Intraoperative baseline oxygen consumption as a prognostic factor in emergency open abdominal surgery.

BACKGROUND: A new anesthesia system, the E-CAIOVX (GE Healthcare) enables the continuous monitoring of oxygen consumption (VO2) and carbon dioxide elimination (VCO2) during the surgical operation. The aim of this study was to evaluate the prognostic role of intraoperative baseline VO2 and VCO2 in an emergency open abdominal operation. METHODS: A total of 103 patients who had an emergency open abdominal operation were enrolled in the study. VO2 and VCO2 were continuously measured from the induction of anesthesia to the end of the operation. RESULTS: There were significant correlations between intraoperative baseline VO2 and body surface area (BSA; P < .001, r = 0.68), VO2 and tidal volume (P < .001, r = 0.59), and VO2 and baseline body temperature (P < .0001, r = 0.49). Also, there were significant correlations between intraoperative baseline VCO2 and BSA (P < .001, r = 0.70), VCO2 and tidal volume (P < .001, r = 0.70), and VCO2 and body temperature (P < .001, r = 0.41). Fifteen (14.6%) of the 103 patients died within 4 months after the operation without having been discharged from hospital. Baseline VO2/BSA was higher in surviving patients (123.7 ± 23.6 mL/min ∙ m(2)) than the deceased (103.8 ± 15.6 mL/min ∙ m(2); P = .002). There was no significant difference in baseline VCO2/BSA levels between surviving (106.2 ± 20.1 mL/min ∙ m(2)) and deceased patients (99.4 ± 21.4 mL/min ∙ m(2)). In multivariate analysis, baseline body temperature lower than 36.2°C (P = .02), serum albumin less than 3.0 g/dL (P = .002), and baseline VO2/BSA less than 111.9 mL/min ∙ m(2) (P = .03) were independent factors. CONCLUSION: Baseline low VO2/BSA less than 111.9 mL/min ∙ m(2) was one of the poor predictors for the prognosis of an emergency open abdominal surgery.

Development and validation of the Calculation of post-Operative Risk in Emergency Surgery (CORES) model.

PURPOSE: This study was undertaken to establish a model to predict the post-operative mortality for emergency surgeries. METHODS: A regression model was constructed to predict in-hospital mortality using data from a cohort of 479 cases of emergency surgery performed in a Japanese referral hospital. The discrimination power of the current model termed the Calculation of post-Operative Risk in Emergency Surgery (CORES), and Portsmouth modification of the Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (P-POSSUM) were validated using the area under the receiver operating characteristic curve (AUC) in another cohort of 494 cases in the same hospital (validation subset). We further evaluated the accuracy of the CORES in a cohort of 1,471 cases in six hospitals (multicenter subset). RESULTS: CORES requires only five preoperative variables, while the P-POSSUM requires 20 variables. In the validation subset, the CORES model had a similar discrimination power as the P-POSSUM for detecting in-hospital mortality (AUC, 95 % CI for CORES: 0.86, 0.80-0.93; for P-POSSUM: 0.88, 0.82-0.93). The predicted mortality rates of the CORES model significantly correlated with the severity of the post-operative complications. The subsequent multicenter study also demonstrated that the CORES model exhibited a high AUC value (0.85: 0.81-0.89) and a significant correlation with the post-operative morbidity. CONCLUSIONS: This model for emergency surgery, the CORES, demonstrated a similar discriminatory power to the P-POSSUM in predicting post-operative mortality. However, the CORES model has a substantial advantage over the P-POSSUM in that it utilizes far fewer variables.

Stroke volume variation obtained with Vigileo/FloTrac™ system during bleeding and fluid overload in dogs.

PURPOSE: Stroke volume variation (SVV) is a parameter for estimating fluid responsiveness. Recently, the Vigileo™ and the Flo-Trac™ sensor (Edwards Lifesciences, Irvine, CA, USA) were made available for clinical use to estimate SVV. The aim of this study was to investigate the relationship between the circulating blood volume and SVV, measured by the Vigileo-FloTrac™ system (SVV-FloTrac) or by central venous pressure (CVP), during a dynamic change in circulating blood transfusion volume, using a continuous constant bleeding and fluid-overload model in dogs. METHODS: Ten anesthetized and mechanically ventilated beagles were used. SVV-FloTrac and CVP were measured during a bleeding period (2 ml/kg/min, 15 min), a stabilization period (15 min), a blood transfusion period (2 ml/kg/min, 15 min), and a 6% hydroxyethyl starch solution overload period (2 ml/kg/min, 15 min). RESULTS: SVV-FloTrac changed significantly when more than 8 ml/kg blood was withdrawn or when more than 8 ml/kg blood was transfused. The change in SVV-FloTrac directly reflected the circulating blood volume change during continuous bleeding and blood transfusion. CVP decreased significantly when more than 4 ml/kg blood was withdrawn or when more than 10 ml/kg was infused, and this indicated that the CVP change did not directly reflect the level of the circulating blood volume change. During the stable circulating blood volume period after blood withdrawal, SVV-FloTrac changed significantly but CVP remained constant. During the fluid overload period, CVP, but not SVV-FloTrac, changed significantly. CONCLUSION: SVV-FloTrac is a sensitive indicator of the dynamic circulating blood volume change during both bleeding and transfusion, but not during either the stable circulating blood volume period after blood withdrawal or the fluid-overload period, in mechanically ventilated dogs.

Development of a comb needle with five needles for securing access to large blood vessels during emergency resuscitation.

PURPOSE: Animal tests have indicated that providing venous-arterial (V-A) bypass extracorporeal circulation immediately after cardiac arrest is a useful resuscitation technique for achieving resumption of a normal cardiac function and brain resuscitation. However, pulsation of the femoral artery cannot be felt in the case of cardiac arrest, and it takes a long time to puncture the femoral artery and vein. We developed a comb needle that has five 18-gauge metallic needles fixed in parallel on a plastic board. In this study, we investigated whether the comb needle would achieve puncturing of the femoral artery and vein in cadavers. METHODS: The comb needle was used to puncture the femoral artery and the femoral vein in 45 donated bodies. We placed the center needle of the comb needle 2 cm perpendicularly caudal to a point approximately one quarter the distance along a straight line connecting the anterior superior iliac spine and the pubic tubercle. An autopsy was performed following puncturing, and it was determined whether needles of the comb needle punctured the femoral artery and/or the femoral vein. RESULTS: Puncturing of both the femoral artery and the femoral vein was achieved in 35 cases (78%). In the left groin, both the femoral artery and the femoral vein were punctured in 16 cases (94%), and in the right groin, both the femoral artery and the femoral vein were punctured in 19 cases (68%). CONCLUSION: Using a comb needle, one insertion can achieve simultaneous puncturing of the femoral artery and the femoral vein with a high success rate in cadavers.

Rapidly induced hypothermia with extracorporeal lung and heart assist (ECLHA) improves the neurological outcome after prolonged cardiac arrest in dogs.

PURPOSE: We reported previously that therapeutic hypothermia with extracorporeal lung and heart assist (ECLHA) improved neurological outcome after 15 min cardiac arrest (CA) in dogs, although 45 min was needed to achieve hypothermia. We now investigate whether rapidly induced hypothermia with ECLHA (RHE) would result in a better outcome than slowly induced hypothermia with ECLHA (SHE) in dogs. METHODS: Fifteen mongrel female dogs were divided into two groups: an RHE (n = 7) and an SHE (n = 8) group. Normothermic ventricular fibrillation was induced for 15 min and the animals were resuscitated by ECLHA. Rapid hypothermia was induced with a heat exchanger added to the ECLHA circuit in the RHE group, and by immersing the drainage tube of the ECLHA circuit in an ice water bath in the SHE group. Hypothermia (33 degrees C) was maintained for 20 h. The dogs were weaned from ECLHA at 24 h after resuscitation and treated for 96 h; neurological deficit scores (NDS) were measured throughout this period. RESULTS: It took 1.6+/-0.8 min to reach 33 degrees C in the RHE group and 49.5+/-12.1 min to reach 33 degrees C in the SHE group. There was no difference in survival rate between the two groups. The NDS at 96 h in the RHE group was better than that in the SHE group (26% (range: 10-28%) versus 32% (26-37%); p < 0.05) although there was no significant difference in NDS between the two groups until 72 h. CONCLUSION: Rapid hypothermic induction might be an important factor to improve neurological outcomes in prolonged CA models.

A moderate dose of propofol and rapidly induced mild hypothermia with extracorporeal lung and heart assist (ECLHA) improve the neurological outcome after prolonged cardiac arrest in dogs.

BACKGROUND AND PURPOSE: Propofol has been shown to protect against neuronal damage induced by brain ischaemia in small animal models. We reported previously that mild hypothermia (33 degrees C) in combination with extracorporeal lung and heart assist (ECLHA) improved the neurological outcome in dogs with cardiac arrest (CA) of 15 min induced during normothermia. In the present study, we investigated the neuroprotective effect of propofol infusion under mild hypothermia with ECLHA in this model. METHODS: Twenty-one female dogs (15 mongrel dogs and 6 beagles) were divided into three groups: Midazolam 0.1 mg/(kg h) infusion group (M, n=7), Propofol 2 mg/(kg h) infusion group (P2, n=7), Propofol 4 mg/(kg h) infusion group (P4, n=7). Normothermic ventricular fibrillation (VF) was induced in all dogs for 15 min, followed by brief ECLHA and 168 h of intensive care. The drug infusion was initiated at a constant rate after the restoration of spontaneous circulation (ROSC) to 24 h. Mild hypothermia (33 degrees C) was maintained for 20 h. Neurological deficit scores (NDS: 0%=normal, 100%=brain death) were evaluated for neurological function from 33 to 168 h. RESULTS: One dog in the M group died, and the remaining dogs survived for 168 h. The P4 group showed better neurological recovery compared with the M group (48 h, 21+/-16% versus 32+/-15%; 72 h, 7+/-6% versus 25+/-11%; 96 h, 6+/-6% versus 21+/-6%; 120 h, 5+/-5% versus 20+/-6%; 144 h, 4+/-4% versus 20+/-6%; 168 h, 4+/-4% versus 20+/-6%, p<0.05). One dog in the P2 and three dogs in the P4 group achieved full neurological recovery (NDS: 0%). The number of intact pyramidal cells in the hippocampal CA1 was greater in the propofol groups than midazolam group (p<0.05). CONCLUSION: The combination of propofol infusion at a rate of 4 mg/(kg h), 24h and rapidly induced mild hypothermia (33 degrees C) with ECLHA might provide a successful means of cerebral resuscitation from CA.

The effects of pre-arrest heparin administration dose for cardiac arrest model using extracorporeal lung and a heart assist (ECLHA) in dogs.

BACKGROUND AND PURPOSE: Clinical and experimental studies have shown that marked activation of blood coagulation occurs in cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Extracorporeal lung and heart assist (ECLHA) is applied in CA patients who cannot be rescued using conventional therapies. We hypothesized that the dose of heparin administered during the pre-arrest period would influence the outcome in a canine model of CA induced by 15 min of normothermia followed by ECLHA, which consists of heparin coating membrane lung and tubing. We therefore investigated the effects of two dose regimes of the pre-arrest heparin for this model. METHODS: Twelve mongrel female dogs were divided into two groups: a group given 200 U/kg heparin (H200, n=6) and a group given 700 U/kg heparin (H700, n=6), group during pre-arrest period. Normothermic ventricular fibrillation (VF) was induced in all dogs for 15 min, followed by 24h of ECLHA with rapidly induced mild hypothermia (33 degrees C) and 120 h of intensive care. Outcome evaluations included: (1) activated coagulation time (ACT); (2) catecholamine dose; (3) hematocrit (Hct) and platelet count; (4) survival rate; (5) neurological deficit scores (NDS); (6) postmortal macroscopic examination with the exception of the brain. RESULTS: In the H200 group, four dogs died of cardiogenic shock within 28 h. The autopsy revealed extensive patchy hemorrhages in the heart and intestine. In the H700 group, the amount of dopamine was significantly lower (6+/-10mg versus 75+/-41 mg, p<0.05) and the survival rate was significantly higher (100% versus 17%, p<0.05) than in the H200 group. The NDS at 120 h in the H700 group was 18+/-8% and the autopsy revealed an almost normal external appearance of the vital organs. There were no significant differences between groups in either the Hct and platelet count during the 24h of resuscitation, and no bleeding complications were observed. CONCLUSION: The use of ECLHA to resuscitate animals in prolonged CA may require a large dose of systemic heparin during the pre-arrest period even if ECLHA circuit was coated with heparin.

Comparison of a new heparin-coated dense membrane lung with nonheparin-coated dense membrane lung for prolonged extracorporeal lung assist in goats.

Thrombosis and bleeding are major complications in cases of prolonged extracorporeal lung assist (ECLA) with an artificial-membrane lung. Antithrombogenic treatment of the artificial-membrane oxygenator and circuits is indispensable for safe ECLA. The efficacy of a new heparin-coated membrane lung with minimal systemic heparinization was evaluated for 7 days and compared with a nonheparin-coated membrane lung in goats. The animals were randomly assigned to either the heparin-coated membrane group (HM group, n = 5) or nonheparin-coated membrane group (NHM group, n = 5). Activated coagulation time (ACT) during ECLA was controlled to below 150 s in the HM group, and to near 200 s in the NHM group. All goats in the HM group were sustained on ECLA for 7 days, but two goats in the NHM group died on the 4th and 6th days, respectively. The mean systemic administration rate of heparin during ECLA was 22.4 +/- 4.4 U/kg/h in the HM group and 39.0 +/- 10.0 U/kg/h in the NHM group. There was a significant difference between the two groups (P < 0.05). The oxygen transfer rate, the Pco(2) difference, the perfusion resistance, and platelet counts showed no significant changes. There was no plasma leakage from the artificial lung. Although several clots were observed in the stagnant areas of the artificial lung, they did not lead to deterioration of the function of the artificial lung. The excellent antithrombogenicity, gas exchange ability, and durability of this new artificial lung with circuits might contribute to successful prolonged ECLA with minimal systemic heparinization.

A comparison of postoperative sore throat after use of laryngeal mask airway and tracheal tube.

PURPOSE: We compared the degree of postoperative sore throat (PST) after use of a laryngeal mask airway (LMA; by two insertion techniques) and a tracheal tube (TT) in adult patients. METHODS: Eighty-six adult patients undergoing surgery of an extremity were randomized into three groups. The LMAs (size 4 for men, 3 for women) and TTs were lubricated with 2% lidocaine gel. After the induction of anesthesia, an LMA with the cuff deflated was inserted and then the cuff was inflated in group A, an LMA with the cuff inflated was inserted in group B, and the trachea was intubated using vecuronium in group C; staff anesthesiologists performed all these methods. LMA cuffs were inflated with the maximum recommended volume of air. TT cuffs were inflated with the minimum volume of air without gas leakage at 20 cm H(2)O pressure. The mode of ventilation depended on the individual anesthesiologists. Blood traces on the devices were examined after their removal. PST was rated immediately after anesthesia and on the first postoperative day, using a three-point score and a 100-mm visual analog scale, respectively. RESULTS: Most of the patients receiving an LMA breathed spontaneously and those receiving a TT underwent controlled ventilation. The ratio of positive blood traces on devices, as well as the degree of PST immediately after anesthesia, was similar in the three groups; however, on the first postoperative day, the severity of PST was greater in the LMA groups than in the TT group ( P = 0.016). The severity of PST was similar with the two LMA insertion techniques. CONCLUSION: In the conditions of our study, LMAs inserted with the cuff either fully inflated or deflated worsened PST compared with TTs.

Preliminary experiment with a newly developed double balloon, double lumen catheter for extracorporeal life support vascular access.

Recently, venovenous extracorporeal life support (VVECLS) using a double lumen catheter has been clinically used to avoid neurologic complications in the treatment of respiratory failure for neonates. However, recirculation, which is a limiting factor for oxygen delivery, still exists, and thus it does not contribute to oxygenation of the patient. We developed a newly designed double lumen catheter with a double balloon (DBDL) catheter for ECLS vascular access and performed two animal preliminary experiments in normal and hypoxic dog models (normal ventilation and one lung ventilation experiments) to investigate whether the DBDL catheter could prevent recirculation and maintain oxygen delivery to systemic circulation. The DBDL catheter (JCT Co., Hiroshima, Japan) of 15 Fr was fabricated from silicone. It consists of two lumens for drainage and return of blood with two balloons (distal and proximal balloons) that prevent oxygenated blood mixing with unoxygenated blood. VVECLS using a DBDL catheter was performed in 13 mongrel dogs (8 dogs for normal ventilation experiment weighing 12.9 +/- 1.6 kg [mean +/- SD], 5 dogs for one lung ventilation experiment weighing 16.6 +/- 2.5 kg [mean +/- SD]) under anesthesia in the two experiments. The bypass flow ranged from 10-40 ml/kg per minute in the normal ventilation experiment. VVECLS in the one lung ventilation experiment was performed with maximal bypass flow for 6 hours (ranged from 25.2 +/- 8.0-28.3 +/- 8.7 ml/kg per minute at balloon inflation and deflation). Recirculation and oxygen transfer of artificial lung with or without balloon inflation during VVECLS were studied. Recirculation decreased with balloon inflation at varied bypass flows during VVECLS in the normal ventilation experiment (varied from 1.5 +/- 14.6-12.8 +/- 16.7%) and for 6 hours after VVECLS initiation in the one lung ventilation experiment (varied from 12.2 +/- 12.2-19.2 +/- 6.5%). In particular, the values at 3 and 6 hours were significantly lower than that of balloon deflation in the one lung ventilation experiment. The difference in O2 content between inlet and outlet in the artificial lung with balloon inflation was significantly higher than that of balloon deflation (varied from 3.7 +/- 1.8-4.8 +/- 1.9 ml/dl, p < 0.05) at the bypass flow of 10-30 ml/kg per minute in the normal ventilation experiment and at 5 hours after VVECLS initiation in the one lung ventilation experiment (varied from 10.6 +/- 1.6-11.7 +/- 1.8 ml/dl). The blood gas analysis of systemic circulation with balloon inflation revealed that the values of PaO2 (varied from 83.8 +/- 11.4-96.9 +/- 23.4 mm Hg) and PaCO2 (37.7 +/- 9.2-40.4 +/- 11.8 mm Hg) were higher and lower, respectively, compared with balloon deflation. In particular, PaO2 level was significantly higher than that of the preECLS value at the bypass flow of 20-40 ml/kg per minute (varied from 83.8 +/- 11.4-96.9 +/- 23.4 mm Hg, p < 0.05). In the one lung ventilation experiment, systemic PaO2 and PaCO2 levels at balloon inflation were higher and lower, respectively, compared with balloon deflation during VVECLS for 6 hours. At balloon inflation, the value of PaO2 at 6 hours after VVECLS initiation was significantly higher than that at balloon deflation. A newly designed DBDL catheter for ECLS vascular access successfully reduced recirculation and maintained oxygen delivery to systemic circulation during VVECLS. These results suggest that a high bypass flow may not be necessarily required in terms of oxygen delivery to systemic circulation when the DBDL catheter was used as an ECLS vascular access.

Does veno-arterial bypass without an artificial lung improve the outcome in dogs undergoing cardiac arrest?

We hypothesized that maintaining circulation and blood pressure by veno-arterial bypass (V-A bypass) without oxygenation would improve cardiopulmonary resuscitation (CPR) and survival rates. A total of 32 dogs, divided into four groups, were subjected to normothermic ventricular fibrillation (VF) for 15 min. The method of CPR was the same in the four groups, except for the method and timing of V-A bypass. We attempted to resuscitate the dogs without V-A bypass (control), with V-A bypass not including an artificial lung during VF, with V-A bypass not including an artificial lung during CPR, and with V-A bypass including an artificial lung during CPR. CPR was continued until restoration of spontaneous circulation (ROSC) or for 30 min. Although blood pressure was well maintained, severe hypoxemia was observed during V-A bypass without an artificial lung. The resultant hypoxemia was very detrimental. ROSC was achieved more easily in all dogs in the bypass group with an artificial lung. No significant difference in survival rates was demonstrated among the four groups (P = 0.11). We concluded that V-A bypass without oxygenation does not improve the chances for CPR and outcome after cardiac arrest in dogs. Our results suggest that oxygenation is indispensable in CPR.