The ability of man to detect added resistive loads to breathing

1. Resistive loads were added to the airways of patients with tracheostomies; the patients were blindfolded and the loads introduced without their knowledge.

2. The ability to detect the loads was the same in a patient with C3 transection (chest wall and diaphragm disconnected from the brain) as in a control group of patients with no neurological lesion.

3. It is concluded that receptors in the chest wall and diaphragm are not involved in the genesis of the sensation by which added resistive loads are detected.

The role of the diaphragm in the sensation of holding the breath

1. Block of the phrenic nerves in three normal subjects, produced by injection of lignocaine in the neck, caused alleviation of the thoracic sensation during breath holding and prolonged breath-holding time.

2. Injection of lignocaine in the neck without nerve block had no effect on breath holding sensation or breath-holding time.

3. A patient with a spinal-cord transection at the third cervical segment with paralysed diaphragm and chest wall, had no sensation in the chest or abdomen during breath holding.

4. This patient maintained normal ventilation by using hypertrophied sternomastoid muscles. During breath holding he experienced no sensation in the neck despite the presence of sternomastoid contraction.

5. There is previous evidence that complete muscular paralysis abolishes breath-holding sensation but that paralysis of all muscles innervated from spinal segments below the eighth cervical has no effect.

Cardiovascular reflex responses to cutaneous and visceral stimuli in spinal man

1. A study has been made of the effects of pinprick and a cold pack applied to the skin above and below the level of denervation, deep inspiration, squeezing the chest, and bladder percussion in non-bedridden patients with chronic, closed, complete, localized transection of the cervical spinal cord. Variables studied were blood pressure, heart rate, calf blood flow, hand blood flow and occluded vein pressure in the hand and foot.2. Cutaneous stimuli above the lesion, mental arithmetic and noise from gunshot produced no response.3. Pinprick and cold applied below the lesion usually produced an increase in mean arterial pressure, little change in pulse pressure or heart rate, clear decreases in calf and hand blood flow, and occasional venoconstriction.4. Deep inspiration produced an initial rise in blood pressure and heart rate which was sometimes followed by a decrease in one or both. Squeezing the chest usually produced an increase in blood pressure and a decrease in heart rate. Both stimuli caused decreases in calf and hand blood flow and venoconstriction, the latter being more common after squeezing the chest.5. Bladder percussion produced contraction of the wall of the bladder and this was regularly associated with increased arterial mean and pulse pressures, a decreased heart rate and calf and hand blood flow, and venoconstriction. The responses occurred whether or not the bladder was full and whether or not a rise of intravesical pressure occurred.

Cardiovascular changes associated with skeletal muscle spasm in tetraplegic man

1. A study has been made of the effect of spontaneous and induced muscle spasms on blood pressure, heart rate, hand blood flow, calf blood flow and occluded vein pressure in the hand and foot in non-bedridden patients with chronic, closed, complete, localized transection of the cervical spinal cord.2. Both types of spasm produced a similar response consisting of an increase in blood pressure and occluded vein pressure and a decrease in heart rate and hand and calf blood flow. The changes commenced within 2-3 sec and usually reached maxima in 20-30 sec. On some occasions there was a temporary initial increase in heart rate and calf blood flow.3. The changes occurred independently of changes in bladder pressure.4. It is concluded that the changes in peripheral blood vessels result from a spinal sympathetic reflex to somatic afferents associated with muscular contraction.

Cardiovascular responses to tilting in tetraplegic man

1. A study has been made of the effect of head-up tilt on blood pressure, heart rate, forearm blood flow and occluded vein pressure in the hand and foot in non-bedridden patients with chronic, closed, complete, localized traumatic transection of the cervical spinal cord.2. In typical responses the blood pressure fell and the heart rate rose progressively for about 2 min, tending to plateau thereafter. The average falls in mean blood pressure for tilts of +30, +45 and +60 degrees were from 68 to 44, 74 to 36 and 70 to 44 mm Hg respectively, and the corresponding heart rate increases were from 67 to 85, 62 to 97 and 62 to 103 beats/min respectively. One patient lost consciousness when his blood pressure was 29/19 mm Hg and one other patient experienced symptoms suggesting cerebral ischaemia.3. Following the return to horizontal, the blood pressure and heart rate usually returned to their previous values within 1 min and the blood pressure tended to overshoot slightly in the following few minutes. No immediate blood pressure overshoot occurred after the tilt except in association with a spasm of skeletal muscles.4. There was consistently a decrease in forearm blood flow, sometimes to unrecordably low levels and a venoconstriction with postural change and it is argued that these changes are the result of spinal cardiovascular reflexes to peripheral vessels. Following the return to the horizontal position, there was occasionally a large immediate increase in forearm blood flow.5. Following the intravenous administration of 3 mg atropine on two occasions, head-up tilting produced further small heart rate increases.6. Spasms of skeletal muscle occur frequently in these patients and greatly modify the effects of postural stimuli. Bladder percussion also modifies the normal response.

Traumatic quadriplegia with ectopic ossification

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