Maximizing efficiency on trauma surgeon rounds

BACKGROUND

Rounding by trauma surgeons is a complex multidisciplinary team-based process in the inpatient setting. Implementation of lean methodology aims to increase understanding of the value stream and eliminate nonvalue-added (NVA) components. We hypothesized that analysis of trauma rounds with education and intervention would improve surgeon efficacy.

MATERIALS AND METHODS

Level 1 trauma center with 4300 admissions per year. Average non-intensive care unit census was 55. Five full-time attending trauma surgeons were evaluated. Value-added (VA) and NVA components of rounding were identified. The components of each patient interaction during daily rounds were documented. Summary data were presented to the surgeons. An action plan of improvement was provided at group and individual interventions. Change plans were presented to the multidisciplinary team. Data were recollected 6 mo after intervention.

RESULTS

The percent of interactions with NVA components decreased (16.0% to 10.7%, P = 0.0001). There was no change between the two periods in time of evaluation of individual patients (4.0 and 3.5 min, P = 0.43). Overall time to complete rounds did not change. There was a reduction in the number of interactions containing NVA components (odds ratio = 2.5).

CONCLUSIONS

The trauma surgeons were able to reduce the NVA components of rounds. We did not see a decrease in rounding time or individual patient time. This implies that surgeons were able to reinvest freed time into patient care, or that the NVA components were somehow not increasing process time. Direct intervention for isolated improvements can be effective in the rounding process, and efforts should be focused upon improving the value of time spent rather than reducing time invested.

Intensive care unit design and mortality in trauma patients

BACKGROUND

The architecture of medical care facilities ca affect the safety of a patient, but it is unknown if the architecture affects outcomes. We hypothesized that patients in rooms who are more visible from the central nursing station would experience better outcomes than those patients in less visible rooms.

MATERIALS AND METHODS

A total of 773 patients admitted to the trauma intensive care service over a 12-mo period were retrospectively evaluated. Outcomes were hospital mortality and intensive care unit (ICU) length of stay (LOS). The unit is designed with a bank of high-visibility rooms (HVRs) directly across from the nursing station and two side sections of low-visibility rooms (LVRs). No formal triage occurs, but patients are prioritized to HVRs as available.

RESULTS

Patients in the HVRs had a 16% mortality (52 of 320); meanwhile, the patients in the LVRs experienced an 11% mortality (49 of 448, P = 0.03). ICU mortality did not differ significantly when controlling for age, Charlson Comorbidity Index (CCI), Head Abbreviated Injury Score, and the Injury Severity Score (ISS) (P = 0.076). Age, CCI, Head Abbreviated Injury Score, and ISS did individually correlate with mortality (age: P = 0.0008; CCI: P = 0.017; and ISS: P < 0.0001). Visibility was not a predictor of ICU LOS or complications among survivors (mean ICU HVR LOS = 4.8 d; mean ICU LVR LOS = 4.7; P = 0.88, n = 661). Only ISS was a significant predictor of ICU LOS and complications (P < 0.0001).

CONCLUSIONS

Trauma patient room placement within the ICU does not relate to mortality rate significantly when corrected for patient acuity. Instead, variables such as age, ISS, and CCI are associated with mortality. A policy of placing more critically ill patients in HVRs may prevent increased mortality in high-acuity patients.

Central venous catheter infections in burn patients with scheduled catheter exchange and replacement

INTRODUCTION

Consensus in the general critical care patient population is that routine central venous catheter change is not necessary, and that central lines should not be rewired in the setting of possible infection. This concept has not carried over into the burn realm. In burn patients the rewiring of lines may lead to increased infection rates.

METHODS

Fifty-nine consecutive critically ill burn patients requiring central line placement were included: 277 central lines and 1691 catheter days. Standard care protocol was followed in all patients, with lines being placed initially by new site insertion, changed over a guidewire on day 6, and moved to a new site on day 12. New sites were used for all suspected or documented line infections. All other care was the same. New site placements were compared to guidewire exchanges. Pediatric patients (under the age of 18) were considered with and separate from adults.

RESULTS

There was no difference in the incidence of catheter-related bloodstream infections (CRBSI) between lines placed by new site access (15.4/1000 catheter days) or by guidewire exchange (15.4/1000). Considering the 979 pediatric line days, there was a distinct difference, with new sites having 16.6/1000, and rewires 25.2/1000. Adults revealed the opposite trend, rewires having no occurrences of CRBSI, and new sites 13.7/1000. Children had a higher rate of CRBSI, 19.4/1000 days, compared to adults at 9.8/1000 days. Children had larger burns (P < 0.0001), more femoral lines (P = 0.0003), and lines closer to the burn wound (P = 0.001).

CONCLUSIONS

In pediatric patients guidewire exchange increased the incidence of infection. This was not noted in adult patients. The utility of guidewire exchange needs to be further investigated in adults, although this data would imply that it may be safe to use routine rewire of lines in adult burn patients. Pediatric patients require an increase in vigilance to minimize CRBSI. Central venous catheters should be removed as soon as not needed and routine change of lines in burn patients needs continued evaluation.

Effects of a restrictive blood transfusion policy on outcomes in children with burn injury

A restrictive blood transfusion policy decreases blood utilization and improves outcomes in critically ill adults, but the impact of a restrictive blood transfusion policy in critically ill children is unclear. The study purpose was to compare the effects of a restrictive with a traditional blood transfusion policy in children with major burn injury. A retrospective review of all blood transfusions administered in a pediatric burn center during a 5-year period was conducted. Children in the traditional group (January 1, 2000, to June 30, 2002), were transfused at a hemoglobin level of less than 10 g/dl. Children in the restrictive group (January 1, 2003, to June 30, 2005, 6 months after the adoption of a restrictive protocol) were transfused at a hemoglobin level of less than 7 g/dl. Patient groups were compared for demographics, ventilator requirements, blood transfusion number, transfusion costs, and outcomes. Of the 1140 patients studied, 266 (24%) received a total of 2577 units of blood. There was no difference in age, TBSA burn, sex, inhalation injury, or mortality between groups. Patients in the traditional group received more blood than the restrictive group (12.3 +/- 1.8 vs 7.2 +/- 1.2 units/patient, P < .001). The mean cost of blood per patient was $2781 for the traditional group and $1489 for the restrictive group. A restrictive transfusion policy in children with burn injury decreases the amount of blood transfused, does not adversely impact patient outcome, and results in significant cost savings to the institution.

Hypothalamic-pituitary-adrenal axis response to sustained stress after major burn injury in children

The hypothalamic-pituitary-adrenal (HPA) axis is responsible for stress response after injury, yet its function after severe burn injury in children is unclear. The purpose of this study was to define the effects of burn injury on the HPA axis and to evaluate the utility of total serum cortisol in measuring adrenal function in children with major burns in the 2 months after injury. Children ages 0 to 17 years who were admitted within 72 hours to our pediatric burn center with 20% TBSA or greater full-thickness burns were eligible for the study. Serum total cortisol, adrenocorticotropic hormone (ACTH), dehydroepiandrosterone, vasopressin, Pediatric Risk of Mortality (PRISM) score, serum albumin level, and electrolytes were obtained on admission and weekly for 8 weeks. An ACTH stimulation test (250 microg for children >2 years, 125 microg for children < or =2 years) was administered weekly at 8:00 am. Total serum cortisol was measured before and 60 minutes after the administration of ACTH. Twenty-five children with mean age 7.6 +/- 1.1 years and TBSA burn 41.8 +/- 3.8% were enrolled in the study. Baseline total serum cortisol was 12.4 +/- 0.7 microg/dl in the 8 weeks after injury and increased to 24.4 +/- 0.8 microg/dl after the administration of ACTH. Cortisol level did not correlate with PRISM score, albumin, vasopressin, ACTH, or mortality. Although the adrenal response to acute and chronic stress is intact after severe burn injury, the ACTH/adrenal feedback loop is disrupted. Random total serum cortisol measurements overestimate adrenal dysfunction; thus, ACTH stimulation testing should be used to assess adrenal function before the administration of exogenous steroids.

Instant Cup of Soup: Design Flaws Increase Risk of Burns

Prepackaged soups are a frequent cause of burn injury. We hypothesize that package design increases the risk for burn injury by affecting container stability. All pediatric scald burns caused by soup, between June 1997 and August 2004, were reviewed for burn and patient characteristics. Instant or "ready-to-eat" soups also were purchased. Safety statements and recommendations as to use of the microwave oven were documented. The height and the areas of the base and top were compared to the angle that a container would tip over on to its side. During the study period, 99 admissions and 80 outpatients were treated for burns caused by soup. Although the burn size was small (mean 5% TBSA) 22 patients required grafting. Of 13 different soups, 11 required the addition of hot water, and 2 were prepackaged for eating out of the container. Twelve containers had round bases and were tall and narrow, with one being shorter and rectangular. The measurements that correlated with the ease of tipping over were the base area, top area, and the ratio of height/base area. The most significant contributor to the ease of tipping over was height. Instant soups are packaged in containers that tend to be tall with a narrow base that predisposes them to being knocked over and spilled. Simple redesigning of instant soup packaging with a wider base and shorter height, along with the requirement for warnings about the risks of burns would reduce the frequency of soup burns.

Results of a protocol of transfusion threshold and surgical technique on transfusion requirements in burn patients

INTRODUCTION

Blood loss and high rates of transfusion in burn centers remains an area of ongoing concern. Blood use brings the risk of infection, adverse reaction, and immunosuppression.

METHODS

A protocol to reduce blood loss and blood use was implemented. Analysis included 3-year periods before and after institution of the protocol. All patients were transfused for a hemoglobin below 8.0 gm/dL.

RESULTS

Operations per admission did not change during the two time periods (0.78 in each). Overall units transfused per operation decreased from 1.56+/-0.06 to 1.25+/-0.14 units after instituting the protocol (p<0.05). Also, units transfused per admission decreased from 1.21+/-0.15 to 0.96+/-0.06 units of blood (p<0.05). This was noticed particularly in burns of less than 20% surface area, declining from 386 to 46 units after protocol institution, from 0.37 to 0.04 units per admission, and from 0.79 to 0.08 units per operation in this group of smallest burns. There was no change noted in the larger burns.

CONCLUSIONS

This study suggests that a defined protocol of hemostasis, technique, and transfusion trigger should be implemented in the process of burn excision and grafting. This will help especially those patients with the smallest burns, essentially eliminating transfusion need in that group.

A prospective, randomized evaluation of intra-abdominal pressures with crystalloid and colloid resuscitation in burn patients

BACKGROUND

The volume of resuscitation in burn patients has been shown to correlate with intra-abdominal pressure (IAP). Limiting volume may reduce consequences of IAP and abdominal compartment syndrome. Colloid resuscitation has been previously shown to limit the volume required initially after burn.

METHODS

Thirty-one patients were prospectively followed. Inclusion criteria were a burn of 25% total body surface area with inhalation injury or 40% total body surface area without. Patients received crystalloid (Parkland formula) or plasma resuscitation. IAP was measured by means of urinary bladder transduction.

RESULTS

Mean age, area of burn, and baseline IAP were not different. Urine output was maintained. There was a greater increase in IAP with crystalloid (26.5 vs. 10.6 mmHg, p < 0.0001). Two patients in the plasma group developed IAP greater than 25 mmHg; only one patient in the crystalloid group maintained IAP less than 25 mmHg. More fluid volume was required with crystalloid resuscitation, 0.26 L/kg, versus 0.21 L/kg (p < 0.005). Correlation was seen in both groups between volume of fluid and IAP (crystalloid, r = 0.351; plasma, r = 0.657; all patients, r = 0.621).

CONCLUSION

Plasma-resuscitated patients maintained an IAP below the threshold of complications of intra-abdominal hypertension. This appears to be a direct result of the decrease in volume required. Lower fluid volume regimens should be given consideration as the incidence and consequences of intra-abdominal hypertension in burn patients continue to be defined.

Modified Separation of Parts as an Intervention for Intraabdominal Hypertension and the Abdominal Compartment Syndrome in a Swine Model

Standard therapy for abdominal compartment syndrome is laparotomy. In many patients, laparotomy involves a recent incision; for others, volume of resuscitation may be the cause. The components separation technique allows difficult abdominal closure. The authors studied the effect of a modified separation of parts on abdominal compartment syndrome in an animal model. Eight pigs were instrumented for measurement of central venous pressure, mean arterial pressure, peak airway pressure, and intraabdominal pressure. Intraabdominal hypertension to 25 mmHg was established with intraperitoneal fluid infusion. Modified separation of parts was performed by sequential release of the abdominal wall layers. With increased intraabdominal pressure, mean arterial pressure (55.3 +/- 12.0 to 65.3 +/- 11.0), central venous pressure (7.7 +/- 2.4 to 13.3 +/- 6.9), and peak airway pressure (20.2 +/- 2.4 to 25.3 +/- 4.1; p < 0.05) also increased. Maximum intraabdominal pressure was 26.0 +/- 1.2 mmHg. Skin incision resulted in a decrease in intraabdominal pressure to 21.7 +/- 4.5, external oblique release to 18.3 +/- 3.9, internal oblique release to 13.2 +/- 4.0, and transversus muscle incision to 7.0 +/- 2.5 mmHg (p < 0.05). With completion of components separation, mean arterial pressure remained increased (63.2 +/- 16.9), central venous pressure decreased (6.8 +/- 3.6; p < 0.05), and peak airway pressure decreased (22.7 +/- 3.9; p < 0.05). Modified separation of parts technique effectively releases intraabdominal hypertension and reverses the physiologic derangements associated with abdominal compartment syndrome in the animal model.

Modified extraperitoneal endoscopic separation of parts for abdominal compartment syndrome

BACKGROUND

Standard therapy for abdominal compartment syndrome (ACS) is laparotomy and temporary abdominal wall closure with significant morbidity. The component separation technique allows for difficult abdominal closure. We studied a modified extraperitoneal endoscopic separation of parts technique on an animal model of ACS.

METHODS

Twelve anesthetized pigs were instrumented for measurement of central venous pressure, arterial pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output, and intraabdominal pressure (IAP). ACS to 25 mmHg was created by infusing saline into an intraabdominally placed bag. Animals were divided in two equal groups. Pigs in group A underwent minimally invasive resection of the nerves supplying the rectus muscles bilaterally. Pigs in group B underwent minimally invasive modified component separation technique bilaterally. Change in IAP and other physiological parameters were recorded.

RESULTS

(Group A) IAP increased significantly from 7.3 mmHg +/- 3.8 to 25.2 mmHg +/- 1.5 with infusion of saline. Following nerve transection on the right side there was a nonsignificant decrease in IAP from 25.2 mmHg +/- 1.5 to 22.3 mmHg +/- 1.4 and following nerve transection on the left side there was a further decrease in IAP to 20.3 mmHg +/- 1.9. (Group B) IAP increased significantly from 3.8 mmHg +/- 0.4 to 24.7 mmHg +/- 0.5 with infusion of saline. Following separation of parts on the right side there was a significant decrease in IAP from 24.7 mmHg +/- 0.5 to 15.0 mmHg +/- 1.7 and there was a further decrease in IAP to 11.3 mmHg +/- 1.4 following separation of parts on the left side. The only significant change in the physiological parameters measured was observed in CVP in both groups.

CONCLUSION

We present a porcine model of extraperitoneal endoscopic release of abdominal wall components as a treatment option for ACS.

Analysis of deep vein thrombosis in burn patients

OBJECTIVE

Deep vein thrombosis (DVT) represents a major cause of morbidity in surgical patients. Controversial reports exist on the incidence of DVT in burn patients. We report our experience over a 10-year period.

METHODS

Patients admitted to our Burn Unit over the period 1991-2001 and diagnosed with DVT were identified. Their records were retrospectively reviewed for demographic factors, extent and severity of burn injury and outcome.

RESULTS

A total of 4102 patients were admitted to the WPH Burn unit during the study period. All patients received routine subcutaneous heparin prophylaxis. Ten patients were diagnosed with DVT (0.25%). Compared to our total burn population, these patients were older (mean age 47 +/- 22.7 years versus 35 +/- 22 years P = 0.14) and had more extensive burns (mean total body surface area (TBSA) 34.7 +/- 25.3% versus 12 +/- 15.7% P = 0.02). Two patients developed non-fatal pulmonary embolism (PE). There were three deaths, none due to thromboembolic disease. There were no complications from the routine administration of subcutaneous heparin.

CONCLUSION

The incidence of DVT in our study is much less than the incidence reported in other critically ill patients and less than that of most reports on burn patients. In our experience, routine heparin prophylaxis is effective for the prevention of DVT in burn patients.

Abdominal Compartment Syndrome as a Consequence of Rectus Sheath Hematoma

Abdominal compartment syndrome is a well-documented entity arising from multiple and various causes. The rise of intra-abdominal pressure by the increase in volume of the peritoneal and retroperitoneal contents has been shown in the resuscitation and evaluation of surgical patients. However, the incidence of constriction of the abdomen causing intra-abdominal hypertension is unknown. Previously limited to burn eschar and externally applied devices (such as MAST trousers), external compression leading to abdominal compartment syndrome has been a limited entity. We report the first documented case of an expansive abdominal wall mass, a rectus sheath hematoma, leading to impending abdominal compartment syndrome.

Abdominal compartment syndrome as a consequence of rectus sheath hematoma

Abdominal compartment syndrome is a well-documented entity arising from multiple and various causes. The rise of intra-abdominal pressure by the increase in volume of the peritoneal and retroperitoneal contents has been shown in the resuscitation and evaluation of surgical patients. However, the incidence of constriction of the abdomen causing intra-abdominal hypertension is unknown. Previously limited to burn eschar and externally applied devices (such as MAST trousers), external compression leading to abdominal compartment syndrome has been a limited entity. We report the first documented case of an expansive abdominal wall mass, a rectus sheath hematoma, leading to impending abdominal compartment syndrome.

Effect of diagnosis and treatment of sinusitis in critically ill burn victims

The purpose of this study was to assess the incidence of diagnosed sinusitis and the effect of diagnosis and treatment on the outcome in critically ill burn victims. Chart analysis of 84 consecutive burn victims requiring mechanical ventilation for greater than 7 days was performed. Sinusitis was diagnosed in 13/84 patients (15%). There was no difference in age or total body surface area burned, or the incidence of inhalation injury, ARDS, pneumonia and sepsis (P>0.05). Co-morbid disease was similar in both the groups. The number of ventilator-dependent days and hospital length of stay were higher in the sinusitis group (P<0.05). The hospital mortality in those diagnosed and treated for sinusitis was 23% (3/13) as opposed to 48% (34/71) in those not diagnosed with sinusitis (P<0.05). Increased number of ventilator-dependent days and longer hospital stay are associated with the diagnosis of sinusitis. Our findings suggest an improved survival in those diagnosed and treated for sinusitis.

The use of routine chest X-ray films after chest tube removal in postoperative cardiac patients

BACKGROUND

The use of routine postoperative chest x-ray films (CXRs) for postoperative cardiac patients has been challenged, suggesting that only clinically indicated CXRs be obtained. The removal of chest tubes has been used as an indication for CXRs. Our hypothesis is that routine postoperative chest tube removal CXRs are not indicated in the asymptomatic postoperative cardiac patient.

METHODS

Charts of 1,021 consecutive postoperative median sternotomy patients were reviewed, focusing on postoperative findings of CXRs, clinical evaluations, and interventions. Those who died prior to tube removal were excluded from the study.

RESULTS

Tubes were removed on postoperative days 1 to 7 (average, 1.45 days). The two groups of patients were comparable in age, gender, procedure, and co-morbidity (p > .01). Seven hundred three patients underwent routine postoperative tube removal CXRs. Abnormal findings were present in 282 patients. Resultant therapeutic intervention was undertaken in 13 patients and 9 were symptomatic. No imaging after routine postoperative CXRs was conducted in 283 patients. These patients remained asymptomatic and required no intervention. Fourteen patients had clinically indicated CXRs after chest tube removal. Two of these patients had additional tubes placed, and 1 patient had follow-up films. In total, there was a 1.5% incidence of therapeutic intervention after chest tube removal. All patients were discharged without further sequelae of their tubes.

CONCLUSIONS

Omission of routine postoperative chest tube removal CXRs in postoperative cardiac patients is safe. The removal of chest tubes in these patients is not an indication for CXRs.

The use of tourniquets in the excision of unexsanguinated extremity burn wounds

PURPOSE

Tangential excision of burns is complicated by blood loss. Tourniquet use decreases blood loss, but adequacy of excision has been questioned. An attempt was made to assess the value of not exsanguinating the limb prior to tourniquet inflation to improve visualization of bleeding points and subsequent engraftment.

METHODS

Eleven excisions of bilateral extremity wounds were performed. One limb was excised without the benefit of a tourniquet, the other with tourniquet but without exsanguination. Tangential excision was performed, hemostasis achieved, and blood loss quantified. Engraftment of skin was assessed at first dressing change and at initial follow-up after discharge.

RESULTS

Area of burn was the same, 4.8% with tourniquet, 5.1% without (P=0.38). Overall blood loss was less with tourniquet control, 100-259 cm(3) (P=0.002); as was blood loss per area, 0.19-0.58 cc/cm(2) (P=0.04). Graft take was similar, 98.2% early and 98.1% later with tourniquet, with 98.2 and 96.8% take without (P>0.1).

CONCLUSIONS

Tourniquet use in the unexsanquinated extremity reduced blood loss without affecting engraftment.

Laparoscopic reoperation for early complications of laparoscopic gastric bypass

BACKGROUND

Laparoscopic Roux-en-Y gastric bypass (LRYGBP) is a popular operation for morbid obesity. Early complications can be treated successfully with a laparoscopic approach. We reviewed our experience with laparoscopic re-exploration in the early postoperative period.

METHODS

The initial 85 patients who underwent LRYGBP by two surgeons at a training hospital were reviewed. All patients who required re-exploration within the first 60 days postoperatively were considered.

RESULTS

Nine patients underwent ten laparoscopic explorations. Mean BMI was 50 kg/m2. One patient underwent revision for proximal anastomotic obstruction at 58 days postoperatively. Three patients developed obstruction at the level of the transverse mesocolon secondary to cicatrix and required laparoscopic release of the scar tissue. Two patients required revision of the jejuno-jejunostomy. Internal hernia through the mesenteric defect at the level of the transverse mesocolon was the cause of bowel obstruction in two patients. One patient underwent lysis of adhesions between the left colon and the transverse mesocolon at 6 days postoperatively. One out of the ten laparoscopic re-explorations was negative for any findings. Eight patients recovered without further complications and one patient required endoscopic dilatations of the proximal anastomosis.

CONCLUSION

In the course of treating morbid obesity with laparoscopic intervention, complications will arise. Laparoscopic exploration for early complications is a safe and feasible option.

Helicopter transportation of burn patients

Analysis of 437 consecutive acute burn patients transported to our burn center revealed 339 transported by ground and 98 by helicopter. There were 18 air transport patients from within a 25-mile-radius, and 80 flown further than 25 miles. Mean age was the same in all groups (P>0.05). Percent total body surface area (TBSA) burned was 8.26% in ground transport patients, significantly less than the 20.35% (within 25 miles) and 21.40% (greater than 25 miles) seen in helicopter transports (P<0.0001). Three percent of ground transport patients and 28% of helicopter patients had inhalation injury (P<0.0001). There was no difference in incidence of inhalation injury among helicopter groups (28 vs. 29%, P=0.8). In patients with coexistent inhalation injury, the mean TBSA burned was significantly larger when compared with the TBSA of burns without inhalation injury (P<0.001). Air transported groups contained patients whose status was not critical based upon lack of inhalation injury and small burn size, and who could have been transported by ground. Non clinical factors such as insurance status, desire to keep ground ambulances in their community, and competing helicopter services reluctant to refuse to transport a patient appears to be factors in choosing air ambulance transportation. Regional single helicopter services and regional cooperative ground ambulance services should reduce use of helicopter transport of burn patients when it is not clinically indicated.

Arginine vasopressin modulation of arterial baroreflex responses in fetal and newborn sheep

The present study was designed to test the hypothesis that the influence of circulating vasopressin (AVP) on the arterial baroreflex control of renal sympathetic nerve activity (RSNA) and heart rate (HR) changes during development. To test this hypothesis, we studied arterial baroreflex-mediated control of HR and RSNA in the presence of increasing plasma levels of AVP in conscious, chronically instrumented fetal, newborn, and adult sheep. In fetal and newborn sheep, increasing plasma AVP levels (from < 10 to > 200 microU/ml) increased resting levels of mean arterial blood pressure (MABP) and decreased HR and RSNA. HR and RSNA baroreflex responses to variations of MABP with nitroprusside and phenylephrine infusion were not modified by elevated AVP levels in either newborn or fetal sheep, except for a small decrease in maximal HR response to nitroprusside infusion in the newborn animals. In contrast, in adults, AVP caused bradycardia and a decrease in RSNA without change in MABP, accompanied by resetting of the arterial baroreflex (decrease in maximal HR and RSNA, decrease in RSNA gain, and shift of HR to lower pressure). To test the hypothesis that the inability of AVP to reset the arterial baroreflex early during development was not secondary to maximal stimulation of V1 receptors during baseline conditions, we investigated the effect of V1-receptor blockade on baseline cardiovascular and arterial baroreflex function in newborn lambs. Administration of a V1-receptor antagonist produced no significant changes in resting MABP, HR, and RSNA and did not influence arterial baroreflex-mediated changes in HR and RSNA. These results indicate that, contrary to adults, circulating AVP does not modulate the arterial baroreflex in fetal and newborn sheep.