Invasion vs Insurgency: US Navy/Marine Corps Forward Surgical Care During Operation Iraqi Freedom

Hypothesis  The transition from maneuver warfare to insurgency warfare has changed the mechanism and severity of combat wounds treated by US Marine Corps forward surgical units in Iraq.

Design  Case series comparison.

Setting  Forward Resuscitative Surgical System units in Iraq.

Patients  Three hundred thirty-eight casualties treated during the invasion of Iraq in 2003 (Operation Iraqi Freedom I [OIF I]) and 895 casualties treated between March 2004 and February 2005 (OIF II).

Interventions  Definitive and damage control procedures for acute combat casualties.

Main Outcome Measures  Mechanism of injury, procedures performed, time to presentation, and killed in action (KIA) and died of wounds (DOW) rates.

Results  More major injuries occurred per patient (2.4 vs 1.6) during OIF II. There were more casualties with fragment wounds (61% vs 48%; P = .03) and a trend toward fewer gunshot wounds (33% vs 43%; P = .15) during OIF II. More damage control laparotomies (P = .04) and more soft tissue debridements (P < .001) were performed during OIF II. The median time to presentation for critically injured US casualties during OIF I and OIF II were 30 and 59 minutes, respectively. The KIA rate increased from 13.5% to 20.2% and the DOW rate increased from 0.88% to 5.5% for US personnel in the First Marine Expeditionary Force area of responsibility.

Conclusions  The transition from maneuver to insurgency warfare has changed the type and severity of casualties treated by US Marine Corps forward surgical units in Iraq. Improvised explosive devices, severity and number of injuries per casualty, longer transport times, and higher KIA and DOW rates represent major differences between periods. Further data collection is necessary to determine the association between transport times and mortality rates.

Operation Iraqi Freedom (OIF) is an ongoing conflict that has changed dramatically since the initial invasion. Following the maneuver warfare that resulted in the capture of Baghdad, Iraq, in April 2003, firm US military bases have been established throughout the country to support the Iraqi government and to fight insurgencies. For purposes of comparison, the maneuver warfare phase of March and April 2003 is referred to OIF I and the phase beginning with the second deployment of the First Marine Expeditionary Force (I MEF) to western and central Iraq from March 2004 to February 2005 is referred to as OIF II.

During OIF I, the Forward Resuscitative Surgery System (FRSS), a small mobile team of 8 personnel, was successfully used for the first time in a fluid battlefield setting. The FRSS, combined with a mobile emergency department capability (Shock Trauma Platoon [STP]), proved to be a valuable asset by providing a far-forward surgical capability that could be quickly moved and reestablished as the battlefield changed. The FRSS teams moved 11 times during OIF I. During this phase of operations, patient movement by air was swift and critical patients typically received surgical care at an FRSS within 30 minutes after injury.¹

Unlike OIF I, medical support for US forces during OIF II has remained stationary. Casualty movement from the battlefield to a battalion aid station (BAS) (echelon 1) or higher level of care is dependent on unit procedures and dictated by the tactical situation.

The effectiveness of the FRSS units during OIF II has been previously described.² This article compares the combined experience of 2 US Marine Corps FRSS units during OIF II from March 1, 2004, to February 28, 2005, with the entire FRSS experience (6 units) during the initial invasion of OIF I. During OIF II, the 2 FRSS units were stationed together at Camp Taqaddum, Iraq. Camp Taqaddum is a logistics and air base located 50 miles west of Baghdad between the cities of Fallujah, Iraq, and Ar Ramadi, Iraq.

The data on all patients treated were collected prospectively during the deployment from March 1, 2004, to February 28, 2005. A Combat Trauma Registry form provided by the Naval Health Research Center, Point Loma, California, was completed for every patient seen and the data were entered into our local database. A similar database was maintained by the FRSS teams during OIF I during March and April of 2003 and was used for the comparison group.

For both groups, patients with airway compromise, a Glasgow Coma Scale score of 8 or lower, or systolic blood pressure of 90 or lower were classified as critical. Injury Severity Scores were calculated for all critical patients.

Since most casualties had multiple injuries, the most significant injury was listed as the primary injury. An injury was considered significant if it required a procedure (ie, chest tube) or operative intervention (ie, soft tissue debridement, laparotomy). For patients with multiple soft tissue injuries on multiple limbs, only large wounds requiring significant debridement were counted. One of us (H.B.) was present during the OIF I and the OIF II FRSS deployments and provided consistent guidance for determining what injuries were entered into the database.

The time, location, and circumstances surrounding individual casualties were obtained from several sources. Frequently, Marines from the unit accompanied casualties to our facility and provided valuable information about the time of injury and weapons used. Field triage tags were used by the aid stations and provided information about the time of injury and initial treatment rendered. Casualty evacuation times and the grid coordinates where the injuries took place were obtained from a secure Internet site maintained by the First Marine Division. Using these sources, we were able to reconstruct the time and location of injury and the times and distances for patient movement for the majority of our critical patients. For the noncritical patients, the time to presentation to our unit was based on patient and witness accounts of the events as well as the secure Internet site.

Casualties were classified as killed in action (KIA) if they died before reaching the care of a physician. Casualties who died after evaluation by a physician at a BAS or elsewhere were classified as died of wounds (DOW). Casualties classified as wounded in action (WIA) had an injury requiring at least a 24-hour admission to an echelon 3 facility or evacuation out of theater. Patients were classified as return to duty (RTD) if they were discharged back to their unit from a BAS or forward surgical unit or if they were discharged after less than 24 hours of observation at an echelon 3 facility. The KIA rate was determined for the I MEF for OIF I and OIF II using the formula KIA rate = KIA / (KIA + DOW + WIA). The DOW rates were calculated using the formula DOW rate = DOW / (DOW + WIA).

Statistical analysis comparing OIF I and OIF II variables was performed using Microsoft Excel 2002 (Microsoft Corporation, Redmond, Washington) and GraphPad InStat version 3.00 for Windows 95 (GraphPad Software, San Diego, California). Values are reported as mean (SD) or raw percentage. Fisher exact test or χ² analysis were used to compare groups where appropriate. Differences were considered statistically significant at P < .05.

The US Marine Corps FRSS/STP units were deployed to support the Marines throughout the I MEF area of responsibility in western and central Iraq. During OIF II, this area of responsibility included the cities of Ar Ramadi and Fallujah in Al Anbar province, sites of frequent insurgent attacks. The FRSS/STPs were initially positioned based on the population at risk and the risk of air evacuation between specific areas. The primary mission of the FRSS is to provide life and limb salvage surgery within a short time of injury on the battlefield. These echelon 2 units referred patients to the 31st Combat Support Hospitals in Baghdad and Balad, Iraq, and both were about 30 minutes' flight time from our location between Fallujah and Ar Ramadi.

The personnel and equipment composing an FRSS and STP have been previously reported.¹ Two FRSS units were combined for variable periods during OIF I. After the 2 FRSS/STP units combined at Camp Taqaddum during OIF II, the staff consisted of 3 general surgeons, 1 orthopedic surgeon, 3 emergency department physicians, 3 anesthesiologists, 1 physician's assistant, 8 nurses, and 35 corpsmen.

Between March 1, 2004, and February 28, 2005, 1096 patients were treated by the FRSS/STP units at Camp Taqaddum. Two hundred one patients were treated for nontrauma medical conditions and the remaining 895 were included in the database as combat casualties. Nine hundred eighty-one operative procedures were performed on 417 casualties (2.4 procedures per operation). The 417 operative cases sustained a total of 1005 major injuries (2.4 per patient). The comparison group of OIF I casualties treated by FRSS/STP teams consisted of 338 total combat casualties, including 91 surgical patients with 145 injuries (1.6 per patient) treated by FRSS teams (Table 1). During OIF I, 40% of casualties treated at the FRSS were Iraqi and this decreased to 23% during OIF II (P < .001). Iraqi casualties included civilians, military personnel, and insurgents (OIF II).

The mechanism of injury for OIF I and OIF II operative cases is shown in Figure 1 and is compared with historical data of Marine casualties during the Vietnam War. The improvised explosive device (IED), or roadside bomb, caused the majority of fragment wounds during OIF II (Figure 2). There were significantly more fragment wounds operated on at an FRSS during OIF II (62%) than during OIF I (48%) (P = .03) and a smaller percentage of operative cases were performed for gunshot wounds during OIF II (33%) than during OIF I (43%), but this did not reach statistical significance (P = .15).

The location of injuries did not differ between OIF I and OIF II (Figure 3). The number of severe injury locations per operative case increased from 1.6 per patient in OIF I to 2.4 per patient during OIF II. During OIF I, 59% of the operative injuries were extremity wounds and 7% were truncal soft tissue injuries. Seven percent of the soft tissue injuries during OIF II were truncal injuries and 60% were extremity injuries.

Nine hundred eighty-one procedures were performed during 417 operations at Taqaddum during OIF II (2.4 per patient). During OIF I, 145 procedures were performed during 91 operations (1.7 per patient). The types and percentages of procedures performed during OIF I and OIF II are shown in Table 2. Fifty-three percent of the cases performed during OIF II were debridement, irrigation, and dressing of extremity or torso wounds (soft tissue injury only) or debridement, irrigation, and splinting (soft tissue injury and fracture) of extremity injuries. This is significantly more than during OIF I (31%; P < .001). During OIF II, 106 of the 367 soft tissue debridements were for torso soft tissue wounds. A total of 33 chest procedures (3%) were performed in OIF II compared with 8% during OIF I (P = .01). Twenty-one thoracotomies were performed, including 11 resuscitative thoracocotomies. No patient who underwent resuscitative thoracotomy survived. These 11 patients had absent or intermittent vital signs on arrival to our unit and all had poor physiologic status (hypothermic and acidotic) secondary to massive hemorrhage from torso and extremity wounds. During OIF II, a total of 166 abdominal procedures were performed during 76 laparotomies. Of these cases, 31 (41%) were damage control and 45 (59%) were definitive laparotomies, compared with 3 (15%) damage control and 17 (85%) definitive laparotomies during OIF I (P = .04).

More emergent extremity procedures, such as amputations (16% vs 4%; P < .001) and fasciotomies (10% vs 5%; P = .01), were performed during OIF I and a higher percentage of head and neck procedures were performed during OIF I (14% vs 6%; P < .001).

Eighty-four (9.4%) of the combat casualties transferred to our unit met our criteria as critical patients during OIF II. These included operative and nonoperative (head injury, airway compromise) patients. Twenty-five patients referred to our unit died en route and were not included in our analysis of critical patients. These patients were considered DOW patients if they died after leaving a BAS en route to our facility. Of 84 patients who met our criteria as critical patients, 64 (76%) survived after treatment at our facility. During OIF I, 21 patients (6%) were classified as critical using the same criteria. Eighteen (86%) of those casualties survived (P = .55). The average Injury Severity Score for all critical patients during OIF I was 21 and it was 25 for critical patients during OIF II. In OIF I, the majority of the critically injured patients were Iraqi (76%) and the 3 critical casualties who died were Iraqi. During OIF II, two-thirds of the critically injured patients were US casualties and the remainder were Iraqi.

Detailed data regarding time to presentation for all casualties were entered into the database during the first 6 months of OIF II. The higher volume of casualties during the latter period allowed this analysis for critical US patients only. During the period from March to August 2004, the average time to presentation (time of injury to arrival at our unit) for all casualties arriving at Camp Taqaddum was 81 minutes (range, 5-480 minutes; median, 60 minutes) and the average time to presentation for patients we operated on was 86 minutes (range, 10-240 minutes; median, 60 minutes). The majority of casualties received during OIF II were injured within a 15-mile radius of our facility.

Time to presentation data were available for 75 critical US patients during the entire OIF II period and the average time to presentation was 66 minutes (range, 15-168 minutes; median, 59 minutes). For US casualties, the median time to presentation for OIF II (59 minutes) was twice that for critical US casualties during OIF I (30 minutes). During OIF II, 32 of these critical US casualties (43%) were taken to an echelon 1 unit (BAS) prior to being evacuated to our unit. The average time to presentation to the FRSS for these patients was 80 minutes (range, 41-150 minutes; median, 73 minutes) vs 56 minutes (range, 15-168 minutes; median, 50 minutes) for those who came directly to us (P = .001). Of those taken to a BAS first, 33% were DOW whereas 28% of critical casualties who came directly to us were DOW (P = .2).

In addition to Marine Corps personnel, US Army personnel and Iraqis were treated by the FRSS units. Only US casualties were included in the analysis of mortality rates. During OIF I, only Marines were operating within the I MEF area of responsibility. During OIF II, Marine Corps and Army personnel were stationed in Al Anbar province and both were included in I MEF casualty data.

During OIF I, 85.8% of casualties in the I MEF area of responsibility were classified as WIA. During OIF II, this rate was 75.4%. There was a difference between Army and Marine Corps casualties who were RTD. Of all Army casualties in the I MEF area of responsibility, 43.4% were RTD while 70.1% of all Marine Corps casualties were RTD during OIF II.

Based on data provided by the I MEF, the KIA rates for OIF I and OIF II were 13.5% and 20.2%, respectively. The DOW rates were 0.88% and 5.5%, respectively. When Army personnel were excluded from the analysis, the Marine Corps DOW and KIA rates during OIF II were 6.1% and 21.6%, respectively.

A total of 20 patients treated at our facility were DOW. Eleven were operative deaths at our facility and 9 died at higher levels of care secondary to head injuries or burns. Six of these patients died at the Combat Support Hospitals in Iraq, 2 died at the echelon 4 hospital in Germany, and 1 died at Brooke Army Medical Center in Texas. Patients who died in the FRSS operating room during OIF II had multiple severe fragment injuries, including pulmonary hilar injury, bilateral grade 5 liver injury, common femoral vessel injury, supraceliac aortic injury, grade 4-5 spleen injuries, multiple colon and small-bowel injuries, and a blunt thoracic aortic injury.

During OIF I, 3 patients were DOW after treatment at an FRSS and all 3 were Iraqi. Two had penetrating head injuries and 1 died of sepsis after an extremity vascular injury.

The US Marine Corps FRSS was designed to provide resuscitative surgical capability during expeditionary maneuver warfare. This report examines the effectiveness of this system during OIF I vs OIF II. This is significant as the battlefield and military mission between the 2 phases of this conflict are different.

The FRSS experiences were different for the 2 periods in the war, and the development of the insurgency in Iraq played a major role in this change. The population of patients (US vs Iraqi) treated at the FRSS has shifted heavily toward US casualties and this is simply because of limited access to the FRSS units for injured Iraqis during OIF II. In addition to having fewer US casualties overall during OIF I, Iraqi casualties had better access to FRSS units and were frequently brought by ground from an adjacent battle. Currently, the majority of Iraqi casualties are taken to Iraqi hospitals and not brought into a secure US camp for treatment.

The use of IEDs has resulted in more fragment wounds and a higher percentage of critically injured patients arriving to the FRSS. A higher percentage of patients arriving at the FRSS are undergoing surgery, and these patients have more injuries and undergo more procedures than casualties during OIF I. The higher percentage of patients undergoing operation at the FRSS during OIF II is due, in part, to an increase in the number of wounds and the severity of wounds per patient. Another contributing factor to this is that the stationary posture of the FRSS during OIF II and the addition of radiology capabilities have allowed the FRSS to perform many nonemergent wound debridements that would have been transferred to the next level of care during maneuver warfare. The time to presentation for these injuries is less important than for critical patients, and many would argue that nonemergent cases such as wound debridements should have been evacuated directly to the Combat Support Hospitals. We felt, however, that it was important to perform early wound debridement in these patients to prevent delays in care and expedite the casualty's medevac to Germany.

Despite a higher rate of blast and fragment injuries during OIF II, the amputation rate was lower than for OIF I. We do not believe this is related to a change in casualty evacuation patterns (more severe extremity injuries flying over us to go to the Combat Support Hospitals) as we were able to track the casualty evacuations from units in Ramadi and Fallujah and saw no such pattern. This difference may be related to weaponry used (majority of casualties in vehicles rather than on foot when hit by an IED) or surgeon experience leading to more limb salvage attempts with vascular shunts and external fixation.

The KIA and DOW rates for the FRSS units used in OIF I were the lowest seen in modern warfare.¹ These low rates have not continued into OIF II, however, as the battle against the insurgency has intensified. During OIF I, every Marine treated at an FRSS survived, but this has clearly changed. Forward surgical units such as the FRSS at Taqaddum have seen higher volumes and higher acuity among the US casualties during OIF II, with a subsequent increase in mortality rates among Marine casualties.

Historically, the KIA rates in major conflicts have been approximately 20%. Death on the battlefield is most commonly due to penetrating wounds to the head (37%), chest (24%), abdomen (9%), and extremity (3%). One-half of these deaths are secondary to exsanguinating hemorrhage and 10% to 20% of such deaths are from extremity wounds.⁴ The injury patterns of KIAs in our experience is consistent with these historical data. The rates of combat casualties who were DOW after being taken to a medical facility has ranged from 3% to 6% since the Korean War.⁴

Operation Iraqi Freedom I was a deviation from this historical pattern and I MEF forces had significantly lower KIA and DOW rates of 13.5% and 0.8%, respectively. There are insufficient data, however, to attribute the low DOW rates of OIF I exclusively to the use of forward surgical units such as the FRSS.

Based on the early success of the FRSS during OIF I, we expected to see similar KIA and DOW rates using small forward surgical units during OIF II. This has not been the case. The data provided by the I MEF for our data collection period of OIF II show KIA and DOW rates that are 20.2% and 5.5%, respectively.

There are many factors that can contribute to this change, including differences in accounting data or thresholds for observing patients overnight at a medical facility. Changes in admission rates for relatively minor injuries could potentially lead to higher WIA rates, which would lower the KIA and DOW rates.⁵ This is demonstrated by differences in our current data between Army and Marine Corps units within the I MEF area of operation. Comparatively, more Army casualties were classified as WIA (admitted to an echelon 3 facility for 24 hours) than Marine casualties. More than 70% of all Marine casualties (includes KIA, DOW, WIA, and RTD) were classified as RTD while less than 45% of all Army casualties were RTD. This results in higher WIA rates and lower DOW and KIA rates for Army personnel. The higher percentage of casualties classified as WIA by the I MEF during OIF I compared with OIF II does account for some of the differences in KIA and DOW rates between the different parts of the conflict.

Other potential reasons for these changes in mortality rates include limited physician and nursing experience, lack of appropriate medical resources, inappropriate allocation of medical resources, more lethal weapons used by insurgents, and delays in casualty evacuation from the point of injury to surgical care.

We believe the use of IEDs by insurgents has significantly contributed to higher mortality rates during OIF II. Evidence of this can be seen in differences in the mechanism of injury between OIF I and OIF II. These data reflect a significant increase in fragment wounds and numbers of injuries and procedures required per casualty.

The location of injuries has not changed significantly between the 2 periods of the conflict. The injury patterns in OIF I and OIF II have a predominance of extremity wounds and head and neck injuries. This distribution of penetrating wounds is consistent with past modern conflicts in Iraq, Afghanistan, and Somalia.^6-9 The body armor worn by US forces has remained the same for both parts of this conflict and has been effective in decreasing torso injuries from small arms and small IED fragments. Despite this, large IED blasts and being near rocket and mortar impacts result in multiple high-velocity fragments that no reasonable amount of body armor can protect against.

Another important factor that affects mortality on the battlefield is the time to presentation to surgical care, particularly for the critically injured patients and patients who require damage control procedures. In the civilian setting, delay in presentation to a trauma center because of a prolonged evaluation or inadequate treatment at a local hospital results in higher mortality rates for these transferred patients.¹⁰ The development of a trauma system can help ensure that patients are taken immediately to the appropriate level of care and can improve survival rates.¹¹

The median time to presentation to an FRSS for a critically injured Marine was 30 minutes in OIF I and 59 minutes in OIF II. This delay resulted in more patients arriving to our FRSS in extremis and requiring damage control procedures. Damage control rates may reflect the fact that critically injured patients who in the past may have died on the battlefield are now arriving at these forward surgical units alive. Alternatively, a higher damage control rate seen at the FRSS may reflect a delay in presentation of salvageable patients. This delay may contribute to these patients becoming cold, coagulopathic, and acidotic in the field or at a BAS prior to arriving at an FRSS. Our experience was consistent with the latter scenario. While we recognize that delay in presentation from the urban battlefield is multifactorial, we believe that a major delay in receiving many critically injured patients was related to their initial evacuation to an aid station rather than directly to surgical care. We were not, however, able to demonstrate a significant difference in DOW rates based on prior treatment at a BAS. Further data collection with larger numbers of critically injured patients will be required to fully assess the impact of presentation times on mortality in this conflict.

We do maintain that the corpsman, medic, and general medical officer treating casualties on the battlefield need clear guidance regarding which patients should be evacuated directly to surgical care. A theaterwide trauma system should provide this guidance with simple protocols. We propose that all casualties requiring litter transport be evacuated directly to surgical care. Only immediate lifesaving measures should be performed in the field (intubation, needle thoracostomy, tourniquets) and rapid transportation to surgical care should be obtained. Additionally, low-volume resuscitation should be taught and emphasized to nonsurgeons providing combat casualty care.¹² The additional benefits of a theaterwide trauma system with central oversight will be improved flow of casualty data between levels of care and a more comprehensive view of the casualty flow.

During OIF I, critically injured patients frequently bypassed echelon 1 care and were appropriately taken away from the battle line directly to the closest FRSS. The FRSS was designed to prevent death in a small subset of casualties who have potentially lethal injuries but are not killed instantly on the battlefield, and survival in these patients is time sensitive.

The nature of the current conflict in Iraq should influence the way that casualties are managed and entered into the medical system. In general, we know the areas where casualties are likely to occur and where the most definitive surgical care is located (much like an urban civilian environment). Recent efforts to consolidate rather than disperse surgical assets and to provide central oversight have addressed this issue. Only with continued data collection and careful attention to the many variables involved will we be able to make definitive statements regarding optimal trauma care in Iraq.

Correspondence: Stacy A. Brethauer, MD, Department of Surgery, Cleveland Clinic Foundation, 9500 Euclid Ave, M61, Cleveland, OH 44195 (brethas@ccf.org).

Accepted for Publication: February 11, 2007.

Author Contributions: Dr Bohman had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Brethauer and Chao. Acquisition of data: Brethauer, Chao, Chambers, Green, and Bohman. Analysis and interpretation of data: Brethauer, Chao, Chambers, Brown, Rhee, and Bohman. Drafting of the manuscript: Brethauer, Chao, and Rhee. Critical revision of the manuscript for important intellectual content: Brethauer, Chambers, Green, Brown, and Bohman. Statistical analysis: Brown. Administrative, technical, and material support: Chao, Chambers, and Green. Study supervision: Chao, Rhee, and Bohman.

Financial Disclosure: None reported.

Disclaimer: The opinions and conclusions contained herein are the private views of the authors and are not to be construed as official or reflecting the views of the US Marine Corps, US Navy, or the Department of Defense.