Rectal arteries

The distal portion of the large intestine is the rectum. Rectal absorptive capacity is considerably less than that of the upper GI tract owing to a limited surface area, a result of the absence of microvilli. Also, the blood supply to colon and rectum is less than that to the small intestine. The rectal artery branching off the inferior mesenteric artery of the... 

Absorption from the rectum depends on various physiological factors such as surface area, blood supply, pH, fluid volume, and possible metabolism by microorganisms in the rectum. The rectum is perfused by the inferior and middle rectal arteries, whereas the superior, the middle, and the inferior rectal veins drain the rectum. The latter two are directly connected to the systemic circulation the superior rectal vein drains into the portal system. Drugs absorbed from the lower rectum are carried directly into the systemic circulation, whereas drugs absorbed from the upper rectum are subjected to hepatic first-pass effect. Therefore, a high-clearance drug should be more bioavailable after rectal than oral administration. The volume of fluid in the rectum, the pH of that fluid, and the presence of stool in the rectal vault may affect drug absorption. Because the fluid volume is... 

Various characteristics of the molecule influence its chances of reaching its target receptor since they influence the nature and extent of the body s effect on it. A drug s pharmacokinetic profile therefore determines the extent of the drug s opportunity to exert its pharmacodynamic effect. While there are various routes for human drug administration (oral rectal intravenous, subcutaneous, intramuscular, and intra-arterial injections topical and direct inhalation into the lungs), the most common for small-molecule drugs is oral administration, and discussions in the first part of this chapter therefore focus on oral administration. (In contrast, biopharmaceuticals are typically administered by injection, often directly into the bloodstream.)... 

How the temperature is measured (i.e., brain vs arterial, venous, tympanic, bladder, or rectal temperature) is also critical, as the core temperature is usually 0.3-1.1°C lower than brain temperature (51). However, it is important to consider that these values may be different in patients with acute cerebral ischemia or trauma. 

Cardiopulmonary parameters and rectal body temperature are determined while the rabbit is in the sling and also at 15 min intervals following induction of anesthesia with the rabbit in lateral recumbency. Heart rate, mean arterial blood pressure, respiratory rate and respiratory pattern are calculated from tracings from the physiological recorder. Arterial blood pH, partial pressure of oxygen (PaQz), and partial pressure of... 

Ketamine is generally administered to patients intravenously, but it is also effective when administered by intramuscular, oral, and rectal routes. The onset of action is generally short (10 to 15 minutes) but the duration of anesthesia of a single dose is long. Ketamine is the only intravenous anesthetic that produces an increase in heart rate and arterial blood pressure. It can also markedly increase cerebral blood flow, oxygen consumption, and intracranial pressure. 

A 25-year-old man had a cardiac arrest after taking one knot or sealed bag of crack cocaine (2.5 g) and was resuscitated. His arterial blood pH was 6.92 and an electrocardiogram showed sinus rhythm, QRS axis 300°, and terminal 40 msec of the QRS axis 285°. After an infusion of sodium bicarbonate, his blood pH was 7.30, his QRS axis 15°, and the terminal 40 msec QRS axis 30°. He passed the bag of cocaine rectally within 12 hours of admission. 

SAFETY PROFILE Poison by ingestion, intraperitoneal, rectal, subcutaneous, and intravenous routes. Human systemic effects by intraarterial route acute arterial occlusion by rectal route respiratory depression, body temperature decrease, general anesthetic. An experimental teratogen. Experimental reproductive effects. An intravenous anesthetic. When heated to decomposition it emits toxic fumes of NOx and Na20. See also PENTOTHAL and BARBITURATES. 

Hanazaki, K., Kawamura, N., Wakabayashi, M., Sodeyama, H., Yoko-yama, S., Sode, Y., Miyazaki, T. Long-term survivor with hver metastases from rectal cancer treated by hepatectomy after hepatic arterial infusion chemotherapy. Hepato-Gastroenterol. 1998 45 816—820... 

Figure 3.6. Formation of a diverticulum, (A) A cross-sectiun of the wail of the colon reveals the mucasal layer (top surface of diagram), pari of the belt of muscle that encircles the gut, and an artery passing through a naturally occurring gap in the muscle. (B) As middle age approaches, weak spots may develop in places where there exist gaps between muscles-(C) Diverticuli develop. The artery follows the path of the outpouching, and it is this part of the artery that may rupture and bleed and produce rectal bleeding in persons with diverticular disease. (Redrawn with permission from Meyers ef ai, 1976.)...

There have been 21 reports of life-threatening disease affecting large arteries in patients treated with cisplatin, bleomycin, and vinblastine in combination for germ cell tnmors (50,51). Five patients died during or after therapy, three from acnte myocardial infarction, one from rectal infarction, and one from cerebral infarction. Other patients who developed major vascular disease, including coronary artery and cerebrovascnlar disease, have been reported. Symptoms occnrred acntely in some (within 48 honrs of starting therapy), and after months or years had elapsed in others. 

Figure 9.52 shows the blood supply to the rectal area. The main artery to the rectum is the superior rectal (haemorrhoidal) artery. Veins of the inferior part of the submucous plexus become the rectal veins, which drain to the internal pudendal veins. Dmg absorption takes place through this venous network. Superior haemorrhoidal veins connect with the portal vein and thus transport dmgs absorbed in the upper part of the rectal cavity... 

Moore, Demetriou and Domino (1975) studied the effects of iproniazid, chlorpromazine and methiothepin on DMT-induced changes in body temperature, pupillary dilatation, blood pressure and EEG in rabbits. Chlorpromazine attenuated or blocked the effects of DMT on these parameters, but iproniazid prolonged the elevated rectal temperatures and mydriasis induced by DMT. Arterial blood pressure and EEG were not markedly altered by pretreatment with iproniazid. 

The IMA supplies colon distal to the splenic flexure including the descending colon, sigmoid colon, and rectum. When embolizing rectal branches off of the superior hemorrhoidal branch of the IMA, one must remember the rich collateral network around the rectum with middle hemorrhoidal branches arising from the internal iliac arteries. The internal iliac arteries should be studied after embolizing a rectal branch to exclude the possibility of collateral flow to the bleeding site. 

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