By W. Kasim. Colby College.
This ing occurred in the brain and may be wide range of deﬁcits presents unique more diffuse because of the more exten- challenges to rehabilitation of individuals sive damage to the brain itself discount 10 mg alavert. Additional injury may occur as an indi- rect result of edema (swelling) of the Types of Traumatic Brain Injury brain effective alavert 10 mg, hemorrhage, or the formation of a hematoma (sac ﬁlled with blood) within There are two types of traumatic brain the skull as a direct result of the injury injuries: itself. Bleeding within the cranial vault is referred to as intracranial hemorrhage. Be- • Open or penetrating head injury cause the brain is conﬁned within the • Closed head injury skull, there is no space available for expan- Open (penetrating) injuries refer to injuries sion if swelling or bleeding should occur. The length of unconsciousness these events can cause additional perma- is also used as a predictor of prognostic out- nent brain damage or death. Generally, the longer the period of Bleeding and blood clots compress the unconsciousness, the more severe the in- brain, increasing intracranial pressure. An jury to the brain and the greater subse- epidural hematoma is bleeding that occurs quent residual effects. An instrument called in the space between the outer membrane the Glasgow Coma Scale (Jennet, Snoek, of the brain (the dura mater) and the skull. Bond, & Brooks, 1981) has become widely Although bleeding generally occurs rapid- accepted as a classiﬁcation system for rat- ly, it may not be recognized immediately. The Individuals who have been injured may scale is used to assess the level of con- carry on a lucid conversation, only to slip sciousness on a continuum ranging from into drowsiness and unconsciousness hours alert to coma state. Epidural hematomas carry a high cording to the level of response in each of mortality rate because they may not be three areas: eye opening, motor response, immediately recognized and consequent- and verbal response (Table 2–2). A subdural hematoma is a hemorrhage The lower the score, the deeper the level of that occurs in the space beneath the dura unconsciousness.
Mitochondria are lo- important because the narrowing of a blood vessel has a cated at the ends of the nucleus and near the surface mem- powerful influence on the rate of blood flow through it (see brane purchase alavert 10mg without prescription. In some smooth muscle cells alavert 10 mg without a prescription, the SR is abundant, al- Chapters 12 and 15). This circular arrangement is also though not to the extent found in skeletal muscle. In some prominent in the airways of the lungs, where it regulates cases, it closely approaches the cell membrane, but there is the flow of air. A further specialization of the circular muscle arrange- The bulk of the cell interior is occupied by three types ment is a sphincter, a thickening of the muscular portion of of myofilaments: thick, thin, and intermediate. The thin fil- the wall of a hollow or tubular organ, whose contraction aments are similar to those of skeletal muscle but lack the CHAPTER 9 Skeletal Muscle and Smooth Muscle 167 Dense body Mitochondrion Myofilaments Caveoli Autonomic nerve fiber Gap junction Nucleus Connective tissue fibers FIGURE 9. General smooth muscle, showing cells in cross sec- Histology of the Mammal. The length of the individual fil- filaments and to transmit the force of contraction to adja- aments is not known with certainty because of their irregu- cent cells. The thick filaments are composed of Smooth muscle lacks the regular sarcomere structure of myosin molecules, as in skeletal muscle, but the details of skeletal muscle. Studies have shown some association the exact arrangement of the individual molecules into fila- among dense bodies down the length of a cell and a ten- ments are not completely understood. The thick filaments dency of thick filaments to show a degree of lateral group- appear to be approximately 2. However, it appears that the lack of a strongly periodic than in skeletal muscle (1. The intermediate fila- arrangement of the contractile apparatus is an adaptation of ments are so named because their diameter of 10 nm is be- smooth muscle associated with its ability to function over a tween that of the thick and thin filaments. Intermediate fil- wide range of lengths and to develop high forces despite a aments appear to have a cytoskeletal, rather than a smaller cellular myosin content. Prominent throughout the cytoplasm are small, dark-staining areas called dense bodies. Because smooth muscle cells are associated with the thin and intermediate filaments and are so small compared to the whole tissue, some mechanical considered analogous to the Z lines of skeletal muscle.
It is also important to remain vigilant with sedated patients having MAC or regional blocks order alavert 10mg with mastercard, as the level of sedation can often deepen without warning buy alavert 10 mg without prescription. The sce- nario of an anesthesiologist who silenced a pulse oximeter alarm because of “false alarms” and then left the head of the bed or became otherwise distracted is seen in a very large proportion of these claims. ESOPHAGEAL INTUBATION Malpractice cases alleging esophageal intubation by the anesthesi- ologist still occur. Intubating the esophagus is not negligent, but the failure to promptly recognize the situation and replace the tube is. In many cases ultimately considered to involve unrecognized esophageal intubations, the anesthesiologists claimed they were sure the endotra- cheal tubes were correctly placed because they had watched them pass directly through the vocal cords. Alternatively, several argued that they had verified bilateral breath sounds over their patients’ chests. In this day and age, for operating room anesthesia, an end-tidal CO2 reading is the only acceptable method of proving correct endotrachial tube placement. Failure to immediately check and record an end-tidal CO2 reading in the presence of a functioning CO2 monitor would not likely be found to meet the standard of care. Chapter 10 / Anesthesiology 127 Anesthesiologists sometimes simply fail to consider the possibility of an esophageal intubation when encountering problems immediately after intubating a patient. It is not uncommon to have anesthesiologists claim that they were sure they were dealing with bronchospasm or prob- lems with the monitors before other physicians arrived to assist them, replacing the endotracheal tubes and correcting the problems. In a healthy preoxygenated patient, it may take up to 30 minutes before the blood pressure and heart rate become unstable in the event of an esoph- ageal intubation. If any patient develops instability in this time frame, esophageal intubation should at least be considered and ruled out. If the anesthesiologist is unsure whether the tube is correctly placed, then it should be removed and the patient ventilated by other means, such as a facemask or LMA. An anesthesiologist in this situation often must con- front concerns both for the mother and her baby. Decisions must be made in haste for the sake of a baby in peril, and a sense of urgency can pervade the anesthesia care as well. Even emergency Cesarean sections (C-sections) can be delayed if there are concerns about the mother’s safety.