Biomedical subjects

Peter Rhee

Publications and source records attributed to Peter Rhee.

82 records · Page 5Linked to original sources

PubMed2003

Searching for the optimal resuscitation method: recommendations for the initial fluid resuscitation of combat casualties.

Resuscitation can exacerbate cellular injury caused by hemorrhagic shock, and the type of fluid used for resuscitation may play an important role in this injury. Unlike some factors in the treatment of combat casualty, the method of resuscitation is under our control. The prevention of cellular injury through wiser resuscitation strategies would be more advantageous than attempting complex immunomodulation after the damage has already occurred. This article summarizes data from a number of studies to illustrate the differential effects of commonly used resuscitation fluids on cellular injury. Our findings show that resuscitation with hypotonic/isotonic crystalloids, including lactated Ringer's (LR) solution, and artificial colloid solutions, elicit severe immune activation and an up-regulation of cellular injury markers. This effect is not seen with plasma, natural colloids (albumin), and fresh whole blood. Hypertonic fluids cause suppression of neutrophil activation and a milder increase in the expression of cell injury markers compared with isotonic fluids. The effect of various resuscitation fluids on core cellular functions such as gene regulation is also summarized in this article. Finally, because of the uniqueness of combat care, a set of new recommendations for initial fluid resuscitation of combat casualties is proposed.

Animals↗

PubMed2003

Comparative analysis of hemostatic agents in a swine model of lethal groin injury.

BACKGROUND: Techniques for better hemorrhage control after injury could change outcome. A large-animal model of lethal, uncontrolled hemorrhage was developed to test whether the use of various hemostatic agents would decrease bleeding and improve early survival. METHODS: A complex groin injury was created in 30 Yorkshire swine (42-55 kg) to produce uncontrolled hemorrhage. This injury included semitransection of the proximal thigh and complete division of the femoral artery and vein. After 5 minutes, the animals were randomized to (n = 6 animals per group) no dressing (ND), standard dressing (SD), SD and Rapid Deployment Hemostat (RDH) bandage, SD and QuikClot hemostatic agent (QC), or SD and TraumaDEX (TDEX). Limited volume 0.9% saline (1,000 mL over 30 minutes) resuscitation was started 30 minutes after injury. We measured blood loss, early mortality (180 minutes), and physiologic markers of hemorrhagic shock (e.g., cardiac output, blood pressure, hemoglobin, metabolic acidosis). RESULTS: Application of wound dressing decreased mortality in all groups compared with the ND group (83% mortality). However, this difference was significant (p < 0.05) only for the QuikClot hemostatic agent (0% mortality). Before the application of dressing (first 5 minutes), there were no differences in blood loss between the groups. After application of dressings, the QC group had the lowest blood loss (4.4 +/- 1.4 mL/kg). CONCLUSION: Of the hemostatic agents tested, QuikClot improved survival and decreased bleeding in a swine model of lethal vascular and soft tissue injury.

Animals↗

PubMed2003

A portable handpump is effective in the evacuation of hemothorax in a swine model of penetrating chest injury.

BACKGROUND: Standard pleural evacuation devices are not practical for use on the battlefield. A small, portable, easy-to-use handpump (HP) that does not require continuous suction for treating hemopneumothorax would offer a major logistical advantage. In addition, using endotracheal tubes instead of regular pleural tubes would help minimize supplies carried on the battlefield. A swine model of penetrating chest injury was designed to test this concept. Our hypothesis was that an HP would be as effective as the standard of care for the evacuation of a large hemopneumothorax. METHODS: A 2-cm lung laceration was created in 18 Yorkshire swine (35-51 kg) under inhaled anesthesia and 1.4 L of blood was infused into the pleural space (200 mL every 15 minutes). Fluid resuscitation (2,000 mL of 0.9% saline) was started 15 minutes after injury, and animals were randomized into one of three groups: group 1, 36-Fr Argyle pleural tube and Pleur-Evac chest drainage unit with 20-cm H2O suction (control); group 2, 36-Fr pleural tube attached to the HP; and group 3, a No. 8 endotracheal tube in the pleural space attached to the HP. After 120 minutes, a thoracotomy was performed to determine the amount of residual blood in the pleural space. RESULTS: Effectiveness of the three methods as a percentage of total blood (evacuated and retained) removed was measured over 2 hours. The handpump (group 2) performed better than the standard of care (group 1) at numerous time points and evacuated significantly (p < 0.05) more blood at the end of the experiment. CONCLUSION: Using the handpump with a pleural tube was more effective than the standard of care in treating traumatic hemothorax. The use of an endotracheal instead of a conventional pleural tube had no adverse impact on efficacy of the pump in evacuating blood from the chest cavity.

Animals↗

PubMed2003

Adolescent assault injury: risk and protective factors and locations of contact for intervention.

BACKGROUND: Violence is a large contributor to morbidity and mortality among adolescents. Most studies assessing markers for violent injury are cross-sectional. To guide intervention, we conducted a case-control study to explore factors associated with assault injury and locations to reach at-risk adolescents. OBJECTIVE: 1) To assess risk and protective factors for adolescent assault injury compared with 2 control groups of youth with unintentional injuries and noninjury complaints presenting to the emergency department and 2) to assess locations of contact with assault-injured youth for prevention programs. METHODS: Face-to-face and phone interviews were conducted with systematic samples of youth aged 12 to 19 years presenting to the emergency department with assault injury, unintentional injury, and noninjury complaints. Youth with intentional injuries were matched to youth in the 2 control groups on age +/-1 year, gender, race, and residency. RESULTS: One hundred forty-seven 147 assault-injured youth completed interviews. One hundred thirty-three assault-injured youth were matched to 133 unintentionally injured and 133 noninjured youth presenting to the emergency department. Compared with the 2 control groups, assault-injured youth were more likely to have had more fights in the past year (odds ratio [OR]: 3.91; 95% confidence interval [CI]: 2.02, 7.58; OR: 4.00; 95% CI: 2.23, 7.18) and fights requiring medical treatment (OR: 35.49; 95% CI: 8.71, 144.68; OR: 80.00; 95% CI: 11.13, 574.80). Eighty percent of assault-injured youth had been in 1 or more fights in the last 12 months compared with 55% and 46% in unintentional and noninjured controls, respectively. Assault-injured youth were more likely to have had previous weapon injuries (OR: 9.50; 95% CI: 3.39, 26.6; OR: 8.50; 95% CI: 3.02, 23.95) and have seen someone shot (OR: 2.00; 95% CI 1.12, 3.58; OR: 2.00; 95% CI: 1.12, 3.58). Eighty-six percent of assault-injured youth had a regular health care provider with 82% reporting a visit within the last year. There were no differences between cases and controls with regard to physician contact, extracurricular activity involvement, school or church attendance, police contact, weapon access or weapon-carrying, or witnessing nonweapon-related violence. CONCLUSIONS: Fighting was common among all groups. Assault-injured youth were more likely to have had previous weapon injuries and were high-risk for future injury. Past fights, past fight injuries, and seeing someone else shot were markers associated with assault injury. Health providers do have access to at-risk teens for clinical risk assessment and intervention.

Accidents↗

PubMed2003

Intubation after cervical spinal cord injury: to be done selectively or routinely?

Patients with cervical spinal cord injuries (CSCIs) often develop acute respiratory failure and require intubation. It is unknown if intubation should be offered preemptively in all CSCI patients or selectively based on signs of acute respiratory failure. The purpose of this study was to evaluate the role of routine early intubation in CSCI patients. The medical records of 68 patients with CSCI were reviewed. Univariate and multivariate analyses were used to identify independent risk factors for the need of intubation. Statistical significance was considered at P < 0.05. Fifty patients (74%) required intubation and 27 (40%) developed pneumonia. Of patients with CSCI above C5, 87.5 per cent required intubation compared with 61 per cent of patients with CSCI at C5-C8 (P = 0.026). Similarly, of patients with complete quadriplegia, 90 per cent required intubation compared to 48.5 per cent of patients with incomplete quadriplegia or paraplegia (P < 0.001). Of 31 patients not presenting with overt signs of acute respiratory failure on admission, 13 (42%) decompensated later and were eventually intubated up to 53 hours after admission. Six of these 13 patients had emergent intubation due to acute desaturation and developed pulmonary complications associated with emergent intubation. There were 3 independent risk factors for the need of intubation: Injury Severity Score > 16, CSCI higher than C5, and complete quadriplegia. The combination of the 2 latter risk factors resulted in intubation in 21 of 22 patients (95%). The majority of patients with CSCI require intubation. In patients with CSCI above C5 and complete quadriplegia, intubation should be offered routinely and early because delays may cause preventable morbidity.

Adult↗

PubMed2002

cDNA array analysis of gene expression following hemorrhagic shock and resuscitation in rats.

UNLABELLED: The aim of this study was to characterize gene expression following hemorrhagic shock and resuscitation with emphasis on the differences between various resuscitation strategies. METHODS: Male Sprague Dawley rats (n = 25; 5/group) were subjected to a three stage hemorrhage and resuscitated as follows: (1) sham hemorrhage; (2) sham resuscitation; (3) lactated Ringer's solution (LR), 3:1 volume; (4) 7.5% hypertonic saline (HTS) 9.7 ml/kg; (5) plasma, 1:1 volume. Liver, spleen, lung and muscle were collected 3 h post resuscitation and cDNA array analysis was performed on the total RNA. RESULTS: Expression of 1,176 genes was analyzed. Following resuscitation, 82 of the genes studied (7%) displayed an altered expression of at least 2-fold compared to the sham hemorrhage group. Depending on organ system under study and resuscitation conditions, expression of these 82 genes was down- or up-regulated, bringing the total number of expression alterations to 167. Largest number of organ-specific changes in gene expression was noted in liver (63/167), followed by lung (57), muscle (25), and spleen (22). Most of the resuscitation strategy specific changes were caused by plasma resuscitation (68/167), followed by LR (51), and HTS (48). In every organ studied, gene expression profile was dependent upon the fluid used for resuscitation. CONCLUSION: Cellular response to hemorrhagic shock, even at the level of gene expression, is dependent on the resuscitation strategy. We have discovered altered expression of genes not previously implicated in the physiology of hemorrhagic shock and resuscitation. Gene array technology provides a rapid and efficient means of dissecting the complex genetic regulation of cellular response to shock.

Animals↗

PubMed2002

Learning and memory is preserved after induced asanguineous hyperkalemic hypothermic arrest in a swine model of traumatic exsanguination.

BACKGROUND: Induced asanguineous hypothermic metabolic arrest (suspended animation) could provide valuable time to repair major vascular injuries if safely induced in patients with trauma. We report a novel method of doing this in a swine model of uncontrolled lethal hemorrhage (ULH) that resulted in preservation of learning ability and memory. METHODS: Yorkshire swine (100 to 125 lb) underwent ULH before rapid intra-aortic infusion of a hypothermic (4 degrees C), hyperkalemic (70 mEq/L) organ preservation solution by a left thoracotomy. Cooling continued until core temperature reached 10 degrees C, and this was maintained for 60 minutes using low-flow cardiopulmonary bypass. Vascular injuries were repaired during this state of suspended animation, which was then reversed, and the animals were observed for 6 weeks. Cognitive functions were tested by training animals to retrieve food from color-coded boxes. Postoperatively, the ability to remember this task and a 75-point objective neurologic scale were used to test neurologic function. In experiment I, ULH was caused by lacerating thoracic aorta (n = 9). Five preoperatively untrained animals were trained to perform the task and compared with control animals (n = 15), and 4 preoperatively trained animals were tested for memory retention postoperatively. In experiment II, ULH was induced by creating an iliac artery and vein injury (n = 15). Animals were kept in shock for 15, 30, and 60 minutes before the induction of hypothermia. RESULTS: In experiment I, surviving animals (7/9) were neurologically intact, and their capacity to learn new skills was no different than for control animals. All pretrained animals demonstrated complete memory retention. In experiment II, survival with 15, 30, and 60 minutes of shock were 80%, 60%, and 80%, respectively. All animals (except 1) in the 60-minute group were neurologically intact and displayed normal learning capacity. CONCLUSIONS: Induction of hypothermic metabolic arrest (by thoracotomy) for repair of complex traumatic injuries is feasible with preservation of normal neurologic function, even after extended periods of shock from an intra-abdominal source of uncontrolled hemorrhage.

Animals↗

PubMed2002

Hypertonic saline: intraosseous infusion causes myonecrosis in a dehydrated swine model of uncontrolled hemorrhagic shock.

BACKGROUND: The Institute of Medicine has recommended intraosseous (IO) infusion of 7.5% hypertonic saline (HTS) for combat casualties in shock. We tested the safety and efficacy of this recommendation in a long-term survival model of uncontrolled hemorrhagic shock using dehydrated swine. METHODS: Fourteen dehydrated Yorkshire swine had placement of a 12G needle in the right anterior tibia under isoflurane anesthesia. Uncontrolled hemorrhage was induced via left iliac artery and vein injury. Animals were kept in shock for 2 hours and then resuscitated over 2 hours with 5 mL/kg of 7.5% HTS given either as 10 small boluses (group I, n = 4) or two large boluses (group II, n = 6) to compare the physiologic response and blood loss. Control animals (group III, n = 4) received an equal volume of 0.9% saline IO and additional intravenous saline to equalize the salt load in all groups. RESULTS: The three groups had similar physiologic responses, with no increase in blood loss following HTS resuscitation. However, between the second and fifth postresuscitation days, the 7.5% HTS resuscitated animals developed soft tissue necrosis or bone marrow necrosis of the right hind leg (group I, 100%; group II, 66.6%; group III, 0%). CONCLUSION: HTS resuscitation effectively restored hemodynamic stability in dehydrated swine without increased bleeding from an uncontrolled vascular injury. However, IO infusion of HTS in this model was associated with a very high rate of local complications. Further investigations should be undertaken before IO use of 7.5% HTS in humans.

Animals↗

PubMed2002

Comparison of the effects of a 50% exchange-transfusion with albumin, hetastarch, and modified hemoglobin solutions.

We compared the hemodynamic effects of replacing 50% of the blood volume of anesthetized rats with an equal volume of five solutions: human serum albumin (HSA), hetastarch, unmodified hemoglobin, diaspirin-crosslinked hemoglobin, and o-raffinose-crosslinked hemgolobin. Control rats were exchange-transfused with their own blood. HSA and hetastarch caused a severe reduction in systemic vascular resistance (SVR), hypotension, and acute renal failure immediately after the exchange-transfusion. Unmodified and diaspirin-crosslinked hemoglobins caused comparable and severe increases in SVR, whereas vasoconstriction induced by o-raffinose-crosslinked hemoglobin was minimal. The increased SVR induced by all hemoglobin solutions resolved over a 2-day period as the hemoglobin was cleared from plasma. Body weight was monitored for 5 days after the exchange transfusion as a measure of the relative long-term efficacy of the exchange solutions tested and increased substantially in control rats (that received blood). Rats that received both crosslinked hemoglobin solutions gained a comparable amount of weight as the control group. By contrast rats that received HSA, hetastarch and unmodified hemoglobin failed to gain weight or lost weight over the same period. In summary: i) HSA and hetastarch are relatively ineffective as resuscitative fluids when administered after the loss of a large volume of blood; ii) diaspirin-crosslinked hemoglobin causes severe vasoconstriction, comparable in intensity to that induced by unmodified hemoglobin; iii) o-raffinose-crosslinked hemoglobin induces minimal vasoconstriction; iv) the vasoactive effects of all hemoglobin solutions are reversible. We conclude, that of all solutions tested, both the short- and long-term effects of an exchange-transfusion with whole blood are most closely reproduced by an exchange with o-raffinose-crosslinked hemoglobin.

Animals↗

PubMedDate not supplied

Nephrectomy versus renal repair after trauma to the kidney: preserve or sacrifice?

The objective of this retrospective study (1992-2003) is to evaluate the effect of nephrectomy in postoperative renal dysfunction. NEPHRECTOMY patients had their kidneys removed and REPAIR patients repaired or only partially resected. All patients were matched 1:1 with controls according to age, Injury Severity Score, Abdominal Abbreviated Injury Score, and mechanism of injury. Outcomes measured were renal dysfunction (serum creatinine > 2 mg/dl for > 2 consecutive days), renal dialysis, length of hospital stay, and mortality. Of 214 patients, 149 were NEPHRECTOMY and 65 REPAIR. Compared to their controls, NEPHRECTOMY and REPAIR patients had a higher rate of renal dysfunction. However, the rate was not different between NEPHRECTOMY and REPAIR. Multivariate analysis found no independent effect of the choice of operation in the development of renal dysfunction. No differences were found in the remaining outcomes measured. We conclude that although renal injury is associated with postoperative renal dysfunction, the type of operation is not. Nephrectomy can be offered when necessary without concerns about increasing the likelihood of postoperative renal failure.

Adult↗