Intraabdominal fluid extravasation (IAFE) after hip arthroscopy is a rare but catastrophic complication that has been documented in both anesthesia and orthopedic literature. IAFE during hip arthroscopy can present with mild symptoms such as hypothermia, abdominal distention, and nausea, but can also have a severe presentation such as abdominal compartment syndrome (ACS) with patients requiring diuresis or surgical decompression.1–3 4
The Multicenter Arthroscopy of the Hip Outcomes Research Network (MAHORN) group concluded after a survey of >25,000 hip arthroscopies that the prevalence of symptomatic IAFE after hip arthroscopy was approximately 0.16%. Risk factors included concomitant iliopsoas tenotomy and high pump pressures.5
IAFE can be diagnosed radiographically either through abdominal/pelvic ultrasonography or computed tomography (CT) scan. However, ultrasonography has the benefit of being portable and more rapid, as well as sparing patients exposure to unnecessary radiation. Point-of-care ultrasound (POCUS) of the abdomen, pelvis, and heart in the form of the Focused Assessment With Sonography for Trauma (FAST) examination has become commonplace in the emergency department setting as an initial screening tool to detect the presence of intraperitoneal free fluid. Previous studies have demonstrated the sensitivity and specificity of FAST for the detection of free fluid to be 0.64 to 0.98 and 0.86 to 1.00, respectively, compared with abdominal CT.6 7 8 , 9
METHODS
Patient Recruitment
The study was approved by the institutional review board at Hospital for Special Surgery (2014–2016). Written informed consent was obtained from all subjects. Patients scheduled for outpatient hip arthroscopy were approached prospectively between April 21, 2014 and March 5, 2015. Inclusion criteria were patients scheduled for primary ambulatory hip arthroscopy with a participating surgeon. Exclusion criteria included the following: age <18 years or >80 years, an ASA physical status classification score of III or greater, chronic pain requiring interventional/chronic pain physician management, and presence of intraabdominal fluid during the preoperative FAST examination.
Intraoperative Procedures and Data Collection
Patients were first induced under anesthesia at the discretion of the anesthesiologist; however, neuraxial anesthetic in the form of either a spinal, epidural, or combined spinal epidural was performed on each patient. After induction, a FAST examination was performed by a trained anesthesiologist to exclude the preoperative presence of intraabdominal fluid. Both anesthesiologists evaluating the patient had extensive experience with POCUS including the FAST examination. One was a regional anesthesiologist trained in ultrasound-guided regional anesthesia with basic perioperative transesophageal echocardiography certification and extensive experience, as well as teaching, in focused transthoracic echocardiography who underwent a formal training course in the FAST examination and had previously performed >25 examinations. The second was a critical care–trained anesthesiologist who also routinely used ultrasound for regional anesthesiology, had testamur status for both basic and advanced transesophageal echocardiography, and had performed well >25 FAST examinations before the study.
Patients were evaluated using a GE LOGIQ e ultrasound (GE Healthcare, WI) utilizing a GE 3S-RS sector transducer. The examination consisted of views of the perihepatic space, perisplenic space, pelvis (longitudinal and transverse), and pericardium. To evaluate for fluid in the perihepatic space (Morison's pouch), the probe was placed in the right upper quadrant (Figure 1A ); for the perisplenic space, the probe was placed in the left upper quadrant (Figure 1B ); the pelvis was evaluated with the probe in the suprapubic space in both longitudinal (Figure 1C ) and transverse (Figure 1D ) orientation; and, for pericardial assessment, the probe was placed subcostal (Figure 1E ). For assessment of the right upper quadrant, the anesthesiologist evaluated for fluid between the liver and the kidney (Morison's pouch; Figure 2 ). For assessment of the left upper quadrant, the anesthesiologist evaluated for fluid between the spleen and the kidney (perisplenic space; Figure 3 ). For assessment of the pelvis, both longitudinal (Figure 4 ) and transverse (Figure 5 ) planes were evaluated. In both men and women, the fluid accumulates in the retrovesicular space behind the bladder, whereas in women, it can initially be seen in the retrouterine pouch (pouch of Douglas; Figure 5 ). For the subcostal view, the anesthesiologist assessed for fluid in the pericardial space (Figure 6 ).
Figure 1.: Probe placement for Focused Assessment With Sonography for Trauma examination. A, Right upper quadrant; B, Left upper quadrant; C, Pelvic longitudinal; D, pelvic transverse; E, Subcostal.
Figure 2.: A, Probe placement for right upper quadrant evaluation; B, Orientation Marker aimed Cephalad; C, Sonoanatomy with the liver on left side of the screen and the kidney on right side. The hepatorenal space or Morison's pouch is between the liver and the kidney.
Figure 3.: A, Probe placement for left upper quadrant evaluation; B, Orientation marker aimed cephalad; C, Sonoanatomy with the spleen on left side of the screen and kidney on right side. The perisplenic space surrounds the spleen is between kidney and diaphragm.
Figure 4.: A, Probe placement for pelvic longitudinal evaluation with orientation marker aimed cephalad. B, Male sonoanatomy with urinary bladder in the near field and retrovesicular space posterior. C, Female sonoanatomy with urinary bladder in the near field, followed but the uterus and the retrouterine space (pouch of Douglas) most posterior.
Figure 5.: A, Probe placement for pelvic transverse evaluation with orientation marker aimed to the patient’s right. B, Male sonoanatomy with urinary bladder in the near field and retrovesicular space posterior. C, Female sonoanatomy with urinary bladder in the near field, followed but the uterus and the retrouterine space (pouch of Douglas) most posterior.
Figure 6.: A, Probe placement for subcostal view with orientation marker aimed to the patient’s left. B, Sonoanatomy scanning through the liver in near field to assess pericardium surrounding heart. LA indicates left artery; LV, left ventricular; RA, right artery; RV, right ventricular.
Postoperatively, the same anesthesiologist repeated the FAST examination and patients with new fluid in either the abdominal or pelvic compartment were diagnosed with IAFE. The amount of fluid present was graded as “small,” “moderate,” or “large” at the discretion of the anesthesiologist based on the size of the fluid collection visualized on the machine. To increase the sensitivity, during the preoperative and postoperative FAST examination, the patients were placed in Trendelenburg position while evaluating the perihepatic and perisplenic space and reverse Trendelenburg to evaluate the pelvic compartment. To prevent the potential for examiner bias, an anesthesiologist blinded to the case-reviewed images from both the preoperative and the postoperative FAST examinations and independently made a diagnosis of IAFE, as well as graded the size. When the 2 examiners disagreed, the images were reviewed by a third independent expert to reach consensus.
In addition to the ultrasound examinations, the total time the hip was placed in traction, the total volume of fluid infused through the arthroscopic fluid pump, and fluid pump pressures were recorded (Table 2 ). Intraoperative surgical interventions, including labral repair/debridement, femoral osteochondroplasty, psoas release, and capsular closure were also recorded (Table 2 ).
Postoperative Data Collection
In the postanesthesia care unit (PACU), patients were assessed every hour for pain by a blinded nurse until discharge or until the first 6 hours after surgery had elapsed, depending on which occurred earlier. Numerical rating scale (NRS) pain scores and total amount of opioid medication consumed were recorded. Postoperative temperature, total amount of antiemetic medications consumed, and time to discharge were also recorded.
Statistical Analysis
Study data were collected and managed using research electronic data capture hosted at Hospital for Special Surgery. Research electronic data capture is a secure, web-based application that is designed to support data capture for research studies. It provides (1) an intuitive inference for validated data entry; (2) audit trails for tracking data manipulation and export procedures; (3) automated export procedures for seamless data downloads to common statistical packages; and (4) procedures for importing data from external sources.10
The study was designed as an investigational pilot study; therefore, no formal power analysis was performed because of limited institutional data on the primary outcome of IAFE. It was determined that enrollment of 100 patients would allow for a reasonably precise estimation of the incidence of IAFE in patients undergoing hip arthroscopy. The observed incidence of IAFE is reported as a point estimate with corresponding 99% Wilson score confidence interval (CI) with continuity correction.14 t tests or Wilcoxon rank sum tests, depending on the distribution of the data. Categorical variables were compared between patients with and without IAFE using χ2 or Fisher exact tests, as appropriate. Continuous and binary postsurgical outcomes were further compared between patients with and without IAFE using linear and log-binomial regression, respectively, to adjust for patient age and sex. Regression analysis based on the generalized estimating equations method with an autoregressive correlation structure was used to perform unadjusted and adjusted comparisons of change in NRS pain score from baseline between patients with and without IAFE over time. The generalized estimating equation method accounts for the correlation between repeated measurements on the same patient, where the autoregressive correlation structure assumes a greater degree of correlation among measurements recorded closer in time. There was no evidence of an interaction between IAFE and time point with respect to change in pain score from baseline, so a single estimate of difference in means with 99% CI was calculated. Effect sizes are reported as difference in means and relative risk for continuous and binary outcomes, respectively, with 99% CIs. All statistical hypothesis tests were 2 sided, with P < .01 considered statistically significant given the pilot nature of the study. Statistical analyses were performed with SAS Version 9.3 (SAS Institute, Cary, NC).
RESULTS Table 1.: Patient Demographics
Table 2.: Surgical Variables
A total of 100 patients were enrolled in the study, and all patients were included in the final analysis. The ages ranged from 18 to 60 years, with a mean age of 32.7 ± 11.2 years. There were 53 women and 47 men. Patient demographics are listed in Table 1 , including patients’ baseline pain scores as well as whether the patient was on opioid medication preoperatively.
Incidence of IAFE
Intraperitoneal fluid either in the abdomen and/or pelvis was found in 16 patients (16%; 99% CI, 8.4–28.1) postoperatively, indicating a diagnosis of IAFE. This result was confirmed by a blinded anesthesiologist. There was an initial disagreement on the diagnosis for 4 patients (4%); however, on review by a third independent expert, the postoperative examination was determined to be negative. Therefore, the remaining 84 patients (84%) were confirmed to not have IAFE.
Figure 7.: Ultrasound image of preoperative and postoperative pelvic longitudinal and transverse view demonstrating a diagnosis of intraabdominal fluid extravasation after hip arthroscopy. Solid red arrow indicates the presence of free fluid.
Figure 8.: Ultrasound image of preoperative and postoperative perihepatic view demonstrating a diagnosis of intraabdominal fluid extravasation after hip arthroscopy. Solid red arrow indicates the presence of free fluid.
Of the 16 patients with confirmed IAFE, 14 had a qualitatively small grade of fluid present (87.5%). One patient was found to have a qualitatively moderate amount of free fluid in the pelvic compartment (Figure 7 ), and 1 patient was found to have qualitatively moderate amount of free fluid in the perihepatic space (Figure 8 ). Fluid was found in the perihepatic space for 4 patients (25%), in the perisplenic space for 3 patients (18.8%), and in the pelvis for 13 patients (81.3%). No patients were found to have fluid within the pericardium.
Postoperative Outcomes Table 3.: Comparison of Postsurgical Outcomes Between Patients With Versus Without Postoperative IAFE
Figure 9.: Change in numeric rating scale (NRS) pain score from baseline in patients with and without intraabdominal fluid extravasation (IAFE) throughout postanesthesia care unit stay. Error bars indicate ± 1 standard error. P = .002.
Patients with IAFE were found to have a significant change in NRS pain scores from their baseline assessment throughout their entire stay (P = .002, 2.1; 99% CI, 0.4–3.9; Figure 9 ). There was a trend toward more postoperative opioid use in patients with IAFE; however, this study was not powered to detect a difference (Table 3 ). There were no statistically significant differences in postoperative antiemetic usage, initial postoperative temperature, and duration of PACU stay (Table 3 ). No patients were diagnosed with ACS.
DISCUSSION
Our results indicate a diagnosis of IAFE after hip arthroscopy in 16% of patients. This is significantly higher than previously reported retrospective study identifying symptomatic IAFE.5
In the last 2 decades, several cases of symptomatic IAFE have been reported. The most frequently proposed recommendation to avoid this complication is careful attention to arthroscopic pump pressure. In the largest study looking at symptomatic IAFE after hip arthroscopy, the MAHORN group found increased pump pressures and concomitant iliopsoas tenotomy to be significant risk factors. The mean pump pressure in the MAHORN study for cases with symptomatic IAFE was 64.92 mm Hg, which is lower than that reported in our study with a mean of 95.5 ± 13.2 mm Hg. Iliopsoas tenotomy was performed in 25 of 40 (63%) cases that developed IAFE in the MAHORN study. A psoas release may potentially create a track for arthroscopic fluid to enter the peritoneal cavity. We did not find evidence of an association between psoas release and the development of IAFE (Table 2 ), but our study is underpowered to evaluate for potential risk factors. However, a likely explanation is that all surgeons in this study delayed the psoas release to the end of the procedure, thereby limiting the potential for significant fluid extravasation. All 3 surgeons involved in this study routinely perform capsulotomies during hip arthroscopy, with 2 of them performing a T-cut for peripheral compartment arthroscopy. Although it would follow that a larger capsulotomy may lead to a higher risk of IAFE, this was not specifically analyzed in this study. The only risk factor that trended toward IAFE incidence in this study was female sex (12 females versus 4 male; P = .054), but it was not statistically significant. Although our study was not powered to evaluate for risk factors, this has not been previously reported and may warrant the use of lower pump pressures when performing hip arthroscopy in females.
Patients with IAFE had, on average, a greater increase in pain score from their baseline assessment throughout their entire PACU stay than patients without IAFE. Patients with IAFE also used more opioids than patients without IAFE; however, this study was not powered to evaluate this fully. There were no differences in postoperative nausea interventions or length of stay. Previously described risk factors including concomitant iliopsoas tenotomy and high pump pressures did not correlate with IAFE; however, this difference was not statistically significant, potentially because of lack of power. These findings suggest that even a small amount of new fluid in the peritoneum worsens the postoperative experience.
There are several limitations to our studies including it being a prospective observational study at a single institution that was not adequately powered to evaluate for risk factors associated with IAFE. The NRS pain scores collected by the blinded PACU nurse did not indicate location of pain; therefore, we were unable to specifically determine if the pain scores were directly from abdomen, pelvis, or hip. However, after adjusting for all other variables, there was a statistically significant correlation to the presence of IAFE and increased pain. Further studies with both a larger sample size as well as involving multiple institutions where surgical techniques may vary will be needed to identify potential surgical and patient risk factors for IAFE.
POCUS is emerging as a new and powerful tool for the anesthesiologist in the perioperative setting for applications assessing the heart,11 12 13 15 , 16 17
Although patient management should be driven by the overall clinical picture and not based solely on ultrasound imaging, the ability to view inside the patient to differentiate between large versus small fluid collections, or fluid collections increasing versus decreasing in size, helps to generate a truly complete clinical picture and avoid delayed detection of major pathology. Because POCUS is becoming more widely utilized by anesthesiologists in all phases of perioperative setting, there is great potential to provide improved patient management for both common clinical scenarios such as hemodynamic instability in the PACU resulting from surgical bleeding into the peritoneum after intraabdominal or endovascular procedures, or, more rare, potentially life-threatening conditions, such as IAFE.
DISCLOSURES
Name: Stephen C. Haskins, MD.
Contribution: This author helped design the study, conduct the study, collect the data, analyze the data, and prepare the manuscript.
Name: Natasha A. Desai, BA.
Contribution: This author helped conduct the study, collect the data, analyze the data, and prepare the manuscript.
Name: Kara G. Fields, MS.
Contribution: This author helped analyze the data and prepare the manuscript.
Name: Jemiel A. Nejim, MD.
Contribution: This author helped design the study, conduct the study, collect the data, and prepare the manuscript.
Name: Stephanie Cheng, MD.
Contribution: This author helped design the study, conduct the study, collect the data, and prepare the manuscript.
Name: Struan H. Coleman, MD, PhD.
Contribution: This author helped conduct the study and prepare the manuscript.
Name: Danyal H. Nawabi, MD.
Contribution: This author helped conduct the study and prepare the manuscript.
Name: Bryan T. Kelly, MD.
Contribution: This author helped conduct the study and prepare the manuscript.
This manuscript was handled by: Maxime Cannesson, MD, PhD.
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