Chapter 133

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2178 PART 6 ■ Specific Considerations syringes should not be used for multiple patients. Emergency drugs should be drawn up daily and discarded at the end of the day. Some people argue that because children seldom have ventricular fibrillation (VF), a defibrillator is not required on trips. The counter-argument is that children of varying ages, and some adults, are treated on these trips and can develop VF. Also, supraventricular and ventricular tachycardia can occur with inadvertent intravascular injection of epinephrine by the surgeon. Successful treatment of these dysrhythmias may require cardiac shock. For these reasons, a defibrillator must be immediately available. It may be impossible to determine when and if locally available anesthesia machines have been serviced. Consequently, it is safer to use anesthesia equipment, including vaporizers, brought by the team. Portable anesthesia machines are available that have many of the features of larger machines. These small machines are durable and function well in hot and cold climates. The vaporizers are both pressure- and temperature-compensated. Standard halothane, sevoflurane, and isoflurane vaporizers can be used with them. Halothane is the most common inhaled anesthetic used in developing countries but is disappearing from many hospitals in developed countries. Consequently, many young anesthesiologists and nurse anesthetists have no experience using it. A medical trip is not the place to learn to do so. Many trip sites have halothane vaporizers. If the team’s isoflurane or sevoflurane vaporizers fail, there is a tendency to try and solve the problem by placing a different agent in a halothane vaporizer. This may lead to the delivery of very high concentrations of anesthetic. As pointed out by Fisher et al., the isoflurane vaporizer can deliver 5% halothane; an enflurane vaporizer can deliver 10% to 12% halothane when the vaporizer is set to 7%. 8 The following must be emphasized: We do not mix drugs and vaporizers at home. We should not do so on trips. It is too dangerous. Patient monitoring should include oxygen saturation, body temperature, heart rate, arterial blood pressure, ECG, and end-tidal CO 2 . 9 Anesthetic gas concentrations are not measured routinely. A precordial stethoscope keeps the anesthesiologist attached to the patient during the case and may help detect respiratory and cardiac problems early. However, if the operating room is noisy, it may be difficult to hear cardiac and respiratory sounds with a precordial stethoscope. A preoperative note should be placed in the patient’s chart along with a copy of the anesthetic record. Anesthetic records should contain the same information recorded in the United States, Canada, and Europe. Returning a copy of the anesthesia record and the surgery and anesthesia notes to the sponsoring organization will aid in quality improvement evaluations. Although it is better to use new circuits and endotracheal tubes for each patient, most anesthesiologists living in developing countries routinely reuse circuits and endotracheal tubes. Some anesthesia providers do this on trips. If they do, the circuits must be washed with soap and water and dried between cases. Endotracheal tubes must be cleaned with soap and water and scrubbed with an endotracheal tube brush to remove all blood and mucus. Once the tubes are clean, they should be soaked in Cidex OPA (Johnson and Johnson Co.) for 10 to 20 minutes to sterilize them. Then they should be rinsed thoroughly with large volumes of sterile water to remove all traces of the Cidex. Cidex OPA effectively kills both bacteria and viruses (including the HIV virus) and is not irritating to tissues. This is a very acceptable protocol for reuse of endotracheal tubes if it can be followed in a busy operating room. If the protocol cannot be strictly followed, a new endotracheal tube is required for each patient. Wall suction may not be available. If not, portable suction devices can be used by anesthesiologists for the induction and awakening from anesthesia and by the surgeons during surgery. Suction catheters that enter the airway, nose, or mouth should be discarded or, if they must be reused, they should be thoroughly cleaned and sterilized after each patient use. Mechanical ventilators are seldom available in the operating rooms of most sites. Consequently, most patients breathe spontaneously throughout surgery. If a Jackson-Reese system is used to deliver anesthesia, gas inflows should exceed 1.75 to 2 × the predicted minute ventilation of the patient (minute ventilation = respiratory rate × tidal volume) to prevent CO 2 rebreathing. These high flow rates can deplete the oxygen supply of the hospital in a short time. Circle systems save gas, are low-resistance, and are economical. Ambu bags should be available in both the PACU and the operating rooms for emergencies (e.g., when the oxygen supply fails). Endotracheal intubation is often required on trips, especially when the surgery is performed on the face or mouth. RAE tubes are the standard for oral/facial surgery. Surgeons frequently place a throat pack during oral surgery to prevent blood from entering the trachea and to reduce the amount of oxygen and anesthetic gases that leak into the mouth. Every member of the operating room team is responsible for assuring that throat packs are removed before endotracheal tubes are removed. Deaths still occur from retained throat packs. 10 Since most patients undergoing intraoral surgery breathe 100% oxygen, there is always the possibility that an airway fire will occur. The three things needed for a fire are present: >30% oxygen, a spark source (cautery), and a combustible material (endotracheal tube). Surgeons must constantly be aware of the danger of airway fires and prevent the cautery from touching the endotracheal tube. Laryngeal mask airways (LMAs) are commonly used to provide an airway and can be used for intermittent positive pressure ventilation with normal lungs. They do not prevent aspiration of blood or gastric contents, and they have a large dead space (Table 133–3). The end-tidal CO 2 is often 60 to 70 mmHg during anesthesia when a LMA is used. The smaller the child, the higher the dead space–induced CO 2 . The elevated CO 2 is usually not a problem, but can contribute to the total anesthetic level. ANESTHETIC TECHNIQUES General Anesthesia Because many of the patients on trips are children, general anesthesia is frequently used. In most cases, a mask induction is done with sevoflurane. Once the patient is asleep, an I.V. is placed and 1 mg/kg of lidocaine (without epinephrine) plus 0.5 mcg/kg of fentanyl (or 0.5 mcg/kg of fentanyl and 1 mg/kg of propofol) can be given to facilitate tracheal intubation. These “cocktails” prevent or blunt stimulation of the airways associated with TABLE 133-3. Dead Space of Laryngeal Mask Airways (LMA) LMA size Dead Space (mL) 1.0 6 1.5 7 2.0 7 2.5 13 3.0 22
CHAPTER 133 ■ Implications for Humanitarian Anesthesia 2179 endotracheal intubation. Preventing stimulation of these reflexes is especially important, because children may have undiagnosed asthma. Intraoperative narcotic administration reduces the need to use high concentrations of inhaled anesthetic. Because N 2 O is seldom available, many anesthesiologists switch from sevoflurane to isoflurane to reduce cost. Isoflurane may also reduce the incidence of postoperative dysphoria. 11 Since most patients breathe spontaneously during surgery, muscle relaxants are seldom used. If muscle relaxants are used, the patient’s lungs must be ventilated by hand when no mechanical ventilator is available. Succinylcholine is reserved for airway emergencies because succinylcholine has been associated with masseter muscle spasm 12 and death. 13 Spontaneous ventilation allows the patient to breathe if the endotracheal tube is accidentally dislodged. It also reduces the amount of oxygen expelled into the pharynx, lessening the likelihood of an airway fire during oral surgery. If there is no need to hand ventilate the patient’s lungs, the anesthesia provider is free to do other things, including give aid if an emergency occurs with another patient. Awakening from anesthesia is frequently a dangerous time. Pharyngeal blood may narrow the nasal passages and cause laryngospasm. Closure of a cleft palate can significantly reduce the space available for the tongue, especially if some degree of Pierre Robin syndrome exists. This increases the likelihood of upper airway obstruction. Patients should usually be awake before the endotracheal tube is removed. If no oxygen is available for use during transport to the PACU, patients should demonstrate adequate oxygen saturations while breathing room air before being taken to the PACU. REGIONAL ANESTHESIA Spinal, caudal, and epidural anesthesia and peripheral nerve blocks are commonly used in appropriate patients. Nerve stimulators are very helpful when performing peripheral nerve blocks, especially if the needle must go through a burn scar. Ultrasoundguided blocks are seldom available. Block anesthesia is cost effective and can reduce operating room turnover time if the block is placed before the previous surgery ends. An extra anesthesiologist can help with this. Blocks done in infants and children are usually done during general anesthesia. Continuous infusion of local anesthetics or narcotics into epidural catheters for postoperative pain relief is rarely done because the infrastructure required for the postoperative care of the patients is lacking. Single-shot caudal blocks with local anesthetics can be done for postoperative pain when appropriate. Peripheral nerve blocks are effective for hand and extremity surgery. Before doing a block one must be certain that the patient can be adequately monitored postoperatively for potential complications. Bilateral infraorbital nerve blocks with 0.25% bupivacaine decrease the postoperative pain associated with cleft lip repair. Injecting 0.25% bupivacaine with 1:200,000 epinephrine into the wound edges or bilateral sphenopalatine ganglion blocks also provide postoperative pain relief after cleft palate repair. Nerve blocks reduce the need for postoperative narcotic administration and the risk for airway obstruction and apnea. POSTOPERATIVE PAIN RELIEF Regional blocks effectively reduce postoperative pain. A combination of a regional block and oral or rectal analgesics are even more effective. Rectally administered acetaminophen (40 mg/kg) reduces pain associated with lip and peripheral procedures. Half of this dose (20 mg/kg) can be administered rectally 4 to 6 hours later if the patient is not taking oral medications by then. Once patients are taking oral medications, the dose of acetaminophen can be reduced to 15 mg/kg with a maximum of 1 gram of drug every 6 hours. The combination of acetaminophen and codeine is commonly used to relieve moderate pain. Administering the appropriate dose of oral acetaminophen (15 mg/kg to 1 g maximum) provides the correct dose of codeine. Ten percent of people cannot convert codeine to morphine and get no pain relief from codeine. They will have some pain relief from the acetaminophen that accompanies the codeine. Fentanyl, methadone, and morphine effectively relieve postoperative pain, but morphine and methadone are unavailable in many countries. Intravenous nalbuphine 5 to 10 µg/kg provides mild sedation and good postoperative pain relief. Adequate pain medication reduces agitation in the PACU and may reduce unwanted bleeding. Intravenous ketorolac effectively relieves postoperative pain, but its use is often limited by the perception that ketorolac causes bleeding. Many patients in developing countries have never taken a drug of any kind before arriving at the hospital for surgery. As a consequence, narcotics may be metabolized more slowly than they are in patients from developed countries. Reduced narcotic metabolism may cause respiratory depression or apnea with commonly-used doses of narcotics in drug-naive children. When used, narcotics should be titrated to effect. If respiratory depression occurs, naloxone can be titrated to restore breathing without reversing pain relief. The beneficial effects of most narcotic reversal agents last 30 to 45 minutes, whereas narcotic effects may be longer. Therefore, patients given naloxone must be observed for more than an hour after administering the drug to assure that respiratory depression does not recur. POSTOPERATIVE CARE Responsibility for patient care in the PACU usually is the purview of the anesthesiologist, who is responsible for providing pain relief, correcting airway problems, administering appropriate fluids, and discharging patients to the ward. Standing PACU orders have their proponents. However, it is usually better to write specific orders for each patient, including the type and quantity of fluid to be administered per hour; the type, dose, and frequency of pain medication administration; whether and when the hemoglobin concentration should be determined; who should be called if problems arise; and how to reach that person (walkie-talkies are very helpful in for this purpose). The number of PACU beds usually equals the number of operating tables. Oxygen is required for each patient. Monitoring includes SaO 2 , arterial blood pressure, heart rate, respiratory rate, and body temperature. Many patients are febrile after surgery due to elevated environmental temperatures or to surgery on infected areas. The latter seeds the circulation with bacteria. Excessive bleeding should prompt the PACU nurse to seek help, save the bloody sponges for review by the surgeons, and determine the patient’s hemoglobin concentration with a hemoglobinometer. Nurses working in the PACU usually care for no more than two patients at a time. The pediatrician/general practitioner assumes care for patients after they are discharged from the PACU. Many hospital wards in
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Chapter 133

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