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![Mechanical Ventilation
• Larger tidal volumes offer no added advantages during ventilation of
anesthetized morbidly obese patients.
• Further increasing tidal volumes offers no benefit.
• No specific ventilatory mode (volume vs. pressure control ventilation
[PCV]) has been found significantly better](https://image.slidesharecdn.com/obesityihcpata-240915140019-af7a8f17/85/OBESITY-Interhospital-case-presentation-ATA-pdf-45-320.jpg)
OBESITY Interhospital case presentation ATA.pdf
- 1. A WEIGHTY OPERATION Dr. ChristabelleIleana L. Toh 2nd year resident Davao Doctors Hospital
- 2.
- 3. CASE NAME J.B. AGE 27year old SEX Male ADDRESS Ecoland Subdivision, Davao City RELIGION Roman Catholic
- 4. CHIEF COMPLAINT Right UpperQuadrant Pain
- 5. HISTORY OF PRESENTILLNESS INTERIM • Tolerated Right Upper quadrant pain 4 MONTHS PTA • Onset Epigastric pain associated with decreased appetite • Consulted with AP • Imaging reveal Gallbladder stone and polyp . Surgery was advised for surgery but they were still undecided ADMISSION • Increasing Right quadrant pain not relieved with Buscopan, opted for admission and surgery
- 6. ADMITTING DIAGNOSIS CHRONIC CALCULOUSCHOLECYSTITIS
- 7. PAST MEDICAL HISTORY •AUTISM SPECTRUM DISORDER • NON HYPERTENSIVE • NON DIABETIC • NON ASTHMATIC • NO ALLERGIES • NO PREVIOUS SURGERY
- 8. PERSONAL SOCIAL HISTORY •Nonsmoker • Non alcoholic beverage drinker • Homeschooled • Able to perform activities of Daily living independently
- 9. GENERAL APPEARANCE AWAKE, ALERT NOTIN RESPIRATORY DISTRESS WEIGHT 138 kg HEIGHT 168cm BMI 49.2 (Obese 3) Blood Pressure 130/90 mmhg Heart rate 92 bpm Respiratory Rate 21 cpm Temperature 36.5 °C
- 10. GENERAL APPEARANCE HEENT ANICTERIC SCLERAE,PINK PALPEBRAL CONJUNCTIVA CHEST/LUNGS EQUAL CHEST EXPANSION, CLEAR BREATH SOUNDS, NO WHEEZING HEART ADYNAMIC PRECORDIUM, DISTINCT HEART SOUNDS, NO MURMUR ABDOMEN SOFT, GLOBULAR, RIGHT UPPER QUADRANT TENDERNESS (deep palpation)
- 11. GENERAL APPEARANCE EXTREMITIES ESSENTIALY NORMAL,STRONG PULSES (-) EDEMA, RASHES NEURO-EXAM GCS 15, ESSENTIALLY NORMAL, NO MOTOR AND SENSORY DEFICITS
- 12. COURSE IN THEWARD
- 13. COURSE IN THEWARD HOSPITAL DAY 1 DAY OF ADMISSION ADMITTED DUE TO RIGHT UPPER QUADRANT PAIN PATIENT WAS SEEN AND EXAMINED ANESTHESIA PLAN EXPLAINED PATIENT WAS PUT ON NPO 8 HOURS PRIOR TO PROCEDURE HOSPITAL DAY 2 PATIENT UNDERWENT CONTEMPLATED SURGERY
- 14. PRE-OPERATIVE EVALUATION LABORATORIES HGB 104L HCT 32 L PLT 243 WBC 5.9 CREA 85 CXRAY - NEGATIVE CHEST ECG - NORMAL SINUS RHYTHM COVID RTPCR - NEGATIVE
- 15. PRE-OPERATIVE EVALUATION SUBJECTIVE RIGHTUPPER QUADRANT PAIN 5-6/10 DECREASED APPETITE OBJECTIVE 130/90 92 21 36.5 AWAKE, COMFORTABLE, NIRD (+) RUQ TENDERNESS, SOFT GLOBULAR ABDOMEN EQUAL CHEST EXPANSION, CLEAR BREATH SOUNDS FULL PULSES MALLAMPATI GRADE 2, GOOD MOUTH OPENING AND NECK MOVEMENT, NO BEARD, NO LACKING TEETH ASSESSMENT ASA 3- morbid obesity
- 16. PRE-OPERATIVE EVALUATION ANESTHETIC PLAN GENERAL ANESTHESIA- TOTALINTRAVENOUS ANESTHESIA UNDER LARYNGEAL MASK AIRWAY DEVICE
- 18. COURSE IN THEWARD PACU NO SUBJECTIVE COMPLAINTS 120-130 mmhg 80s-90s bpm 98-99% o2 saturation (2lpm nasal cannula) HOSPITAL DAY 3 TOLERABLE POST OP PAIN NO NAUSEA/VOMITING FLATUS + BM + TOLERATES DIET 130/70 mmhg, 82bpm, 98% o2 saturation DISCHARGED
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- 20. Pre-Operative Evaluation Airway Anatomic changesin Obese patients ➢Limitation of neck movement (short, thick neck, thick submental fat pads; suprasternal, presternal, and posterior cervical fat) ➢Excessive pharyngeal fat ➢Large breasts – in females
- 21. Pre-Operative Evaluation ofObese Patients Airway Neck circumference > 40cm- difficult airway management General Fat Distribution peripheral obesity deposition is predominantly in the lower body central obesity= associated with increased oxygen consumption and increased incidence of cardiovascular disease.
- 22. Pathophysiology in anObese Patient
- 23. Respiratory changes inObesity • Chest wall and lung compliance • Decreased FRC, Vital Capacity and Total Lung Capacity • Decreases in FRC and ERV are the most commonly reported abnormalities of pulmonary function in obese Oxygen Consumption, Work of breathing, Carbon Dioxide production
- 24. Cardiovascular changes inObesity • Blood volume, Cardiac Output, LV wall thickness Increased Proinflammatory and prothrombotic mediators • Total Blood Volume increase 50 mL/kg • Increased cardiac output by 20 to 30 mL per kilogram of excess body fat. • Left ventricular hypertrophy, related to the duration of obesity
- 25. GASTROINTESTINAL • Risk ofRegurgitation • Higher gastric volume and lower Ph- increases risk of severe pneumonitis • Current Fasting Guidelines are acceptable • Associated liver abnormalities : fatty infiltration, inflammation, focal necrosis, and cirrhosis
- 26. Renal and Endocrine •Impaired glucose tolerance – resistance of peripheral adipose to insulin • Glomerular Hyperfiltration - Increased Renal Blood Flow, Glomerular Filtration Rate and renal tubular resorption
- 27. PHARMACOKINETIC PRINCIPLES • Modifieddrug dosing because of obesity-related increases in lean body weight (LBW), cardiac output, and blood volume • Dosing is generally based on volume of distribution for bolus doses, and on clearance for infusions or repeat boluses. • Vd of relatively lipophilic drugs is increased by obesity • Drug clearance is generally higher in individuals with obesity
- 28. FORMULA IDEAL BODY WEIGHT(kg) = HEIGHT (cm) – X X= 100 MALES; X= 105 FEMALES LEAN BODY WEIGHT Males 1.1 x TBW – 0.0128 X BMI X TBW Females 1.07 x TBW – 0.0128 X BMI X TBW 68kg 65.4kg
- 29. FORMULA PREDICTED BODY WEIGHT •Males: PBW (kg) = 50 + 0.91 × (height (cm) − 152.4); • Female PBW (kg) = 45.5 + 0.91 × (height (cm) − 152.4) 65.9 kg
- 31. Intra-operative Care Patientpositioning Supine or head-down (Trendelenburg) positions - Decreased lung volumes and increased work of breathing - increased venous blood return
- 32. Intra-operative Care Patientpositioning Head-up position (reverse Trendelenburg, or semi- sitting/"semi-Fowler“ • improve respiratory function - reduce pressure on the chest wall and diaphragm. • improves both mask ventilation and the view at laryngoscopy
- 33. Intra-operative Care Patientpositioning Prone • increased functional residual capacity (FRC), lung compliance, and oxygenation • Patient supports should be placed • abdomen should be compression-free
- 34. Intra-operative Care Patientpositioning Lateral decubitus removes the weight of the abdomen from the diaphragm Lithotomy position decreases lung volumes by shifting abdominal contents towards the diaphragm
- 35. Intra-operative Care Generalanesthesia -higher incidence of hypoxia and respiratory events - desaturate more quickly during apneic periods,
- 36. Intra-operative Care Generalanesthesia Difficulty with airway management • increased frequency of aspiration , complications with the use of supraglottic airways, difficulty intubation, airway obstruction during emergence • risk factor for both difficult mask ventilation and difficult laryngoscopy
- 37. Intra-operative Care Generalanesthesia Difficulty with airway management Risk factors for difficult mask ventilation: ●Age older than 55 ●Body mass index (BMI) >26 or 30 kg/m2 ●presence of a beard ●Lack of teeth ●History of snoring/sleep apnea ●Abnormal neck anatomy ●Male sex ●Short thyromental distance (TMD) (<6 cm) ●Severely limited mandibular protrusion ●Mallampati class 3 or 4
- 38. Intra-operative Care Generalanesthesia Difficulty with airway management Difficult supraglottic airway device use • Small mouth opening (<3 finger breadths) • Neck radiation • Tonsillar hypertrophy • Fixed cervical spine flexion deformity • Applied cricoid pressure • Obesity • Poor dentition or large incisors • Male sex
- 39. Intra-operative Care Generalanesthesia Difficulty with airway management Difficult intubation • Prior difficult intubation • Small mouth opening (<3 finger breadths) • Mallampati class 3 or 4 • Shortened TMD (<6 cm) • Shortened sternomental distance (<12 cm) • Limited neck mobility • Limited mandibular protrusion or upper lip bite test (ULBT) grade 3 • Thick neck (circumference >40 cm)
- 42. Intra-operative Care Generalanesthesia Choice of airway device • mask ventilation is generally restricted to brief anesthetics -difficulty with mask fit and handling, or obstruction • more likely to require controlled ventilation • more likely to require intubation rather than a supraglottic airway • SGA may not maintain a seal at the higher airway pressures • second generation SGAs -allow higher seal pressures, and provide a gastric vent.
- 43. Intra-operative Care Generalanesthesia Choice of airway device Clinically important features of SGA use: •Easily placed blindly •Less hemodynamic response to placement than laryngoscopy and ETT placement •Lower risk of bronchospasm •Does not protect against laryngospasm Clinically important features of ETT use: •May be difficult to place •Requires deeper level of anesthesia for placement than SGA •Stimulus for bronchospasm •High peak pressures possible •Protects against aspiration
- 44. Intra-operative Care Generalanesthesia
- 45. Mechanical Ventilation • Largertidal volumes offer no added advantages during ventilation of anesthetized morbidly obese patients. • Further increasing tidal volumes offers no benefit. • No specific ventilatory mode (volume vs. pressure control ventilation [PCV]) has been found significantly better
- 46. Intra-operative Care Generalanesthesia Ventilation management • Set TV of 6 to 8 mL/kg predicted body weight (PBW) • Adjust respiratory rate to maintain normocapnia • Limit FiO2 to the level required to maintain peripheral arterial oxygen saturation (SpO2) • individualized PEEP to optimize lung compliance • Maintain head-up (reverse Trendelenburg) position, whenever feasible.
- 47. Mechanical Ventilation • PositivePEEP is the only ventilatory parameter that has consistently been shown to improve respiratory function in obese subjects • series of three short (6 seconds) inflations of large tidal volume reaching an inspiratory pressure of 40 to 55 cmH2O. • aims to open and maintain the patency of small airway units, therefore improving ventilation–perfusion matching and oxygenation.
- 48. Laparoscopic Procedures in ObesePatients
- 49. Effects of CO2pneumoperitoneum in obese patients • Primary (due to CO2 absorption) and secondary (due to increased intra- abdominal pressure) • Hypercarbia: stimulation of autonomic nervous system, cardiac arrhythmias, tachycardia and vasoconstriction in the pulmonary vessels. • Pulmonary: cephalad shift of the diaphragm, decreased frc, increased physiologic dead space, increases airway pressures • Acidosis has depressant effect on myocardial contractility • Adjustments in ventilation are necessary to maintain normocapnia
- 50. Effects of increasedintraabdominal pressure during pneumoperitoneum: • Obese patients better tolerate pneumoperitoneum • Intra abdominal pressure 5 mmHg in non-obese; chronically elevated to 9-10 mm Hg in obese persons • Cephalad direction of diaphragm resulting in increased pleural pressure • Effects: decrease venous return, decreases preload, increases after load and reduction in cardiac flow
- 51. Effects of pneumoperitoneumon respiratory mechanics • Decrease respiratory compliance • Increase airway pressure • Increase respiratory rate • Increase minute ventilation • Reduce tidal volume
- 52. INTRAOPERATIVE VENTILATION STRATEGIES •There is no difference between PCV and VCV in terms of better clinical outcome • PCV- guarantees ensure minimal tidal volume at lower peak inspiratory pressure • Tidal volume should be adjusted accordingly • Studies have shown that recruitment maneuver (RM) and PEEP application in obese patients imporove oxygenation and pulmonary mechanics Recommendations for ventilation of obese : • 6-8 ml/kg • VCV/ PCV MODE • titration of respiratory rate according to normocapnia • optimal PEEP, • PIP or Ppl< 30 cm H2O
- 53. LARYNGEAL MASK AIRWAY Uses: -Temporary method to maintain an open airway - Immediate life-saving device - be used as an alternative to intubation - effective method of ventilation • Designed to be inserted blindly through the mouth and into the hypopharynx to seal around the glottic opening allowing for ventilation R RESTRICTION O OBSTRUCTION D DISTORTION S SPACE/ SPINE
- 55. LARYNGEAL MASK AIRWAY Clinicalsigns of incorrect SAD position include the following: 1. resistance to SAD insertion in the hypopharynx; 2. SAD dislodgement during cuff insufflation; 3. bite block malaligned with incisors; 4. poor oropharyngeal airway seal (OPLP; intracuff pressure); 5. ineffective gas exchange 6. no drain tube patency;
- 56. LARYNGEAL MASK AIRWAY Correctivemaneuvers: 1. Jaw thrust to correct initial downfolding of the epiglottis; 2. Adjustment of the position of the distal esophageal cuff; 3. Changing the SAD to a device with a reinforced tip configuration if the cuff folds over backwards persistently; 4. Using a different size, type, or brand 5. Using a larger size of SAD or reinflating the cuff to an intracuff pressure of 40–60 cm H2O if cuff hypoinflation is observed; and 6. Change to a silicone-cuffed SAD when folding in the cuff is causing an air leak.
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