Open abdomen (OA) and temporary abdominal closure (TAC) have become common tools used to manage patients with a wide variety of surgical problems. This technique was initially described as a temporizing measure used in unstable trauma patients that were treated with damage control laparotomy (DCL) for severe trauma. Open abdomen has been adapted by surgeons to treat emergency general surgery (EGS) patients. This has resulted in the widespread utilization of both OA and TAC in many practices.1
Traditionally, patients with an OA have been subjected to prolonged mechanical ventilation after initial operation, likely due to the need for repeated take-back to the operating room for second look operations or to attempt abdominal closure. This can have an impact on patient outcomes, as 10% to 20% of patients who are mechanically ventilated for longer than 48 hours may develop ventilator-associated pneumonia (VAP), with a subsequent twofold increase in mortality.2
Currently, there are no data-driven guidelines or randomized studies available to guide respiratory management, particularly, the feasibility of extubating patients treated with an OA. Weaning protocols with defined extubation criteria have been shown to increase the rates of earlier extubation in both medical and surgical patients,3,4 as the use of a protocol-directed mechanical ventilation weaning decreases the subjective nature of the decision to extubate. However, protocol directed weaning and the application of extubation criteria to patients with an OA and TAC has not been sufficiently studied.5
At our hospital, we routinely extubate patients with an OA and TAC when criteria for extubation is met. The aim of our study was to review our current practices with regard to the feasibility and safety of extubation in patients with an OA. We hypothesized that patients who were extubated with an OA would have a decrease in ventilator hours and as a result would have a lower rate of VAP without an increase in extubation failures.
A retrospective review from January 2014 to February 2016 of all trauma and EGS patients managed at our institution with OA and TAC was performed. Institutional Board Review approval was obtained. Patients that died within 24 hours of index operation or those with nonsurvivable head injuries were excluded.
The Parkland Hospital Surgical Intensive Care Unit (SICU) mechanical ventilation liberation protocol can be found in Figure 1 and allows for independent assessments by the respiratory therapy team to determine readiness for extubation. The protocol is organized in a stepwise fashion. This includes a daily screen for spontaneous awakening trials (SAT), obtaining an arterial blood gas within a defined set of parameter goals (pH ≥ 7.33 ≤ 7.55, PaO2 ≥ 65, PaCO2 ≥ 30 ≤ 50, SpO2 > 90%), ensuring hemodynamic stability and an absence of cardiac ischemia or an increase in intracranial pressure. Then, if the following conditions are met: minute ventilation volume of 15 L/min or less, positive end-expiratory pressure of 8 cm H2O or less, FiO2 of 0.5 or less, and a rapid shallow breathing index (RSBI) less than 105, then a spontaneous breathing trial (SBT) is performed for 30 to 60 minutes. After meeting extubation criteria, a final approval from the SICU team is necessary prior to extubation.
In our hospital, we predominately use an Abthera OA negative pressure wound therapy (KCI USA, San Antonio, TX) for TAC, but other methods can be used depending on specific patients’ needs, available resources and physician preference. Other options include the use of a Wittmann patch (Starsurgical, Burlington, WI), Bogota bag, polypropylene mesh, biological mesh, and Barker vacuum pack.
Data collected included: patient demographics, pulmonary function at time of extubation with OA, intensive care unit (ICU) length of stay (LOS), ventilator hours, Injury Severity Score (ISS) for trauma patients and sequential organ failure assessment (SOFA) scores for EGS patients. The number of extubation events and ventilator-free hours were calculated for each patient. Adverse events such as the need for reintubation with an OA and VAP were collected. Ventilator-associated pneumonia was defined as that with onset after 48 hours of mechanical ventilation diagnosed by clinical, laboratory, and imaging findings and variation of the ventilator mechanics by the treating team and subsequent appropriate management. Failed extubation was defined as an unplanned intubation within 48 hours after a planned extubation.
Patients were divided into cohorts consisting of those who were successfully extubated with an OA and those who were not. Mann-Whitney U and χ2 analyses were performed to compare continuous and categorical variables. Significance was set at α = 0.05 for two-tailed tests. Statistical analysis was performed in SPSS (version 184.108.40.206; IBM, Redmond, WA).
Overall, 52 patients (20 trauma, 32 EGS) were managed with an OA and TAC during the study period. Indications for an OA were: intra-abdominal contamination in four (7.7%) patients, concern for intra-abdominal hypertension in 12 (23.1%), severe intra-abdominal hemorrhage in 8 (15.4%), planned second look in 25 (48.1%), and necrotizing abdominal wall infection in 3 (5.8%). An Abthera was used as primary TAC device in all patients at least once during their hospital stay. However, in 19 (36.5%) patients, additional methods of TAC were used, either in conjunction with an Abthera device or on their own. The most common secondary method was Wittman patch, 17 (32.7%); followed by Bogota bag, 2 (3.8%); polypropylene mesh, 2 (3.8%); biological mesh, 1 (1.9%); and Barker vacuum pack, 1 (1.9%). Some patients might have used more than one secondary method.
Twenty-five patients (6 trauma, 19 EGS) had at least one extubation event while being managed with an OA. Four (16%) patients were extubated in the operating room at the end of a surgical procedure. The rest were extubated in the SICU following our mechanical ventilator liberation protocol (Fig. 1). All patients were undergoing SAT and were hemodynamically stable. One patient had an intracranial pressure monitoring device in place and his recordings were consistently below 20 mm Hg. All of the patients had a RSBI lower than 105. The rest of their pulmonary function parameters were within acceptable ranges and they were extubated under physician discretion, as per our protocol. Specific parameters are described in Figure 2. There were 108 extubation events in total with a median of 3 (interquartile range, 1–5) extubation events per patient. The median ventilator-free hours for patients who were extubated was 101 hours (interquartile range, 39.42–260.46) (Fig. 3). The relationship between extubation events and ventilator time saved is shown in Figure 4. Emergency general surgery patients who were successfully extubated with an OA had lower median SOFA scores (4.0 [2.0–7.0] vs. 7.0 [6.0–9.5], p = 0.01) (Fig. 5) than those who remained intubated; however, there was no difference in ISS between trauma patients (Fig. 6). Emergency general surgery patients had an extubation event with an OA more often than trauma patients (59.4% vs. 30%, p = 0.03) also had a longer duration with an OA (226.2 hours [66.5–412.1] vs. 65.4 hours [33.6–106.4], p < 0.01). There was no difference in age, gender, ICU LOS or admission GCS between cohorts.
There was no difference in ICU LOS between patients that were extubated with an OA and those that were not and this persisted when independent comparisons were made between the trauma and EGS groups. Nine patients (17.3%) developed VAP, of which 8 were never extubated with an OA. Patients that were never extubated while with an OA had higher rates of VAP (30.8% vs. 3.8%, p = 0.01). Of those patients who were never extubated, 7 passed a SBT but remained intubated. Reasons for not extubating were: planned take-back to the OR 3 (42.9%), unavailable reason 3 (42.9%) and altered mental status 1 (14.3%). One patient required re intubation for respiratory dysfunction after a trial of extubation with an OA.
In this study, we reviewed our current practices with regards to extubation in patients with an OA and TAC. Our results suggest extubation with an OA is safe in trauma and EGS patients, possibly decreasing VAP rates with minimal risk of extubation failure, and thus confirm our initial hypothesis.
The practice of early extubation with an OA is not novel but beyond a recent study that exclusively reviewed extubation in trauma patients with an OA,6 we are unique in providing data to support the feasibility of extubation in EGS and trauma patients managed with this approach. In the study by Sujka et al.,6 they focused on trauma patients with no comment on patients with an OA as a consequence of nontraumatic entities, even though they comprise a significant subset of those managed with an OA. Our entire population included 52 patients and the majority (61.5%) were EGS. In these EGS patients, 59.4% were extubated with an OA, in comparison to only 30% of the trauma patients. This suggests EGS patients had less pulmonary compromise than the trauma patients. Furthermore, the difference in median SOFA score in the EGS group between those extubated and those that were not (4.0 [2.0–7.0] vs. 7.0 [6.0–9.5], p = 0.01) implies a less ill population, and as such, prudence should be exercised when interpreting outcomes in this group.
In the past, the presence of an OA with its potential risk of evisceration and a perception of an altered respiratory physiology due to the lack of abdominal wall integrity may have dissuaded clinicians against extubation.7 Mondal et al.8 reported that an intact abdominal wall musculature contributes to the respiratory physiology by creating a subdiaphragmatic negative pressure that assists in lung expansion. If the abdominal pressure is lost, as in OA, a compensatory change in the contraction patterns of the respiratory musculature prevents brisk collapse of the lung during expiration. These changes persist beyond abdominal closure as the thoracoabdominal pressure gradient is reestablished.
In addition, failing extubation can lead to higher rates of VAP, as well as higher mortality and periprocedural complications from reintubation.9–12 Extubation failures are undesired, but a 0% rate implies prolonged mechanical ventilation past the ideal time for discontinuation.13 In patients admitted to the ICU, reported rates of extubation failure range from 10% to 20%,14 but this may be far from optimal.13 In our series, one patient who was extubated with OA needed to be urgently re intubated. While this is a lower rate than found in other reports, our small sample size limits the generalizability of these results. Our results show higher VAP rates in OA patients who had no attempts at extubation (30.8% vs. 3.8%, p = 0.01). While most of these patients passed an SBT, they remained intubated, usually due to plans for take-back to the operating room. This suggests that physician discretion prevented earlier liberation from mechanical ventilation. Despite our best efforts for early extubation, there is an opportunity for improvement in our SICU.
Recommendations regarding the respiratory management of patients with an OA are scarce. The international consensus for OA in trauma does not comment on this patient population in their guidelines,15 and other authors have made management suggestions based mainly on expert opinion.7,16,17 The OA advisory panel is a multidisciplinary group of general, trauma, and plastic surgeons that created guidelines for the management of OA. These guidelines state extubation in these patients should be based solely on pulmonary function, in lieu of OA status.16 Moreover, guidelines specifically designed for the management of OA in nontrauma patients have not commented on the timing or safety of extubation in these patients.18
While the guidelines have not been conclusive in this group of patients, the benefits of early extubation have been defined in the general population. Longer duration of mechanical ventilation is a risk factor for the development of VAP19,20 which can increase hospital LOS, mortality and hospital-related costs.20,21 The Parkland Hospital Surgical ICU mechanical ventilation liberation protocol is a step-wise approach to increase the efficiency and improve objectivity during the extubation process. However, the final decision for extubation remains with the SICU team and can be impacted by other factors such as planned re exploration.
The findings from our current study suggest that patients with an OA do not require continuous mechanical ventilation if they meet criteria for extubation. Plans for reexploration should be considered, but should not be the main guiding factor, in the decision for extubation. Based on our data, and the available literature, we recommend full ventilatory support to maximize oxygen delivery during the immediate period after a DCL but as the patient's condition evolves, the ventilatory support should be individualized to the specific status.16,17 Ventilatory support for patients with TAC should include ventilatory protective strategies,7,17 adequate sedation to prevent TAC dislodgment,17 and daily spontaneous awakening and SBT with early extubation when clinically feasible. Moreover, from a resource allocation perspective, extubated patients can be managed in a stepdown unit rather than ICU, which can potentially decrease hospital costs.6
This retrospective study is limited by the inherent characteristics of a retrospective methodology. The SOFA score differences, between extubated EGS patients and those that were not, questions the necessity of initially managing these patients with OA. However, it is difficult, if not impossible, to review each patient situation, operative environment, and primary determinate of these decisions retrospectively. Several prospective initiatives evaluating the effectiveness of DCL in trauma patients (NCT02706041) and EGS patients (NCT03163095) are ongoing and will provide high-quality data to better define objective clinical indications beyond discretion of the surgeon.22,23
This study provides much needed data regarding the feasibility of extubation in trauma and EGS patients managed with an OA and TAC. Benefits of early extubation may include lower VAP rates in this population. Plans for reexploration hinder the decision to extubate in these patients.
L.R.T. participated in the literature search, data collection, writing, data analysis, data interpretation, figure, tables and submission. J.B.I. participated in the literature search, study design, data collection, data analysis, data interpretation, writing and corrections. T.D.M. participated in the study design and editing. A.T. participated in the study design and data interpretation. H.B.C. participated in the literature search, data collection and writing. R.T. participated in the literature search, data collection, data interpretation and study design. A.T.C. participated in the data collection, writing and figure. C.T.M. participated in the study design, data interpretation and editing. A.L.E. participated in the study design and corrections. M.W.C. participated in the study design, data interpretation, correction and submission.
We would like to thank Dave Primm for help in editing this article.
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the article. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
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Keywords:© 2018 Lippincott Williams & Wilkins, Inc.
Open abdomen; damage control laparotomy; trauma; EGS