Retraction notice to "Recoveries of post-tetanic twitch and train-of-four responses after administration of vecuronium with different inhalation anaesthetics and neuroleptanaesthesia" [Br J Anaesth 1993; 70: 402-404]

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief of British Journal of Anaesthesia. The study is retracted for the following reasons: Statistical analysis suggests that the data may be fabricated. Y Saitoh provided a statement in a personal communication to a member of the editorial board of British Journal of Anaesthesia that the study was not approved by the Institutional Review Board and that no evidence exists to support the study findings. Additionally, the Japanese Society of Anesthesiologists has recommended retraction of this article: http://www.anesth.or.jp/english/pdf/news20170925.pdf.

Retraction notice to "Relationship between post-tetanic twitch and single twitch response after administration of vecuronium" [Br J Anaesth 1993; 71: 443-444]

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief of British Journal of Anaesthesia. The study is retracted for the following reasons: Y Saitoh provided a statement in a personal communication to a member of the editorial board of British Journal of Anaesthesia that the study was not approved by the Institutional Review Board and that no evidence exists to support the study findings.

Retraction notice to "Post-tetanic count and single twitch height at the onset of reflex movement after administration of vecuronium under different types of anaesthesia" [Br J Anaesth 1994; 72: 688-690]

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief of British Journal of Anaesthesia. The study is retracted for the following reasons: Y Saitoh provided a statement in a personal communication to a member of the editorial board of British Journal of Anaesthesia that the study was not approved by the Institutional Review Board and that no evidence exists to support the study findings.

Pulmonary administration of prostacyclin (PGI2) during partial liquid ventilation in an oleic acid-induced lung injury: inhalation of aerosol or intratracheal instillation?

OBJECTIVE

The purpose of this study was to investigate the effects of aerosolized prostacyclin (A-PGI2) and intratracheally instilled prostacyclin (I-PGI2) during partial liquid ventilation (PLV) on gas exchange and pulmonary circulation in rabbits with acute respiratory distress.

DESIGN

Prospective control study.

SETTING

A research laboratory at a university medical centre.

SUBJECTS

Sixty-nine Japanese white rabbits.

INTERVENTION

Lung injury was induced by oleic acid and the animals were divided into five groups of ten each: a mechanical gas ventilation (GV) group, an A-PGI2 group, a PLV group, an A-PGI2+PLV group and an I-PGI2+PLV group. PLV, A-PGI2+PLV and I-PGI2+PLV groups received 15 ml/ kg perflubron intratracheally while receiving mechanical GV. A-PGI2 and A-PGI2+PLV groups received aerosolized PGI2 (50 ng/kg/min) in combination with GV or PLV, respectively. The I-PGI2+PLV group was instilled 50 ng/kg/min PGI2 intratracheally in combination with PLV.

RESULT

After lung injury, all animals developed hypoxia, hypercarbia and pulmonary hypertension. The improvement of partial pressure of arterial oxygen (PaO2) in the A-PGI2 and PLV groups was transient, whereas the A-PGI2+PLV and I-PGI2+PLV groups showed consistent improvement throughout the experiment. The PaO2 values of the I-PGI2+PLV group were significantly higher than those of the other groups 120 min after treatment. The mean pulmonary artery pressure (PAP) significantly decreased after treatment in the A-PGI2, APGI2+PLV and I-PGI2+PLV groups.

CONCLUSIONS

The results suggest that both aerosolized and intratracheally instilled PGI2 improve oxygenation and reduce PAP during PLV in oleic acid lung injury.

Midazolam and ketamine inhibit glutamate release via a cloned human brain glutamate transporter

PURPOSE

In cerebral ischemia/anoxia, the glutamate transporter runs in reverse and releases glutamate into the extracellular space, causing irreversible neuronal damage. Intravenous anesthetics attenuate overall glutamate release and prevent neuronal injury during anoxia/ischemia, but their effect on the glutamate transporter is variable.

METHODS

A human glial glutamate transporter (hGLT-I) cDNA was isolated by screening a human cerebral cortical library. Cloned cDNA was transfected in Chinese hamster ovary cells. The effect of the intravenous anesthetics midazolam (0.3 to 30 microM), ketamine (10 to 100 microM), thiopental (30 to 300 microM), and propofol (3 to 30 microM) on reversed uptake of L-glutamate via hGLT-I was examined by whole-cell patch-clamp.

RESULTS

Midazolam at a concentration 3 microM reduced outward currents arising from reversed L-glutamate uptake via hGLT-I in a concentration-dependent manner. While, ketamine at 100 microM attenuated the same outward currents, to 53.3+/-11.4% of those seen in controls without anesthetics (P<0.05, n=5). In contrast, neither thiopental nor propofol showed effects on outward currents mediated by reversed operation of hGLT-I.

CONCLUSIONS

These results suggest that midazolam and ketamine, but not thiopental and propofol, have a capacity to inhibit glutamate release via GLT- I directly.

Effects of mild versus deep hypothermia on a cloned human brain glutamate transporter (GLT-1) expressed in Chinese hamster ovary cells

Glutamate transporters, widely distributed in the brain and spinal cord, maintain extracellular glutamate concentrations below neurotoxic levels. In cerebral ischemia/anoxia, the glutamate transporter runs in reverse and releases glutamate into the extracellular space, causing irreversible neuronal damage. Although hypothermia reduces the elevation of extracellular glutamate concentration during cerebral ischemia/anoxia, little is known about the effect of hypothermia on the glutamate transporter. A human glial glutamate transporter (hGLT-1) cDNA was isolated by screening a human cerebral cortical library, and cloned cDNA was stably transfected in Chinese hamster ovary (CHO) cells. Effects of deep hypothermia (22 to 23 degrees C) on uptake and release of L-glutamate via hGLT-1 were investigated by whole-cell patch-clamp. The control study was performed at 34 to 35 degrees C. The hGLT-1 transporter had the capacity to take up extracellular L-glutamate under essentially physiological ionic conditions, whereas this transporter promoted release of L-glutamate under a nonphysiological condition mimicking complete ischemia. Deep hypothermia decreased a) uptake and b) release of L-glutamate via hGLT-1 to a) 4.8+/-4.8% (P < .01, n = 7) and b) 19.0+/-4.5% (P < .01, n = 15) of control values, respectively. The results suggest that deep hypothermia is a potent inhibitor of glutamate uptake by intact glial cells as well as glutamate release from glial cells under certain pathophysiological circumstances. The balance between these antagonistic effects of hypothermia may attenuate the elevation of the extracellular glutamate concentration during ischemia/anoxia.

Uptake and elimination of sevoflurane in rabbit tissues--an in vivo magnetic resonance spectroscopy study

PURPOSE

Previous pharmacokinetic studies of fluorinated anesthetics using 19F-magnetic resonance spectroscopy (19F-MRS) have focused on the brain. Investigation of other tissues would give more precise information about the pharmacokinetics of inhalational anesthetics. In this study we investigated the pharmacokinetics of uptake and elimination of sevoflurane in brain, liver, muscle, venous blood and arterial blood of rabbits.

METHODS

Twenty rabbits were examined by 19F-MRS conducted at 4.7 Tesla using a 1-cm-diameter surface coil for brain (n = 4), liver (n = 5) and muscle (n = 5), and a 1.3-cm-diameter surface coil for arterial (n = 3) and venous (n = 3) blood. Sevoflurane, 4% in oxygen, was administered for 120 min, followed by 120 min elimination.

RESULTS

Both the uptake and elimination kinetics were best fitted by a biexponential curve which was divided into fast and slow components. During the uptake experiment the time required to reach half of the maximum spectroscopic intensity in each tissue was 1.6 min in arterial blood, 4.7 min in liver, 12.2 min in venous blood, 14.4 min in brain and 20.9 min in muscle. During the elimination experiment the time required to reach half maximum intensity was 2.4 min in arterial blood, 6.3 min in liver, 13.4 min in venous blood, 19.6 min in brain and 28.7 min in muscle.

CONCLUSIONS

Sevoflurane uptake or elimination in the tissues examined followed biexponential kinetics. In this rabbit model, sevoflurane uptake and elimination were fastest in arterial blood, followed, in order, by liver, venous blood, brain and muscle.

The effects of hypothermia on a cloned human brain glutamate transporter (hGLT-1) expressed in Chinese hamster ovary cells: -[3H]L-glutamate uptake study

Hypothermia provides neuroprotection that inhibits increases in extracellular glutamate concentration during ischemia; however, the effect of hypothermia on the glutamate transporter is uncertain. A human glial glutamate transporter (hGLT-1) cDNA, isolated by screening a cDNA, library was cloned and stably transfected into Chinese hamster ovary cells. We assessed the effects of temperature on transporter activity in [3H]L-glutamate flux experiments at 23, 32, and 37 degrees C. Hypothermia of 23 degrees C and 32 degrees C decreased [3H]L-glutamate uptake at 60 min, to 76.7%+/-7.3% (P < 0.05, n = 5) and 70.7%+/-7.5% (P < 0.05, n = 5) of uptake at 37 degrees C, respectively. Reversed uptake of preloaded [3H]L-glutamate via hGLT-1 was not observed at any temperature. The specific uptakes (Q10 values) for 37 degrees C to 32 degrees C and 32 degrees C to 23 degrees C at 30 min were 3.48 and 2.37, whereas they were 2.17 and 0.91, respectively, for 60 min. These changes suggest that hypothermia attenuates uptake of extracellular glutamate via hGLT-1 in a temperature- and time-dependent manner.

IMPLICATIONS

Under certain pathologic conditions, including cerebral ischemia and traumatic brain injury, glutamate neurotoxicity may initially be propagated by hypothermia due to relative failure of glutamate uptake via Human Glial Glutamate Transporter before a subsequent recovery of uptake.

Laryngeal mask airway insertion using propofol without muscle relaxants: a comparative study of pretreatment with midazolam or fentanyl

We determined the effects of pretreatment with midazolam or fentanyl on the ease of laryngeal mask airway insertion using propofol without a muscle relaxant. One hundred and eighty ASA class I or II patients were randomly allocated to one of three groups, 60 patients per group, to receive either placebo (Group C), midazolam 0.05 mg kg-1 (Group M) or fentanyl 2 micrograms kg-1 (Group F), respectively. Following intravenous administration of these drugs, Group C received propofol 2.5 (Group C-2.5) or 3.0 mg kg-1 (Group C-3.0). Group M and Group F received propofol 2.0 or 2.5 mg kg-1 (Group M-2.0, M-2.5, F-2.0 and F-2.5, respectively). There was a smaller incidence of severe head and limb movements on LMA insertion in Group M-2.5, Group F-2.0 and Group F-2.5 than in Group C-2.5. Airway obstruction and inadequate jaw relaxation, which were occasionally recognized in Group C and Group F patients, were not observed in Group M-2.5. Overall the ease of LMA insertion was significantly better in Group M-2.0, Group M-2.5 and Group F-2.5 than in Group C-2.5, however, the blood pressure in Group F after LMA insertion was significantly lower than in Group M. We conclude that pretreatment with midazolam 0.05 mg combined with propofol 2.5 mg kg-1 provides safe and satisfactory conditions for LMA insertion.

[A multicenter study for evaluating a new intubating laryngeal mask airway]

A multicenter study was performed to evaluate the success of endotracheal intubation using an intubating laryngeal mask (ILM, Fastrach) in patients in ASA status I or II, aged 20 years or more, who underwent general anesthesia. A total of 191 patients were studied, and 24 of them were estimated difficult to intubate by the ordinary method with laryngoscope. Endotracheal intubation was successfully performed through ILM in 162 of the 191 (success rate of 84.8%). The mean time required for intubation in these successful cases was 19.1 seconds. The success rate did not depend on the clinical experience of anesthesiologists, and the individual success rate was improved as they became more experienced. Of the 24 patients who had been estimated difficult to intubate with laryngoscope, 23 were successfully intubated with success rate of 95.8%. In summary, endotracheal intubation through ILM was easy regardless of the anesthesiologist's experience, and seemed to be valuable for patients who were difficult to intubate.

Improvement of renal dysfunction in dogs with endotoxemia by a nonselective endothelin receptor antagonist

OBJECTIVES

During endotoxemia, there is a marked and intractable decrease in systemic blood pressure, as well as profound vasoconstriction of the renal artery, thereby leading to septic shock and acute renal failure. The purpose of this study was to elucidate the effect of endothelin-1, a potent endothelium-derived vasoconstrictor peptide, on the hemodynamic and renal vascular changes seen in endotoxemia.

DESIGN

Prospective, comparative, experimental study.

SETTING

Laboratory at a university hospital.

SUBJECTS

Thirty-two male mongrel dogs (12.1+/-0.4 kg) under pentobarbital anesthesia.

INTERVENTIONS

Four groups of animals were studied: a) the lipopolysaccharide (LPS) group (n = 10), which received LPS (250 ng/kg/min for 2 hrs); b) the TAK-044 (a nonselective endothelinA/ endothelinB receptor antagonist) plus LPS group (n = 12), which received a bolus of TAK-044 (5 mg/kg) 0.5 hr before the start of LPS infusion; c) the TAK-044 plus vehicle group (n = 5), which received the same dose of TAK-044 0.5 hr before the start of vehicle infusion; and d) the control group (n = 5), which received only vehicle infusion.

MEASUREMENTS AND MAIN RESULTS

Changes in systemic and renal hemodynamics, blood gas, and renal function were measured at baseline, and at 0.5, 1, 2, 3, and 4 hrs. Infusion of LPS resulted in significant decreases in mean arterial pressure, arterial pH, Pao2, base excess, urine volume, renal blood flow, creatinine clearance, and urine osmolality. The administration of TAK-044 before LPS infusion did not affect the LPS-induced hypotension. In contrast, the receptor antagonist prevented LPS-induced metabolic acidosis and hypoxemia, and improved LPS-induced decreases in urine volume, renal blood flow, creatinine clearance, and urine osmolality, whereas TAK-044 or vehicle administered alone resulted in no significant hemodynamic or blood gas changes. Plasma endothelin-1 concentrations significantly increased after LPS infusion, with or without TAK-044.

CONCLUSIONS

The present study suggests that endothelin-1 plays an important role in the impaired renal hemodynamics and renal function associated with endotoxemia, and that endothelin receptor antagonists may be useful as therapeutic agents for acute renal failure during endotoxemia.

Accelographic and mechanical post-tetanic count and train-of-four ratio assessed at the great toe

We examined post-tetanic count (PTC) and train-of-four (TOF) ratios at the great toe assessed accelographically or mechanically and compared these with post-tetanic count and train-of-four ratios evaluated mechanically at the thumb in 24 patients who were given vecuronium. An acceleration transducer was attached to the right great toe, a force transducer to the left great toe and another force transducer to the thumb of the left hand. In the PTC group (n = 12) and TOF group (n = 12), post-tetanic count and train-of-four ratios were simultaneously recorded using the two great toes and the thumb of the left hand respectively. Accelographic post-tetanic count at the great toe was greater than the post-tetanic count at the thumb; however, mechanical post-tetanic count at the great toe was lower than the mechanical post-tetanic count at the thumb. Accelographic and mechanical train-of-four ratios at the great toe were greater than the mechanical train-of-four ratios at the thumb. But mechanical train-of-four ratios at the great toe became similar to mechanical train-of-four ratios at the thumb as the degree of neuromuscular block lessened. In conclusion, the mechanical post-tetanic count at the great toe is lower than the mechanical post-tetanic count at the thumb. In contrast, mechanical train-of-four ratios at the great toe are greater than the mechanical train-of-four at the thumb. Nevertheless, as the mechanical train-of-four ratios at the great toe became comparable with the mechanical train-of-four ratios at the thumb, mechanical assessment of the train-of-four ratio at the great toe may be useful for the evaluation of residual neuromuscular block.

Treatment of pulmonary hypertension and hypoxia due to oleic acid induced lung injury with intratracheal prostaglandin E1 during partial liquid ventilation

BACKGROUND

Partial liquid ventilation using perfluorocarbon liquids may be of therapeutic benefit in patients with acute respiratory failure. This study investigated the effects of prostaglandin E1 (PGE1) delivered intratracheally during partial liquid ventilation on lung function and pulmonary circulation in rabbits with acute respiratory distress syndrome.

METHODS

Lung injury was induced by intravenous oleic acid in adult Japanese white rabbits, 1 h after which they were divided into four groups of 10 animals. Group 1 received mechanical ventilation alone, group 2 received aerosolized PGE1 (5 microg followed by 0.1 microg x kg(-1) x min(-1)) under mechanical ventilation combined with 5 cm H2O positive end-expiratory pressure, and groups 3 and 4 received partial liquid ventilation with 15 ml/kg perflubron. Group 4 received a 5-microg bolus followed by 0.1 microg x kg(-1) x min(-1) PGE1 instilled intratracheally (not by aerosol) in combination with partial liquid ventilation. Measurements were performed at 30-min intervals for 120 min after lung injury.

RESULTS

After lung injury, hypoxemia, hypercapnia, acidosis, and pulmonary hypertension developed in all animals and were sustained in groups 1 and 2 throughout the experiment. The partial pressure of oxygen in arterial blood of animals in group 3 improved with initiation of treatment, with statistical significance achieved at the 30 and 60 min time points as compared with controls. Group 4 animals had immediate and sustained increases in the partial pressure of oxygen in arterial blood that were significant compared with all other groups during the experiment. Statistically significant reductions in mean pulmonary artery pressure were seen only in group 4 animals compared with all other groups.

CONCLUSIONS

These results suggest that PGE1 delivered intratracheally during partial liquid ventilation may be a useful therapeutic strategy for patients with the acute respiratory distress syndrome.

Post-tetanic burst count and train-of-four during recovery from vecuronium-induced intense neuromuscular block under different types of anaesthesia

Recovery of neuromuscular blockade after vecuronium 0.2 mg kg-1 was measured by post-tetanic burst count (PTBC) and train-of-four (TOF) in 120 adult patients anaesthetized by one of four techniques: neuroleptanaesthesia or one minimum alveolar concentration of isoflurane, enflurane, or sevoflurane. Onset of recovery was taken when there was reflex movement in response to carinal stimulation. The time course of recovery measured by burst count was similar for all four types of anaesthesia. Recovery of each of the twitches of the TOF was significantly shorter under neuroleptanaesthesia than under isoflurane, enflurane, or sevoflurane anaesthesia [times to return of T1 were 41.4 +/- 5.4, 51.5 +/- 10.6, 52.2 +/- 10.0, or 55.3 +/- 11.2 min (mean +/- SD). P < 0.05]. The burst count at the onset of reflex movement was less under neuroleptanaesthesia than under isoflurane, enflurane, or sevoflurane anaesthesia (16.3 +/- 4.8, 26.7 +/- 6.7, 27.7 +/- 6.8, 28.0 +/- 8.4, P < 0.05). The ratio of first twitch to control twitch at the onset of reflex movement was the same for all four types of anaesthesia.

[Usefulness of the intubating laryngeal mask airway for cases with predicted difficult intubation]

We evaluated the usefulness of the intubating laryngeal mask airway (ILMA) in patients who were predicted to have possible difficult airway. Patients with possible difficult airway were defined as those with limited head extension, Mallampati's classification of grade IV, thyro-mental distance < 4 cm, or Cormack grade III-IV on the laryngoscopy. The control group was consisted of the patients without these conditions or impaired mouth opening. Insertion of the ILMA was successfully performed in all patients of both groups. In the group of possible difficult airway, 83% of patients were intubated through the ILMA successfully, and in the control group, 86%. We conclude that the ILMA may become an additional tool in patients with difficult intubation.

Modified double burst stimulation of varying stimulating currents

BACKGROUND

Using modified double burst stimulation (modified DBS), sufficient level of recovery from neuromuscular blockade (train-of-four (TOF) ratio > 0.7) can properly be diagnosed. Modified DBS may often be applied in awake patients in the postanesthetic care unit. As the stimulating current decreases, the neurostimulation-induced discomfort becomes less for awake subjects. It is relevant to investigate the usefulness of the modified DBS delivered at low currents.

METHODS

One hundred and twenty-one adult patients undergoing nitrous oxide-oxygen-isoflurane anesthesia were randomly divided into one of four groups: group 50 (n = 40), group 30 (n = 40), group 20 (n = 40), and supramaximality group (n = 1). After administration of vecuronium, in one hand and forearm (fixed arm), the degree of neuromuscular blockade was quantified mechanically. In the contralateral arm (free arm), modified DBS stimuli were delivered at 50, 30, and 20 mA in groups 50, 30, and 20, respectively. An observer determined tactilely on the free arm the presence or absence of fade in response to the modified DBS applied at 50, 30, and 20 mA. In one patient (the supramaximality group), modified DBS ratios (D2/D1) were examined at 50, 40, 30, 20, and 10 mA before administration of vecuronium. Moreover, discomfort associated with modified DBS applied at 50, 30, and 20 mA was evaluated using a 10-cm visual analog scale (VAS) in 15 awake volunteers.

RESULTS

Probabilities of detection of fade in response to modified DBS in groups 50, 30, and 20 were 90, 86, and 96% (TOF ratios of 0.61-0.70), 62, 73, 94*#% (0.71-0.80), 26, 39, and 79*#% (0.81-0.90), and 4, 33*, and 51*#% (0.91-1.00), respectively. *P < 0.05 as compared to group 50. #P < 0.05 as compared to group 30. Supramaximal responses to D1 and D2 could be elicited at a current > or = 30 mA. The mean VAS scores were 8.7, 6.5*, and 4.1* when stimulated at 50, 30, and 20 mA, respectively. *P < 0.05 as compared to 50 mA. #P < 0.05 as compared to 30 mA.

CONCLUSION

Modified DBS-induced discomfort becomes less as the stimulating current decreases. However, when stimulated at 30 or 20 mA, fade in response to modified DBS is felt in too many cases, even after neuromuscular blockage subsides to an adequate level.

Amrinone improves right ventricular ejection fraction and oxygen delivery without deterioration of extravascular lung water in canine oleic acid pulmonary injury

Fourteen mongrel dogs were anaesthetized and mechanically ventilated with oxygen. After oleic acid was administered intravenously, amrinone 1 mg/kg was intravenously administered to one group followed by a continuous infusion of 10 micrograms/kg/min for one hour (amrinone group, n = 7). Isovolumetric saline was administered to the control group (n = 7). Amrinone slightly lowered PaO2 but significantly increased oxygen delivery and improved gastric intramucosal pH (pHi) during the first 30 minutes (7.33 +/- 0.13) compared with the control group (7.21 +/- 0.06, P < 0.05). The pHi remained higher in the amrinone group (7.30 +/- 0.15) than in the control group (7.16 +/- 0.06, P < 0.05) after the drug was withdrawn. Extravascular lung water was significantly augmented after oleic acid injection and sustained in all animals for the remainder of the study.

Tracheal intubation through the intubating laryngeal mask airway (LMA-Fastrach) in patients with difficult airways

The intubating laryngeal mask airway was used in 31 adult patients in whom tracheal intubation was known or suspected to be difficult. The intubating laryngeal mask airway was successfully inserted in 30 patients and provided a clinically patent airway. In the remaining one patient it was impossible to insert the device correctly. Tracheal intubation through the device was successful in 28 of 30 patients (93%). These results suggest that the intubating laryngeal mask airway has a potential role for tracheal intubation in adult patients with difficult airways.

Beneficial effect of atrial natriuretic peptide on pulmonary gas exchange in patients with acute lung injury

STUDY OBJECTIVES

The purpose of this study was to investigate the effect of i.v. infusion of atrial natriuretic peptide (ANP) on hemodynamics, pulmonary gas exchange, and urine volume during mechanical ventilation with positive end-expiratory pressure (PEEP) in patients with acute lung injury.

DESIGN

Prospective, randomized, comparable study.

SETTING

ICU of a university hospital.

PATIENTS

Forty patients with moderate acute lung injury (lung injury score > or = 2.0) who required mechanical ventilation with PEEP were studied.

INTERVENTIONS

The patients were randomly divided into two groups: ANP group (n=20) and control group (n=20). The ANP group received genetic recombination alpha-human ANP (carperitide) at the rate of 0.1 microg/kg/min for 24 h. The control group did not receive ANP.

MEASUREMENTS AND RESULTS

Hemodynamic and blood gas parameters, and urine volume were measured at baseline, 3 h, and 24 h after initiating the ANP infusion. Plasma ANP concentrations markedly (p<0.01) increased from 112.0+/-27.0 to 1,868.3+/-385.3 pg/mL after 24 h in the ANP group, whereas they remained unchanged in the control group. In the ANP group, hemodynamic parameters did not change, but PaO2/FIO2 (fraction of inspired oxygen) and thoracic compliance significantly (p<0.01) increased at 24 h after initiating the ANP infusion, associated with significant (p<0.01) decreases in lung injury score and shunt. Urine volume significantly (p<0.01) increased during 0 to 3 h after initiating the ANP infusion. In the control group, hemodynamics, pulmonary gas exchange, and urine volume did not significantly change during the study period. There were significant differences in PaO2/FIO2 (24 h), thoracic compliance (24 h), lung injury score (24 h), and urine volume (3 h) between the two groups.

CONCLUSION

The results suggest that ANP infusion induces diuresis and improves pulmonary gas exchange in patients with acute lung injury during mechanical ventilation with PEEP.

[Anesthetic management of a patient with protein C deficiency associated with pulmonary thromboembolism]

A patient with protein C deficiency associated with massive pulmonary embolism underwent open heart tromboembolectomy. The operation was successfully performed under cardiopulmonary bypass using a usual dose of heparin 3 mg.kg-1. The effect of heparin was successfully reversed by the administration of protamine sulfate 6 mg.kg-1. Perioperative administration of fresh frozen plasma or protein C concentrates might be necessary to manage hypercoagulability in a patient with protein C deficiency.

The combination of partial liquid ventilation and inhaled nitric oxide in the severe oleic acid lung injury model

STUDY OBJECTIVES

To elucidate the efficacy of the combination of inhaled nitric oxide (NO) and partial liquid ventilation (PLV) in ARDS.

DESIGN

Prospective, randomized, controlled study.

SETTING

A research laboratory at a university medical center.

SUBJECTS

Thirty-two rabbits.

INTERVENTIONS

Animals were anesthetized and ventilated via tracheostomy (tidal volume=40 mL; respiratory rate=25 breaths/min; fraction of inspired oxygen=0.99). After 0.08 mL/kg (0.071 g/kg) oleic acid was administered via the central venous route, animals were randomly divided into the following four groups depending on the ventilatory mode: (1) Gas ventilation (GV)-control group: GV was continued throughout the study; (2) GV-NO group: NO inhalation (10 ppm) was performed under GV; (3) PLV-control group: PLV using perflubron (15 mL/kg) was continued until the end of the study; and (4) PLV-NO group: NO inhalation (10 ppm) was performed under PLV.

MEASUREMENTS AND RESULTS

NO inhalation improved PaO2 in the PLV-NO group (from 133+/-20 to 167+/-23 mm Hg; p=0.0008), but not in the GV-NO group (from 67+/-6 to 63+/-9 mm Hg), although pulmonary vascular resistance decreased both in the GV-NO (from 4,604+/-328 to 4,337+/-322 dyne x s x cm(-5); p=0.0116) and the PLV-NO group (from 4,727+/-665 to 4,112+/-560 dyne x s x cm(-5); p=0.0036). (Data were expressed as mean+/-SEM.)

CONCLUSION

PLV augmented the effect of inhaled NO on pulmonary gas exchange. The combination of PLV and NO inhalation could be effective in severe ARDS.

Pathologic role of endothelin-1 in septic shock

To elucidate the pathologic role of endothelin-1 (ET-1) in septic shock, we measured plasma ET-1 concentrations after bacterial lipopolysaccharide (LPS) administration in dogs and determined systemic, pulmonary, and renal hemodynamics and blood gas parameters with or without the nonselective ET receptor antagonist TAK-044. Plasma ET-1 concentrations increased significantly after LPS administration, which correlated positively with mean arterial pressure, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, and central venous pressure. LPS infusion induced hypotension, metabolic acidosis, hypoxemia, and renal dysfunction. TAK-044 prevented LPS-induced metabolic acidosis, hypoxemia, and renal dysfunction, but not hypotension. These findings suggest that increased circulating ET-1 plays a compensatory role in the reversal of systemic vasodilatation in septic shock, but exerts deleterious effects on renal and pulmonary circulation.

Detrimental effect of a non-selective nitric oxide synthase inhibitor on the energy state of the liver following acute endotoxemia in rabbits

BACKGROUND

The effect of nitric oxide synthase (NOS) inhibitors in septic shock is very controversial. It is known that the administration of NOS inhibitors to normal subjects itself increases pulmonary vascular resistance with a concomitant decrease of cardiac output. Therefore, the hypothesis was tested that the detrimental effects of a non-selective NOS inhibitor on liver energetics in a rodent model of endotoxemia are mediated by the adverse pulmonary circulatory effect of the drug itself.

METHODS

Twenty anesthetized rabbits were instrumented and two separate experiments (a magnetic resonance spectroscopic study and a hemodynamic study) were performed under similar conditions. Animals were assigned randomly to either a control group (group 1; animals received lipopolysaccharide (LPS) at a dose of 400 microg/kg alone) or a treatment group (group 2; animals received NG-nitro-L-arginine methyl ester (L-NAME) at a dose of 7.5 mg/kg, 75 min after administration of LPS).

RESULTS

In group 1, slight decreases in hepatic adenosine triphosphate (ATP) value were observed. In group 2, the decreases in ATP values were more prominent than those observed in group 1. LPS produced an acute drop in mean arterial pressure (MAP) with a concomitant increase in pulmonary vascular resistance (PVR) and a reduction in the cardiac output (CO) at 30 min after LPS. The administration of L-NAME caused a transient increase in MAP with a concomitant increase in systemic vascular resistance at 2 h after LPS. However, these changes in PVR and CO were more prominent than in group 1.

CONCLUSION

These results suggest that alterations within the pulmonary circulation may be a contributing factor which was responsible for the non-selective NOS inhibitor-induced acute hepatic energy derangement after LPS.

[Anesthetic management of abdominal gunshot wound--a report of three cases]

This is a case report of anesthetic management of abdominal gunshot wound. Two patients had upper abdominal wound involving the liver and the inferior vena cava. They died of uncontrolled bleeding. Third patient had lower abdominal injury involving the ascending colon and small intestine. The patient survived the injury and showed good recovery. In a case of the abdominal gunshot injury, prompt diagnosis and laparotomy are mandatory. Multiple intravenous routes are necessary in the upper part of the body for massive infusion and transfusion. Unusual hemostasis methods such as atrio-caval shunt or abdominal clamping of the aorta must be considered in case of injury in the inferior vena cava.

Recovery of post-tetanic count and train-of-four responses at the great toe and thumb

We have studied the recovery of post-tetanic count and train-of-four responses at the great toe and thumb accelerographically after the administration of vecuronium 0.2 mg.kg-1. Sixty adult patients scheduled for anaesthesia with nitrous oxide and isoflurane were studied. The times to the return of the first post-tetanic twitch were comparable at the great toe and thumb (mean (SD) times: 30.0 (6.5) min and 35.0 (8.5) min, respectively). Recovery of post-tetanic count followed similar time courses at the great toe and thumb. Also, time to the return of the first twitch of the train-of-four did not differ significantly at the great toe and the thumb (47.5 (9.6) min vs. 49.7 (10.5) min). Similarly, time to the return of the second, third and fourth twitches of the train-of-four did not significantly differ at the great toe and the thumb. However, the value of the first twitch of the train-of-four, expressed as a proportion of control twitch, was significantly higher than that at the thumb between 50 min and 110 min after the vecuronium injection, and the train-of-four ratio at the great toe was significantly higher than that at the thumb between 60 min and 100 min after the vecuronium injection.

Continuous intra-arterial blood gas monitoring during oesophagectomy

PURPOSE

To evaluate the clinical usefulness of the continuous intra-arterial blood gas (CIABG) monitoring system, Paratrend 7, during differential lung ventilation (DLV) in 12 patients undergoing oesophagectomy.

METHODS

Anaesthesia was induced with propofol and was maintained with isoflurane, oxygen and air, supplemented by an epidural infusion of mepivacaine. Arterial samples for estimation of blood gases (ABG) were taken just before and 5, 10, 20, 30, 60, and 90 min after the pleura was opened. The pH, PO2, and PCO2 values displayed by the CIABG monitor, which were recorded prior to the arterial blood sampling, were compared with the results of ABG analysis.

RESULTS

Eighty-four blood samples were obtained and the ranges for the measured variables were PCO2 24.8-57.4 mmHg, PO2 47-449 mmHg, and pH 7.30-7.49. The correlation between CIABG and ABG measurements was strong and significant (r values: PCO2 0.80, PO2 0.93, pH 0.94). The overall bias +/- precision between the two methods was PCO2 0.9 +/- 3.1 mmHg, PO2 -1 +/- 40 mmHg, %PO2 0.8 +/- 21.6%, pH 0.00 +/- 0.02. For PO2 values < 150 mmHg, the biases +/- precision were PO2 -5 +/- 17 mmHg, %PO2 -2.1 +/- 20.7%.

CONCLUSION

The agreement between CIABG and ABG measurements was better for PCO2 and pH than for PO2. Although the CIABG system is clinically useful for monitoring trends in blood gas changes, the accuracy of the PO2 value may be unacceptable during DLV because the error is theoretically < 34 mmHg with 95% reliability in the clinically important range of PO2, < 150 mmHg.

[Effects of thiopental and sevoflurane on hemodynamics during anesthetic management of electroconvulsive therapy]

The effect of thiopental and sevoflurane (1 MAC, 2 MAC) on hemodynamics was assessed in a randomized study involving 38 adult patients undergoing electroconvulsive therapy (ECT). Blood pressure, heart rate and electrocardiogram (ECG) were monitored during the ECT procedure. After oxygenation, hypnosis was induced with a bolus injection of thiopenal (TPS) 4 mg.kg-1. Muscle relaxation was achieved by succinylcholine, 1 mg.kg-1 intravenously before ECT procedure. Ventilation was assisted using a face mask with 100% oxygen (TPS group), 1.7% sevoflurane (1 MAC group) or 3.4% sevoflurane (2 MAC group), plus 50% nitrous oxide and 50% oxygen. Thereafter, an electrical stimulus was administered. A total of 150 treatment sessions were evaluated. The rate pressure product increased in every group right after ECT, but the use of sevoflurane (2 MAC) significantly diminished the response compared with sevoflurane (1 MAC) and thiopental. In the sevoflurane (2 MAC) group, no ventricular arrhythmias were observed. In general, it seems that sevoflurane (2 MAC) is as effective as thiopental and sevoflurane (1 MAC) as an induction agent for ECT.

Evaluation of residual neuromuscular block using train-of-four and double burst stimulation at the index finger

We examined the percentage of tactile detection of fade in response to train-of-four (TOF), double burst stimulation3,3 (DBS3,3), or DBS3,2 at the index finger compared with that at the thumb during continuous infusion of vecuronium. One hundred five adult patients were studied. At TOF ratios (T4/T1) of 0.41-0.70, fades in response to TOF were more frequently identified by tactile means at the index finger than at the thumb (58% vs 26%, P < 0.05). Similarly, at TOF ratios of 0.61-0.90, fades in response to DBS3,3 were more frequently detected at the index finger than at the thumb (55% vs 15%, P < 0.05), and at TOF ratios of 0.81-1.00, the percentage of detection of fade in response to DBS3,2 was higher at the index finger than at the thumb (72% vs 40%, P < 0.05). In addition, baseline displacement of the index finger or thumb during tactile assessment of fade in response to neurostimulation was measured videographically. The baseline displacement of the index finger was significantly less than that of the thumb (P < 0.05). In summary, the percentage of tactile detection of fade in response to neurostimulation at the index finger is higher than at the thumb, and the absence of fade in response to DBS3,3 at the index finger is a good indicator of adequate recovery from neuromuscular block. This is probably because of the smaller baseline displacement of the index finger.

Effects of carboxy-PTIO on systemic hemodynamics, liver energetics, and concentration of liver metabolites during endotoxic shock in rabbits: a 31P and 1H magnetic resonance spectroscopic study

OBJECTIVE

To investigate the effects of 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO), a nitric oxide scavenger, on the lipopolysaccharide-induced hypotension, hepatocellular dysfunction, and liver damage in endotoxic rabbits.

DESIGN

Experimental, comparative study.

SETTING

Laboratory of a university hospital.

SUBJECTS

Eighteen Japanese white rabbits (3.0 to 3.2 kg body weight) anesthetized with ketamine-xylazine were studied.

INTERVENTIONS

We randomly divided the rabbits into three groups: saline controls (group 1, n = 5); animals receiving lipopolysaccharide (400 micrograms/kg) alone (group 2, n = 8); and animals receiving lipopolysaccharide plus carboxy-PTIO at a rate of 0.17 mg/kg/min for 3 hrs (group 3, n = 5). Blood gases and mean arterial pressure (MAP) were monitored. In vivo phosphorus-31 magnetic resonance spectra were continuously obtained every 30 mins. In addition, the livers were sampled and underwent fractionation at 7 hrs after lipopolysaccharide administration. The hydrophilic and hydrophobic extracts from the livers were analyzed by in vitro hydrogen-1 and phosphorus-31 magnetic resonance spectroscopy.

MEASUREMENTS AND MAIN RESULTS

After the administration of lipopolysaccharide, the first phase of decrease in MAP within 30 mins was followed by partial recovery within the next 30 mins. In group 2, MAP started to decrease progressively within 180 mins after lipopolysaccharide administration (second phase) and decreased by 33% from the baseline value to 49 +/- 9 mm Hg at 420 mins. In contrast, the infusion of carboxy-PTIO significantly attenuated the second decrease in MAP (68 +/- 10 mm Hg, at 420 mins). In group 2, a slow and progressive decrease in adenosine triphosphate (ATP) and increase in inorganic phosphate concentrations occurred from 120 mins after lipopolysaccharide administration, and continued throughout the observation period. These changes were accompanied by a progressive decrease in intracellular pH. On the other hand, in group 3, there were no significant changes in ATP and inorganic phosphate concentrations compared with the controls from 120 to 360 mins after lipopolysaccharide administration. Moreover, restorations of both arterial and hepatocellular acidosis were observed in group 3. The differences of the degree of liver damage--as determined by the total amount of phospholipid, free fatty acids concentration, and membrane fluidity--were not significant among the three groups. Three of eight rabbits in group 2 died within 7 hrs, but no animal in the other two groups died during the study.

CONCLUSIONS

The results of this study indicate that the infusion of carboxy-PTIO: a) prevented the delayed hypotension associated with endotoxic shock in rabbits; b) returned the hepatocellular ATP concentrations nearly to the level of the controls and alleviated hepatocellular acidosis; c) normalized various hydrophilic metabolites, such as lactate and alanine in the liver; and d) did not exacerbate liver injury after the administration of lipopolysaccharide. These findings indicate that carboxy-PTIO, a nitric oxide scavenger, may have a positive vasopressor effect during hypodynamic septic shock without exacerbating liver injury.

[The effect of low-dose prostaglandin E1 on serum and urinary fluoride concentrations in patients anesthetized with sevoflurane]

We investigated the effects of low-dose prostaglandin E1 (PGE1) on serum and urinary concentrations of inorganic fluoride in 39 adult patients undergoing upper abdominal surgery. Anesthesia was maintained with a combination of N2O-O2-sevoflurane and thoracic epidural anesthesia. Twenty-two patients received infusion of PGE1 at a rate of 0.02 micrograms.kg-1.min-1 throughout surgery. Seventeen patients served as control by not receiving PGE1. Serum inorganic fluoride concentrations (FB) were determined before the induction of anesthesia and 0, 2 and 24 hours after the end of anesthesia. Urinary inorganic fluoride concentrations (FU) were determined before the induction of anesthesia, and 0, 24 and 48 hours after the end of anesthesia. These was no difference between PGE1 group and control group in anesthetic dose (MAC hours) of sevoflurane. In both groups, FB peaked at the end of anesthesia. In PGE1 group, UB peaked at the end of anesthesia, while in control group, it peaked 24 hours after anesthesia. There were differences between groups neither in FB nor in FU throughout the study period. The relationships between anesthetic dose and fluoride concentrations, however, differed significantly between the groups. In control group FB values of 0, 2 and 24 hours after anesthesia correlated positively with MAC hours, respectively, while in PGE1 group they did not. Similarly in control group, FU values of 24 and 48 hours after anesthesia correlated positively with MAC hours, respectively, while in PGE1 group, they did not. Thus in patients receiving high-dose sevoflurane, FB and FU tended to be lower in PGE1 group than in control group. In contrast, in PGE1 group, urinary excretion of fluoride during surgery correlated positively with MAC hours, while in control group, it did not. Urinary fluoride excretion during surgery was significantly greater in PGE1 group than in control group. These results suggested that PGE1 might prevent elevation of serum and urinary fluoride concentrations in patients receiving high-dose sevoflurane. This effect might result from enhanced urinary excretion of fluoride with PGE1.

Increased plasma concentrations of brain natriuretic peptide in patients with acute lung injury

PURPOSE

This study was performed to elucidate the pathophysiological role of brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP) in acute lung injury.

MATERIALS AND METHODS

We sequentially measured plasma concentrations of immunoreactive BNP and ANP in 10 patients (mean age, 63 years (with acute lung injury and compared those with hemodynamic parameters and pulmonary functions.

RESULTS

Plasma concentrations of immunoreactive BNP and ANP were markedly elevated at entry into the study. Plasma BNP concentrations during the early course (3 days) showed significant (P < .01) positive correlations with systemic vascular resistance index (r = .708) and pulmonary vascular resistance index (r = .573), but a negative correlation with cardiac index (r = .608). Plasma ANP concentrations showed a significant (P < .05) positive correlation with pulmonary capillary wedge pressure (r = .398). Plasma BNP in 4 patients who died and 1 patient with acute renal failure remained elevated during the entire hospital length of stay (12 days).

CONCLUSION

These findings suggest that circulating BNP plays an important role in acute lung injury along with ANP as a compensatory mechanism for cardiac dysfunction accompanied by increased systemic vascular resistance index and pulmonary vascular resistance index. Circulating BNP may be a sensitive humoral marker for the degree of ventricular dysfunction associated with acute lung injury.

[The effect of low-dose prostaglandin E1 on intra- and post-operative liver function]

We investigated the effects of low-dose prostaglandin E1 (PGE1) on intra- and post-operative liver function in 109 adult patients undergoing upper abdominal surgery. Patients were divided into 2 groups; Control group (n = 42) and PGE1 group (n = 67). In PGE1 group, PGE1 was infused throughout surgery at a rate of 0.02 microgram kg-1 min-1. In both groups, anesthesia was maintained with a combination of inhalational and thoracic epidural anesthesia. Epidural anesthesia was maintained with 1.5% lidocaine infused epidurally at a constant rate (8 +/- 2 ml.hr-1). The continuous epidural infusion of lidocaine was initiated before surgery and discontinued at the end of surgery. Preoperative and postoperative liver function was evaluated with blood chemistry examination. Intraoperative liver function was evaluated in 84 patients (33 in control group and 51 in PGE1 group) by measuring plasma lidocaine concentration. Plasma lidocaine concentration was determined 1 and 3 hours after the initiation of lidocaine infusion and 0 and 2 hours after its termination. There were no differences between the groups in doses and infusion rates of lidocaine. In both groups, lidocaine concentration increased progressively as infusion was continued. Lidocaine concentration was significantly lower in PGE1 group than in control group at the end of the infusion. In 22 patients in control group and 35 in PGE1 group who received high-dose lidocaine (> 8 mg.kg-1), lidocaine concentration remained significantly lower in PGE1 group than in control group throughout the infusion period. The difference in lidocaine concentrations between the groups increased progressively as infusion was continued, though the doses and the infusion rates of lidocaine were not different between the groups. Postoperative liver function did not differ between the groups. Because removal of lidocaine from blood to liver parallels hepatic blood flow, the lower plasma lidocaine concentration in PGE1 group indicated that hepatic blood flow was higher and liver function was better-maintained with PGE1 during anesthesia and surgery. Low dose PGE1 thus improved intraoperative liver function during upper abdominal surgery.

[The effect of low-dose prostaglandin E1 on intra- and post-operative renal function]

We investigated the effects of low-dose prostaglandin E1 (PGE1) on intra- and post-operative renal function in 109 adult patients undergoing upper abdominal surgery. Anesthesia was maintained with a combination of thoracic epidural combined with inhalational anesthesia. Sixty-seven patients received PGE1 at a rate of 0.2 microgram.kg-1.min-1 throughout surgery. Forty-two patients, who did not receive PGE1, served as control. Pre- and post-operative renal function was evaluated with serum levels of BUN and creatinine (Cr), while intra-operative renal function was evaluated mainly with urine output and urine flow rate during anesthesia. Urinary Na excretion and creatinine clearance (Ccr) were determined during surgery in limited cases. Urine output and urine flow rate during anesthesia were greater in PGE1 group than in control group, whereas infusion volumes and infusion rates were not different between the groups. In PGE1 group, urine flow rate was greater during surgery than before surgery, while in control group, it was unchanged. Na excretion during anesthesia was also greater in PGE1 group than in control group. In control group, Na excretion and Ccr were smaller during surgery than before surgery, while in PGE1 group, they were unchanged. Postoperative serum BUN and creatinine levels were not different between the groups. Decreased Na excretion and decreased Ccr in control group indicated that renal function was depressed during surgery, whereas unchanged Ccr, unchanged Na excretion and increased urine flow rate in PGE1 group indicated that renal function was well-maintained during surgery with PGE1. Low-dose PGE1 thus prevented depression of renal function during surgical anesthesia.

Train-of-four and double burst stimulation fade at the great toe and thumb

PURPOSE

We compared probabilities of tactile detection of fade in response to train-of-four (TOF), double burst stimulation3.3 (DBS3.3), and DBS3.2 at the great toe with those at the thumb.

METHODS

One hundred and thirty adult patients anaesthetized with nitrous oxide, oxygen, isoflurane, and fentanyl were studied. At varying degrees of neuromuscular block caused by vecuronium, an observer determined the presence or absence of fade in response to TOF DBS3.3, or DBS3.2 at the great toe and that at the thumb. The relationship between T1/T0 or TOF ratio (T4/T1) measured at the great toe and that at the thumb was also examined.

RESULTS

When TOF ratios were 0-0.10, 0.11-0.20, 0.21-0.30, 0.31-0.40, 0.41-0.50, 0.51-0.60, 0.61-0.70, and 0.71-1.00, the probabilities of detection of fade in response to TOF at the great toe (thumb) were 77 (100), 66 (100), 58 (96), 52 (77), 39 (38), 26 (23), 2(4), and 0(0)%, respectively (P < 0.05 at TOF ratio 0-0.40). Similarly, the probabilities of detection of fade in response to DBS3.3 at the great toe were lower than at the thumb when TOF ratios were 0.21-0.80, and those in response to DBS3.2 at the great toe were lower than at the thumb when TOF ratios were 0.61-0.80. A dose relationship was observed between T1/T0 or TOF ratio at the great toe and that at the thumb.

CONCLUSION

This study suggests that the probability of tactile detection of fade in response to TOF, DBS3.3, or DBS3.2 at the great toe is less than that at the thumb. The present results may be because the flexor hallucis brevis muscle is more resistant to non-depolarizing neuromuscular relaxant than the adductor pollicis muscle and that the ratio of fade in response to neurostimulation at the great toe is higher than at the thumb.

[The effect of low-rose prostaglandin E1 on circulation, respiration and body temperature during surgical anesthesia]

We investigated the effects of low-dose prostaglandin E1 (PGE1) on circulation, respiration, and body temperature during surgical anesthesia. We studied 109 adult patients undergoing upper abdominal operations under thoracic epidural combined with inhalational anesthesia. Patients were divided into 2 groups; Control group (n = 42) and PGE1 group (n = 67). In PGE1 group, PGE1 infusion was started at the rate of 0.02 microgram.kg-1.min-1 before the induction of anesthesia and was terminated at the end of surgery. There were no differences between the groups in demographic, anesthetic and surgical characteristics. After treatment with PGE1, arterial pressure decreased slightly but significantly, resulting in lower arterial pressure in PGE1 group than in control group before the induction of anesthesia. After the induction of anesthesia, however, arterial pressure decreased significantly in both groups, and the differences in arterial pressure between the groups were not observed any more during surgery. Heart rate was not different between the groups throughout the study period. Intraoperative urine output was greater in PGE1 group than in control group. PaO2/FIO2 ratio was not different between the groups both before and during anesthesia. Rectal temperature remained slightly but significantly lower in PGE1 group throughout surgery. Rectal-to-palm temperature gradient tended to be smaller in PGE1 group 1 hour after the induction of anesthesia. Low-dose PGE1 reduced arterial pressure. However, the difference in arterial pressure between the groups was so small that the difference disappeared during surgery. Meanwhile, low-dose PGE1 increased urine output, suggesting that renal blood flow was better-maintained with PGE1. In spite of several investigations reporting an unfavorable effect of PGE1 on PaO2, low dose PGE1 did not affect PaO2 in this study. Finally low-dose PGE1 reduced core temperature, though slightly, probably through redistribution of the body heat.

Inhaled nitric oxide improved the outcome of severe right ventricular failure caused by lipopolysaccharide administration

OBJECTIVE

To evaluate the efficacy of nitric oxide (NO) inhalation against endotoxin-induced lung injury.

DESIGN

Randomized prospective short-term study.

SETTING

University school of Medicine Laboratory.

INTERVENTIONS

Animal experiment (using 16 Japanese white rabbits). The animals inhaled NO at a concentration of 10 ppm.

MEASUREMENTS AND RESULTS

The rabbits were randomly divided into the NO inhaling group (n = 7) and the control group (n = 9). Both groups received continuous infusion of 1200 mcg lipopolysaccharide (LPS) and the NO group inhaled 10 ppm NO during the LPS administration. In the control group, severe right ventricular (RV) failure was observed at 30-90 min of LPS infusion, and 4 of 9 animals died within 90 min of LPS infusion. In the NO group, none of the animals died and the early phase hemodynamic deterioration was milder than in the control group. But pulmonary gas exchange was not significantly different between the two groups throughout the study. At the end of the study there were no significant differences in any parameters of the surviving animals between the two groups.

CONCLUSION

Although an improvement of pulmonary gas exchange was not demonstrated, NO inhalation (10 ppm) improved the outcome of severe RV failure caused by LPS infusion.

Comparative actions of propofol and thiopentone on cell membranes of isolated guineapig ventricular myocytes

We have examined the effects of propofol and thiopentone on membrane potentials and currents of isolated guineapig ventricular myocytes using the whole-cell patch-clamp technique. After current clamping, propofol at concentrations greater than 0.5 mumol litre-1 shortened the plateau and action potential duration (APD) (P < 0.05). Thiopentone 10 mumol litre-1 prolonged APD (P < 0.05), whereas concentrations of 50 mumol litre-1 or higher decreased plateau height (P < 0.05) and resting membrane potential (RMP) (P < 0.05) with abbreviation of the prolonged APD. With voltage clamping, propofol 1 mumol litre-1 decreased the L-type Ca2+ current (ICa,L) to 88.4% of control (P < 0.01) without affecting the delayed rectifier K+ current (IK) and propofol 10 mumol litre-1 decreased ICa,L and IK to 75.0% (P < 0.01) and 78.4% (P < 0.01), respectively, with no effect on the inward rectifier K+ current (IK1). Thiopentone 10 mumol litre-1 decreased ICa,L to 88.5% (P < 0.01) and IK to 78.3% (P < 0.05), while thiopentone 100 mumol litre-1 depressed ICa,L to 82.8% (P < 0.01), IK to 27.0% (P < 0.01) and IK1 to 67.3% (P < 0.05). These results indicated that propofol, at concentrations greater than those that are clinically relevant, shortened APD mainly by suppression of ICa,L, and the biphasic effects on APD by thiopentone were caused by depression of IK, and concomitant suppression of ICa,L and IK1 at higher concentrations. The distinct cardiodepressant effects of propofol and thiopentone may be, at least in part, attributed to different actions on membrane Ca2+ and K+ currents.

Double burst stimulation2,3: a new stimulating pattern for residual neuromuscular block

PURPOSE

We present a new stimulating pattern: double burst stimulation2,3 (DBS2,3) for evaluating residual neuromuscular block.

METHODS

Forty adult patients were studied. For DBS2,3, two burst stimuli were applied every 750 msec. The first consisted of two tetanic stimuli of 0.2 msec duration and the second of three tetanic stimuli of 0.2 msec duration. At varying degrees of neuromuscular block induced by vecuronium, the presence or absence of fade, or the presence or absence of waxing (i.e., the feeling that the muscular contraction in response to the second burst was stronger than that to the first) was determined by an observer blinded to the depth of neuromuscular block. In addition, the relationship between the train-of-four (TOF) ratio and DBS2,3 ratio was established at varying depths of neuromuscular block (TOF ratio 0.04-1.00).

RESULTS

The probabilities of tactile detection of fade in response to DBS2,3 were 100, 76, 15, 9, 3, 0, and 0% at a TOF ratio of 0-0.40, 0.41-0.50, 0.51-0.60, 0.61-0.70, 0.71-0.80, 0.81-0.90, and 0.91-1.00, respectively. Waxing in response to the DBS2,3 was identified in 0, 6, 32, 84, and 98% of cases when the TOF ratios were 0.00-0.60, 0.61-0.70, 0.71-0.80, 0.81-0.90, and 0.91-1.00, respectively. A close linear relationship existed between the TOF ratio and DBS2,3 ratio (r = 0.96, P < 0.000001).

CONCLUSION

DBS2,3 is of clinical use because when residual neuromuscular block is clinically important, fade can be identified, but once neuromuscular function returns to a sufficient level, waxing can be detected.

RETRACTED ARTICLE: Dibutyryl cyclic AMP increases the contractility of fatigued diaphragm in dogs

The effects of dibutyryl cyclic AMP (DBcAMP) on the contractility of nonfatigued and fatigued diaphragms were studied in 36 anesthetized and mechanically ventilated dogs. The animals were divided into four groups. In group C1 (n=8), dogs without fatigue received only Ringer's lactate solution. In group D1 (n=8), dogs without fatigue were given a continuous infusion of DBcAMP 0.2 mg·kg(-1)·min(-1). In groups C2 and D2 (n=10 each), diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20 Hz applied for 30 min. In group D2, after producing fatigue, DBcAMP 0.2 mg·kg(-1)·min(-1) was administered. In groups C2, only Ringer's solution was administered during this period. Diaphragmatic contractility was assessed by measuring the transdiaphragmatic pressure (Pdi, cmH2O). No difference in Pdi was observed in groups C1 and D1. After diaphragmatic fatigue in groups C2 and D2, Pdi at low-frequency (20-Hz) stimulation decreased significantly compared with the prefatigue values (group C2; 9.3±1.9vs 12.5±2.4, group D2; 9.3±2.1vs 12.5±2.6; mean±SD;P<0.05), whereas no change in Pdi was observed at high-frequency (100-Hz) stimulation. In group D2, Pdi at both stimuli increased significantly with an infusion of DBcAMP compared with the fatigue values (20 Hz; 13.3±3.3vs 9.3±2.1, 100 Hz; 23.4±3.6vs 21.3±3.2;P<0.05). In group C2, the speed of recovery from fatigue was relatively slower at 20-Hz stimulation than at 100-Hz stimulation. It is concluded that DBcAMP increases the contractility of fatigued diaphragm, but that this agent does not affect the contractility of nonfatigued diaphragm.

Recovery of post-tetanic and train-of-four responses at the first dorsal interosseous and adductor pollicis muscles in patients receiving vecuronium

PURPOSE

To compare recovery of accelographical responses to post-tetanic twitch (PTT) and train-of-four (TOF) stimuli obtained at the first dorsal interosseous muscle (DI) with those at the adductor pollicis muscle (AP) after administration of vecuronium 70 micrograms.kg-1.

METHODS

Sixty adult patients were randomly assigned to one of four groups: PTT-DI (n = 15), PTT-AP (n = 15), TOF-DI (n = 15), or TOF-AP (n = 15) group. In PTT-DI and PTT-AP groups, responses to PTT were measured accelographically at the DI and at the AP, respectively. In TOF-DI and TOF-AP groups, responses to TOF were measured at the DI and at the AP, respectively.

RESULTS

The T1/T0 (T0 = control) was greater in the TOF-DI than in TOF-AP group throughout recovery (P < 0.05), and the T4/T1 was greater in the TOF-DI than in TOF-AP group during the 30-40 min after vecuronium injection (P < 0.05). Time to the return of the first response to PTT (post-tetanic count(1), PTC1) was less in the PTT-DI than in the PTT-AP group (17.7 +/- 4.2 vs 21.7 +/- 5.6 min, mean +/- SD, P = 0.0341). The post-tetanic count PTC (number of single twitch stimuli in response to PTT) was greater in the PTT-DI than in the PTT-AP group during the 10-30 min after vecuronium (P < 0.05). Time to the return of T1 was less in the TOF-DI than in the TOF-AP group (23.1 +/- 6.0 vs 27.6 +/- 4.9 min, P = 0.0334).

CONCLUSION

Recovery of responses to PTT and TOF stimuli occurred earlier at the DI than at the AP.

Increased circulating adrenomedullin, a novel vasodilatory peptide, in sepsis

Human adrenomedullin (hAM), a potent vasodilatory peptide originally identified in pheochromocytoma, has been shown to be present in various human tissues and circulate in human plasma. We measured plasma concentrations of immunoreactive hAM in patients with sepsis who had been admitted to intensive care unit (ICU). Plasma hAM concentrations in 12 septic patients upon entering the ICU were extremely elevated (107 +/- 139 fmol/ml: mean +/- SD) compared to those of 16 age-matched normal subjects (7.9 +/- 3 fmol/mL). Among 10 patients with normal renal function, plasma hAM levels either decreased or increased during the hospital course; the former group survived and the latter group succumbed. Two patients with acute renal failure had markedly elevated plasma hAM levels during the early course, which declined rapidly during the recovery course. High performance liquid chromatography of plasma extracts from one patient with acute renal failure revealed a single major component of immunoreactive hAM coeluting with authentic hAM (1-52) during acute and recovery phase. Plasma hAM concentration showed positive correlations with heart rate, right atrial pressure, and serum creatinine concentration, but not with other hemodynamic variables. These data suggest that a marked increase in circulating hAM in sepsis may be caused by its decreased clearance and/or its enhanced synthesis by multiple organ dysfunction, and that increased endogenous hAM may be involved in the mechanism of cardiovascular abnormalities associated with sepsis.

Post-tetanic burst count: a stimulating pattern for profound neuromuscular blockade

The purpose of this study was to compare the pattern of recovery from vecuronium 0.07 mg.kg-1 induced neuromuscular blockade using post-tetanic burst count (PTBC)-(three short tetanic bursts of 0.2 msec duration every 20 msec given every second following a tetanus), and post-tetanic count (PTC)-(0.2 msec single twitch stimuli given every second following a tetanus) using an accelerometer in 60 adult patients during nitrous oxide-oxygen-isoflurane anaesthesia. In addition, the relationship among PTBC, PTC, and T1 (the 1st response in the train-of-four (TOF) stimulation) was examined to investigate whether the PTBC had an advantage over the PTC or TOF for evaluating intense neuromuscular blockade. The PTBC was greater than PTC during the 15-35 min after the administration of vecuronium (unpaired t test with Bonferroni's correction, P < 0.05). Time to the return of PTB response was shorter than that of PTT (17.7 +/- 3.2 vs 22.7 +/- 3.7 min, unpaired t test, P = 0.0005). Time from the return of PTB to that of T1 was longer than the time from the return of PTC to that of T1 (13.3 +/- 2.6 vs 9.2 +/- 2.8 min, unpaired t test, P = 0.0003). At the return of T1, PTBC was greater than PTC (14.3 +/- 6.9 vs 9.4 +/- 2.3, unpaired t test, P = 0.0153). These results suggest that, using PTBC, a more profound level of neuromuscular blockade can be evaluated than that using PTC.

Optimal stimulating current for train-of-four stimulation in conscious subjects

The purpose of this study was to determine the optimal stimulating current for train-of-four (TOF) monitoring with regard to the return of TOF response and the discomfort associated with TOF. Two variables were examined at 60, 50, 40, 30, and 20 mA: (1) times from administration of vecuronium 80 micrograms.kg-1 to returns of responses to TOF determined accelographically in 75 anaesthetised patients and (2) discomfort associated with TOF in 15 awake volunteers using visual analogue scale (VAS). Times to return of the first response to stimulation at 60, 50, 40, and 30 mA were not different (29.1 +/- 11.2, 30.1 +/- 12.0, 31.9 +/- 12.6, and 35.4 +/- 14.2 min, respectively, mean +/- SD). However, time to the return of the first response elicited at 20 mA (53.7 +/- 21.6) was longer than at higher currents (P < 0.05). Similarly, with regard to the second, third, and fourth responses, the time to the return at 20 mA was longer than at the other currents (P < 0.05). The VAS associated with TOF at 60, 50, 40, 30, and 20 mA were 7.3 +/- 1.9, 6.7 +/- 1.8, 6.0 +/- 2.0, 4.1 +/- 2.1, and 2.7 +/- 2.3, respectively. The VAS at 30 mA was less than at 60 and 50 mA (P < 0.05), and at 20 mA was less than at 60, 50, and 40 mA (P < 0.05). In conclusion it is suggested that, when testing conscious patients, 30 mA is the optimal stimulating current for TOF monitoring because it represents the best compromise of neuromuscular monitoring and patient discomfort.

Effects of nitric oxide synthase inhibitor on hemodynamic change and O2 delivery in septic dogs

To elucidate the role of nitric oxide (NO) in septic shock, we measured hemodynamic and pulmonary gas changes in anesthetized dogs after intravenous administration of bacterial lipopolysaccharide (LPS) with or without NO synthase inhibitor, NG-nitro-L-arginine (L-NNA). Infusion of LPS (250 ng.kg-1.min-1) for 2 h decreased mean arterial pressure over 1-4 h. Although L-NNA (10 mg/kg) blocked LPS-induced hypotension, it decreased cardiac index, oxygen delivery index, arterial pH, and arterial PO2 and increased systemic vascular resistance index in the presence or absence of LPS. Administration of NG-nitro-D-arginine (D-NNA, 10 mg/kg) alone caused fewer hemodynamic effects (increased systemic vascular resistance index and decreased cardiac index) than L-NNA alone. Our study provides evidence that L-NNA prevents endotoxin-induced hypotension but decreases cardiac output and oxygen delivery, effects that may, in part, be due to a nonspecific NO synthase-independent event. Thus clinical use of NO synthase inhibitors for the treatment of septic shock should be cautiously considered.

Post-tetanic burst: a new monitoring method for intense neuromuscular block

A new stimulation pattern for evaluation of intense neuromuscular block (post-tetanic burst (PTB)) was compared with post-tetanic twitch (PTT) during spontaneous recovery from vecuronium-induced neuromuscular block. Thirty adult patients were allocated to two equal groups and we measured times from administration of vecuronium 0.1 mg kg-1 to return of PTB and PTT responses, and evoked responses to PTB and PTT stimuli. For PTB stimulation, a 50-Hz tetanus was applied at 50 mA for 5 s, and after a pause of 3 s, a 50-Hz burst stimulation was applied, consisting of three impulses at 50 mA. PTB stimuli were delivered every 5 min. Similarly, PTT consisted of a tetanus, a 3-s pause and one single twitch stimulation repeated every 5 min. Time to return of the PTB response was significantly shorter than that of PTT (mean 23.7 (SD 7.9) compared with 30.7 (7.0) min) (P = 0.0160), although evoked responses to PTB did not differ significantly from those of PTT throughout recovery from vecuronium-induced neuromuscular block. This study suggested that PTB was more sensitive in evaluating intense neuromuscular block than PTT.