Glossary anesthesia

General anesthesia

General anesthesia in patients undergoing diagnostic or therapeutic procedures.

1. Indication

Abdominal and thoracic procedures
Head and neck soft tissue procedures
Lateral decubitus and prone procedures
Procedures in morbid obesity
Emergency procedures in patients at risk for aspiration (RSII - rapid sequence induction and intubation)

2. Contraindication

None

3. Required

Detailed informed consent discussion
Physical examination and history
Possibly additional studies (e.g., lab panel, chest films, cardiological studies)
Patient informed consent

4. Workflow description

Device check by the nurse anesthetist
Nursing staff premedicates patient at least 30 minutes before surgery is started, with midazolam oral syrup dosed as suggested below:

> 65 years: 0.1 mg/ kg
≦ 65 years: 0.15 mg/ kg
≦ 45 years: 0.2 mg/kg

Upon transfer of patient to nurse anesthetist

Check name of patient
Check surgical field
Ask patient if fasting
Attach leads for monitor, ECG, NIBP, pulse oximetry
IV access and infusion
Document baseline measurements in anesthesia record
Prepare induction medication and materials needed for ventilation
Position patient on OR table
Anesthesiologist reviews the documents and checks them for completeness
Preoxygenate the patient with 100% oxygen via face mask
Administer opiate observing blood pressure and time to onset
Administer hypnotic until blink reflex lapses
Bag-valve-mask ventilation, possibly with an oropharyngeal airway
Check BVM ventilation and relax patient
Open mouth and check teeth
With the laryngoscope and by patient positioning adjust the oral, pharyngeal and laryngeal axes for best view of the glottis
Intubate trachea, under direct vision if possible
Check black marking on tube
Block tube
Ventilate and auscultate
Secure tube and oropharyngeal airway
Transport patient into OR
Hook up patient to ventilator in the OR
Check capnometry
Adjust flow, FiO2 and concentration of anesthetic gas
Hook up patient to monitor units
Check patient position
After checking for possible allergies administer antibiotics
Insert central venous and/or arterial catheter
Maintain patient's core body temperature
Administer medications to maintain anesthesia
Release patient to OR team
Prepare preemptive analgesia protocol

5. Intraoperative monitoring

Single-channel ECG
NIBP
Pulse oximetry
Capnometry
Check ventilation settings
Measure end-expiratory CO2 concentration
Measure inspiratory and expiratory anesthetic gas concentration
Measure inspiratory and expiratory oxygen concentration
Measure urinary excretion
Neuromuscular monitoring
Temperature

6. Emergence

Check retained relaxation
Check opiate overhang
Wash out anesthetic gas through high-flow setting
Prepare suction unit
Restore patient's spontaneous breathing
Extubate in presence of protective reflexes
Oral or endotracheal suction
Observe patient's respiration after extubation
Test vigilance
Inform recovery room

7. Hand over to recovery room

Hand over patient to nursing staff of recovery room
Check drains
Check vigilance
Hook up to monitor units
Administer oxygen if needed
Anesthesiologist discharges patient from recovery room

Author: Prof.C. Diefenbach, MD Head, Department of Anesthesiology and Surgical Intensive Care

St. Katharinen-Hospital Frechen GmbH, Germany

Laryngeal mask anesthesia

General anesthesia in patients undergoing diagnostic or therapeutic procedures.

1. Indications

General anesthesia of up to 90 – 120 minutes
Peripheral procedures
Ensuring oxygenation in exceptional cases, e.g., in difficult-to-intubate patients

2. Contraindications

Morbid obesity
Increased risk of aspiration (e.g., not fasting, GERD)
Lateral decubitus and prone procedures
Relative: Head and neck soft tissue procedures
Intraabdominal and thoracic surgery

3. Required

Detailed informed consent discussion
Physical examination and history
Possibly additional studies (e.g., lab panel, chest films, cardiological studies)
Patient informed consent

4. Workflow description

Device check by nurse anesthetist
Nursing staff premedicates patient at least 30 minutes before surgery is started, with midazolam oral syrup dosed as suggested below:

> 65 years: 0.1 mg/kg

≦ 65 years: 0.15 mg/kg

≦ 45 years: 0.2 mg/kg

Upon transfer of patient to nurse anesthetist:

Check name of patient
Check surgical field
Ask patient if fasting
Hook up standard monitoring leads/lines: ECG, NIBP, pulse oximetry
IV access and infusion
Document baseline measurements in anesthesia record
Prepare induction medication and materials needed for ventilation
Position patient on OR table
Anesthesiologist reviews the documents and checks them for completeness
Pre-oxygenate the patient with 100% oxygen via face mask
Administer opiate observing blood pressure and time to onset
Administer hypnotic until blink reflex lapses
Open mouth and check teeth
Once anesthesia is deep enough insert laryngeal mask
Check for possible leaks, ventilate and auscultate
Transport patient into OR
Hook up patient to ventilator in the OR
Check capnometry
Adjust flow, FiO2 and concentration of anesthetic gas
Hook up patient to the monitor units
Check patient position
Maintain patient's core body temperature
Administer medications to maintain anesthesia
Release patient to OR team
Prepare analgesia protocol

5. Intraoperative monitoring

Single-channel ECG
NIBP
Pulse oximetry
Capnometry
Check ventilation settings
Measure end-expiratory CO2 concentration
Measure inspiratory and expiratory anesthetic gas concentration
Measure inspiratory and expiratory oxygen concentration

6. Emergence

Check opiate overhang
Wash out anesthetic gas through high-flow setting
Restore patient's spontaneous breathing
Remove the laryngeal mask with blocked or unblocked cuff
Oral suction if needed
After removal of laryngeal mask observe respiration
Check vigilance

7. Hand over to recovery room

Hand over patient to nursing staff of recovery room
Check drains
Check vigilance
Hook up to monitor unit
Administer oxygen if needed
Obtain pain history and administer treatment
Anesthesiologist discharges patient from recovery room

8. Hints and notes

If after placing the laryngeal mask the level of anesthesia is not deep enough, the patient may develop hiccups which may not lapse despite deepening anesthesia, requiring a fast-acting relaxant for resolution

Unlike conventional laryngeal masks the Proseal® model allows ventilation with a peak pressure up to 25 mbar, permitting its use in obese patients. Since this dual-lumen mask also allows insertion of a gastric tube, it is possible to suction gastric juice in aspiration-prone patients.

Author: Prof.C. Diefenbach, MD Head, Department of Anesthesiology and Surgical Intensive Care

St. Katharinen-Hospital Frechen GmbH, Germany

Anesthesia in thyroid surgery

Thyroid surgery is performed under general anesthesia and controlled ventilation.

1. Aspects relevant for anesthesia in thyroid surgery

Preoperative

Thyroid function should be studied before surgery. The aim should be normal thyroid function. Large goiters may present problems during intubation. Preoperative workup therefore includes a chest film for tracheal assessment (position, narrowing). The preoperative ECG should be checked for signs of hyperthyroid (e.g., sinus tachycardia, atrial fibrillation, extra systole, ST segment changes) or hypothyroid (e.g., sinus bradycardia, blocks) metabolism.

Ensure adequate premedication in hyperthyroid patients, while in hypothyroid patients the premedication should be dosed carefully.

Intraoperative

Due to the semi-Fowler or beach chair position with reclined head and the location of the surgical field with its draping, a Woodbridge tube should be used. Painstaking tube fixation with adhesive tape is required to prevent accidental extubation or tube dislocation during the procedure. Ensure secure closure of the eyelids by taping them shut.

Intraoperative recurrent nerve stimulation with needle electrodes may sometimes puncture the tube cuff. Thus, always keep materials for intubation at hand including a spare tube.

Large goiters and hyperthyroidism may be complicated by significant blood loss.

Postoperative

In rare cases, postoperative respiratory problems may arise in:

Injury to the recurrent nerve
Tracheomalacia
Secondary bleeding with significant hematoma
Soft tissue edema in the surgical field

2. Required

Detailed informed consent discussion
Physical examination and history, possibly resulting in additional studies
Patient informed consent

3. Workflow description

Device check by the nurse anesthetist
Nursing staff on ward premedicates patient with midazolam oral syrup at least 30 minutes before surgery is started.
If difficult intubation is expected in large or partly retrosternal goiters, keep materials for difficult intubation at hand (McCoy spatula, laryngeal masks in different sizes, Fast-Trach® laryngeal mask, Eschmann introducer, possibly fiberscope).
Preoxygenate the patient with 100% oxygen
Respecting its time to onset administer the opioid (e.g., fentanyl, sufentanil)
Once the opioid effect has taken hold inject the hypnotic (e.g., propofol) until the blink reflex lapses
Bag-valve-mask ventilation, possibly with an oropharyngeal airway
Check BVM ventilation and relax patient
Open mouth and check teeth
Laryngoscopy and then intubate trachea under direct vision, if possible
Check black marking on tube
Block tube
Ventilate and auscultate
Carefully secure tube and oropharyngeal airway with adhesive tape
Hook up patient to ventilator in OR
Check capnometry
Adjust flow, FiO2 and concentration of anesthetic gas
Hook up patient to the monitor units
Position patient for surgery

4. Intraoperative monitoring

Single-channel ECG
NIBP
Pulse oximetry
Capnometry
Ventilation settings (pressure, volume)
Measure end-expiratory CO2 concentration
Measure inspiratory and expiratory concentration of oxygen and anesthetic gas
Neuromuscular monitoring
Temperature measurement (ear thermometer)

5. Emergence

Check retained relaxation
Check opiate overhang
Wash out anesthetic gas through high-flow setting
Prepare suction unit
Return patient to spontaneous respiration
Extubate in presence of protective reflexes
Oral or endotracheal suction
Observe patient's respiration after extubation
Hand over patient to recovery room

6. Recovery room

Hookup patient to monitor units (NIBP, pulse oximetry, ECG monitor)
Administer oxygen if needed
Obtain pain history and administer treatment
Order pain protocol for ward
Check airways, hematoma, drains
Discharge patient from recovery room

Author: Prof.C. Diefenbach, MD Head, Department of Anesthesiology and Surgical Intensive Care

St. Katharinen-Hospital Frechen GmbH, Germany

Anesthesia in laparoscopic surgery

Anesthesia for laparoscopic procedures with pneumoperitoneum, e.g., hernia repair, cholecystectomy, colon surgery.

Laparoscopic surgery with pneumoperitoneum is performed under general anesthesia and controlled ventilation.

1. Aspects relevant for anesthesia in surgery under pneumoperitoneum

a) Rise in paCO2

b) Interference with respiratory mechanics

c) Interference with hemodynamics

d) Increased rate of postoperative nausea and vomiting (PONV)

a) Rise in paCO2

Since the body rapidly absorbs the CO2 instilled in the abdominal cavity, this will elevate the paCO2. The CO2 absorption rate depends on the intraabdominal pressure, area of absorption (peritoneum) and the perfusion of the peritoneum/wall of the peritoneal cavity. The higher the intraabdominal pressure the stronger the compression of the vessels, thereby decreasing the CO2 absorption. Therefore, bleeding off the CO2 at the end of the procedure will temporarily boost its absorption.

During surgery, the minute ventilation must be increased by about 20%, but rarely by up to 50%. The controlling parameter here is the end-expiratory CO2 concentration. In functionally impaired cardiac patients the pneumoperitoneum may severely depress their cardiac output. Since patient capacity for CO2 elimination is markedly impaired in these cases, the paCO2 will be significantly higher than might be expected by the end-expiratory CO2 concentration. In case of doubt, arterial blood gas analysis will settle the issue.

b) Interference with respiratory mechanics

The peritoneum displaces the diaphragm craniad and mechanically impedes respiration/ventilation. This effect may be reinforced by specific patient positioning maneuvers (e.g., Trendelenburg position in intestinal surgery). Similarly, intraperitoneal gas instillation and Trendelenburg positioning will diminish the FRC by about 40%. And the peak ventilation pressure will increase by about 40% as well. These conditions may displace the tracheal bifurcation craniad by 2 - 3 cm. Therefore, in dropping oxygen saturation consider tube dislocation with unilateral ventilation.

c) Interference with hemodynamics

The intraperitoneal pressure increase is paralleled by a decrease of about 20% in the venous return and cardiac output. At the same time the peripheral vascular resistance will increase. The increased intrathoracic pressure will also increase the vascular resistance in the lungs. In pneumoperitoneum, the heart rate will increase by about 10%. Peritoneal distention, particularly when the gas is just being instilled, may result in reflex vagotonia with bradycardia, particularly if anesthesia is shallow. Always keep atropine ready in these operations.

d) Increased rate of postoperative nausea and vomiting (PONV)

For laparoscopic surgery, the rate of postoperative nausea and vomiting (PONV) has been reported up to 50%. Prophylactic administration of 8 mg dexamethasone after induction and 0.625-1.25 mg DHB is recommended in patients so predisposed.

For laparoscopic surgery, some anesthesiologists recommend the insertion of a gastric tube after induction of anesthesia. During mask ventilation with accidental or unnoticed insufflation of air into the stomach, this is supposed to protect the stomach against injury when introducing the trocars and decrease the risk of aspiration during extubation.

2. Required

Detailed informed consent discussion
Physical examination and history, possibly resulting in additional studies
Patient informed consent

3. Workflow description

Device check by the nurse anesthetist
Nursing staff on ward premedicates patient with midazolam oral syrup at least 30 minutes before surgery is started.
Preoxygenate the patient with 100% oxygen
Respecting its time to onset administer the opioid (e.g., fentanyl, sufentanil)
Once the opioid effect has taken hold inject the hypnotic (e.g., propofol) until the blink reflex lapses
Bag-valve-mask ventilation, possibly with an oropharyngeal airway
Check BVM ventilation and relax patient
Open mouth and check teeth
Laryngoscopy and then intubate trachea under direct vision, if possible
Check black marking on tube
Block tube
Ventilate and auscultate
Secure tube and oropharyngeal airway with adhesive tape
Hook up patient to ventilator in the OR
Check capnometry
Adjust flow, FiO2 and concentration of anesthetic gas
Hook up patient to the monitor units
Position patient for surgery

4. Intraoperative monitoring

Single-channel ECG
NIBP
Pulse oximetry
Capnometry
Ventilation settings (pressure, volume)
Measure end-expiratory CO2 concentration
Measure inspiratory and expiratory concentration of oxygen and anesthetic gas
Neuromuscular monitoring
Temperature measurement (ear thermometer)

5. Emergence

Check retained relaxation
Check opiate overhang
Wash out anesthetic gas through high-flow setting
Prepare suction unit
Return patient to spontaneous respiration
Extubate in presence of protective reflexes
Oral or endotracheal suction
Observe patient's respiration after extubation
Hand over patient to recovery room

6. Recovery room

Hookup patient to monitor units (NIBP, pulse oximetry, ECG monitor)
Administer oxygen if needed
Obtain pain history and administer treatment
Order pain protocol for ward
Anesthesiologist discharges patient from recovery room

Author: Prof. Dieffenbach, MD Head, Department of Anesthesiology and Surgical Intensive Care

St. Kathrinen-Hospital Frechen GmbH, Germany

Spinal anesthesia

Spinal anesthesia lends itself for procedures below T9-10 (about the level of the umbilicus). The planned procedure should not last more than three hours at most. Patients perceive extended periods of time on the OR table as uncomfortable.

1. Indications

Typical indications for spinal anesthesia include:

Fracture treatment of the lower extremities, knee and hip arthroplasty
Inguinal hernia
Perineal surgery
Transurethral resection
Cesarean section

2. Contraindications

Patient refusal
Coagulation disorders
Lack of communication with the patient
Infection at puncture site
Certain neurologic disorders

3. Required

Detailed informed consent discussion
Physical examination and history
Patient informed consent not only for the regional anesthesia, but also general anesthesia in case of complications or if spinal anesthesia fails
Moderately dosed premedication ordered by anesthesiologist. The patients should not be sedated too much because they still must sit.

4. Workflow description

Upon transfer check patient identity and the planned procedure (patient file, informed consent documents)
Attach monitor leads for: ECG, NIBP, pulse oximetry
IV access and infusion
Document baseline measurements in anesthesia record
Prepare induction medication and materials for ventilation for possible emergency situations (e.g., extreme cardiovascular reaction, total spinal anesthesia)
Ready atropine and theodrenalin
Position patient sitting on OR table
Check lab panel, particularly INR, pTT and platelet count, WBC and CRP
Support sitting patient with hanging shoulders
Thoroughly prep the skin with disinfectant (single-shot contact time of 60 seconds is sufficient, no wiping, the skin must be wetted)
The anesthesiologist wears face mask and scrub cap
Thoroughly disinfect hands (contact time at least 30 seconds)
Sterile draping with fenestrated drape
Local anesthesia with 1-3 mL local anesthetic (e.g., scandicaine 1%)
Puncture spinal canal with 24G Sprotte cannula and introducer
Check CSF reflux for any blood
Record any paresthesia
Slowly inject local anesthetic (e.g., isobaric or hyperbaric 0.5 % carbostesin, hyperbaric 4% scandicaine) into the subarachnoid space without barbotage
Withdraw spinal cannula
Apply sterile adhesive
Position patient supine on OR table
Transport patient into OR
Check spread of anesthesia
Elevate upper body of patient, if needed
Avoid patient hypothermia
Document the procedure in the anesthesia record and the vital signs after spinal anesthesia has been performed
Release patient to OR team

5. Intraoperative monitoring

Single-channel ECG
NIBP
Pulse oximetry
Vigilance
Spread of spinal anesthesia

6. Hand over to recovery room

Patients are monitored in the recovery room until their spinal anesthesia begins to wear off (e.g., fading motor block).
Regular check of vital signs
Postoperative analgesia, e.g., with 1 g metamizole p.o.
Upon transfer to the ward patients may eat and drink without restriction, except in PONV
Ambulation is permitted once motor and sensory block have lapsed completely
Initial ambulation only aided by the nursing staff
Inform patient of possible post-spinal headache
Point out possible micturition disorders

Author: Prof.C. Diefenbach, MD

Head, Department of Anesthesiology and Surgical Intensive Care

St. Katharinen-Hospital Frechen GmbH, Germany

Thoracic epidural anesthesia in gastrointestinal surgery

In epidural anesthesia, analgesics (e.g., local anesthetics, opioids) are administered into the space surrounding the dural sac. After gastrointestinal procedures, thoracic epidural anesthesia not only offers analgesic effects but also positive effects on the cardiac (less myocardial ischemia), pulmonary (less atelectasis, pneumonia) and gastrointestinal (faster recovery of motility) physiology of the patient.

1. Indications

Colon surgery
Pancreatic resections
Gastric resections
Cystectomy with neobladder
Abdominal aortic surgery

2. Contraindications

Patient refusal
Coagulation disorders (see below)
Lack of communication with the patient
Infection at puncture site
Anatomical changes in the spine
Certain neurologic disorders

2.1 Epidural anesthesia and anticoagulation

To prevent any bleeding complications in anticoagulated patients, certain time intervals must be met before and after insertion/withdrawal of epidural catheters. The German Society of Anesthesia and Intensive Care (DGAi) has consented pertinent guidelines which are updated regularly and reflect current scientific knowledge. The most important rules are listed below (version February 2009).

UFH: on fractionated heparin, NMH: low molecular weight heparin

3. Workflow description

Upon transfer check patient identity and the planned procedure (patient file, informed consent documents)
Attach leads for monitoring: ECG, NIBP, pulse oximetry
IV access and infusion
Document baseline measurements in anesthesia record
Check lab panel, particularly INR, pTT and platelet count, WBC and CRP
Position patient sitting on OR table
Thoroughly prep the skin with disinfectant (single-shot contact time of 60 seconds is sufficient, no wiping, the skin must be wetted)
Thoroughly disinfect hands (contact time at least 30 seconds)
Face mask, sterile gown and scrub cap for anesthesiologist
Identify desired location for puncture by counting the palpable spinous processes, e.g., starting with the prominent 7th cervical vertebra. The line between the lower tips of the shoulder blades transects the spine at the level of the C7 and may therefore be used as a reference.
A rule of thumb for the level of puncture is that the tip of the epidural catheter should rest roughly in the middle of the segments to be blocked. The following table may serve as reference when selecting the puncture level.

The spinous processes of T1 and T2, as well as T10-12 are almost horizontal in the sagittal plane. The other spinous processes T3-9 differ in their angulation and overlap each other. This central region of the thorax therefore requires a steeper angle of puncture (about 45° to the skin).
Sterile draping with fenestrated drape
Infiltrate puncture site with local anesthetic (1-3 mL scandicaine 1%) Contact with the bones when probing the anatomy with the thin needle helps to define the direction of puncture with the Tuohy needle
Introduce the 17G or 18G Tuohy needle with mounted 10 mL syringe filled with saline
Advance the needle under continuous pressure on the plunger of the syringe. Thumb and index finger of the left hand (when right-handed) hold the wings of the needle, while middle finger, ring finger and little finger firmly rest on the patient's back. This is a mandatory safety measure against sudden and unplanned deep advance of the needle. While advancing the needle the right thumb (when right-handed) exerts steady pressure on the plunger.
Both control of the needle slowly advancing through the tissue and the pressure on the plunger are technically demanding. Because of possible injury to the spinal cord, thoracic epidural anesthesia should only be performed by experienced physicians.
Withdraw the needle in case of paresthesia and/or muscle twitching.
Correct the needle position in case of unilateral paresthesia and in accidental puncture of an epidural vein.
When passing through the flaval ligament the plunger of the syringe will suddenly give way (loss of resistance).
Gently inject saline into the epidural space.
Remove the syringe and advance a 20G catheter no more than 3-4 cm into the epidural space, with the opening of the Touhy needle pointing craniad or caudad but not to the side.
After successful aspiration testing administer a 3-5 mL test dose of local anesthetic (e.g., scandicaine). Wait at least 5 minutes for any effect of the test dose in case of subarachnoid malposition.
Cutaneous catheter fixation. For monitoring over the next few days, cover the puncture side with sterile transparent adhesive.
After repositioning the patient induce general anesthesia.

4. Medication in epidural anesthesia

Intraoperative

The rule of thumb for the volume to be administered is about 1 mL of local anesthetic for each segment to be anesthetized. Usually, in single injections this calls for 6-10 mL of local anesthetic. For intraoperative administration, the patient should be in stable cardiovascular condition before the first injection. Particularly in general anesthesia the spreading epidural anesthesia may result in significant blood pressure loss. These adverse reactions should preferably be treated with vasoconstrictive medication and not by administering excessive volume.

Postoperative

Postoperative analgesics are best administered with the pump continuously injecting the local anesthetic into the epidural catheter. Low dose bupivacaine (e.g., 0.25%) or ropivacaine (0.1-0.2%) is well suited for this. Motor function should not be impaired. If needed, the local anesthetic may be combined with an opioid (e.g., sufentanil) and administered via the injection pump. This may improve analgesia without blocking motor function.

5. Hints and notes

Do not advance the catheter more than 3 – 5 cm. In many cases, advancing the catheter further may deflect its tip to one side or even flip it caudad thereby producing an inadequate effect.
Iatrogenic perforation of the dura is seen in 0.3-1.2% of thoracic epidural anesthesia cases, and postspinal headache in 70-80% of patients.
Injection rate, height and body weight do not correlate with the required dose of local anesthetic.
The indwelling catheters are visited daily and the following findings obtained and recorded: Pain score, spread of analgesia, signs of motor block, bladder function, appearance of puncture site. When combining the local anesthetic with an opioid also check for itching, nausea/vomiting, signs of systemic opioid effect (e.g., respiratory depression, sedation).
Usually, the catheter is removed on postoperative day 4 to 7 (only by an anesthesiologist). In doing so, the time intervals regarding any anticoagulation must be observed (see above). The catheter is only withdrawn after the effect of the local anesthetic has worn off; this will ensure early detection of neurologic symptoms resulting from the presence of epidural hematoma.

Signs of epidural hematoma:

Sharp pain in the back and legs
Sensory deficits
Weakness or paralysis in both legs

Signs of epidural abscess (S. aureus):

Severe back pain and tenderness
Fever and leukocytosis
Progressive para-/tetraparesis

In general, care of patients with indwelling epidural catheters calls for close operation with the nursing staff of the patient’s ward. The staff should be properly trained to recognize the symptoms of neurologic complications in overdosed or underdosed epidural anesthesia.

Author: Prof.C. Diefenbach, MD

Head, Department of Anesthesiology and Surgical Intensive Care

St. Katharinen-Hospital Frechen GmbH, Germany