Comparative study of heart rate variability between healthy human subjects and healthy dogs, rabbits and calves.

Several studies have been performed to assess heart rate variability (HRV) in several species such as humans, dogs, pigs, calves, rabbits and rats. However, haemodynamic parameters are totally different in each animal, and optimal animal models for studying HRV corresponding to human HRV are still unclear. The purpose of this study was to assess HRV in human subjects and to compare those HRV data with canine, bovine and rabbit HRV data. The heart rate in the human subjects (62.8 +/- 7.4 bpm) was significantly lower than that in dogs (124.2 +/- 18.8 bpm, P < 0.001), calves (73.4 +/- 10.5 bpm, P < 0.05), and rabbits (217.3 +/- 21.5 bpm, P < 0.001). The low-frequency waves (LF) (57.9 +/- 65.8 ms(2)/Hz) and high-frequency waves (HF) (33.8 +/- 49.1 ms(2)/Hz) in rabbits were significantly lower than human LF (1216.3 +/- 1220.7 ms(2)/Hz, P < 0.05) and HF (570.9 +/- 581.3 ms(2)/Hz, P < 0.05). Dogs and calves showed similar LF (991.1 +/- 646.1 ms(2)/Hz and 547.0 +/- 256.9 ms(2)/Hz, respectively), HF (702.1 +/- 394.1 ms(2)/Hz and 601.0 +/- 666.6 ms(2)/Hz, respectively) and LF/HF (2.0 +/- 1.3 and 2.5 +/- 1.9, respectively) when compared with the human data. The present study shows that dogs and calves revealed similar HRV values as those which relate to humans. Large deviation of the HRV values in rabbits compared with humans might be considered when conducting animal studies using those animals to reflect human clinical situations.

[A case of intraoperative pulmonary embolism associated with lupus anticoagulant].

A 51-yr-old woman developed pulmonary embolism while undergoing surgery for breast cancer with Auchincloss method. General anesthesia was maintained with propofol and fentanyl. The course of anesthesia and operation were uneventful until the skin was sutured, when unexplained severe circulatory collapse developed. A widely dissociated EtCO2-PaCO2 suggested pulmonary embolism. The pulmonary circulation was restored 10 minutes after the start of heparin therapy, and the intravenous heparin administration was continued. The patient was extubated uneventfully 24 hours postoperatively. Lung perfusion scintigrams showed defect in right lower lungs (S 6, S 9). Venograms of the lower extremity disclosed thrombosis of the right popliteal vein. Furthermore, lupus anticoagulant was noted in the serum. Patients with antiphospholipid syndrome often develop pulmonary complications including pulmonary embolism and pulmonary hypertension. Intra-operative pulmonary embolism associated with lupus anticoagulant is a rare case.

Ultrasound-guided infraclavicular brachial plexus block: an alternative technique to anatomical landmark-guided approaches.

BACKGROUND AND OBJECTIVES: Infraclavicular brachial plexus block has been used less than other approaches because of its less uniform landmarks and the necessity of a longer needle, which increases the patient's discomfort. To overcome these drawbacks, we applied ultrasound guidance to infraclavicular approach and prospectively evaluated its feasibility and usefulness in 60 patients undergoing upper extremity surgery. METHODS: A 7.0-MHz ultrasound probe was placed near the lower edge of the clavicle, and a transverse view of the subclavian artery and vein was visualized. Using a needle guide, a 23-gauge needle was advanced under real-time ultrasound guidance, and 1.5% lidocaine with 1:200,000 epinephrine was injected near the subclavian artery, 15 mm medially and 15 mm laterally to the artery. The extent of sensory and motor block was evaluated at 30 minutes after the injection. RESULTS: An adequate ultrasound image was obtained for all the patients. In 57 patients (95%), surgery was performed without supplementation of any other anesthetics or analgesics. The complete sensory block was obtained in 100% of patients for the musculocutaneous and medial antebrachial cutaneous nerves, 96.7% for the median nerve, and 95% for the ulnar and radial nerves. The complete motor block was achieved in 100% of patients for the musculocutaneous nerve, 96.7% for the median nerve, 90% for the ulnar nerve, and 93.3% for the radial nerve. No evidence of any complications was identified. CONCLUSIONS: Real-time ultrasound guidance facilitates accurate infraclavicular approach to the brachial plexus. It could be used as an alternative to the landmark-guided techniques.

Respiratory jugular venodilation: its anatomic rationale as a landmark for right internal jugular vein puncture as determined by ultrasonography.

OBJECTIVE: To reveal anatomic factors that determine the visibility of respiratory jugular venodilation, a landmark for right internal jugular vein puncture, in ventilated patients. DESIGN: Prospective observational study. SETTING: Single community hospital. PARTICIPANTS: Adult patients undergoing general endotracheal anesthesia. INTERVENTIONS: Anatomy of the right neck, including the carotid artery and internal jugular vein, was evaluated in a blind manner using 7.5-MHz ultrasonography in patients simulating the position for internal jugular vein puncture. Anatomic variables correlated with the visibility of respiratory jugular venodilation were analyzed. MEASUREMENTS AND MAIN RESULTS: Of 124 patients, respiratory jugular venodilation was observed in 94 patients (75.8%). Satisfactory quality of ultrasound image was obtained for all patients. The visibility of venodilation correlated with the extent of change of the vein size during a respiratory cycle but not with the end-expiratory or end-inspiratory vein diameter. These results indicated that there was no correlation between the vessel size and the visibility of venodilation, suggesting that it is rational to attribute the increased success rate of the respiratory jugular venodilation-guided puncture to accurate vein localization rather than to a larger target size. Among the demographic variables examined, body weight and obesity correlated with the visibility of venodilation, but age, gender, and height did not correlate. In obese patients, the respiratory change of the vein diameter was smaller, and the vein was deeper. CONCLUSIONS: The visibility of respiratory jugular venodilation does not correlate with the vein size but with the extent of its dynamic change during a respiratory cycle.

Respiratory jugular venodilation: a new landmark for right internal jugular vein puncture in ventilated patients.

OBJECTIVE: To report a new technique for right internal jugular vein puncture using respiratory jugular venodilation as a landmark for vein location. DESIGN: Prospective observational study. SETTING: Single community hospital. PARTICIPANTS: Two hundred patients undergoing right internal jugular vein cannulation under general anesthesia. INTERVENTIONS: Catheter placement was attempted using respiratory jugular venodilation as the primary landmark. When it was not applicable, an alternative technique using the carotid pulse as a landmark was used. MEASUREMENTS AND MAIN RESULTS: Visibility of the venodilation, the number of needle passes, the success rate, and the incidence of arterial puncture were analyzed. Respiratory jugular venodilation was observed in 158 patients (79%). In this group of patients, the jugular vein was cannulated at the first attempt in 83.5% of patients, and arterial puncture occurred in one patient (0.6%). In the remaining 42 patients (21%) lacking the visible venodilation, catheter placement was accomplished at the first attempt in 42.9% of patients (p<0.01 v. the venodilation-visible group), and 4 patients (9.5%) suffered arterial puncture (p<0.01). The overall incidence of arterial puncture was 2.5%. The success rate of cannulation (within four needle passes and no arterial puncture) was 98.1% in the venodilation-visible patients and 73.8% in the others (p<0.01), with the overall success rate of 93%. CONCLUSIONS: Respiratory jugular venodilation can be identified in a large proportion of ventilated patients. This experience suggests that respiratory jugular venodilation could be favorably used as the primary landmark for right internal jugular vein puncture in anesthetized patients.