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Introduction: Spinal and paraspinal infections (SPIs) are a potential complication following traumatic spinal column injury, and we sought to determine the association of antibiotic prophylaxis on SPI development following a spinal gunshot wound (GSW)., Methods: A single-center retrospective cohort study was performed on adults who sustained a GSW to the spinal column over 11 y. Patients were excluded if they died within 24 h or had a mechanism other than GSW. Antibiotic use and injury patterns were analyzed., Results: A total of 330 patients were included in analysis. Most were male (88%), Black (79%), and averaged 27 y old. Mortality was 4%. Prophylactic antibiotics were administered in 65%; and median duration was 5 d. Nine patients (2.7%) developed SPI. Hollow viscus injury (HVIs) (66.7% versus 23.1%, P < 0.001), primarily colon injuries (55.6% versus 12.5%, P < 0.001), were independently associated with SPI. Antibiotic use was not associated with a decrease in SPI (3% versus 2%; P = 0.41). Of the patients who developed SPI, seven received 3 d of antibiotics or less, and this was not statistically significant (P = 0.49)., Conclusions: Patients with HVIs have a higher incidence of SPI, following spinal GSW. Although antibiotic use and duration did not have a statistically significant association with SPI, no patient, even with HVIs, who received 4 or more days of antibiotics developed an infection. Due to the low incidence of SPI, a multicenter trial may help determine the optimal duration of prophylactic antibiotics. However, we recommend a maximum of 4 d of antibiotics for SPI prophylaxis following GSW., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Civilian extremity trauma with vascular injury carries a significant risk of morbidity, limb loss, and mortality. We aim to describe the trends in extremity vascular injury repair and compare outcomes between trauma and vascular surgeons., Methods: We performed a single-center retrospective review of patients 18 years or older with extremity vascular injury requiring surgical intervention between January 2009 and December 2019. Demographics, injury characteristics, operative course, and hospital course were analyzed. Descriptive statistics were used to examine management trends, and outcomes were compared for arterial repairs. Multivariate regression was used to evaluate surgeon specialty as a predictor of complications, readmission, vascular outcomes, and mortality., Results: A total of 231 patients met our inclusion criteria; 80% were male with a median age of 29 years. The femoral vessels were most commonly injured (39.4%), followed by the popliteal vessels (26.8%). Trauma surgeons performed the majority of femoral artery repairs (82%), while vascular surgeons repaired the majority of popliteal artery injuries (84%). Both had a similar share of brachial artery repairs (36% vs. 39%, respectively). There were no differences in complications, readmission, vascular outcomes, and mortality. Median time from arrival to operating room was significantly shorter for trauma surgeons. There was a significant downward trend between 2009 and 2017 in the proportion of total and femoral vascular procedures performed by trauma surgeons. On multivariate regression, surgical specialty was not a significant predictor of need for vascular reintervention, prophylactic or delayed fasciotomies, postoperative complications, or readmissions., Conclusion: Traumas surgeons arrived quicker to the operating and had no difference in short-term clinical outcomes of brachial and femoral artery repairs compared with patients treated by vascular surgeons. Over the last decade, there has been a significant decline in the number of open vascular repairs done by trauma surgeons., Level of Evidence: Therapeutic/Care Management, Level IV., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

A tenth of all pediatric liver transplantations (LTs) are performed for unresectable liver malignancies, especially the more common hepatoblastoma (HBL). Less understood are outcomes after LT for the rare hepatocellular carcinoma, nonhepatoblastoma embryonal tumors (EMBs), and slow growing metastatic neuroendocrine tumors of childhood. Pediatric LT is increasingly performed for rare unresectable liver malignancies other than HBL. We performed a retrospective review of outcomes after LT for malignancy in the multicenter US Scientific Registry of Transplant Recipients (SRTR; n = 677; 1987-2015). We then reviewed the Children's Hospital of Pittsburgh (CHP; n = 74; 1981-2014) experience focusing on LT for unresectable hepatocellular cancer (HCC), EMBs, and metastatic liver tumors (METS). HBL was included to provide reference statistics. In the SRTR database, LT for HCC and HBL increased over time (P < 0.001). Compared with other malignancies, the 149 HCC cases received fewer segmental grafts (P < 0.001) and also experienced 10-year patient survival similar to 15,710 adult HCC LT recipients (51.6% versus 49.6%; P = 0.848, not significant [NS], log-rank test). For 22 of 149 cases with incidental HCC, 10-year patient survival was higher than 127 primary HCC cases (85% [95% confidence interval (CI), 70.6%-100%] versus 48.3% [95% CI, 38%-61%]; P = 0.168, NS) and similar to 3392 biliary atresia cases (89.9%; 95% CI, 88.7%-91%). Actuarial 10-year patient survival for 17 EMBs, 10 METS, and 6 leiomyosarcoma patients exceeded 60%. These survival outcomes were similar to those seen for HBL. At CHP, posttransplant recurrence-free and overall survival among 25 HCC, 17 (68%) of whom had preexisting liver disease, was 16/25 or 64%, and 9/25 or 36%, respectively. All 10 patients with incidental HCC and tumor-node-metastasis stage I and II HCC survived recurrence-free. Only vascular invasion predicted poor survival in multivariate analysis (P < 0.0001). A total of 4 of 5 EMB patients (80%) and all patients with METS (neuroendocrine-2, pseudopapillary pancreatic-1) also survived recurrence-free. Among children, LT can be curative for unresectable HCC confined to the liver and without vascular invasion, incidental HCC, embryonal tumors, and metastatic neuroendocrine tumors. Liver Transplantation 23 1577-1588 2017 AASLD., (© 2017 The Authors. Liver Transplantation published by Wiley Periodicals, Inc. on behalf of American Association for the Study of Liver Diseases.)

Background & Aims: Hepatocyte transplantation partially corrects genetic disorders and has been associated anecdotally with reversal of acute liver failure. Monitoring for graft function and rejection has been difficult, and has contributed to limited graft survival. Here we aimed to use preparative liver-directed radiation therapy, and continuous monitoring for possible rejection in an attempt to overcome these limitations., Methods: Preparative hepatic irradiation was examined in non-human primates as a strategy to improve engraftment of donor hepatocytes, and was then applied in human subjects. T cell immune monitoring was also examined in human subjects to assess adequacy of immunosuppression., Results: Porcine hepatocyte transplants engrafted and expanded to comprise up to 15% of irradiated segments in immunosuppressed monkeys preconditioned with 10Gy liver-directed irradiation. Two patients with urea cycle deficiencies had early graft loss following hepatocyte transplantation; retrospective immune monitoring suggested the need for additional immunosuppression. Preparative radiation, anti-lymphocyte induction, and frequent immune monitoring were instituted for hepatocyte transplantation in a 27year old female with classical phenylketonuria. Post-transplant liver biopsies demonstrated multiple small clusters of transplanted cells, multiple mitoses, and Ki67 + hepatocytes. Mean peripheral blood phenylalanine (PHE) level fell from pre-transplant levels of 1343±48μM (normal 30-119μM) to 854±25μM (treatment goal ≤360μM) after transplant (36% decrease; p<0.0001), despite transplantation of only half the target number of donor hepatocytes. PHE levels remained below 900μM during supervised follow-up, but graft loss occurred after follow-up became inconsistent., Conclusions: Radiation preconditioning and serial rejection risk assessment may produce better engraftment and long-term survival of transplanted hepatocytes. Hepatocyte xenografts engraft for a period of months in non-human primates and may provide effective therapy for patients with acute liver failure., Lay Summary: Hepatocyte transplantation can potentially be used to treat genetic liver disorders but its application in clinical practice has been impeded by inefficient hepatocyte engraftment and the inability to monitor rejection of transplanted liver cells. In this study, we first show in non-human primates that pretreatment of the host liver with radiation improves the engraftment of transplanted liver cells. We then used this knowledge in a series of clinical hepatocyte transplants in patients with genetic liver disorders to show that radiation pretreatment and rejection risk monitoring are safe and, if optimized, could improve engraftment and long-term survival of transplanted hepatocytes in patients., (Copyright © 2016 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Background & Aims: Altered extrahepatic bile ducts, gut, and cardiovascular anomalies constitute the variable phenotype of biliary atresia (BA)., Methods: To identify potential susceptibility loci, Caucasian children, normal (controls) and with BA (cases) at two US centers were compared at >550000 SNP loci. Systems biology analysis was carried out on the data. In order to validate a key gene identified in the analysis, biliary morphogenesis was evaluated in 2-5-day post-fertilization zebrafish embryos after morpholino-antisense oligonucleotide knockdown of the candidate gene ADP ribosylation factor-6 (ARF6, Mo-arf6)., Results: Among 39 and 24 cases at centers 1 and 2, respectively, and 1907 controls, which clustered together on principal component analysis, the SNPs rs3126184 and rs10140366 in a 3' flanking enhancer region for ARF6 demonstrated higher minor allele frequencies (MAF) in each cohort, and 63 combined cases, compared with controls (0.286 vs. 0.131, P = 5.94x10-7, OR 2.66; 0.286 vs. 0.13, P = 5.57x10-7, OR 2.66). Significance was enhanced in 77 total cases, which included 14 additional BA genotyped at rs3126184 only (p = 1.58x10-2, OR = 2.66). Pathway analysis of the 1000 top-ranked SNPs in CHP cases revealed enrichment of genes for EGF regulators (p<1 x10-7), ERK/MAPK and CREB canonical pathways (p<1 x10-34), and functional networks for cellular development and proliferation (p<1 x10-45), further supporting the role of EGFR-ARF6 signaling in BA. In zebrafish embryos, Mo-arf6 injection resulted in a sparse intrahepatic biliary network, several biliary epithelial cell defects, and poor bile excretion to the gall bladder compared with uninjected embryos. Biliary defects were reproduced with the EGFR-blocker AG1478 alone or with Mo-arf6 at lower doses of each agent and rescued with arf6 mRNA., Conclusions: The BA-associated SNPs identify a chromosome 14q21.3 susceptibility locus encompassing the ARF6 gene. arf6 knockdown in zebrafish implicates early biliary dysgenesis as a basis for BA, and also suggests a role for EGFR signaling in BA pathogenesis.

Objective: To evaluate the effects on the potency of a bilateral cavernosal nerve-sparing approach to robot-assisted radical cystectomy (RARC) in a preoperatively potent population., Patients and Methods: We conducted a retrospective review of 254 patients who underwent RARC between 2003 and 2012 at our single institution. We identified 33 men who were younger than 65 years and had evidence of preoperative erections on chart review. Twenty-nine of them underwent a bilateral nerve-sparing procedure, with 28 (97%) having concomitant creation of a continent urinary diversion., Results: Median follow-up was 32.9 months. Postoperatively, 13 (45%) patients had documented erections sufficient for penetration with or without the use of phosphodiesterase 5 inhibitors. Additional 6 (21%) were potent with intracavernosal injections (ICI), and the remaining 10 (34%) failed ICI usage, had on-going medical issues, or lost interest in sexual activity. With univariate analysis, no significant difference was found between those who recovered erections and those who did not on a wide range of demographic, operative, and perioperative factors, including age, comorbidities, operative time, or pathologic stage. Despite neurovascular bundle preservation, there was no local cancer recurrence and no positive soft tissue margins., Conclusion: A cavernosal nerve-sparing robot-assisted approach to radical cystectomy allows for recovery of potency without sacrificing oncologic outcomes even with higher risk disease as compared to historical open or laparoscopic series. Further studies are required to help elucidate why some men have better recovery in this setting than others.

Objective: The aim was to report a single surgeon's experience comparing open and robot-assisted laparoscopic extravesical ureteral reimplantation (RALUR) to treat vesicoureteral reflux (VUR)., Subjects and Methods: We retrospectively reviewed the outcomes of RALUR and open extravesical ureteral reimplantations consecutively performed by a single surgeon between January 2008 and December 2010 using the da Vinci(®) Surgical System. Both groups of patients were subjected to identical pre- and postoperative care protocols., Results: During the defined study interval, 20 open and 20 RALUR procedures were completed by a single surgeon at our institution. Gender and VUR grade were similar in both cohorts. Operative times were longer in the RALUR group, but postoperative opioid use (morphine equivalents) was significantly lower in the RALUR group (RALUR: 0.14 mg/kg, open: 0.25 mg/kg, p = 0.021). There was no significant difference in estimated blood loss (EBL) or length of hospitalization (LOH). The overall rate of surgical complications was similar; however, the complications in the open group tended to be less severe than those occurring in the RALUR group. On follow-up, after a median of 52 months for open surgery and 39 months for RALUR, two children had developed a febrile urinary tract infection in both groups, of which one in the open group had persistent VUR., Conclusion: This single-surgeon experience of open and initial experience with RALUR performed with the same surgical technique on consecutive cohorts with identical post-surgical care protocol allows a comparative analysis of outcomes for a surgeon transitioning to RALUR. The RALUR reduces postoperative analgesic requirements while yielding similar clinical outcomes as the open technique., (Copyright © 2014 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

We examined factors that affect decision-making for families presented with a phase I clinical trial of hepatocyte transplant as a potential alternative to liver transplant for their children among two groups: (i) families who were actually offered enrollment in the hepatocyte trial and; (ii) families whose children had liver transplants before the trial was available. We conducted semi-structured interviews about actual and hypothetical decision-making regarding trial participation and used grounded theory analysis to identify common themes. The most common motivator for participation was decline in the child's health. The most common deterrent was lack of data from prior hepatocyte transplants, particularly when compared with data available about liver transplant. Interviewees' point of comparison for evaluating relative benefits and risks of hepatocyte transplant oscillated between the alternative of doing nothing while waiting for a liver (the relevant alternative) vs. the alternative of getting a liver. These results suggest that families' reluctance to participate may result from misconceptions about severity of the child's disease, underestimating risks of liver transplant, or confusion about the role of hepatocyte transplant in the treatment pathway. Clarification of available treatment alternatives and associated risks as part of informed consent may improve the quality of decision-making regarding trial enrollment., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Historically, the mainstay of soft-tissue reconstruction in the groin and lower abdomen has been the anatomically consistent, easily elevated rectus abdominis flap, with variations. Insetting the rectus abdominis flap here requires creating an abdominal wall defect through which to pass the pedicle, which raises the risk of donor-site morbidity. Although popular as a free flap, the anterolateral thigh flap as a pedicled flap in the groin and lower abdomen has not been directly compared with the rectus abdominis flap., Methods: Retrospective record review was conducted on 39 patients who underwent groin or lower abdominal wall reconstruction (30 anterolateral thigh flap and 10 rectus abdominis flap procedures) to address oncologic defects, lymphadenectomy, and complications of vascular bypass. Patient demographics and comorbidities, flap characteristics, postoperative complications, and time to heal were compared., Results: All patients in both the anterolateral thigh and rectus abdominis flap groups healed at the flap recipient sites. Despite similar patient characteristics, wound cause was different between the groups, with more infected wounds being treated in the anterolateral thigh flap group. Early postoperative complication rates were similar in both groups. Anterolateral thigh flap patients had shorter time to healing, with lower rates of delayed (>30 days) postoperative complications compared with rectus abdominis flap patients. Six rectus abdominis flap patients developed delayed abdominal incisional hernias. No donor- or recipient-site complications were encountered in anterolateral thigh flap patients after 90 days., Conclusion: The pedicled anterolateral thigh flap is the preferred choice for reconstruction of wounds in the groin and lower abdomen.

Background: Liver transplantation (LTx) for hepatoblastoma appears to be increasing. Favorable tumor histology is increasingly linked to survival after surgical resection and could also determine posttransplantation outcomes., Methods: To evaluate national trends in tumor and LTx incidence as the basis for observations at some LTx centers, and determinants of survival after LTx for hepatoblastoma, we queried the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) registry representing 9.451% of the U.S. population (1975-2007), the United Network for Organ Sharing (UNOS, 1988-2010, n = 332), and Children's Hospital of Pittsburgh database (CHP, 1987-2011, n = 35)., Results: In the United States, hepatoblastoma cases increased 4-fold, LTx for hepatoblastoma increased 20-fold, and hepatoblastoma surpassed other unresectable liver malignancies requiring LTx by nearly 3-fold. Actuarial 5-year patient survival exceeded 75%. Recurrences in 16% were greater after segmental LTx in the total U.S. experience (P = .049). At CHP, 5 children died from recurrences (n = 4) and sepsis (n = 1). Tumors were epithelial (57%) or mixed epithelial-stromal (42%), Children's Oncology Group stage III (77%) or IV (23%). Recurrences were related to previous pulmonary metastases (P = .016), and tumor necrosis <50% (P = .013), but not to small cell undifferentiated tumor histology (P = NS). Hepatic artery thrombosis was more common after LTx for hepatoblastoma compared with nonmalignant indications (P = .0089). Thirty-three children received pre-LTx chemotherapy, 88.6% with cisplatin, and 85.7% received post-LTx chemotherapy., Conclusion: Outcomes after LTx for hepatoblastoma may benefit from improved detection and treatment of pretransplantation metastases, adequate tumor lysis after chemotherapy, and perioperative antithrombotic agents but are unaffected by undifferentiated tumor histology., (Copyright © 2013 Mosby, Inc. All rights reserved.)

Purpose: We report our experience and present our technique with the robot-assisted laparoscopic ipsilateral ureteroureterostomy (IUU) in the management of ureteral duplication with ectopia in children., Patients and Methods: We reviewed our institutional experience for all patients who underwent a robot-assisted laparoscopic IUU at the University of Minnesota Amplatz Children's Hospital between December 2010 and October 2011. An intraoperative, three-port technique was used after a ureteral stent was placed into the ipsilateral lower pole. Demographic information, diagnosis, operative time, hospital course, complications, and follow-up were all evaluated., Results: Our series included four female patients and one male patient with a mean age of 61 months (6 to 182 mos). All five had a diagnosis of upper pole ectopic ureters, one of which was associated with an ureterocele. Mean total operative time was 225 minutes (181 to 253 min), and mean hospital stay was 1.2 days (1-2 days). There were no intraoperative complications. In follow-up, at the time of ureteral stent removal, pyelonephritis developed in one patient, but all patients had resolution of their presenting symptoms including urinary tract infections and incontinence. A significant reduction in upper pole hydronephrosis was seen in all patients., Conclusions: Our experience indicates that robot-assisted laparoscopic IUU is safe and effective in the management of ureteral duplication anomalies in children.

Background and Purpose: Despite the evolution and progressive improvements of ureteroscopes, problems related to visibility and maneuverability can still hinder the goals of surgical intervention. We evaluate the attributes of a dual-channel flexible ureteroscope compared with a single-channel device and discuss the implications for expanded techniques afforded by this new technology., Materials and Methods: In vitro measurements of active deflection, irrigant flow through the working channel, luminescence, and optical resolution were performed between the single-channel Wolf Viper and the dual-channel Wolf Cobra ureteroscopes. Characteristics were obtained with the working channels both empty and with combinations of a 200 μ holmium aser fiber, 3.0F biopsy forceps, and 1.5F, 2.4F, and 2.8F nitinol basket. Luminescence from each scope was measured using a commercial luminometer. Three blinded physicians rated the optical resolution captured electronically using a standard test image., Results: The single-channel scope has improved upward deflection both empty and with all but the largest single tools, with an improved range of 4 to 15 degrees. The dual-channel scope has superior downward deflection across all comparisons (average increase of 24.5 degrees) and superior upward deflection with large or multiple instruments in the working channel. Baseline flows through each individual-channel of the dual-channel scope were slower than the larger single-channel ureteroscope. Because flow can be provided through a dedicated port in the dual-channel configuration, however, overall flow, depending on instrumentation, can be up to 37 times faster than the single-channel (range 1.5-37×). Optical resolution and luminescence are comparable between the two scopes., Conclusion: The dual-channel flexible ureteroscope provides similar deflection characteristics to the current single-channel scope. Deflection and flow characteristics are superior, however, when larger or multiple simultaneous instruments are used in the working channel. These benefits may facilitate the development and implementation of novel endoscopic procedures.

A recent model for olfactory foraging by procellariiform seabirds suggests that these birds use biogenic sulfur compounds to locate productive areas for foraging in the southern oceans. The present study refines a simple approach to test birds' responses to odors on land and extends our knowledge to a northern species, the Leach's storm-petrel (Oceanodroma leucorhoa). Rather than working at sea, we tested the behavioral response to dimethyl sulfide (DMS) at night in breeding colonies on Kent Island, New Brunswick, Canada. Birds were presented with either 5 ml DMS (100 micro mol l(-1) concentration) or control (water) solutions from a platform 1.5 m in height positioned in a flyway 10 m from a breeding colony. We also tested birds' responses to cod liver oil, a well-established olfactory attractant of procellariiforms foraging at sea. Leach's storm-petrels approached DMS presentations nearly twice as frequently as they approached controls. We next compared the distribution of approaches against a Poisson process to test for evidence of social cueing. We found that approaches to DMS were significantly clustered. By contrast, the distribution of approaches did not depart significantly from a Poisson distribution for either cod liver oil or control presentations. Taken together, these results suggest that Leach's storm-petrels can smell DMS and potentially use it as a foraging cue. The results are consistent with the hypothesis that the detection of biogenic sulfur compounds in combination with other cues assists birds in locating foraging hotspots.

Recently, it has been shown that prior to surgery a transrectal ultrasound (TRUS) study of the prostate and pubic arch can effectively determine pubic arch interference (PAI), a major stumbling block for the prostate brachytherapy (radioactive seed implantation) procedure. This PAI determination is currently being done with digital images taken directly from an ultrasound (US) machine. However, 70-75% of US machines used in prostate brachytherapy do not have a method to save or transfer digital image data for external use. To allow PAI assessment regardless of US platform and to keep costs to a minimum, we need to digitize the images from the US video output when there is no direct digital transfer capability. D/A and A/D conversions can introduce quantization error and other noises in these digitized images. The purpose of this work is to assess the image degradation caused by digitization and quantitatively evaluate whether after digitization it is still possible to accurately assess PAI. We used a PAI assessment algorithm (developed in previous research by our group) to predict the location of the pubic arch on both digital images and those captured after digitization. These predicted arch locations were compared to the "true" position of the pubic arch as established during surgery. Despite apparent image degradation due to the D/A and A/D conversions, we found no statistically significant difference between the accuracy of the predicted arch locations from the digitized images and those from the digital images. By demonstrating equally accurate determination of pubic arch locations using digital and digitized images, we conclude that TRUS-based PAI assessment can be easily and inexpensively performed in clinics where it is needed.

Energy expenditure (EE), carbon dioxide production (rCO2), water turnover (rH2O), and urine production (UP) were measured to determine nutrient requirements of U.S. Navy divers during saturation dives. Parameters were measured in a normal surface environment (n = 10) and in 0.56 MPa (n = 9) and 3.17 MPa (n = 11) helium-oxygen environments. Daily EE, rCO2, and rH2O were measured with the doubly labeled water method for 10-14 days in each environment. Daily UP was determined by 24-h urine collection for 5- to 10-day periods in each environment. Divers consumed a mixed diet composed of 30% calories from fat, 15% protein, and 55% carbohydrate. Both EE and rCO2 increased significantly relative to surface conditions at 0.56 MPa (13 +/- 4% and 11 +/- 4%) and 3.17 MPa (14 +/- 4% and 11 +/- 3%), but there was no difference between dives. Water turnover was not significantly affected by the hyperbaric environment. UP was significantly greater than surface conditions at 0.56 MPa (53 +/- 19%) but not at 3.17 MPa (38 +/- 18%). Increased EE is attributed to thermal stress caused by the helium-oxygen environment. Increased UP may have been caused by decreased evaporative water loss.

To compare fluid and ion changes during cold (25 degrees C) and thermoneutral head-out immersion (HOI) 9 men were studied under 4 resting conditions lasting 3 h: 2 in 35 degrees C and 2 in 25 degrees C water. At each temperature, subjects consumed 250 ml of either water or a 7% glucose polymer solution every hour to evaluate possible differences in fluid composition. Plasma volume increased by 3.9% for 35 degrees C and decreased by 9.7% for 25 degrees C HOI after 3 h. Urine flow increased significantly during HOI, but there were no differences between water temperatures (35 degrees C: 8.37 +/- 0.44; 25 degrees C: 9.55 +/- 0.57 ml.min-1). Free water clearance and urinary sodium excretion were also elevated during HOI, but water temperature did not alter the magnitude of the response. No HOI-induced kaliuresis was noted. Finally, there was a significant cold-induced increase in serum potassium and sodium, but this reflected largely the decrease in plasma volume. In sum, differences in water temperature seemed to have minimal influence on fluid and cation changes, an indication that immersion is the primary stimulus. Whether greater differences would be noted with colder water remains to be determined.