Treatment of hemorrhagic shock in dogs with verapamil: effects on survival and on cardiovascular lesions.

Dogs were subjected to a standardized hemorrhagic shock procedure. Some were treated with verapamil and others were untreated. It was found that the dogs treated with verapamil were protected from the damaging effects of hemorrhagic shock on the heart. This was true even in treated dogs that had a rapid heart rate maintained by means of an intracardiac pacing electrode. In addition, the treated dogs did not show the intestinal hemorrhage that is usually seen in dogs subjected to hemorrhagic shock. Finally, it was found that verapamil treatment increased the survival rate of shocked dogs in comparison with control dogs which were not treated.     

Cardiac denervation and adrenalectomy. Its effects on myocardial lesions of hemorrhagic shock in dogs

Myocardial lesions were seen in dogs subjected to experimental hemorrhagic shock. In contrast, dogs that had been previously surgically treated by cardiac denervation and adrenalectomy, showed less myocardial damage. The latter group also had a substantially decreased myocardial I-norepinephrine content and a much lower plasma I-norepinephrine response to shock when compared with the control shock dogs. In contrast, "sham shock" dogs had no myocardial lesions, and normal myocardial and plasma I-norepinephrine contents.     

Periodontitis contributes to initiation,progress and aggravation of septic shock; a feasible hypothesis

This hypothesis states that active aggressive periodontitis is an important source of putative endotoxin contributing to the onset of septic shock syndrome [SSS]. Consequently patients with periodontitis may be more prone to developing SSS in predisposing conditions.     

Effects of vagal afferent stimulation on ON and OFF cells in the rostroventral medulla: relationships to nociception and arterial blood pressure.

1. Extracellular recordings of 125 neurons in the rostroventral medulla (RVM) were performed in 35 rats that were maintained in a light plane of anesthesia with methohexital. The neurons were classified as ON, OFF, or NEUTRAL cells, depending on their response to noxious heat applied to the tail. ON cells showed an increase in firing rate just before the tail flick (TF), OFF cells showed a decrease in firing rate just before the TF, and NEUTRAL cells showed no correlation between neural activity and the TF. 2. The effects of electrical stimulation of cervical vagal afferents (VAS) on 1) the activity of ON, OFF, and NEUTRAL cells, 2) TF latency, and 3) arterial blood pressure (ABP) were determined at intensities less than or equal to the intensity of VAS necessary to inhibit the TF reflex to a cutoff latency of 10 s. VAS excited 70.8% of the ON cells and inhibited 77.8% of the OFF cells at greater intensities, including intensities that inhibited the TF. However, 55.6% of the OFF cells inhibited by the threshold intensity of VAS to inhibit the TF reflex were excited by lesser intensities of VAS (less than 50% of the intensity that inhibited the TF) that facilitated the TF reflex, and 14.3% of the ON cells excited by the threshold intensity of VAS to inhibit the TF reflex were inhibited by lesser intensities of VAS. VAS had mixed effects on NEUTRAL cells. VAS excited 23.7% and inhibited 10.5% of the NEUTRAL cells that had somatic receptive fields. VAS excited 12.9% and inhibited 9.7% of the NEUTRAL cells that had no identified somatic receptive field. The excitation of ON cells and inhibition of OFF cells produced by VAS at the intensity to inhibit the TF are opposite to predicted outcomes on the basis of current theories on the function of ON and OFF cells in nociception. 3. VAS produced a depressor response at intensities ranging from approximately 50% to 100% of the VAS intensity necessary to inhibit the TF reflex to the cutoff latency. At lesser intensities, VAS occasionally produced a small pressor response. 4. ON and OFF cells generally showed marked fluctuations in background activity, shifting between active and inactive states. The levels of background neural activity were correlated with mean ABP. ABP levels were lower when ON cells were active and OFF cells were inactive than when ON cells were inactive and OFF cells active.(ABSTRACT TRUNCATED AT 250 WORDS)     

Skin perfusion pressure measured by isotope washout in legs with arterial occlusive disease. Evaluation of different tracers, comparison to segmental systolic pressure, angiography and transcutaneous oxygen tension and variations during changes in systemic blood pressure

The skin perfusion pressure (SPP) measured as the isotope washout cessation external pressure is valuable in selection of major amputation level. Five methodological investigations important to clinical use were carried out: (1) In five normal legs and 10 legs with arterial occlusive disease (AOD), 131I- -antipyrine (131I- -a.p.) was compared to Na(131I-) and 99Tcm-pertechnetate (99Tcm). The average SPP by 131I- -a.p. and by 131I- were approximately equal, 57.0 mmHg (range 18-93) compared to 56.3 mmHg (range 13-88) (P greater than 0.1). The average SPP by 99Tcm was just slightly higher, 60.3 mmHg (range 18-98) (P less than 0.02). The average washout constant for the three different tracers were approximately equal and correlated statistically significant with the SPP; (2) In 59 legs with AOD, segmental SPP was compared to segmental systolic blood pressures on the thigh, calf, ankle and first digit (strain gauge technique). The two different methods correlated statistically significant at all four levels, but the systolic blood pressures were higher than the SPP in particular in diabetic legs; (3) Angiograms in 35 legs with AOD showed that the SPP on the ankle was only consistently decreased in legs with arterial occlusions at two levels or more; (4) In 47 legs with AOD, the SPP on the calf or on the thigh was compared with transcutaneously measured pO2. The two different methods correlated statistically significant, but the scatter was great; (5) During induced variations in systemic blood pressure in seven patients (12 legs with AOD), the segmental SPP and the segmental systolic blood pressure were found on average to vary in proportion with intra-arterial mean and systolic pressure respectively; however, this proportional relationship was not valid for the individual leg. It is concluded that 99Tcm is as suitable as the 131I- -labelled tracers in estimating the SPP. The SPP is significantly correlated to skin blood flow, to systolic blood pressure, to tc pO2 and to angiographic findings. Correction of SPP for systemic blood pressure changes can be made in proportion with the measured variations in systemic mean blood pressure, but only for groups of patients.     

Quantification and localisation of damage in rat muscles after controlled loading; a new approach to study the aetiology of pressure sores.

To obtain more insight in the aetiology of deep pressure sores, an animal model was developed to relate controlled external loading to local muscle damage. The tibialis anterior muscle (TA) and overlying skin of a rat were compressed between indentor and tibia. Loads of 10, 70 and 250kPa at skin surface were applied for 2 or 6h. During half of the 10 and 250kPa experiments interstitial fluid pressure (IFP) in the TA was measured. The TAs were excised 24h after load application. Both amount and location of damage were assessed by histological examination using a semi-automated image-processing program. In six of eleven loaded muscles damage was found. The damage was located from superficial to deep muscle tissue in a zone never exceeding the diameter of the indentor. The IFP measurements interfered with the occurrence of damage; application of 10 and 70kPa loads only caused damage when combined with IFP measurements, whereas IFP measurements increased damage at 250kPa loads. The results showed that the developed animal model can be used to provoke local damage by applying a controlled load and that the amount and location of damage can be assessed using the newly developed techniques.