2Linked to original sources

PubMed1999

Male gender is a risk factor for major infections after surgery.

BACKGROUND: Accumulating clinical and epidemiological evidence suggests significant gender differences in the incidence of and outcome following major infection. In a rodent model of hemorrhagic shock, investigators have shown that males manifest depressed cell-mediated immunity that is reversed by castration or pharmacologic testosterone receptor blockade. Female rats, in contrast, show enhanced immune function that is reduced to male levels by testosterone administration. This sexual dimorphism is believed responsible for the improved outcome in female mice following septic challenge. HYPOTHESIS: Male gender is a risk factor for major infections following severe injury. DESIGN: Five-year prospective cohort study ending October 1998. SETTING: Urban level I regional trauma center. PATIENTS AND METHODS: A total of 545 trauma patients older than 15 years with an Injury Severity Score greater than 15 and survival more than 48 hours were prospectively identified and studied. Collected data included age, injury mechanism, and Injury Severity Score. Major infections, defined as pneumonia, abdominal and pelvic abscess, wound infection requiring operative debridement, and meningitis, were tabulated. The occurrence of major infections in males and females was compared using multiple logistic regression analysis. MAIN OUTCOME MEASURE: Postinjury major infectious complications. RESULTS: Of the 545 patients, 135 (24.8%) were female and 410 (75.2%) were male. Major infections occurred in 219 (40.2%) patients. Logistic regression confirmed that male gender is an independent risk factor for major infections (P=.04) after controlling for age and Injury Severity Score. Males had a 58% greater risk of developing a major infection (odds ratio, 1.58; 95% confidence interval, 1.01-2.48). CONCLUSIONS: Male gender is associated with a dramatically increased risk of major infections following trauma. This effect is most significant following injuries of moderate severity (Injury Severity Score 16-25) and persists in all age groups.

Adolescent↗

PubMed1999

Age of transfused blood is an independent risk factor for postinjury multiple organ failure.

BACKGROUND: Blood transfusion has repeatedly been demonstrated to be an independent risk factor for postinjury multiple organ failure (MOF). Previously believed to represent a surrogate for shock, packed red blood cell (PRBC) transfusion has recently been shown to result in neutrophil priming and pulmonary endothelial cell activation. We have previously observed that the generation of inflammatory mediators is related to the length of PRBC unit storage. The purpose of this study was to determine if age of transfused PRBC is a risk factor for the development of postinjury MOF. METHODS: Using our prospective database of trauma patients at risk for developing MOF, we identified patients who developed MOF (MOF+) and received 6 to 20 units of PRBCs in the first 12 hours following injury. A similar cohort of patients, matched for ISS and transfusion requirement, who did not develop MOF (MOF-) were also identified. The age of each unit of PRBC transfused in the first 6 hours was determined. Multiple logistic regression was performed to determine if age of transfused blood is an independent risk factor. RESULTS: Sixty-three patients were identified, 23 of whom were MOF+. There was no difference in ISS and transfusion requirement between MOF+ and MOF- groups. MOF+ patients, however, were significantly older (46+/-4.7 years versus 33+/-2.3 years). Moreover, mean age of transfused blood was greater in the MOF+ patients (30.5+/-1.6 days versus 24+/-0.5 days). Similarly, the mean number of units older than 14 and 21 days old were greater in the MOF+ patients. Multivariate analysis identified mean age of blood, number of units older than 14 days, and number of units older than 21 days as independent risk factors for MOF. CONCLUSION: The age of transfused PRBCs transfused in the first 6 hours is an independent risk factor for postinjury MOF. This suggests that current blood bank processing and storage technique should be reexamined. Moreover, fresh blood may be more appropriate for the initial resuscitation of trauma patients requiring transfusion.

Adult↗

PubMed1999

Optimizing screening for blunt cerebrovascular injuries.

BACKGROUND: The recognition that early diagnosis and intervention, prior to ischemic neurologic injury, has the potential to improve outcome following blunt cerebrovascular injuries (BCVI), led to a policy of aggressive screening for these injuries. The resultant epidemic of BCVI has created a dilemma, as widespread screening is impractical. We sought to identify independent predictors of BCVI, to focus resources. METHODS: Cerebral arteriography was performed based on signs or symptoms of BCVI, or in asymptomatic patients with high-risk mechanisms (hyperextension, hyperflexion, direct blow) or injury patterns. Logistic regression analysis identified independent predictors. RESULTS: A total of 249 patients underwent arteriography; 85 (34%) had injuries. Independent predictors of carotid arterial injury were Glasgow coma score < or =6, petrous bone fracture, diffuse axonal brain injury, and LeFort II or III fracture. Having one of these factors in the setting of a high-risk mechanism was associated with 41% risk of injury. Of patients with cervical spine fracture, 39% had vertebral arterial injury. CONCLUSIONS: Patients sustaining high-risk injury mechanisms or patterns should be screened for BCVI. In the face of limited resources, screening efforts should be focused on those with high-risk predictors.

Adult↗

PubMed1999

Blunt carotid arterial injuries: implications of a new grading scale.

BACKGROUND: Blunt carotid arterial injuries (BCI) have the potential for devastating outcomes. A paucity of literature and the absence of a formal BCI grading scale have been major impediments to the formulation of sound practice guidelines. We reviewed our experience with 109 BCI and developed a grading scale with prognostic and therapeutic implications. METHODS: Patients admitted to a Level I trauma center were evaluated with cerebral arteriography if they exhibited signs or symptoms of BCI or met criteria for screening. Patients with BCI were treated with heparin unless they had contraindications, and follow-up arteriography was performed at 7 to 10 days. Endovascular stents were deployed selectively. A prospective database was used to track the patients. RESULTS: A total of 76 patients were diagnosed with 109 BCI. Two-thirds of mild intimal injuries (grade I) healed, regardless of therapy. Dissections or hematomas with luminal stenosis (grade II) progressed, despite heparin therapy in 70% of cases. Only 8% of pseudoaneurysms (grade III) healed with heparin, but 89% resolved after endovascular stent placement. Occlusions (grade IV) did not recanalize in the early postinjury period. Grade V injuries (transections) were lethal and refractory to intervention. Stroke risk increased with injury grade. Severe head injuries (Glasgow Coma Scale score < or =6) were found in 46% of patients and confounded evaluation of neurologic outcomes. CONCLUSION: This BCI grading scale has prognostic and therapeutic implications. Nonoperative treatment options for grade I BCI should be evaluated in prospective, randomized trials. Accessible grade II, III, IV, and V lesions should be surgically repaired. Inaccessible grade II, III, and IV injuries should be treated with systemic anticoagulation. Endovascular techniques may be the only recourse in high grade V injuries and warrant controlled evaluation in the treatment of grade III BCI.

Adolescent↗

PubMed1999

Neutrophils are primed for cytotoxicity and resist apoptosis in injured patients at risk for multiple organ failure.

BACKGROUND: Postinjury multiple organ failure (MOF) is the result of a dysregulated systemic inflammatory response in which primed neutrophils (PMNs) are sequestered in tissues, vulnerable to activation through secondary insults. Apoptosis is critical to the normal clearance of these sequestered PMNs. Conversely, dysfunctional apoptosis prolongs the PMN functional life span, potentially exacerbating PMN-mediated tissue injury and the development of MOF. We hypothesized that severe trauma, in addition to priming PMNs, provokes dysfunctional PMN apoptosis. METHODS: Neutrophils were harvested daily from 12 severely injured patients at high risk for MOF, cultured for 24 hours, and assessed for apoptosis with use of acridine orange-ethidium bromide staining and fluorescence microscopy. Priming for elastase release was measured in freshly isolated patient PMNs. Plasma from patients was assessed for its ability to delay apoptosis of normal PMNs. RESULTS: Four patients (33%) had MOF. Neutrophil apoptosis was profoundly delayed in severely injured patients throughout the 5-day study period. Priming for elastase release was augmented concomitantly. Patients' plasma delayed apoptosis of normal PMNs. CONCLUSION: In patients at high risk for postinjury MOF, PMNs are not only primed for cytotoxicity but also resist apoptosis. The dysfunctional apoptosis is attributed, at least in part, to a plasma-borne mediator. The net effect may facilitate hyperinflammatory organ injury.

Adolescent↗

PubMed1998

Staged physiologic restoration and damage control surgery.

The fundamental objective of staged laparotomy is to accomplish definitive operative management in a calculated, stepwise fashion based on the patient's physiologic tolerance. This important concept has emerged from collective experience with massive acute abdominal injuries but clearly extends to elective operative procedures and surgical challenges in other torso compartments. Whereas the inability to achieve hemostasis is due most frequently to a recalcitrant coagulopathy following trauma, other scenarios include inaccessible venous injuries, coexisting extraperitoneal life-threatening injuries, uncertain viability of abdominal contents, and the inability to reapproximate abdominal fascia due to reperfusion-induced visceral edema. There are five critical decision-making phases of staged laparotomy: I, patient selection; II, intraoperative reassessment; III, physiologic restoration in the surgical intensive care unit; IV, return to the operating room for definitive procedures; and V, abdominal wall reconstruction. The abdominal compartment syndrome (ACS) is a common, often insidious complication of staged laparotomy. In fact, during phases II and III there is often a delicate balance between effective pressure tamponade of capillary bleeding and the untoward effects of the ACS. During phases IV and V a frequent dilemma is how to enclose the abdominal contents to reduce protein loss and facilitate patient mobilization.

Abdominal Injuries↗

PubMed1998

Resuscitation of the injured patient with polymerized stroma-free hemoglobin does not produce systemic or pulmonary hypertension.

BACKGROUND: Hemoglobin-based blood substitutes appear poised to deliver the promise of a universally compatible, disease-free alternative to banked blood. However, vasoconstriction following administration of tetrameric hemoglobins has been problematic, likely because of nitric oxide binding. Polymerized hemoglobin is effectively excluded from the abluminal space because of its size, and is thus less likely to perturb vasorelaxation. We therefore hypothesized that hemodynamic responses would be no different in injured patients receiving polymerized hemoglobin versus banked blood. METHODS: Injured patients requiring urgent transfusion were randomized to receive either polymerized hemoglobin or banked blood. Systemic arterial pressure, pulmonary arterial pressure, cardiac index, pulmonary capillary wedge pressure, systemic vascular resistance, and pulmonary vascular resistance were measured serially. RESULTS: There was no difference in any of the measured hemodynamic parameters between patients resuscitated with polymerized hemoglobin versus blood. CONCLUSIONS: Polymerized hemoglobin given in large doses to injured patients lacks the vasoconstrictive effects reported in the use of other hemoglobin-based blood substitutes. This supports the continued investigation of polymerized hemoglobin in injured patients requiring urgent transfusion.

Adult↗

PubMed1998

The unrecognized epidemic of blunt carotid arterial injuries: early diagnosis improves neurologic outcome.

OBJECTIVE: To determine the benefit of screening for blunt carotid arterial injuries (BCI) in patients who are asymptomatic. SUMMARY BACKGROUND DATA: Blunt carotid arterial injuries have the potential for devastating complications. Published studies report 23% to 28% mortality rates, with 48% to 58% of survivors having permanent severe neurologic deficits. Most patients have neurologic deficits when the injury is diagnosed. The authors hypothesized that screening patients who are asymptomatic and instituting early therapy would improve neurologic outcome. METHODS: The Trauma Registry of the author's Level I Trauma Center identified patients with BCI from 1990 through 1997. Beginning in August 1996, the authors implemented a screening for BCI. Arteriography was used for diagnosis. Patients without specific contraindications were anticoagulated. Endovascular stents were deployed in the setting of pseudoaneurysms. RESULTS: Thirty-seven patients with BCI were identified among 15,331 blunt-trauma victims (0.24%). During the screening period, 25 patients were diagnosed with BCI among 2902 admissions (0.86%); 13 (52%) were asymptomatic. Overall, eight patients died, and seven of the survivors had permanent severe neurologic deficits. Excluding those dying of massive brain injury and patients admitted with coma and brain injury, mortality associated with BCI was 15%, with severe neurologic morbidity in 16% of survivors. The patients who were asymptomatic at diagnosis had a better neurologic outcome than those who were symptomatic. Symptomatic patients who were anticoagulated showed a trend toward greater neurologic improvement at the time of discharge than those who were not anticoagulated. CONCLUSIONS: Screening allows the identification of asymptomatic BCI and thereby facilitates early systemic anticoagulation, which is associated with improved neurologic outcome. The role of endovascular stents in the treatment of blunt traumatic pseudoaneurysms remains to be defined.

Adolescent↗

PubMed1998

Clinically relevant concentrations of ethanol attenuate primed neutrophil bactericidal activity.

BACKGROUND: Acute alcohol intoxication is associated with an increased risk of infection in the injured patient. The impact of clinically relevant levels of ethanol (ETOH) on neutrophil (PMN) bactericidal activity remains ill-defined. PMN priming optimizes microbicidal activity by enhancing oxygen radical production, degranulation, and adhesion molecule up-regulation. We hypothesized that clinically relevant levels of ETOH attenuate these primed PMN responses critical to eradicate infection. METHODS: After incubation with ETOH (0-1.0%), isolated human PMNs were primed with beta-acetyl-gamma-O-alkyl and activated with N-formyl-methionyl-leucyl-phenylalanine. Superoxide generation was measured by cytochrome c reduction, elastase release was measured by cleavage of methoxysuccinyl-ala-ala-pro-val-p-nitroanilide, and CD11b was measured by fluorescent monoclonal antibody staining. Bactericidal activity was assessed by Staphylococcus aureus killing. RESULTS: ETOH attenuated superoxide production dose-dependently with significance at 0.3% ETOH. Elastase release was attenuated starting at 0.2% ETOH, and CD11b expression was reduced starting at 0.4% ETOH. S. aureus killing was impaired dose-dependently with significance at 0.3% ETOH. CONCLUSION: Clinically relevant concentrations of ETOH attenuate PMN functions critical in host defense against invading pathogens. These results provide direct in vitro evidence consistent with previous in vivo data that acute alcohol intoxication is important in the pathogenesis of trauma-related infections.

Alcoholic Intoxication↗

PubMed1998

Hypertonic saline activates lipid-primed human neutrophils for enhanced elastase release.

BACKGROUND: Ongoing clinical trials have revived interest in hypertonic saline (HTS) for postinjury resuscitation; these studies have documented serum Na+ concentrations > or = 170 mmol/L. Recent animal studies have shown that HTS enhances T-cell and monocyte function, but effects on the polymorphonuclear neutrophil (PMN) remain unclear. The postinjury lipid mediators platelet-activating factor (PAF) and leukotriene B4 (LTB4) have been implicated in PMN priming for cytotoxicity, which is believed to be important in the pathogenesis of multiple organ failure. We hypothesized that HTS would stimulate PMN superoxide (O2-) and elastase release from PAF- and LTB4-primed PMNs. METHODS: Isolated PMNs from five donors were primed for 5 minutes with 200 nmol/L PAF or 1 micromol/L LTB4 in Kreb's-Ringer's phosphate with dextrose at a Na+ concentration of 140 mmol/L (normal serum Na+ concentration), pelleted, and resuspended in Kreb's-Ringer's phosphate with dextrose for 10 minutes at a Na+ concentration of 130 to 170 mmol/L. O2- generation was measured by superoxide dismutase-inhibitable reduction of cytochrome c and elastase release by cleavage of N-methoxysuccinyl-Ala-Ala-Pro-Val p-nitroanilide. RESULTS: HTS with Na+ concentration up to 170 mmol/L had no significant effect on O2- production or elastase release from quiescent cells. Na+ concentration of 160 and 170 mmol/L, however, activated PAF- and LTB4-primed PMNs for enhanced elastase release with no effect on O2- production. CONCLUSION: In clinically relevant concentrations, elevated Na+ activates lipid-primed neutrophils for enhanced elastase degranulation. Consequently, the administration of HTS in the early postinjury resuscitation period, when PMNs are maximally primed, may activate PMN elastase release and thereby promote the development of multiple organ failure.

Humans↗

PubMed1998

Prostaglandin E1 attenuates cytotoxic mechanisms of primed neutrophils.

In a recent clinical trial, liposomal prostaglandin E1 (PGE1) improved oxygenation, increased compliance, and decreased ventilator dependency in patients with adult respiratory distress syndrome (ARDS), thus renewing interest in PGE1 as a potential modulator of inflammation. The neutrophil (PMN) is believed to play a key role in the development of ARDS. Consequently, we investigated the effects of PGE1 on three components of the neutrophil inflammatory response: reactive oxygen species (ROS) generation, protease release, and surface expression of adhesion molecules. Human neutrophils were incubated with PGE1 and then primed with platelet-activating factor (PAF) and activation with N-formyl-methionyl-leucylphenylalanine (fMLP). PGE1 at a dose range of (10[-8] to 10[-5] M) attenuated primed/activated (PAF/fMLP) PMN superoxide anion generation and elastase release. In contrast, PGE1 doses > or =10[-5] M were required to attenuate PAF-stimulated neutrophil upregulation of CD11b/CD18 adhesion molecules. PGE1 also diminished the duration of the PAF-induced cytosolic calcium (Ca2+) flux. Our results suggest that plasma levels of PGE1 attained in patients with ARDS may attenuate ROS and protease neutrophil cytotoxicity but may not effectively block PMN-endothelial cell (EC) adhesion. This attenuation may occur through abrogation of the Ca2+ influx.

Alprostadil↗

PubMed1997

Selective management of penetrating neck trauma based on cervical level of injury.

BACKGROUND: Selective surgical exploration of penetrating neck wounds is now the standard of care, but the safety and cost effectiveness of selective diagnostic testing remains controversial. We herein review our 18-year prospective evaluation of a progressively selective approach. PATIENTS AND METHODS: Since 1979, 312 patients sustained penetrating trauma to the anterior neck; 75% were stabbed and 24% were shot. Zone I was penetrated in 13%, zone II in 67%, and zone III in 20%. RESULTS: In all, 105 (34%) of the patients had early exploration (16% were nontherapeutic). Of the 207 (66%) observed, 1 (0.5%) required delayed exploration. Length of stay was 8.0 days following exploration, 5.1 days following negative exploration, and 1.5 days following observation. In the last 6 years, 40% have had adjunctive testing: 69% of zone I, 15% of zone II, and 50% of zone III injuries. CONCLUSION: Selective management of penetrating neck injuries is safe and does not mandate routine diagnostic testing for asymptomatic patients with injuries in zones II and III.

Humans↗

PubMed1997

Nitric oxide attenuates platelet-activating factor priming for elastase release in human neutrophils via a cyclic guanosine monophosphate-dependent pathway.

BACKGROUND: Nitric oxide (NO) has proven benefits in treating adult respiratory distress syndrome (ARDS). The protective mechanism remains unclear, but cyclic guanosine monophosphate (cGMP)-dependent signal transduction pathways have been suggested. Our laboratory has implicated polymorphonuclear neutrophil (PMN) priming and subsequent activation in the pathogenesis of postinjury ARDS and has shown that NO inhibits superoxide anion production from activated PMNs. More recently, the pivotal role of elastase in PMN-mediated tissue injury has been emphasized. Consequently, our study hypothesis was that NO attenuates platelet-activating factor (PAF) priming for elastase release through a cGMP-dependent pathway in human PMNs. METHODS: PMNs isolated from human volunteers were preincubated with the NO donor 3-morpholinosydnonimine hydrochloride (SIN-1; 10(-6) to 10(-2) mol/L), cGMP (10(-3) mol/L), or the cell-permeable cGMP analog dibutyryl-cGMP (10(-3) mol/L) for 10 minutes. The cells were then primed with platelet-activating factor (PAF) 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (200 nmol/L), which was followed by N-formyl-methionyl-leucyl-phenylalanine (fMLP) activation (1 mumol/L). Elastase release was measured by the cleavage of N-methoxysuccinyl-Ala-Ala-Pro-Val p-nitroanilide (AAPV-pNA). RESULTS: NO (through SIN-1) significantly attenuated elastase release from PAF-primed PMNs in a dose-dependent manner. Cell-permeable dibutyryl-cGMP attenuated PMN elastase release similar to NO, but cGMP (not cell-permeable) had no effect. CONCLUSIONS: NO attenuates elastase release from PAF-primed PMNs through an intracellular cGMP-dependent signal transduction pathway. These findings may partially explain the beneficial effects of NO in the treatment of postinjury ARDS and add to our knowledge of the complex intracellular pathways involved in NO/PMN interactions.

Adult↗

PubMed1996

Cardiopulmonary effects of combined nitric oxide inhibition and inhaled nitric oxide in porcine endotoxic shock.

BACKGROUND: Nitric oxide synthase (NOS) inhibition has been shown to potentiate lipopolysaccharide (LPS) associated pulmonary hypertension, which may worsen right ventricular (RV) dysfunction and decrease cardiac output during sepsis. This study evaluates whether inhaled nitric oxide can ameliorate the adverse cardiopulmonary effects of NOS inhibition during endotoxemia. METHODS: After an infusion of Escherichia coli LPS (200 micrograms/kg), animals were resuscitated with saline (1 mL/kg/min) and observed for 3 hours while mechanically ventilated (FIO2, 0.6; VT, 12 mL/kg; positive end-expiratory pressure, 5 cm H2O). The LPS group (n = 6) received no additional treatment. The N-nitro-L-arginine methyl ester (NAME) group (n = 5) received L-NAME, a NOS inhibitor, 50 micrograms/kg/min for the last 2 hours. The NO+NAME group (n = 6) received inhaled NO (40 ppm) and L-NAME for the last 2 hours. The control group (n = 5) received only saline without LPS. Hemodynamic data and blood gases were collected hourly for 3 hours. RESULTS: L-NAME worsened LPS-associated pulmonary hypertension and RV dysfunction as reflected by decreased RV ejection fraction. Inhaled nitric oxide significantly decreased pulmonary hypertension and improved RV ejection fraction and stroke work index. There were no adverse systemic effects. CONCLUSIONS: Inhaled nitric oxide reverses pulmonary hypertension seen with L-NAME treatment during endotoxemia and may be a useful adjunct to NOS inhibition in the treatment of septic shock.

Administration, Inhalation↗

PubMed1995

Do prehospital trauma center triage criteria identify major trauma victims?

OBJECTIVE: To evaluate anatomic, physiologic, and mechanism-of-injury prehospital triage criteria as well as the subjective criterion of provider "gut feeling." DESIGN: Prospective analysis. SETTING: A state without a trauma system or official trauma center designation. PATIENTS: Patients treated by emergency medical services personnel statewide over a 1-year period who were injured and met at least one prehospital triage criterion for treatment at a trauma center. MAIN OUTCOME MEASURES: Outcome was analyzed for injury severity using the Injury Severity Score and mortality rates. A major trauma victim (MTV) was defined as a patient having an Injury Severity Score of 16 or greater. The yield of MTV and mortality associated with each criterion was determined. RESULTS: Of 5028 patients entered into the study, 3006 exhibited a singular entry criterion. Triage criteria tended to stratify into high-, intermediate-, and low-yield groups for MTV identification. Physiologic criteria were high yield and anatomic criteria were intermediate yield. Provider gut feeling alone was a low-yield criterion but served to enhance the yield of mechanism of injury criteria when the two criteria were applied in the same patient. CONCLUSIONS: A limited set of high-yield prehospital criteria are acceptable indicators of MTV. Isolated low- and intermediate-yield criteria may not be useful for initiating trauma center triage or full activation of hospital trauma teams.

Adolescent↗

PubMed1995

Effects of inhaled nitric oxide on right ventricular function in endotoxin shock.

Sepsis has been shown to cause right ventricular (RV) dysfunction, which may be related to pulmonary hypertension and increased RV afterload. This study evaluates the effects of inhaled nitric oxide (NO), a selective pulmonary vasodilator, on RV function in a porcine model of endotoxemia. After an infusion of Escherichia coli lipopolysaccharide (LPS; 200 micrograms/kg), animals were resuscitated with saline (1 mL/kg/min) and observed for 3 hours while being mechanically ventilated (Fio2 = 0.6, tidal volume = 12 mL/kg, and peak end-expiratory pressure = 5 cm H2O). The LPS group (n = 5) received no additional treatment. The NO group (n = 5) received inhaled NO (40 ppm) for the last 2 hours. The control group (n = 5) received only saline without LPS. Hemodynamic data and blood gases were collected hourly for 3 hours. LPS resulted in pulmonary hypertension and RV dysfunction as indexed by a decreased RV ejection fraction and increased RV end-diastolic volume. Inhaled NO significantly decreased pulmonary hypertension and significantly increased RV ejection fraction and oxygen delivery without adverse effects. In conclusion, inhaled NO significantly improved pulmonary hypertension and RV dysfunction in a porcine model of endotoxemia and should be a useful therapeutic modality in selected septic patients.

Administration, Inhalation↗

PubMed1995

Effects of nitric oxide synthase inhibition on regional blood flow in a porcine model of endotoxic shock.

The results of early studies suggest that nitric oxide (NO) synthesis inhibition may be therapeutic in sepsis, but recent data indicate that NO inhibition may be harmful. This study investigates the effects of NO synthesis inhibition with N-nitro-L-arginine methyl ester (NAME) on regional blood flow following endotoxemia. Anesthetized, instrumented swine were randomly divided into four groups. Controls received normal saline resuscitation (NSR) at 1 cc/kg/min beginning at T0. The lipopolysaccharide group (LPS) received NSR and Escherichia coli LPS, 200 micrograms/kg at T0. The LPS+NAME group received NSR and LPS at T0, plus NAME (50 micrograms/kg/min) starting at T1. The NAME group received only NSR and NAME. Hemodynamic data, regional blood flow, and gastric intramucosal pH (pHi) were measured hourly. LPS increased renal and carotid blood flow consistent with a hyperdynamic state. Mesenteric blood flow was decreased. Treatment of endotoxic animals with NAME decreased renal and carotid blood flow. Mesenteric blood flow and gastric pHi were improved by NAME. NO inhibition in endotoxic shock results in decreased carotid and renal blood flow, by decreasing cardiac output. Mesenteric blood flow and perfusion were improved; however, this requires further study for validation.

Amino Acid Oxidoreductases↗

PubMed1994

Detrimental hemodynamic effects of nitric oxide synthase inhibition in septic shock.

OBJECTIVE: To investigate the physiologic effects of nitric oxide synthase inhibition with N-nitro-L-arginine methyl ester in an acute resuscitated model of porcine septic shock. DESIGN: Randomized control trial. SETTING: Animal research facility. STUDY SUBJECTS: Domestic Yorkshire swine. INTERVENTIONS: Twenty-four animals were randomly divided into one of four treatment groups as follows: normal saline resuscitation (NSR) (control group); NSR plus 200 micrograms/kg of lipopolysaccharide (LPS) at 1 hour after baseline (LPS group); NSR, LPS, and a continuous infusion of 50 micrograms/kg per minute of N-nitro-L-arginine methyl ester (NAME) at 1 hour after baseline (LPS/NAME group); and NSR and NAME (NAME group). All animals received NSR at 1 mL/kg per minute starting at baseline. MAIN OUTCOME MEASURES: Mean arterial pressure (MAP), systemic vascular resistance index (SVRI), mean pulmonary arterial pressure (MPAP), and pulmonary vascular resistance index (PVRI) were measured at baseline and hourly for 4 hours. Values at baseline and 3 hours are given below as mean (+/- SE). RESULTS: All variables remained unchanged in the control group. The administration of LPS produced a systemic hyperdynamic response characterized by a decrease in MAP and SVRI from 66.0 +/- 3.9 to 55.0 +/- 2.8 mm Hg (P < .05) and from 422.0 +/- 22.0 to 272.0 +/- 29.0 mm Hg.min.kg/L (P < .05), respectively. The administration of LPS produced an increase in MPAP and PVRI from 16.3 +/- 0.8 to 30.0 +/- 1.3 mm Hg (P < .05) and from 37.0 +/- 5.3 to 119.0 +/- 13.0 mm Hg.min.kg/L (P < .05), respectively. In the LPS/NAME group, NAME infusion normalized MAP and increased SVRI from 506.0 +/- 40.0 to 642.0 +/- 72.0 mm Hg.min.kg/L (P < .05). Infusion of NAME potentiated LPS-induced pulmonary hypertension, increasing MPAP and PVRI from 16.8 +/- 0.6 to 36.0 +/- 2.8 mm Hg (P < .05) and from 59.0 +/- 3.5 to 319.0 +/- 64.0 mm Hg.min.kg/L (P < .05), respectively. Infusion of NAME alone increased MAP from 74.0 +/- 1.3 to 100.0 +/- 4.1 mm Hg (P < .05) and had no significant effect on MPAP and PVRI. CONCLUSIONS: The potentiation of LPS-induced pulmonary hypertension following NAME infusion suggests that inhibition of nitric oxide synthase may have a limited role in the treatment of septic shock.

Amino Acid Oxidoreductases↗